Have Humans Come Close To Extinction?

waytoomuchcoffee writes "According to a new study, our virtually identical DNA indicates humans were close to extinction about 70,000 years ago. Another take on the same study tells how being lactose intolerant in adulthood was normal, and being able to digest lactose became a survival advantage after dairy farming was invented."

Comments

Diversity in a small group

[Inexile2002]

Unlike our close genetic relatives - chimps - all humans have virtually identical DNA. In fact, one group of chimps can have more genetic diversity than all of the six billion humans alive today.

Something about that struck me. If the natural state of affairs is for a wide genetic diversity even in a small group - such as the chimps, then why wasn't there a similar diversity in the 2000 people who went on to sire the rest of us.

Think about it. A chimp troop can consist of up to 60-70 chimps for a big troop. Assume all but around 30 troops are killed off leaving around 2000 chimps. If a single troop of those chimps could have more genetic diversity than all of humanity - ie. more than the 2000 people who sired us then 2000 chimps would have around 30 times more diversity. (Or more than that depending on how much more diversity in a chimp troop than there is in humanity.)

So, either humanity dwindled down by chance to 2000 people who happened to have little genetic diversity, or there was some common genetic trait that selected for those specific people. Or something. But then who knows... maybe chimps are just naturally genetically diverse and we're not... or maybe I just missed something that the writer thought was too technical for the article.

Still, the numbers bothered me.

Re:Diversity in a small group

[Anonymous Coward]

> So, either humanity dwindled down by chance to
> 2000 people who happened to have little genetic
> diversity, or there was some common genetic
> trait that selected for those specific people.
> Or something. But then who knows... maybe
> chimps are just naturally genetically diverse
> and we're not... or maybe I just missed
> something that the writer thought was too
> technical for the article.

Nah, there's no extra explanation needed .. its a well known phenomena, called the 'founder effect' - and the reason why those chimps in that troop are as genetically diverse as they are is because of gene shuffle between groups.

Think about it; if you are isolated, alone and there is no one else around, the diversity is naturally going to suffer - interbreeding will see to that. However, chimps haven't gone through the same genetic pruning because groups/tribes mate with each other.

Re:Diversity in a small group

[shaitand]

That or they started out different, then screwed like mad until the gene pool wasn't all that drastically different anymore... much like they would have to do to go from 2000 to 4 billion. Just a thought. Makes me wish I was there *sighs*

Re:Diversity in a small group

[zaad]

Something about that struck me. If the natural state of affairs is for a wide genetic diversity even in a small group - such as the chimps, then why wasn't there a similar diversity in the 2000 people who went on to sire the rest of us.

IANAG(eneticist), but I would say that this is most likely due to a concept known as founder's effect in population genetics. There looks like there's an interesting page curtesy of googlecache.

Think of it in these terms. Whatever your genetic diversity happens to be, if you reduce a population from two million down for two thousand, you're going to lose a lot of diversity. Further, especially that population reduction was due to some selection pressure (may immunity to some disease), you're going to target a very select subset of the population (known as hard selection). So what happens is that you end up with much less genetic diversity than you would have otherwise (diversity takes time to build up).

In the case of the chimps, if they've not gone through a recent "extinction" scare, and have had a long, long time for their genome to diverge and mutate, even if you just sample a small group of 60 or so chimps, they're going to exhibit much more diversity simply because they've had so much more time for their genome to wander or drift.

Does that make more sense?

Re:Diversity in a small group

[AllenChristopher]

And moreover, when that little group discovers something like the hatchet, they suddenly outcompete everything that eats the same food as them, but isn't in the tribe and isn't told the secret. Time and again, one tribe wipes out all the tribes nearby with a new weapon or other new technology, thinning the gene pool.

In the 1300s, there certainly weren't a billion people of European descent. There were more like 50 million. That's barely thirty generations ago. This sort of thing happened in pre-history as well.

Re:Diversity in a small group

[aug24]

What you are missing, I think, is that diversity reduces in small total populations.

Chimps, can and do change troops, interbreed with other troops, exist as lone males, etc. If they were reduced to 2000 or so then they would not maintain their current level of genetic diversity as, for example, fewer males would have the opportunity of siring offspring.

Hence it is not a like-for-like comparison. You are comparing pre-small-pool chimps with post-small-pool humans. Although given the state of the world's primates, it won't be long before you can make the comparison fairly :(

J.

Re:Diversity in a small group

[EvilTwinSkippy]

Just look in the Bible. (I'm a secularist myself, but the old testimate is an entertaining folk tale.) How many Son's did Abraham have? You have Lot who had a lot of kids by his daughters. I mean incest, polygamy on a mass scale, all the makings of a really shallow gene pool.

Then you have Kings from other cultures who would spread their seed wide and far. You see the same behavior in rock stars and sports figures today. How many kids did Jim Morrison sire? How about Wilt Chamberlin? Hell even Ben Franklin got around. In every cult what happens? The cult leader fucks all the groupies.

Women are drawn to success. Men are drawn to breed with healthy women. In less enlightened times someone Enronized our Gene pool by being really successful and not being dumb enough to die young before they spread.

Re:Diversity in a small group

[Muad'Dave]

Unlike our close genetic relatives - chimps - all humans have virtually identical DNA. In fact, one group of chimps can have more genetic diversity than all of the six billion humans alive today.

Why doesn't such impressive genetic diversity in the chimp world translate to more obvious facial/structural diversity as is seen in the wildly differing appearances of humans?

To put it another way, if they're so genetically diverse, why do they all look alike? I'm sure Jane Goodall, et al, can tell different troops and individuals apart, but I sure can't. Perhaps chimps think we all look the same, huh?

Re:Diversity in a small group

[shaitand]

That's not exactly a followable story... it doesn't get very far. Adam and Eve had two children, One killed the other then left got married and founded a city. Who did he marry if the only humans in existance were he, his mother, and father?

Re:Diversity in a small group

[JanneM]

That we don't see the differences is likely one part of the answer - people that have never been exposed to members of a different regional group of humans do have trouble seeing differences between them as well (though that is likely more and more uncommon as modern media exposes just about everybody to the diversity available).

More important, our great variance is due to the fact that we use facial characteristics as an identifying badge - there is plenty of selection pressure to vary this. Chimps may not (I do not know this for certain) ascribe nearly as large a weight to facial features in identifying others. There is no selection pressure to vary this, and thus it all settles in a common optimum.

Re:Diversity in a small group

[EvilTwinSkippy]

Like I said, an entertaining Folk Tale.

While you are at it, where did the notion of a Virgin Birth come from. Go back to the Gospel. The only notes (where mentioned) about Jesus' beginnings was that his mother became Pregant our of wedlock. The "Holy Spirit" could have been anything from pathenogesis to Joseph being particularly randy one night. His reaction was shame and embarrasment, recall, not jealosy.

Also note the Bible refers to Christ being rejected by his brothers and sisters.

And yes I have read the whole thing all the way through. The circumstances of Christ's birth are mentioned in only 1 gospel, another mentions his being visited by Kings as a child, and the other 2 start off with him as an adult. I don't remember which ones, but it's bugging me enough to go digging for it...

Re:Diversity in a small group

[thomasmd]

this is off topic, but - it 's fairly well agreed upon by scholars that the greeks mistranslated the hebrew word used to describe Mary (purposefully) into the word virgin, while it actually just meant maiden, or young woman, or something like that.

Re:Diversity in a small group

[Muad'Dave]

...people that have never been exposed to members of a different regional group of humans do have trouble seeing differences between them as well...

Agreed, but they don't have any trouble distinguishing them from any _other_ group, including their own. Any human can readily see the differences between what are commonly called 'ethnic groups', whatever the underlying genetic meaning,if any. I don't remember ever seeing an analog among other primates. How does the genetic diversity of, say, cats or dogs stack up against that of chimps? Has being domesticated and gentically artifically manipulated raised their level of diversification beyond that of chimps? Or people?

Re:Diversity in a small group

[JanneM]

I believe (though I do not have the numbers to back it up) that at least dogs are relatively homogenous as well, compared to chimpanzees.

As a clarification: species that aren't living in "clusters" (troops, family units or whatever), do not have the same need to distinguish between themselves. Plenty of group-living species (many birdflocks come to mind) do not need to identify most individuals either. And many species that are living in groups and need to identify individuals do so by smell (or by sound), not by visual appearance. It would be interesting to see if, for instance wolves or lions have as variegated smell signatures as we have facial configurations. No idea on how to go about that, though.

Re:Diversity in a small group

[Anonymous Coward]

I have some other explanation - humans are more
violent against each other than chimps.

'Let's kill all those loosers'
approach common for humans but not so for chimps
clearly reduces genetic diversity.

Especially when you take into acount that the
development of humans accelerated a lot
so some groups were superior in technology.

Just imagine the decrease in genetic diversity
if Adolf Hitler succeeded.

Re:Diversity in a small group

[Anonymous Coward]

Any human can readily see the differences between what are commonly called 'ethnic groups', whatever the underlying genetic meaning,if any

I wouldn't be so quick to assume that. There are cases in Africa where people can easily identify members of dozens ethnic groups that to Western eyes basically look all the same, whereas when faced with some people that Westerners would classify as "black," these same Africans may be prone to see them as European.

In the Caribbean you still find finer discriminations like yellow and high yellow, not totally unlike the US, but definitely using skin color to see race in a different way. Can YOU tell the difference between yellow and high yellow? Yellow and brown? Yellow and white? Are you certain were I to plop you down somewhere that you wouldn't be mistaken for belonging to a group other than the one you ascribe yourself to?

You also see in Africa the phenomenon of regarding skin tone apart from other characteristics, such that bright skinned people are seen to be llike Europeans, regardless of other characteristics that Europeans see as essential to defining race. Kind of like a very old European view of fairness.

As for chimps, yeah Goodall probably has a keen eye, but I think the question would come down to chimp social organization, not just one of familiarity and strangeness. That's where I'd look for evidence of chimp racism, but I'm not holding my breath.

Re:Diversity in a small group

[jstott]

Something about that struck me. If the natural state of affairs is for a wide genetic diversity even in a small group - such as the chimps, then why wasn't there a similar diversity in the 2000 people who went on to sire the rest of us.

You need diversity to preserve the diversity. If you have a small population and they start inter-breeding, you'll wipe out most of your diversity in fairly short order because, before long, everyone will have the same common set of ancestors (and thus, a relative lack of genetic diversity). In short, past history is everything in genetics.

Re:Diversity in a small group

[Anonymous Coward]

While two data points are fascinating, what is the FULL story?

Do we know the "diversity" of other species? I mean, are bacteria "more diverse" than hydra, who are more diverse than reptiles, who are more diverse than primates, with humans being the least diverse? I don't mean to sound homo-sapien centric, but could it not be that our mechanisms are just so complex that the room for error is very small for us to survive? To the point made earlier of survival of the fittest reducing diversity, wouldn't that type of balance naturally "reduce" diversity?

What a liability for humans!

[1nv4d3r]

So do your part to ensure diversity, and make sweet love with someone genetically different (read: hot) under some power lines near a microwave running with the door open. "For the sake of the species" never made a better pick-up line.

(Just don't give her your name--she might expect you to help raise your special freak).

Re:What a liability for humans!

[yarbo]

sounds like the setup for Geek Love. A circus family that intentionally tried to produce freaks for their show. It was an excellent book.

Re:What a liability for humans!

[Anonymous Coward]

Another thing people could do is have other men impregnate their wives, so that none of her children have the same father.

Jesus Christ...

[tha_mink]

Lactose Intolerant?...You have got to be kidding me!... The major side effect of lactose intolorance is gas? How(why?) could you possibly know about million year old farts? Jesus fucking christ!

Re:Jesus Christ...

[eggstasy]

Million year old farts? Now that's what I call an OLD fart! ;^)

Re:Jesus Christ...

[DustMagnet]

I don't know why this story was news. I've known it since college.

Anyway, farts is the problem, but indirectly. If you are lactose intolerant, you're body can't break down lactose, so you get few calories from it. The energy is wasted on fart generating bacteria.

Hey, I never knew you could watch a post drop each time you hit preview!

Re:Jesus Christ...

[BlackMagi]

According to a new study, the old study was right!

-BM

Re:Jesus Christ...

[arkane1234]

Lactose intolerancy is a little bit more than just some farts... it's not like eating chili or something :)

It can really mess your day up... the major side effect of lactose intolerance is massive gastrointestinal issues stemming from the lactose not being broken down. I have it, and believe me it's not just gas or I could definately handle that.

Additional Comments on reflection

[Inexile2002]

Thinking about that, I didn't make myself clear on something. What I was trying to say was that if a single troop of 60 to 70 chimps can have X diversity, shouldn't a group of 60 to 70 humans - a close relative of the chimp - also have X diversity. What struck me about the article is that their implication is that those 2000 people they say sired us had less diversity than 60 to 70 chimps.

Makes you wonder if it has something to do with human females being fertile year round. If I recall, chimp females are not. Because chimps can only mate at certain times, there is less oppurtunity for one male to sire all the children in a troop. In a human harem type social group, this could be easily accomplished which would cut down the genetic diversity considerably. Do this for a couple of generations and you might end up with a population with a depressed gene pool. Anyway, just arm chair theorizing off the top of my head. (Gotta use that anth degree for something.)

Re:Additional Comments on reflection

[zenyu]

Makes you wonder if it has something to do with human females being fertile year round. If I recall, chimp females are not. Because chimps can only mate at certain times, there is less oppurtunity for one male to sire all the children in a troop.

I think the article isn't specific enough to judge whether sexual practices have anything to do with it. Pygmy Chimps (Bonobos) always look like they are in heat and like humans who never look like they are fertive have sex with anything that moves. But most chimps have a stratified society where only one male at a time has sex with all the females. The females do cheat on him, but I don't know how common those children are. Even the Amish have plenty of out of 'falsely fathered' children so I don't think humans should be less diverse due to sexual exclusivity.

More likely there where several rounds of near human extinction and just the latest one was sometime in the last 100,000 years. We also have this nasty habit as a species to eat those that aren't 100% human...perhaps our competitors had similar tastes ;) (JK! -- no homo erectus, homo neanderthalis hate mail pls)

Re:Additional Comments on reflection

[Inexile2002]

You're right of course, the article is too vague. It was really just musing onto the keyboard. I'm not advancing a theory or anything. There could be many explanations for the low genetic diversity including subsequent death of lineages, genetic advantages of a sub-group (the whole scikle cell anemia - malaria connection) etc. Also, there was some genetic bottlenecking, where an even smaller group populates most of the world and the remainder stays behind in Africa.

I remember reading that if you took any world wide sample non-Africans - ANY sample no matter how diverse - and an equal number of randomly sampled Africans from the same villiage, you'd find more genetic diversity in the African villiage. The argument being that there was some genetic bottneck on the way out of Africa and only a tiny minority of the gene pool actually left.

Oh, and if us Neaderthals were still cheesed about that whole cannibalism thing, we'd let you know. We're over it. We ate you guys too. It's all good.

Re:Additional Comments on reflection

[maxume]

One thing that might be a factor that you don't seem to have mentioned is that most chimps are probably under considerably higher environmental pressure than the average human. The genetic makeup of todays typical human doesn't really have all that much to do with the continuation of his genetic line. It seems like the increased pressure for selection in the chimps would cause them to evolve faster than humans do. I don't really mean evolve in the sense of becoming greater as a species, but in the sense of becoming better suited to a particular environment.

If two sub groups of chimps each evolved under rather disparate conditions, and then crossbred, it would seem that their genetic diversity would increase. Considering that we as humans don't really evolve to any particlar environment anymore(we move around way to much), and we crossbreed pretty much constantly, perhaps the chimps are just doing a good job of playing survival of the fittest?

Re:Additional Comments on reflection

[Madcapjack]

Since evolution is a two step process: first mutation, then selection, we wouldn't expect selection to increase diversity. mutation is responsible for increasing diversity. selection decreases diversity. diversity might be a selective advantageous property of populations, and in some cases there might evolve (by selection) functions that increase diversity. sexual reproduction is one such thing.

Re:Additional Comments on reflection

[Martin Spamer]

Your first post was pretty clear and interesting question.

A prolonged & extreme selective pressure is a cause of reduced diversity. An obvious candidate must be the last Ice-Age which also fits nicely into the time frame. This issue has recently been covered in a excellent BBC documentary series Walking with Cavemen, which also featured a figure of 2000 females in a significantly reduced human population. I suspect the last programme was based at least partly on this research.

The programme suggested that until the Ice Age human 'tribes' where extended family size (~12) but survival in the Ice-Age was linked with a strong selective pressure for larger groups (~200). Socialisation allowed specialisation and increased expertise, this allowed food shortages to be more readily smoothed out. Socialisation and Specialisation both required elevated intelligence.

A idea to consider is that the number of people could have been larger than the 2000 suggested but the genetic heritage of the extras doesn't survive today; consider the effect of evolutionary shock caused by the large group coming into contact with smaller groups, the larger would quickly swamp the genetics of the smaller group. The larger group would be more genetically diverse than the smaller group and more resistant as a group to any diseases pool.

Also consider the negative impact on genetic diversity of plagues and pandemics, Influenza, Small Pox, Cholera, Black Death, many of these have surely sweep the world before recorded history leaving only immune populations, and reducing diversity.

Re:Additional Comments on reflection

[JanneM]

Well, there are other factors as well. Normally, that troop will outbreed quite a lot with other troops, which will keep it diverse and smother out much of the randomness.

But if there are only on the order of hundreds of individuals available, small random effects will start to have an impact. Not every individual will reproduce equally effectively, even if they are genetically equally viable - due to accidents, and other random effects, you will tend to get an inverse power-law like distribution with small numbers oif individuals. So, in that troupe of 2k individuals, maybe twenty to fifty of them will in reality be the progenitors of the majority of the offspring - others will have caught a disease, or be infertile, or have their children all die early, or have a falling out with their partner or whatever.

By the time the population is large enough that individual chance is smothered out, the individuals will in practice all stem from a small subpopulation of those that were available at that earlier time.

Re:Additional Comments on reflection

[maxume]

I would have to agree, given a single population, but I don't really see how what you say applies to two isolated populations that accidently come together and Get Busy...

Re:Additional Comments on reflection

[Paracelcus]

I think an overlooked factor in your very reasonable hypotheses is that the group(s) in question were already very closely interrelated as small isolated communities are wont to be. A possible scenario would be that the surviving enclave of humanity was mostly in one contiguous area, like the island of Java for instance. let's say that three thousand years previously the original Homo Sapiens arrived in a relatively small group of ninety individuals that then slowly spread out through the available land, You can see that the genetic profile of the islanders would tend to be very uniform.

Re:Additional Comments on reflection

[zlexiss]

But can selective pressure also have an effect on the mutuation rate?

In other words, will increased stress in the organism (through environmental change or whatnot), cause the organism to increase its mutation rate as a possible response?

Thought I'd seen something on this, but too lazy to look for a cite.

Re:Additional Comments on reflection

[ShieldW0lf]

It's not survival that's relevant now... it's quantity.

You know those deadbeats? The slut with 4 kids, and the guy with 7 by 3 different women?

He's your replacement.

Re:Additional Comments on reflection

[maxume]

I recall somthing about E. coli doing this, but I am also way to lazy to look for a citation. It seems that in more stressful environments, a gene that increased their rate of mutation would activate...

Re:Additional Comments on reflection

[Madcapjack]

But can selective pressure also have an effect on the mutuation rate?..will increased stress the organism to increase its mutation rate as a possible response?

I've heard that there is actually one species of bacteria that actually does increase mutation rate in response to environmental pressure, but I expect that kind of adaptation would only be valuable when the period between replication events is small.

Another thing that people ought to consider is that mutation does very much the same thing as 'selection'. If I have allele A and I fail to reproduce as a consquence of having an expressed allele A, then it has been selected against. However, mutation prevents the replication of Allele A, not (probably) because of how Allele A is expressed phenotypically, but because it was just "unlucky", and thus is non-directional.

Re:Additional Comments on reflection

[kmilani2134]

The interesting thing is that scientists have found that chimps (I believe what I saw was about the Bonobos) have two different types of sperm. Half the sperm actually serve the purpose of forming a sperm "wall" or barrier to keep other monkey's sperm from reaching the females egg.

I guess it pays to be first.

Re:Additional Comments on reflection

[Anonymous Coward]

Human sperm does this too.

Close to Extinction?

[Sunlighter]

Arguably, in spite of our numbers, we're close to extinction now.

Hey, good to know we got out of it last time.

Re:Close to Extinction?

[Imperator]

Well, 2000 of us made it last time anyway. Hey, I call a spot!

Re:Close to Extinction?

[Associate]

Yeah, but odds are the last time it wasn't our fault. If we were to die off say today about 3PM EST, it'd probably be because of something stupid we did. Hell, with the odds being 50/50, I feel lucky. Vegas here I come.

Re:Close to Extinction?

[Anonymous Coward]

Hey, good to know we got out of it last time.

So no more making fun of the "Duck and Cover" drills, ok?

More Info & complete paper

[MonkeyBoyo]

Here is the abstract from the The American Society of Human Genetics article, and here is Stanford's press release on the story.

And are the web pages of Marcus W. Feldman and Noah Rosenberg From Rosenberg's research page, here is access to a PDF of the journal article.

advantages

[larry bagina]

being able to digest lactose became a survival advantage after dairy farming was invented."

But being lactose intolerant was an advantage once fart-lighting was invented.

Not clear

[GCP]

The thing that should have bothered you is the utter ambiguity of such a claim. This is just one of those "newspaper statistics" that sound as though they mean something but don't.

What is the diversity of all humans? Is it more than the diversity between the two most different humans? What is the means of quantifying difference? Is there some standard, or are there lots of standards, or are there just countless ways, each of which yields a different answer?

What about the diversity in a group of chimps? Is that a family of chimps, or a small group randomly chosen from all chimps, such as one might find at some zoos?

I'm just not sure how to interpret the comparison of diversity between a small group (of chimps) and a large group (all humans). Size of group wouldn't have been mentioned, presumably, if it weren't part of the equation. What part?

Unless you know what it is they really mean, I'm not sure it makes much sense to go looking for deeper meaning.

Re:Not clear

[TakenName]

Maybe I'll just stay in bed in the morning too and never say anything about anything again except maybe Firewall ACLs since that is the one thing out there that I can honestly say I know enough about to have an opinion on. Oh, and beer. And tits. And sports. Thats it, you've opened my eyes, thank you oh enlightened one. I'll never talk about anything ever again except beer, tits, sports and work.

Mmmmm. Beer.

Re:Not clear

[Inexile2002]

First off, tits and beer rock. Sports... I can take of leave.

As for the parent comment, I studied anthropology in school and did a rather large term paper on genetic diversity. Not the topics in the articles exactly, but enough that I do know what I mean, and I think I know what they mean.

As for the genetic diversity, usually, they mean exactly what the term would imply. The different genotypes that occur in a given sample. In humans, it doesn't mean the difference between the two most genetically different people. The problem with discussing the difference between the two most genetically different people is that it implies a range. That's not the case, there isn't some genetic continuum or between disparate people. There are other people who might not be as genetically different as the two extremes but possess novel genes that the two extremes lack, thus they contribute to the over all diversity.

Your problem (other than being a contrariam who would rather criticize the discussion than contribute to it) is that you're used to thinking in terms of the quantifiable and the continua. There is a continual, quantifiable spectra of light for example, so you try to apply this thinking to other non-continuous phenomena.

If geneticists needed to discuss gene diversity in some sort of quantifiable measure, it would eliminate their ability to discuss relevant topics. Unless you are referring to a specific sample of genes, you can't quantify the diversity. So you just call it diversity instead of lamenting the lack of a standardized "Gene-ino" quanta. Just because they haven't sampled every gene of every human doesn't mean they can't make statements about human genetic diversity.

And another thing, it doesn't really matter which group of chimps they were talking about. The point stands even if it is only true for a single chimp troop out of all the chimp troops in the world. If somewhere out there there are 60 - 70 chimps with more diversity than all of humanity, then chimps possess more diversity, and a scientist will ask why.

invention of dairy farming

[alonsoac]

being able to digest lactose became a survival advantage after dairy farming was invented.

So at some point some humans said:

"Hey lets invent dairy farming!"
"Hmm, but we're all lactose intolerant..."
"What the heck, if we take this crap every day we'll eventually mutate and some generations down they will be thanking us."

Nice long-term thinking there, thanks!

Re:invention of dairy farming

[Anonymous Coward]

"Hey lets invent dairy farming!"
"Hmm, but we're all lactose intolerant..."
"What the heck, if we take this crap every day we'll eventually mutate and some generations down they will be thanking us."

"Hey, lets elect Dubya."
"But he is a drunkard, and he is dangerous..."
"What the heck, if we take this guy we'll eventually mutate and some generations will be thanking us. If Earth still exists then."

Re:invention of dairy farming

[JanneM]

More likely, you would give the milk to children (who aren't intolerant). Those children that developed intolerance later would have access to the food source for longer than the others, and live longer (in times of food shortages at least).

Besides, cheese is low enough in lactose that even people with just a slightly higher tolerance could eat it without too much adverse effects. And in some African populations, there are consequently a tradition of making cheese but not drinking the milk directly (other than for children), and their level of tolerance is at an intermediate level.

Re:invention of dairy farming

[Madcapjack]

This is a problem for a simplistic account of the evolution of lactose intolerance. But I would suppose that it would only be necessary that those who were not lactose intolerant consume milk, for it to be partially explanatory of how lactose tolerance might become dominant in a population given that those who were both lactose tolerant and consumed milk were at a reproductive advantage compared to those who weren't lactose tolerant. But I'm not sure of the extent of discomfort caused by lactose intolerance. Can lactose intolerants eat heavily processed dairy products?

Even better prediction.

[Stonent1]

Within the next 50 years, about half of us will be dead!

Alternative Interpretation

[Iainuki]

I'm not sure I buy the article's argument that "humans" came close to extinction. I think another possibility is that what they're looking at is a speciation event: that's the point that homo sapiens sapiens branched off from immediate predecessors. If that group had been killed, we wouldn't be here, but I'm not sure the homo genus would have died off.

Re:Alternative Interpretation

[Muhammar]

The gene study only suggests that we all have common ancestors from a small group (perhaps only few thousand) which was pretty geneticaly homogennous and lived maybe 70 000 years ago.

There are many possible scenarios: one possibility is that tribes originating from an isolated small group of individuals got lucky for some random reason, while the other prehistoric people did not make it to the current gene pool. But it does not necesserily follow that everybody other must have died at once, exactly around that time. Maybe the other prehistoric people were living happily along for millenia, just thinking that hunting with the handaxe is a good idea and did-not want to have anything to do with those imbred short-sighted teet-seeking inovators with narrow shoulders and concave rib-cage. But the lactose tolerancy incidentaly infered immunity against bad infection outbreak caused by canibalism, which in turn was a result of sudden unability to hunt because of the hand-axe repeated strain injury.

Actually what they said was...

[Inexile2002]

"I dare you to drink that."
"No, I dare you."
"Ok, we all dared, so we all drink."

Then they all got sick except one who not only brained them with a club and sired children with thier wives... After that, he taught his sons how he got all the foxy wives and they went to neighboring villiages...

Re:Actually what they said was...

[EvilTwinSkippy]

Hmmm. And we are all decended from that bastard. Way to go Great^45 Grandpa!

Re:Actually what they said was...

[Havokmon]

Hmmm. And we are all decended from that bastard. Way to go Great^45 Grandpa!

Or, more specifically, we're all bastard descendants..

Re:Actually what they said was...

[Zork the Almighty]

Can imagine how brave the first person to eat an egg was ?

Dogs

[Beryllium Sphere(tm)]

Robert K. Wayne of UCLA has estimated that we may have domesticated wolves as much as 100,000 years ago.

What if it was 70,00 years ago? Did our partnership with dogs save our species?

Re:Dogs

[Scaba]

I think it is, in fact, the wolves who domesticated us; well, domesticated our chimpanzee ancestors. Through careful breeding they were able to create an entirely new species which they called "Aaaaooooooooooooooo!!!!!" (which is also their name for everything else). But they quickly became bored with us, sniffed one another's asses, and then chased down a gazelle for an early supper.

Re:Dogs

[EvilTwinSkippy]

(In the prehistort past...)

Lassi: Woof Woof

Timmy: Ug, what Lassie? Mass extinction coming.

Lassi: Woof Woof

Timmy: Ug, If me survive me eat Lobster and mate many times.

Lassi: Ruff, Woof, Woof

Timmy: Oh, nevermind, Oggg being chased by tiger. Me gettem beer and watchum show.

Lactose intolerace

[Nice2Cats]

The ability to digest milk after puberty is still only widespread in Caucasians and some parts of Africa, as I happen to know because I am one of the Caucasians who is not a mutant and had to give up my ice cream orgies with puberty (puberty did have its compensations). This is why lactase pills (which contain the emzyme required to break down the milk sugar lactose into glucose and (I believe) galactose) are selling like mad.

The BBC had one of their unevitably brilliant documentations about the rise of mankind a few weeks again on German television where they pointed out that humanity must have been really, really close to the gutter before it exploded. Then this big, black rectangle came and showed them how to use the thigh bone of a pig to kill...oh, never mind...

Re:Lactose intolerace

[2nd Post!]

Yeah, it's interesting as I'm one of the few adult Asians I know who *isn't* lactose intolerant.

Ice cream, milk, cheese... I love them all.

Re:Lactose intolerace

[EvilTwinSkippy]

I'm really curious about why digesting milk is such a big deal? Until the 20th century we had absolutely no way of storing milk long enough to consume it.

Before that it was either right out of the cow, or in the form of cheese where the lactose is nicely broken down by fermentation.

Like all points, there are exceptions. I do recall one culture in Africa subsists on a food product made by mixing the blood of the cattle with the milk. But they are nomads who maintain too small a cattle population to afford to kill one on a regular basis.

Re:Lactose intolerace

[Planesdragon]

I'm really curious about why digesting milk is such a big deal? Until the 20th century we had absolutely no way of storing milk long enough to consume it.

Cows and cheese.

Milk only needs to last for a few hours, at most, outside of the cow. Cheese lasts for quite a bit longer--and quite a few types of cheese set off "lactose intolerant" people.

A cow can subsists on grass--a person cannot, though they can subsist on milk from goats or cow. Cut the grass, thus making for a safer home, and get food too--yeah, that's a big thing.

Re:Lactose intolerace

[JanneM]

There seems to be a direct correlation between a) lactose tolerance and domestication of cattle; and b) lactose tolerance and mean annual sunlight at the site.

The first one is pretty easy to explain - those that can avail themselves of that byproduct will have a better chance in times of need. The second one is very likely due to the fact that absent sunlight, milk is one of very few natural sources of vitamin D. If you try to eke out a living at 60 degrees north, drinking milk or not doing so can mean the difference between life and death.

Re:Lactose intolerace

[Martin Spamer]

how being lactose intolerant in adulthood was normal, and being able to digest lactose became a survival advantage after dairy farming was invented.

Preceding the domestication of cattle; for lactose intolerant to arrise, it must have offered some survival advantage.

Re:Lactose intolerace

[arkane1234]

I'm just trying to imagine how milk was harvested before the domestication of cattle...

I'm picturing a mass army of hunters, with painted bodies to blend in to the environment, silently stalking the herd of cows. Suddenly, a violent explosion of activity occurs, and thousands of hunters bolt towards the herd with bucket in hand, tackling the slower cows and draining the milk from their teets.

That, my friend, is Darwin in action =)

Re:Lactose intolerace

[WotanKhan]

"Preceding the domestication of cattle; for lactose intolerant to arrise, it must have offered some survival advantage."

Makes sense. If mother's milk is inedible to all but the infant, its a lot more likely the infant will get fed when the parents are hungry.

Re:Lactose intolerace

[eglamkowski]

Milk is not very common or popular in China, and the government there has been making a big push to get the people drinking it for health reasons. But they also had to set up a special hotline to handle all the cases of lactose intolerant people drinking it for the first time. And that'd be most of them.

http://www.fb.com/issues/analysis/China_Briefing_I ssue19.pdf

I read the original Wall Street Journal article referenced, but don't have reg at wsj.com so can't link to it. It was quite interesting.

Re:Lactose intolerace

[tuxedobob]

Uh, isn't milk fortified with vitamin D? I didn't think that was natural.

Re:Lactose intolerace

[JanneM]

Vitamin D is present in the milk fat. Modern-day people don't want their milk that fat, so milk is usually reduced. To compensate for the loss of vitamin D, it is added back in.

Noah's ark

[DJ Rubbie]

Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

Before you mod me down into oblivion for sounding like a self-righteous Creationist, do note that other cultures have references to a catastrophical flood (such as the Chinese, apparently the character for ship is that story).

Re:Noah's ark

[Tyreth]

No, probably not. After all, animals too were choked off at this point in history, with 2 of each kind and 7 of those that were considered clean (edible animals). So it doesn't explain it.

However, what could explain it is the habit for humans to commit genocide at times, and also to breed within the family. These have both occurred in large scales in the past. Families would stick together very strongly (tens, hundreds, thousands of people). They would sometimes wipe out entire family lines in a war. They would marry as exclusively as possible within families. Along with disease, etc, that cuts a population down. I'd see that as a better creationist explanation.

On a related note, mitochondrial DNA seems to indicate that our common mother (mitochondrial eve) existed ~6000 years ago, less than the 70,000 years proposed here. It was originally thought that mitochondrial eve existed ~200-250,000 years ago. However, new research in 1997 (off memory) indicated that mutations in mtDNA occurred far more rapidly than assumed (assumptions were based on evolutionary expectations for mitochondrial eve). This resulted in the new date. Take note: I've had many evolutionists come back and quote the original article saying "See! It says 200,000 years, not the 6,000 creationists quote. Just another example of creationist lies". However, they failed to look at the top of the article which was dated (Again, off memory) 1996, a year before the new research was discovered. I thought I'd mention that to save potential embarrasment.

A reference can be found here, though I used to refer to the article on creationscience.com - the author is slow to update (including the now outdated moon-dust argument) so I am putting less focus on that resource.

More articles can be found here.

Hope this helps.

Re:Noah's ark

[aug24]

No.

Because.

Because.

Oh all right, because...

1) The Noah story isn't set that long ago. According to the ages listed in the pentateuch, that only happened about five thousand years ago.

2) All the other animals would also have small diversities, unless it was a special wacky kind of flood that only drowned humans.

J.

Re:Noah's ark

[MonkeyDluffy]

No.

There is no evidence whatsoever that there was a worldwide flood - and a disaster of that magnitude would leave lots of evidence. And nobody told the Egyptians and Chinese about it - their civilizations were going strong before, during, and after when the flood supposedly occurred.

Many cultures have flood stories, because towns are usually located near good water supplies such as lakes and rivers. Which flood on occasion.

-MDL

Re:Noah's ark

[EvilTwinSkippy]

One other point:

Ever population has a magic number that determine the minimum number of individuals required to maintain its existance. For birds this number is about 4,000. We witnessed one population recently dip below the magic number and cease to exist: the Carrier Pidgeon. There were some pretty heroic attempts on the part of humans to get the population back on its feet, but all for naught.

Giving the benefit of the doubt that the bible simply didn't count women, you have 9 breeding pairs. (Noah, his wife, 8 sons, 8 wives.) Now, a woman can carry 1 child at a time, about every other year in primative conditions. (It's not until recently that we've become well nourished enough to have back-to-back pregancies.)

Going for the benefit of the doubt again, we will assume that all of the women start off this breed-a-thon at around 14 or so, with fertility tailing off around 36. 36-14=22=11

Each woman can effectively have about 11 pregancies, about 1/3 of them will not go to term, and another 1/3 will die before age 5. Rounding up, we effectively have each woman bringing about 4 kids into the world before her body wears out.

If you think I'm being pessimistic with these numbers, they did not have pre-natal care, vitamins, or even a steady food supply. I'm just working with rough estimates based on what goes on in the third world, which is about the best guess for what conditions would be like following the complete distruction of the Earth. (And I'm not even factoring in death during labor.)

We are going to estimate that the population can quadruple in size every generation. By that estimate... damn. You actualy have about 38 million people after 400 years.

But this estimate is completely bunk. If you look through historical estimates, until the 19th century humans NEVER even doubled in size within a generation. Our growth rate before shows a doubling about avery 1000 years or so. Mind you that is taking into account disease, wars and disasters,

So whatever happened, you need a much larger population than 8, or even 2. There are more than 8 different genes controlling eye color. The chances that 8 individuals in the same family all had type AB+ blood, as well as O- blood is also unlikely.

The "Mitochondrial Eve" theory is a mathematical extraction. Frankly I use the same sort of estimates to show that throwing a light switch would generated in infinite amount of current, for an infantesimally small fraction of a second immediately after it's thrown. Our number systems are terrible about handling beginning and endings.

Which is probably why the big guy simply started by stating THIS is on. THIS is off, and was content to just flip on and off for the first day.

Re:Noah's ark

[Anonymous Coward]

No, the Noah's Ark story is in reference to the Black Sea Flood, which happened about 7,000 years ago. The Black Sea was an in-land lake, then the water from the Agean sea broke across and flooded it. The Noah's Ark story came from mythology of Mesopotamia, likely a rememberance of what happened.

Re: Noah's ark

[Black Parrot]

> Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

No. As others have already pointed out, (a) the biblical flood supposedly happened 4000-5000 years ago, not 70,000 years ago, and (b) geology soundly refutes any and all claims of a global flood (this being realized by the parsons who invented geology, already by 1820), and (c) all animals would also have to have genetic bottlenecks at the same time (or more recent, due to other causes), and (d) there are a very large number of additional problems with the flood yarn, which we can go into if you wish.

Of course, you could always sweep everything under the rug by claiming that God patched everything up with miracles afterward, to make it look like the flood never happened. But theology is no more capable of investigating such bizarre claims than science is.

> Before you mod me down into oblivion for sounding like a self-righteous Creationist, do note that other cultures have references to a catastrophical flood

And lots of cultures have references to multiple gods. Do you put the same weight on those traditions, or do you just pick the ones that you think supports your own position?

> (such as the Chinese, apparently the character for ship is that story).

I think that particular claim is that the character is the composition of the characters for "8" and "mouth". Extraordinarily weak evidence for a flood, even if the claim about the symbols is true. Basically someone has noticed that out of all the writing systems in the world they can find one symbol that has a very weak association with one story in their favorite mythology. This is nothing more than a posteriori data scumming.[*] Given the amount of data they have to work with, the only surprise is that they haven't found a better match with the target mythology.

[*] I use the roguelike term "scumming", since the obvious "data mining" has a very different connotation.

Re: Noah's ark

[cybermace5]

The actual article (not the headline) said sometime within the last 100,000 years, not 70,000 years. The 70,000 year figure was given for the theorized split between hunters and gatherers.

Also I see people quoting as fact that animals do not have a similar genetic bottleneck. Where are you getting this information? When this story was posted on Slashdot sometime last year, I looked for similar research on animals and could not find any.

The story I read last year was much more detailed in the methodology used to determine the existence of a bottleneck. They were not comparing genetic diversity with chimps, they were analyzing patterns of genetic diversity within the human race itself correlated with human reproductive patterns. Humans and chimps do not have identical reproductive behavior, and perhaps chimps (taking into account their own reproductive patterns) should have even MORE genetic diversity than current levels.

And I'd still like to see the evidence that "animals" do not show any signs of a recent bottleneck, since everyone seems to be generalizing "animals" from the briefly mentioned (and not explicitly studied) chimps.

Re:Noah's ark

[Bowling Moses]

"On a related note, mitochondrial DNA seems to indicate that our common mother (mitochondrial eve) existed ~6000 years ago, less than the 70,000 years proposed here."

One nit to pick. Going back to the original "Research News" article in Science (vol 279 issue 5347 pg 28-29), we see that instead of this being evidence for a ~6000 year old mitochondrial eve, we have to reconsider some of our beliefs about mitochondrial DNA (mtDNA), or more specifically a region of mtDNA called the D-loop, which comprises only 7% of mtDNA and which most mtDNA studies have used. One of the biggies is that most mtDNA studies use "so-called "noncoding" sequences of the control region of mtDNA, which do not code for gene products and therefore are thought to be free from natural selection." to quote the article. Another is to check and see if we are instead hitting "hotspots," regions with above-average mutation rates; hotspots will have more back- and parallel-mutations which will cloud the picture. A third is that the mutation rate may vary over time. A fourth is to investigate the issue of heteroplasmy--having multiple mtDNA sequences, even though for a given region there should be only one. For a while it was thought to be rare, now 10-20% of the population could be heteroplasmic. All of these issues would need to be addressed by the creationists before it could be considered evidence of a ~6,000 year old mitochondrial eve rather than a problem with the underlying assumptions of the technique. Indeed, with the advancement of our ability to manipulate and sequence DNA, we no longer have to utilize only 7% of the mtDNA--we can sequence the whole thing--all 16,000 or so base pairs of it. A recent study published in Nature (vol 408 pg 708-713, Dec. 2000) using mtDNA--all of it--found that the D-loop (used in most mtDNA studies) does not have a constant mutation rate. The study goes on to show (again using the whole mtDNA sequence) that the date of "mitochondrial eve" is about 170,000 years ago. A more reader-friendly report by the author of the Nature paper can be found here.

Re:Noah's ark

[baudbarf]

Going for the benefit of the doubt again, we will assume that all of the women start off this breed-a-thon at around 14 or so, with fertility tailing off around 36. 36-14=22=11

You've done your homework! However, with all due respect, I have some potential oversights to point out. Bear in mind that, according to the Bible, the average lifespan in this time period was something like 900 years, and therefore I would extend the age of fertility accordingly.

If you think I'm being pessimistic with these numbers, they did not have pre-natal care, vitamins, or even a steady food supply.

If we are, indeed, pitting the Bible against mathematics, don't forget to factor in the variable of the "blessing of God" on their reproductive efforts; and the fact that at this point in human history they were MUCH closer to physical perfection than we are, therefore the success rate of births would (I assume) be higher than now.

Re: Noah's ark

[Black Parrot]

> On a related note, mitochondrial DNA seems to indicate that our common mother (mitochondrial eve) existed ~6000 years ago, less than the 70,000 years proposed here. It was originally thought that mitochondrial eve existed ~200-250,000 years ago. However, new research in 1997 (off memory) indicated that mutations in mtDNA occurred far more rapidly than assumed (assumptions were based on evolutionary expectations for mitochondrial eve). This resulted in the new date. Take note: I've had many evolutionists come back and quote the original article saying "See! It says 200,000 years, not the 6,000 creationists quote. Just another example of creationist lies". However, they failed to look at the top of the article which was dated (Again, off memory) 1996, a year before the new research was discovered. I thought I'd mention that to save potential embarrasment.

Actually, the Loewe and Sherer letter cited by your favorite creationist Web site does not argue for a 6,000 year old mitochondiral eve; they merely mention in passing that that would be the untenable effect of basing a molecular clock on one specific mDNA site that has come under investigation. They spend the rest of their letter proposing ways of understanding the mutation rates that would naively yield the date that they themselves reject.

If you search for "mitochondrial eve" at PubMed and read the abstracts of more recent papers you will see other papers cautioning the use of mDNA for calibrating biological clocks.

Also, very recent articles are still dating the y-Adam to 50,000-170,000 years ago. This is somewhat problematic for people who misunderstand "mitochondrial eve" to be the female founder of the species and think she lived a mere 6,000 years ago, as she would have had to get bonked by a 44,000-164,000 year old man. [cite: Howard JM, '"Mitochondrial Eve", "Y Chromosome Adam", testosterone, and human evolution', Riv Biol. 2002 May-Aug;95(2):319-25 - though I have only seen the abstract, which is available on PubMed.]

Re:Noah's ark

[Tablizer]

note that other cultures have references to a catastrophical flood

The shear laws of probability dictate nasty floods in any given region every few thousand years or so. IOW, every place on Earth probably has had nasty floods that would have ruined dwellings, crops, and/or hunting lands, etc. to such an extent that it had a big impact on the local population. Note that it does not have to be the whole world at the same time. Remember, they did not have telegraphs back then.

Re:Noah's ark

[EvilTwinSkippy]

Bear in mind that, according to the Bible, the average lifespan in this time period was something like 900 years, and therefore I would extend the age of fertility accordingly.

That's bull:

• Gensis 25:7 Altogether, Abraham lived a hundred and seventy-five years.
• Numbers (multiple) - References to "All men between thirty and fifty.
• Joshua 5:6 - The Israelites had moved about in the desert forty years until all the men who were of military age when they left Egypt had died, since they had not obeyed the LORD .
• 2 Samuel 19:32 - Now Barzillai was a very old man, eighty years of age.
• 2 Chronicals 24:15 - Now Jehoiada was old and full of years, and he died at the age of a hundred and thirty

The only man to live 800 years was Adam.

Now ask me, if women had extended fertility why does the bible in Genesis 18:11 state:

Gensis 18:11 Abraham and Sarah were already old and well advanced in years, and Sarah was past the age of childbearing.

So yes, there was a limit to fertility. Outside of Kings and other notable figures, Isrealite rarely lived past 40 (Joshua 5:6). And that was the men mind you, until recently the leading cause of death for women was childbirth.

Re:Noah's ark

[Tired_Blood]

2) All the other animals would also have small diversities,

Sounds logical, but not really. If diversity is dependant upon the offspring and mutations passed on to them, then the longer it takes to produce the next generation, the less diversity for that species when compared to other species, over the same time-frame.

unless it was a special wacky kind of flood that only drowned humans.

I doubt it. Why bother with all the animals then?

Re:Noah's ark

[baudbarf]

I'm sorry, I was not very clear. Allow me to clarify.

If you comb Genesis, you'll find that lifespans were very high until immediately after the flood, when they rapidly dropped to less-incredible levels.

Gen 5:5 - So all the days of Adam that he lived amounted to nine hundred and thirty years and he died.

Gen 5:8 - So all the days of Seth amounted to nine hundred and twelve years and he died.

Gen 5:11 - So all the days of EÂnosh amounted to nine hundred and five years and he died.

Gen 5:14 - So all the days of KeÂnan amounted to nine hundred and ten years and he died.

Gen 5:17 - So all the days of MaÂhalÂaÂlel amounted to eight hundred and ninety-five years and he died.

Gen 5:20 - So all the days of JaÂred amounted to nine hundred and sixty-two years and he died.

Gen 5:23,24 - So all the days of EÂnoch amounted to three hundred and sixty-five years. And EÂnoch kept walking with the [true] God. Then he was no more, for God took him.

Gen 5:27 - So all the days of MeÂthuÂseÂlah amounted to nine hundred and sixty-nine years and he died.

Since, in this context, we are interested only in natural life spans, we will not count E'noch's age, since he was taken by god (see: Hebrews 11:5) So I'm seeing an average pre-flood lifespan of about 920 years.

Now take a look at post-flood lifespans (look at Genesis 11:10):

Gen 9:29 - So all the days of Noah amounted to nine hundred and fifty years and he died.

Shem: 600 years
ArÂpachÂshad: 438 years
SheÂlah: 433 years
EÂber: 464 years
PeÂleg: 239 years
ReÂu: 239 years
SeÂrug: 230 years
NaÂhor: 148 years
TeÂrah: 205 years

Graph the data, It's remarkable how immediately after the flood, lifespans dropped like that!

And I'm sorry, I didn't mean to imply that women's fertility was unlimited - I just meant that it probably was extended in relation to the extended ages that were enjoyed in this short period.

Please remember that my information really doesn't apply to anything past immediate-post-flood events.

Re: Noah's ark

[jpkunst]

And I'd still like to see the evidence that "animals" do not show any signs of a recent bottleneck, since everyone seems to be generalizing "animals" from the briefly mentioned (and not explicitly studied) chimps.

Well, if you believe that animals show signs of having a recent genetic bottleneck, then the onus of proof rests with you. Not the other way around.

JP

Re: Noah's ark

[BCGlorfindel]

Actually, the Loewe and Sherer letter cited by your favorite creationist Web site does not argue for a 6,000 year old mitochondiral eve; they merely mention in passing that that would be the untenable effect of basing a molecular clock on one specific mDNA site that has come under investigation. They spend the rest of their letter proposing ways of understanding the mutation rates that would naively yield the date that they themselves reject.

A little more background on the Parsons paper. Untill the Parsons paper, mutation rates in ALL mtDNA regions were believed to be neutral. The projection made by the creationist site use precisely the same mtDNA clock methods that where used by evloutionary scientists to predict the 100k year MTeve before the high rates were discovered. To that point the mutation rates for the 100k year old MTeve were generated off mutation rates predicted from the divergence between chimp and human mtDNA. Nobody had tried measuring actual mutation rates from human forensic evidence. Parsons was the first to measure observed rates, and discovered a mutation rate 20x higher than the rates predicted by the chimp/human calibration. Parsons rejection of this rate was primarily based on the ridiculously high rate compared to the relatively low differences between chimp and human mtDNA. If mtDNA was neutral and chimp/human diverged ~5ma then the observed mutation rate was impossible. Thus the non-neutrality of mtDNA was proposed.

If you search for "mitochondrial eve" at PubMed and read the abstracts of more recent papers you will see other papers cautioning the use of mDNA for calibrating biological clocks.

And most of them have been trying to justify the difference between observed mutation rates in mtDNA with those predicted from chimp/human divergence rates. The explanation has always been that the random observed mutation rate in current studies is different than the fixation rate over millions of years. Selective pressure and hotspots were random mutations cancel each other out are among proposed explanations. The creationist conjecture that the chimp/human divergence assumptions are wrong are rejected out of hand as ridiculous. The coincidental 6k years for MTeve and same approx date from biblical records is merely that, a coincidence. Some people though don't reject that big a coincidence as lightly.

Re: Noah's ark

[cybermace5]

Um, is your brain in backwards? I did not claim there was a bottleneck, I was asking people to prove their claim that there isn't! I'm not the one making an unsubstantiated claim here!

Re:Noah's ark

[EvilTwinSkippy]

This is getting to be a rather interesting thread. I must conceed that your citations are for more pertinant to the matter at hand than mine.

Even by biblical standards, odd stuff was afoot following the flood. So can we agree to summarize all of the facts of the matter as this: It is a miracle that the human race survived whatever was going on.

Re: Noah's ark

[Black Parrot]

> Graph the data, It's remarkable how immediately after the flood, lifespans dropped like that!

Which of course makes your claim completely useless as an explanation of how the species survived after the flood - even if it were true. You have apparently forgotten the context in which you first brought it up.

Re:Noah's ark

[Tackhead]

> After all, animals too were choked off at this point in history, with 2 of each kind and 7 of those that were considered clean (edible animals). So it doesn't explain it.

"Yeah! How come all us land animals get cut down to two specimens, but all the friggin fish get off with a free pass! And don't tell me that somehow us mammals deserved it, 'cuz God let all the dolphins off scot-free too!"
- Some Angry Quadruped, ca. 6000 BC

Re: Noah's ark

[baudbarf]

Well, I'm trying to present all the data, rather than selecting only the data that supports my claims. We're looking for truth here, not ammunition to feed our arguments.

I believe my point to be valid because lifespans took several generations to get low enough to present a danger to reproduction - remember, with a system of exponential growth, such as this one, it's the earliest generations that contribute most to the overall population.

Re: Noah's ark

[Black Parrot]

> Giving the benefit of the doubt that the bible simply didn't count women, you have 9 breeding pairs. (Noah, his wife, 8 sons, 8 wives.)

Actually, the standard version of the story says 3 sons and 3 wives; thus only three breeding pairs. The story in Genesis clearly states that the three sons repopulated the whole earth, so Noah and his wife cannot be counted as a fourth breeding pair.

And of course you get a genetic bottleneck of a mere 5 people (Noah, Mrs. Noah, and the three daughters in law) unless Mrs. Noah screwed around, in which case the three sons could each have 50% of their DNA from outsiders and 50% from Noah, giving 5 people plus three halves, or 6.5 "virtual people" if you want to do the math that way. (And notice that the 6.5 goes beyond biblical literalism, since the Genesis story plainly states, at least twice, that the three boys were the sons of Noah.)

The flood myth really doesn't match this news story very well, offering a maximum of 6.5 people at 4000-5000 years ago instead of ~2000 people at 70,000 years ago. Those would be very different genetic bottlenecks, in terms of the genetic diversity that would be seen in the species today.

But this pales with respect to the problems for the "unclean" species, which would have all been winnowed down to a single breeding pair at the 4000-5000 year ago horizon. ...to say nothing of the problems for trees and freshwater fish, but that's a completely different discussion.

BTW, notice that we have human bodies from hundreds or even thousands of years ago, which is to say a great fraction of the way back to the purported date of the purported flood. Does anyone who believes the flood myth want to make a clear, unambiguous statement about what we should find regarding the genetic diversity of those bodies?

Re:Noah's ark

[BCGlorfindel]

Going back to the original "Research News" article in Science (vol 279 issue 5347 pg 28-29), we see that instead of this being evidence for a ~6000 year old mitochondrial eve, we have to reconsider some of our beliefs about mitochondrial DNA (mtDNA), or more specifically a region of mtDNA called the D-loop, which comprises only 7% of mtDNA and which most mtDNA studies have used. One of the biggies is that most mtDNA studies use "so-called "noncoding" sequences of the control region of mtDNA, which do not code for gene products and therefore are thought to be free from natural selection." to quote the article.

The D-Loop may only comprise 7% of mtDNA but it was used because it was the most likely neutral section. The rest of the sequence codes for proteins and is likely selective. The only reason using this section is a 'problem' is if there are other factors affecting the sections fixation rate, which your following points summarize.

Another is to check and see if we are instead hitting "hotspots," regions with above-average mutation rates; hotspots will have more back- and parallel-mutations which will cloud the picture.

Which is currently being researched, but also has a heavy reliance on divergence times between chimp/human. Creationists aren't going to be compelled to reject a rate based on the fact it doesn't fit chimp/human divergence times. To them, that's just more evidence against the chimp/human divergence ever having happened.

A third is that the mutation rate may vary over time.

And may vary within lineages as well. Which is were this idea came from, our common chimp/human ancestor may have had a different mutation rate than humans do now, and so the current observed mutation rates are not valid for projections. This has been backed up by observing different random mutation rates in chimp mtDNA versus human mtDNA. But again, creationists only see this as more evidence that chimp and human never were related.

A fourth is to investigate the issue of heteroplasmy--having multiple mtDNA sequences, even though for a given region there should be only one. For a while it was thought to be rare, now 10-20% of the population could be heteroplasmic. All of these issues would need to be addressed by the creationists before it could be considered evidence of a ~6,000 year old mitochondrial eve rather than a problem with the underlying assumptions of the technique.

The bigger issue here is that the result of a 6,000 year old MTeve is the reason that the assumptions of the underlying technique are being questioned. Creationists were laughed at for saying the 100,000 year old date for MTeve was because of a problem with the underlying assumptions of the technique. And now they are laughed at for accepting the underlying assumptions of the technique. Yes, many creationist sites are simply jumping from one band wagon to another to get the results they wish. But don't make out as though there isn't a similar tendency on the other side of the fence. Rejecting the observed mutation rate because it is too high(evolutionists) is every bit as bad as rejecting a predicted rate because it is too low(creationists).

Re: Noah's ark

[tuxedobob]

Uh, yeah. As someone pointed out to me recently, "pure logic" dictates that something isn't until you can prove it is. My personal issue with this, though, is that until recently, humans did not have a bottleneck 70,000 or so years ago. Read that again if it made sense.

Anyway, I think what you really meant to say is that no research exists to make a claim one way or another, and that it isn't fair to assume there isn't one simply because no research has been done.

That's another issue I have with the "pure logic" crowd. If I don't know for certain about something, I have to assume it isn't the case. Find someone using "pure logic" and conspiracy theory and you can forget about useful conversation.

Oh, and I can't prove the article is true, because I don't have proof the source is true, and I can't prove that the article was written without bias, etc.

Re:Noah's ark

[tuxedobob]

Keep in mind one other thing: the Bible doesn't generally mention slaves unless they are pertinent to the story at hand. Noah (and his sons) may well have had slaves, and in fact, I would hope they did, considering the number of animals they must have taken care of! Of course, there would be no point in mentioning them in the story. They weren't the holy ones.

Re: Noah's ark

[cybermace5]

I don't have a problem when people want to present theories, what-if scenarios, and even partial or inconclusive research. It's ok if they make a statement, but qualify it by saying it's not really nailed down yet. We'd get nowhere if people didn't make careful assumptions and then try to prove them right or wrong. We need to operate on confidence levels, not Boolean states.

But I don't appreciate it when a statement is made as fact, and there is zero fact or even anecdotal evidence provided to support the claim. Present it as a theory, not as a fact. By the way, your hair is purple with orange stripes. ;-)

Re: Noah's ark

[Black Parrot]

> The coincidental 6k years for MTeve and same approx date from biblical records is merely that, a coincidence. Some people though don't reject that big a coincidence as lightly.

The "coincidence" is irrelevant, because (a) it is now known that the site in question is not appropriate for calibrating a biological clock, and (b) the "mitochondrial Eve", regardless of the dating, does not indicate when the species originated.

And then there's the date of the "y Adam", which sadly does not support your coincidence-based thinking.

You do understand what "mitochondrial Eve" and "y Adam" are all about, don't you? Why they represent a terminus ante quem for the origin of the species rather than a date for the origin of the species? And why their lifetimes could have been many millenia apart? And that the labels of "Adam" and "Eve" were good ways of catching the public's imagination, but are actually very misleading?

Re: Noah's ark

[BCGlorfindel]

You do understand what "mitochondrial Eve" and "y Adam" are all about, don't you? Why they represent a terminus ante quem for the origin of the species rather than a date for the origin of the species? And why their lifetimes could have been many millenia apart? And that the labels of "Adam" and "Eve" were good ways of catching the public's imagination, but are actually very misleading?

Yes, I'm fully aware of what the terms really mean vs. what many misunderstand them to mean.

The "coincidence" is irrelevant, because (a) it is now known that the site in question is not appropriate for calibrating a biological clock, and (b) the "mitochondrial Eve", regardless of the dating, does not indicate when the species originated.

a.) We now know the site is inappropriate for calibrating a biological clock primarily from cross referencing with... chimp mtDNA and the conclusions drawn from the relative rates. Observed rates of random mutations in chimps and other primates have brought about the conclusion that mtDNA random mutation rates vary based on genetic lineage. Thus making a bad biological clock over long time frames. Inconsistancies between observed random mutation rates in human mtDNA and predicted rates based on human/chimp mtDNA differences over ~5ma suggest that D-Loop mutations in mtDNA are non neutral over long time frames. BUT all of these evidences invalidating the use of mtDNA as a biological clock are strongly based on the assumption of human/chimp common ancestry ~5ma.

b.)Absolutely correct. The date of mtEve only suggests our last common maternal ancestor, who could easily have been one among a large population of similar females. However, that no way precludes mtEve being the biblical eve.

And then there's the date of the "y Adam", which sadly does not support your coincidence-based thinking.

And sadly, the date is based only on chromosome fixation rates from evolutionary based thinking(predicted chimp/human divergence dates). Much like mtEve was before Parsons measured observed random mutation rates.

Re:Noah's ark

[aug24]

Sounds logical, but not really. If diversity is dependant upon the offspring and mutations passed on to them, then the longer it takes to produce the next generation, the less diversity for that species when compared to other species, over the same time-frame.

OK, I should've said that they will have a level of diversity consistent with a very low population five thousand years ago.

I doubt it. Why bother with all the animals then?

I don't know. Perhaps because it's just a story, not real, and so doesn't have to make sense?!

J.

Re: Noah's ark

[lovebyte]

all animals would also have to have genetic bottlenecks at the same time
except fish, obviously!

Re:Noah's ark

[Anonymous Coward]

other cultures have references to a catastrophical flood

floods are common around the world. you think this might have something to do with it?

Re:Noah's ark

[AJWM]

There is no evidence whatsoever that there was a worldwide flood - and a disaster of that magnitude would leave lots of evidence.

Well, actually, there is and it did. But more like 12,000 (or a bit more) years ago than 5,000. Namely, the rather quick end of the last Ice Age.

Mind, most of the Ice Age coastal areas are still under a couple hundred feet of water.

But yes, most flood legends do seem to arise in river valley civilizations, where the river undergoes seasonal flooding. (It's that seasonal deposit of fresh silt that makes the land so fertile as to encourage civilization there in the first place.)

Re:Noah's ark

[Bowling Moses]

"But don't make out as though there isn't a similar tendency on the other side of the fence. Rejecting the observed mutation rate because it is too high(evolutionists) is every bit as bad as rejecting a predicted rate because it is too low(creationists)."

Is it? I think the actions of main-stream science and "scientific" creationism bear witness to the vast difference between the two. We used this dating technique for a while, and then it was discovered that the mutation rate of the D-loop that we were using was ~20 fold higher than what we expected. What happened? The creationists trumpeted it as evidence for their "model," completely ignoring other possibilities and were extremely happy with their one piece of data that they believed supported their religious view, however out of line with all other information that one bit of data might be. Main-stream scientists scratched their heads and wondered why this one bit of evidence was now so far out of line with their expectations based on information from multiple of lines of inquiry. Main-stream science looked, and in 2000 a plausible explanation and a correction for the MTeve date was published. The investigation of mtDNA, as you mentioned, still continues. As a result of the information learned, our methods may have to be slightly modified; mainly it looks like a study using the D-loop must be relegated to recent events, whole mtDNA for old events. What happened with the creationists? They stopped thinking about the issue when they could construe it to look in their favor. Worse, since it has become clear that the 6000 year old date is based on a faulty study, they failed to correct themselves. The "scientific" creationists betray themselves by their actions.

Re:Noah's ark

[BCGlorfindel]

Is it? I think the actions of main-stream science and "scientific" creationism bear witness to the vast difference between the two.

Main stream creationism is made up of about 90% yahoos who claim to be 'scientists' but would at best be described as journalists/evangelists. I didn't mean to compare main stream science to main stream creationism. The idea of creationism though isn't invalidated simply because many uncredible people defend it. My point was merely that when common descent is a starting assumption it will affect the conclusions. My previous post pointed out examples of such, and you again re-iterate those claims as follows:

We used this dating technique for a while, and then it was discovered that the mutation rate of the D-loop that we were using was ~20 fold higher than what we expected. What happened?
snip the part about creationist tomfoolery, I agree their sudden about face was unfounded.
Main-stream scientists scratched their heads and wondered why this one bit of evidence was now so far out of line with their expectations based on information from multiple of lines of inquiry.

The multiple lines of inquiry you refer to are ALL based on the assumption of chimp/human common ancestry. From a creationist stance, rejecting the predictions on that assumption in favor of the observed data is not unreasonable. The fact that the method main stream science had accepted as valid suddenly matches the bible nicely is interesting to creationists. Scientifically, they aught to do some work to confirm the validity of the method before making any claims about a method they had formerly rejected. But aside from that, on the surface this seems to be better evidence for creationism than common descent. And the data was all obtained by main stream science, using accepted main stream methods.

As a result of the information learned, our methods may have to be slightly modified; mainly it looks like a study using the D-loop must be relegated to recent events, whole mtDNA for old events.

And again, this change of method is based on... you guessed it, the assumption of chimp/human common descent. Chimp and human mtDNA have different rates of random mutation in the D-loop region(the 2000 study you refer to), and this is the main evidence that mtDNA is an invalid clock for old events. You may not like my putting this spin on things, but from a creationist stance here is what you see. Main stream science predicted the rate of mtDNA mutation based on chimp/human divergence assumptions. When main stream science actually measured the real rates they found those rates were 20X higher than expected. Main stream science made theories and changed assumptions about mtDNA behaviour to explain this. They then confirmed these theories by data taken from chimp and human lineages, which was of course based on the assumption of chimp/human common descent. Now, if your a creationist, that whole turn around was basically side stepping observed evidence that did not fit the common descent assumption, and confirming the invalidity of the observed evidence based on data dependent on the assumption of common descent. As a creationist, that kind of situation doesn't invalidate the initial results from where I sit.

Re:Noah's ark

[Bowling Moses]

"The multiple lines of inquiry you refer to are ALL based on the assumption of chimp/human common ancestry. From a creationist stance, rejecting the predictions on that assumption in favor of the observed data is not unreasonable. The fact that the method main stream science had accepted as valid suddenly matches the bible nicely is interesting to creationists. Scientifically, they aught to do some work to confirm the validity of the method before making any claims about a method they had formerly rejected. But aside from that, on the surface this seems to be better evidence for creationism than common descent. And the data was all obtained by main stream science, using accepted main stream methods"

If we wish to test a hypothesis and expect X, and set up dozens of different experiments with different points of view based on different underlying assumptions and experimental methods, when all but one produces X, does that allow some group to proclaim Y? No. A much more reasonable approach would be to go back to that one experiment and try to find out why it doesn't match the others--whether or not you believe X or Y. This is exactly the case we have with mitochondrial eve. We went back to this dating method using the D-loop, and found that this loop does not behave as expected. It does not matter if we assume a 5 million year last common ancestor with a chimpanze or not. If we expanded the last common human-chimp ancestor to a 1-10 million year range the study would have still produced discrepancies between the D-loop and the rest of the mtDNA. If a creationist still wishes to argue that we're still making assumptions even though when we look at the fossil record we've expanded our range to a ridiculous point, then we no longer are arguing about our mtDNA dating technique but instead are arguing about paleontology and geology (and physics if they start questioning some of the radiometric dating techniques). This is well beyond the scope of the paper I referenced and again shows the difference between main-stream science and "scientific" creationists.

Re:Noah's ark

[BCGlorfindel]

If we wish to test a hypothesis and expect X, and set up dozens of different experiments with different points of view based on different underlying assumptions and experimental methods, when all but one produces X, does that allow some group to proclaim Y?

And this is not the situation that occurred, it is only your misunderstanding of the lead-up to parsons paper. There were NO experiments done to observe the behaviour of the D-Loop prior to Parsons paper. The dozens of experiments you speak of were ALL conducted as follows: Human and Chimp mtDNA D-Loops are differ by X, and chimps and humans diverge Y years ago, thus the mutation rate of the D-Loop is X/Y. The FIRST experiment to measure the D-Loop's actual rate gave a rate 20 times higher than X/Y. Based on this, scientists proposed that in spite of the fact the D-Loop appears neutral by every known test, we must assume neither X nor Y can be adjusted to fit the experimentally observed rate.

If we expanded the last common human-chimp ancestor to a 1-10 million year range the study would have still produced discrepancies between the D-loop and the rest of the mtDNA

First off, the human-chimp divergence would need to have occurred 250,000 years ago to fit the data, so no self respecting scientist is going to propose anything like that. Secondly, considering that about 90% of the remainder of mtDNA consists of genes, your dead right there are discrepancies between how the D-Loop and the rest of the mtDNA behave. The nearly the entirety of the rest of the sequence appears to be under strong selective pressure. The D-Loop does not, and we knew this before any of Parsons tests were done. In fact, the discrepancies in behaviour are the very reason studying the D-Loop was chosen over the entirety of the sequence, it was less influenced by selection and thus a better clock. Your only deceiving yourself to believe that the unacceptably high mutation rate is not the primary reason for the rejection of the D-Loop as a reliable molecular clock.

Re:Noah's ark

[Bowling Moses]

"And this is not the situation that occurred, it is only your misunderstanding of the lead-up to parsons paper"

No, apparently I have not made myself clear. What I am refering to (and mentioned previously in passing) is the ample evidence from many different fields (geology, archaeology, paleontology, linguistics...) that provide evidence that humanity is ancient, a point Parsons also makes: "Using our empirical rate to calibrate the mtDNA molecular clock would result in an age of the mtDNA MRCA of only ~6,500 y.a., clearly incompatible with the known age of modern humans. Even acknowledging that the MRCA of mtDNA may be younger than the MRCA of modern humans, it remains implausible to explain the known geographic distribution of mtDNA sequence variation by human migration that occurred only in the last ~6,500 years." Science by its very nature is conservative, so we look at the possibilities primarily by order of plausibility. To consider a date of ~6,500 years is true, we must first investigate all other more plausible explanations first, explanations that I mentioned way back in my first post which the creationists, now six years after the publication of Parson's paper, have yet to consider.

"There were NO experiments done to observe the behaviour of the D-Loop prior to Parsons paper."

This is false. Parsons cites another study conducted along similar lines to his own (Howell, N. et al (1996) Am. J. Hum. Genet. 59, 501-509); he also cites phylogenic studies looking at the same issue. It is interesting that the creationists chose not to cite either the phylogenetic studies or the similar, earlier study (Howell, 1996).

"The dozens of experiments you speak of were ALL conducted as follows: Human and Chimp mtDNA D-Loops are differ by X, and chimps and humans diverge Y years ago, thus the mutation rate of the D-Loop is X/Y."

see the first point and below. And secondly, not all studies were done on humans and chimps, or necessarily between different species.

"The FIRST experiment to measure the D-Loop's actual rate gave a rate 20 times higher than X/Y."

Again, false. It looks like that rate is being revised downwards as well--see Gibbons, A. (1998) Science 279, 28-29: " Several teams of evolutionists promptly went back to their labs to count mtDNA mutations in families of known pedigree. So far, Stoneking's team has sequenced segments of the control region in closely related families on the Atlantic island of Tristan da Cunha, where pedigrees trace back to five female founders in the early 19th century. But neither that study nor one of 33 Swedish families has found a higher mutation rate. 'After we read Howell's study, we looked in vain for mutations in our families,' says geneticist Ulf Gyllensten of Uppsala University in Sweden, whose results are in press in Nature Genetics. More work is under way in Polynesia, Israel, and Europe." Gibbons also mentions that a five-fold higher rate than anticipated is found when all the available data at that time was pooled from multiple studies. Both statemenst the creationists again chose not to mention when citing the article.

"Based on this, scientists proposed that in spite of the fact the D-Loop appears neutral by every known test, we must assume neither X nor Y can be adjusted to fit the experimentally observed rate."

This is incorrect. The D-loop, as mentioned by Parsons: "While the CR [control region of the D-loop] is certainly under less selectional constraint than coding genes, the region has crucial regulatory functions and internal sub-regions display quite different levels of variation both within and between species. Some portions of the CR are thus not as free to evolve as others and it is quite plausible that selectional constraint, while clearly present, need not be absolute between one generation and the next. In this light, it is interesting to note that the observed substitution of the nucleotide at position 234 occurs w

Wacko Sci-Fi Theory

[EvilTwinSkippy]

Perhaps humans haven't always lived here. Think about it, most cultures have an Atlantis-like legend, and a Flood/Migration legend.

Could it be possible that we are the decendents from a crashed spacecraft? Maybe I played Homeworld too often, but doesn't it seem funny that we are the only primates that can:

• Swim
• Choke to death on food (Apes and monkeys can breathe and drink at the same time.)
• Lose our Virginity.
• Cry

(A great site that goes into more detail is: Here.)

At times we have more anatomically in common with a Seal than an ape. Not enough to make me buy a tinfoil cap, but precisely how does an otherwise aquatic creature "evolve" on an Savanna, and then ddevelop their first civilization in the middle of a desert?

Re:Wacko Sci-Fi Theory

[Anonymous Coward]

"Lose our virginity."

Riight...

Re:Wacko Sci-Fi Theory

[EvilTwinSkippy]

Chimps, Gorillas, Monkeys, et. all do not have Hymen. Hymen are rare amoung land-dwelling mammals. The feature IS common in aquatic mammals.

Re:Wacko Sci-Fi Theory

[bananahammock]

Swim? I thought we were the only primates who canâ(TM)t swim instinctively. We have to be taught. Then again, I could be wrong.

Re:Wacko Sci-Fi Theory

[Xilman]

Swim? I thought we were the only primates who canâ(TM)t swim instinctively. We have to be taught. Then again, I could be wrong.

I believe you are semi-wrong. Very young infants can certainly swim instinctively. At around 18 months old they seem to have an instinctive fear of water (unless, of course, they've been encouraged to swim for the previous year or so). It's been suggested that this fear is a survival characteristic, in that you are much less likely to be eaten by crocodiles (probably) or sharks (possibly) if you don't go swimming.

Paul

Re:Wacko Sci-Fi Theory

[jericho4.0]

First; Sorry some idiot modded you flamebait because he thought your a kook.

Second; The features you mention are (I think) quite well explained be Dessmond Morris's 'Aquatic Ape' hypothesis. This says that modern humans are descended from a bunch'o'monkeys that were forced out from the trees/savahna of Africa and found a niche in a reef that existed off the east coast of Africa much like the great barrier reef. I'm not sure about the virginity thing, but the others fit well. It also explains our webbed hands/feet, hairlessness, downturned noses, and fasination with bikinis.

I think the strongest argument for this is the fact that newborns can swim.

Re:Wacko Sci-Fi Theory

[Tyreth]

The problem with this is the similarity of the human method of design, the commonality of DNA, etc. Evolutionists use this as an argument of common ancestor, creationists use it as an argument of common designer. Either way, it eliminates the extra-terrestrial option, UNLESS the aliens too originated from earth (or all life on earth from them), but diverged at some point then rejoined.

Re:Wacko Sci-Fi Theory

[Silburn_Luke]

Second; The features you mention are (I think) quite well explained be Dessmond Morris's 'Aquatic Ape' hypothesis.

Actually it was Alister Hardy who first coined the hypothesis. Desmond Morris mentions it in passing in 'The Naked Ape' and it was picked up by Elaine Morgan as an alternative to what she called 'The Mighty Hunter' narrative of human origins in her 1972 pop feminism book 'The Descent Of Woman'. It is Morgan who is the published writer most identified with Aquatic Ape Hypothesis.

Pro/anti flamefests are a regular occurence on various human origins fora which is probably why the earlier post got moderated as flamebait.

Regards
Luke

Re:Wacko Sci-Fi Theory

[EvilTwinSkippy]

Now you have to ask yourself: how?

I realize that all of these traits are probably dormant in all mammals, and were simply re-expressed in humans through mutation. The enlarged forehead of humans is actually a common feature of infant apes, our forehead simply doesn't receed during maturity. (Though you wouldn't know it looking at the behavior of some people.)

But there is a big problem. We somehow successfully mutated several major features in our Genome in the blink of an eye. To boot, we did it with a relatively small gene pool. Granted, the two could aggrivate each other.

Something REALLY wierd happend at some point in our developmental past. In the absence of any records, fossils, or talking ghosts just about any answer is good.

Re: Wacko Sci-Fi Theory

[Black Parrot]

> > "Lose our virginity."

> Riight...

He seems to be arguing that geeks aren't humans.

Re: Wacko Sci-Fi Theory

[Black Parrot]

> Swim? I thought we were the only primates who canâ(TM)t swim instinctively.

Supposedly chimps have so little body fat that they sink like a rock in the water, and zoos have to be careful about using moat in their chimp displays like they do with so many other animals.

Re:Wacko Sci-Fi Theory

[Anonymous Coward]

So naturally until we have scientific evidence we're going to say that it was gods bidding.

Re:Wacko Sci-Fi Theory

[KillerBob]

... Kinda.

Instinctively, infants will hold their breath if their face is covered. The same holds true when they are immersed in water. But we do have an instinctive swimming method that works fairly well: the dog paddle. It's pure physical strength that prevents a baby from being able to swim instinctively.

What I've noticed as a former lifeguard is that when people drown, their instinctive motion is similar to climbing a ladder. In fact, they're dog-paddling, except that they're vertical. Likewise, the first stroke kids "learn" when they start swimming is the dog paddle. Other strokes, such as front crawl, back crawl, breast stroke, side stroke, etc. are not natural motions. They're swimming motions that we have learned over time to use, because they're more efficient.

The thing is... nobody teaches how to "dog paddle". It's just something that you do.

So yes... infants can "swim". At least, they could if they had the strength and/or stamina to swim. They certainly have an instinctive swimming stroke.

Re:Wacko Sci-Fi Theory

[Zirnike]

I prefer the space aliens idea. More realistic.

Re:Wacko Sci-Fi Theory

[Anonymous Coward]

No, no, no. The aliens obviously genetically engineered us, starting from the existing primates on this planet.

Re:Wacko Sci-Fi Theory

[OpenSourced]

For a possible (rather reasonable) explanation, read "The descent of woman" by Elaine Morgan. She theorizes that human beings are part acuatic, that part of our evolution happened at sea, or rather at the coast making extensive use of the sea. That explains the biped position (to walk into sea as far as possible), the hairlessness (you drop hair as a thermo insulator and get fat instead if you know what's good for you, when you are at sea), the big nose with downward-pointing holes, the crying (eliminates salt by being more saline than normal fluids), and, although she doesn't mention it, the fact that you cannot run faster than a dog, but sure can you swim faster. She made a convincing argument.

Re: Wacko Sci-Fi Theory

[Anonymous Coward]

ahahaha, hilarious :)

Re:Wacko Sci-Fi Theory

[Anonymous Coward]

OK. Will you please tell us what in the world you mean by the claim that we are the only primates which can loose our virginity. Enquiring minds want to know.

(Or maybe we don't. I'm sure I'll be sorry I asked.)

BBC's writer clearly didn't do his homework

[zaad]

It's shocking how much better the San Francisco Chronicle article is to the BBC article.

Clearly both writers had the same source to work with, but the sfgate article was much more researched, thought-out, and nicely tied together. Even when I had only read the BBC article, I was shocked at how poorly structured the article was.

If you're only going to read one of the two, read the sfgate piece.

Re:BBC's writer clearly didn't do his homework

[Madcapjack]

You are quite right. It is much better. Too bad the original post didn't cite this article instead.

Re:BBC's writer clearly didn't do his homework

[waytoomuchcoffee]

You are quite right. It is much better. Too bad the original post didn't cite this article instead.

Um, I did.

And for 700,000 years...

[clambake]

...we have kept trying.

Genetic Lactose Intolerance

[MonkeyBoyo]

What triggered the writeup was the The American Society of Human Genetics journal article. For some reason the SFGate link also discussed the genetics of lactose intolerance, and here I will give some references and discuss how this is relevant to early human evolution and perhaps bottlenecks.

Genetic lactose intolerance (= hypolactasia = non-production of lactase enzymes past weaning) has a hereditary component (Sahi 1994)

It is assumed that thousands of years ago all people had hypolactasia in the same way as most mammals do today. At that time in cultures where milk consumption was started after childhood, lactase persistence had a selective advantage. Those people with lactase persistence were healthier and had more children than people with hypolactasia, and the frequency of the lactase persistence gene started to increase.

The Cambridge World History of Food (2000) has a good article on the science and geography of lactose intolerance. This problem is not caused by the gene that creates lactase but instead by another gene (LAC*R (lactase restriction)) that kicks in later and ramps down the primary gene. (The other allele LAC*P allows lactase production to persist) However that article says:

it seems most likely that the European and Arabia-Sahara centers of LAC*P prevalence, and the Uganda-Rwanda center (if it in fact exists), arose independently. Population movement and gene flow can be very extensive and, no doubt, have played a substantial role around the centers. Despite the efforts of some authors to find a common origin in the ancient Middle East, it is simpler to suggest independent origins than to postulate gene flow from the Middle East to Scandinavia and to the interior of East Africa. The problem might be resolved in the future if gene sequencing could show that the LAC*P alleles in Sweden and Saudi Arabia are, in fact, the same or are distinct forms of the gene with a similar function.

â¦

Finally, the LAC*P and LAC*R genes are interesting far beyond their biomedical significance. Along with linguistics, archaeology, and physical anthropology, further research on lactase genes and other genetic markers will provide clues to the prehistory of peoples, their migrations and interminglings, and the origins and development of major language families.

However in 2002 the LAC*P gene was identified and sequenced within a Finnish population and was found to be the same as those in the rest of the world. This means that genetic adaptation for adult milk drinking evolved early and all milk-drinkers have ancestors in some early population in the middle-east or Africa.

The problem with equating lactose intolerance with genetics is that people will see this as an either/or situation â" either you can eat it or you can't. The fact is that most intolerant people can consume small to medium amounts of lactose with no problem. Major milk problems are more often the result of allergies.

Eventually there is the issue of culture. Fermented milk products (e.g. yoghurt and cheese) may be easier to digest than raw milk. Do the cheese/yoghurt eaters have a cultural advantage? Or have they disadvantaged other cultures?

Re:Genetic Lactose Intolerance

[lukesl]

One interesting thing about "lactose intolerance" is that it's really the default state. Most people in the world are lactose intolerant, with the exception of some rich Western Europeans. Funny how the norm is defined.

Don't panic! It can all be explained Mr Gorilla

[madmarcel]

(Without reading the article...)

I don't know much about genetics but....

IIRC genetic diversity also indicates how
old a 'species' is.

Hence, given the widespread genetic diversity in chimpansees and the low genetic diversity in humans, you can deduce that chimpansees have been around much longer than humans.

The other explanation could be that a single group of humans were so succesfull at some point in the past that we are all descendants of that group.
(oops, thats the same as coming close to extinction - just phrased a different way :)

There are groups of people in the world that are very much genetically distinct from the rest of us. (Eh, Read "The Naked Ape" by whatshisname...)
( Isolated pockets of genetic diversity...stuff like that )

Another explanation could be the life span of chimpansees...anyone know how long they life in the wild? Short lifespan? Females are almost constantly pregnant. Now compare that to humans...long lifespan...relatively low pregnancy rate ( welll...) That could also explain the difference in genetic diversity?
Phrased another way - for an equivalent period of time there might have simply been more generations of chimpansees compared to generations of humans.

Could that account for the difference in genetic diversity (as well)?

BBC should check it's own archives...

[EvilSuggestions]

I don't expect the BBC to do an exhaustive search of all the peer review journals every time they do a science story, but they should at least check their own archives to help explain an curious conundrum like this one.

The date given for the bottleneck, ~70,000 years ago, coincides perfectly with the largest volcanic explosion in the last half million years. One that spewed thousands of times as much ash as produced in the 1980 Mt. St. Helens eruption.

The explosion of Toba in Indonedia around 74,000 years ago probably caused a greater than 5 degree drop in average global temperature that lasted over 6 years. 5 degrees may not seem like much but that global average may translate to over a 15C drop in the summertime temperatures in the temperate regions and would have devestating effects on many of the plants we relied on for food.

Point is that most of what I just mentioned (and much more) can be found in a few articles on their own web site:

• Humans came close to extinction (1998)

  A new hypothesis about recent human evolution suggests that we came very close to extinction because of a "volcanic winter" that occurred 71,000 years ago.

  That article discusses a bottleneck of perhaps 15,000 humans. So the only real news is that the estimate of the bottleneck has been cranked back by an order of magnitude.
• BBC Horizon - Supervolcanoes (1999/2000)
• Supervolcanoes could trigger global freeze (2000)
• Walking with Cavemen (2003)

If it was going to work, it would have by now...

[leonbrooks]

...for Coca Cola.

Well, heck, it seems to have worked for Microsoft software, doesn't it? (-:

Yes, but...

[leonbrooks]

Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

You'd want to pick your eight very carefully, and only five of them would count anyway (unless Shem, Ham and Japheth were adopted sons). There are ancient rumours that Shem looked Caucasian, Ham was black (weird discussion here) and Japheth was basically Asian, I don't know how much credence to give them.

I'd be interested in seeing an experiment with humans like the one that produced an "Aurochs" in Europe some time ago, and a genetic analysis of the results, to see just how well the genetics all fitted together again if it's so. Pity about the two-decade generation time.

Big Volcanic blast ~70K yrs. ago?

[budalite]

This "news" is pretty old. There was even a Learning Channel (or Discovery) show a couple of years ago about the idea of "supervolcanoes", one of which could rest beneath Yellowstone and one (Toba) that, they think, blasted ~70K years ago, causing global average temperatures to drop and nearly causing our species to become extinct. Interesting stuff.

Not Dogs: Cats

[EvilTwinSkippy]

Cats domesticated us.

Think about it. We build structures and pile food in there to draw the mice for them to eat!

We have all seen cat owners. Every house has a little shrine for the kitty cat. They reserve the best seats in the house and the better windows for the cat. And all for what? So the cat can ignore our existance except when it needs to be petted, or just mess with our minds.

Re:Not Dogs: Cats

[Eccles]

Back in my day I had to write games in BASIC, on a 4.7Mhz computer with no hard disk and 128K of RAM.

Hmmph. After a few years of programming, I moved *up* to assembly language on a 1 Mhz 6502 with 64K of RAM.

These young whippersnappers...

Re:Not Dogs: Cats

[SirTreveyan]

After a few years of programming, I moved *up* to assembly language on a 1 Mhz 6502 with 64K of RAM.

These young whippersnappers...


I moved up to programming on a 500kHz 4004 with 5 kb of RAM ( 1 kb code segment and 4 kb data segment ) with a grand total of 45 assembly instructions.

Prior to that I had been programming on Greek abax, the same device that Archimedes was working with when he was killed by a Roman soldier.

Re:Not Dogs: Cats

[Sloppy]

64K of RAM? You spoiled brat! I remember programming my VIC20, wishing I had one of those fancy 64K machines. OTOH, I probably would have gone insane, waiting for something that big to load from the tape drive, so maybe it was for the best.

Re:Not Dogs: Cats

[Eccles]

64K of RAM? You spoiled brat! I remember programming my VIC20

Yes, but the 64K was a move *up*. I was programming before there were Vic 20s... I only missed punch cards in college by a year.

That would be the Masai. (admittedly -partly -OT)

[SolemnDragon]

And on the subject of the Masai, cattle are sacred to them, a gift from the god(s), and they generally don't kill them. In fact, they gave the USA fourteen cows in the wake of 9/11- a collective donation from many tribes, and (for them) a priceless gift. Our ambassador refused to accept it.

I don't know what happened to the cows. I do know that the Masai do, indeed, drink blood and milk mixtures. Having lived with a Jewish roommate, i can remember the look of horror on her face as she tried to interpret it into kosher food concepts.

Lactose Intolerance is not the only intolerance out there... Gluten intolerance hits 7% of the population (including me.) More women than men, mostly northern european descent. Me with my scottish pale skin and my german grey eyes, it's got my grandmum, my mum, my sister, and me. Skipped both brothers.

Part of my point being - there are genetic variations that are gender specific, there are genetic variations that are region-specific, and there are genetic variations that we're only just discovering. Another part of my point being- Lactose intolerance is unbelievably common. And i miss ice cream and milk. Lactase tablets aren't enough for a lot of people out there, that's how severe we're talking... I think maybe there are a number of changes that happened regionally, and now we're seeing the results as cultures blend. My dentist talked about it all the time, how asian teeth and african teeth and european teeth are similar but jawlines differ, and when you get different genes kicking in for jawbone and teeth it sometimes leads to really good combinations and sometimes leads to surgical correction so that the kid can chew. He said this in a completely nonracist way; he thought it was a great idea to blend genetic and cultural groups together, so he was more than happy to help correct the results of problem combinations, because they could usually be helped and their appearance meant that new combinations were always being created.

Oh, and about the Masai. Don't mess with a people who kill lions by hand. These are the people from the movie the ghost and the darkness- flushing out lions by shouting and beating the brush...

Toba

[4of12]

I'm surprised that article didn't pick up on the theory that the bottleneck in the genetic line about 70K years ago might well have been due to the eruption of the Toba supervolcano that was regarded as one of the most significant eruptions in the last 2 million years. That kind of climatic change from such an eruption could well be responsible.

Re:Toba

[Black Parrot]

> I'm surprised that article didn't pick up on the theory that the bottleneck in the genetic line about 70K years ago might well have been due to the eruption of the Toba supervolcano that was regarded as one of the most significant eruptions in the last 2 million years.

Yeah, this "news" is pretty old. I've heard the exact hypothesis that you suggest scores of times on talk.origins over the past several years.

Re:That would be the Masai. (admittedly -partly -O

[EvilTwinSkippy]

Thank you, it was the Masai I was thinking about. I just was too lazy to google around and find it. I've got a mind that remembers really off the wall facts, and can call them up on demand. Details... well, they don't seem to store quite as well.

For my part, I react rather violently to a protein generated by dust mites, and my immune system is not too fond of mold and mildew either. Wherever my ancestors came from, they must not have kept a lot of food in the fridge, and if the stayed indoors must have kept the place spotless. Which is odd, because most of my family is from Ireland, which is rainy and damp, where you are stuck inside a lot in an environment that is a breeding ground for mildew.

Go figure.

Do your bit for genetic diversity!

[A55M0NKEY]

Wear uranium underwear!

Re:Do your bit for genetic diversity!

[Anonymous Coward]

1. Wear uranium underwear!

2. ?????

3. Profit!

One Word

[LittleGuy]

Gilgamesh.

Every civilization that can trace its culture back to Mesopotamia has its own version of the epic.

RTFA

[BoomerSooner]

We are all from about 2000 people. This is why our genetic diversity is non-existant. The Bible is fucking fiction. Unfortunately that means Christianity is bullshit. Ah well, fear driven religion is where it's at. At least Scientology has the balls to straight up make you pay to be "enlightened". Oh wait so do the Mormons (Jesus in North America? lol, that is fucking hilarious).

Genetically similar = extinction

[bobthemuse]

I don't get it... How does being genetically similar make us close to extinction? I can see how it would slow evolution, assuming a low rate of non-lethal mutation. Are they assuming that a cataclysmic event (such as a disease) will occur and we won't have the genetic diversity to find people who are immune? Then again, maybe this makes sense. Think of the recent major disease outbreaks... AIDS, SARS, etc... what percentage of the population is immune to these diseases again?

Re:Genetically similar = extinction

[Anonymous Coward]

Past tense: not close to extinction but that we were once on the verge of extintion in the distant past (~70,000 years ago). This shows up due to the in the lack of a greater genetic variation in us. Genetic variations occur naturally at a determined rate and therefore allow you to calculate the time since the common ancestor.

Re:Genetically similar = extinction

[ChrisMaple]

You reversed cause and effect. Being close to extinction in this case means a very small population. A very small population is likely to have a reduced amount of genetic diversity.

Measure of genetic diversity

[bobthemuse]

As I remember from high school biology, doesn't only a small percentage of our DNA code for useful information? The reset was just junk that is cut out during protein synthesis (introns? extrons? I forget the terms...) Is this included in the study? Could it be that chimps are also extremely genetically uniform in the areas that matter, but they have more diverse "junk" material than us? Then again, I seem to remember someone saying that the "junk" DNA plays a vital part in evolution? Argh, guess I shouldn't have slept through those classes! Now we'll all become extinct!

Re:Measure of genetic diversity

[thomasmd]

they don't mention "junk" DNA, and I couldn't even find the original article (why in the hell wouldn't the BBC reference it?). What is called junk DNA makes up the vast amount of our 3 billion base pairs, but junk DNA is different than intron DNA (and exon), and there is increasing evidence that Junk DNA may actually be very important. As far as diversity, that usually refers to differences within coding DNA, not junk DNA.

Re: Measure of genetic diversity

[Black Parrot]

> As I remember from high school biology, doesn't only a small percentage of our DNA code for useful information? The reset was just junk that is cut out during protein synthesis (introns? extrons? I forget the terms...)

I think they call the junk "enrons".

SARS Alert!

[Anonymous Coward]

Subject says it all.

Re:SARS Alert!

[2nd Post!]

Asians who eat dairy products are SARS flags now?

Swimming

[TamMan2000]

In 1959 Koshima macaque monkeys learned to swim, ever since then the entire group can swim...

Also in American colonial times the only human swimmers were witches...

The other arguments are interesting, but the swimming one is weak.

Re:Swimming

[InsaneNinja]

The "witches that could swim" thing may have something to do with the rough work at the time.. Since everyone in the area was farmers, blacksmiths, shopkeepers, or jobs such as that..

Low bodyfat = bad floaters/swimmers

and since the commmunity was ruled by manly men types.. the weak people or lazy women, aka outcasts.. could float, and were an easy scapegoat

we are almost all lazy today compaired to those times, which is why most of us have an easy time swimming

at least thats my ideas on that subject..

Re:Swimming

[TamMan2000]

The best swimmers are among the people with the lowest body fat, just look at triathletes, and olympic swimmers.

I used to be much more plump than I am now, and swimming was no easier (perhaps harder) then, than now.

People just weren't taught to swim.

lactose intolerance

[Mr. Slippery]

Lactose intolerance is the norm in many parts of the world.

LOL

[Martin Spamer]

LOL. Though I was actually thinking more along the lines of "souring the mothers breast milk" allowing the mother to suckle another infant.

Goats, not cows

[Tablizer]

Why didn't they domesticate goats for milk production instead of cows? Goats don't produce lactose in their milk. We can't easily switch now because goat milk tastes too different from cow's milk. We are too used to the taste. Cow milk is kind of like the QWERTY of milk.

Re:Goats, not cows

[Anonymous Coward]

Goat products fucking reek you spastic. Try actually eating goat meat or something. And goat meat has lactose in it (surprise - it's milk ffs.)

I know what happened

[Tablizer]

Tribes leaders started outsourcing all the hunting to the Neanderthals, and almost ruined humanity.

4000? Whooping Crane

[ChrisMaple]

Ever population has a magic number that determine the minimum number of individuals required to maintain its existance. For birds this number is about 4,000.

Whooping cranes reached a population low of 22 (16 if you count only those that now have descendants). The population as of 1993 was 150 and growing.

We lazy cows managed to tame humans ...

[Anonymous Coward]

As gathering food on our own was getting harder
we decided to breed a special kind of humans -
such that can drink our milk. These humans
started to provide us with food and shelter.

I must admit - taming of humans was the greatest
achievement in our lazy cows history.

Diversity in small groups

[aldousd666]

The genetic diversity in small groups means that there is a large (and most likely old, or geographically spread out) gene pool. A wandering chimp from a far off tribe has a thirty second affair with a local, throwing a whole new set of genes into the mix; thus all the other kids could possibly mate with the child of this 'affair' and be combining not only local, but distant DNA. This implies that the people who gave us all the line of DNA we have, didn't intermix with other tribes because there weren't any. If there were others, then people from different places in the world would be more genetically diverse than they are. They would have contributed their isolated and separate DNA chains to their lines, only crossing others later, when people went global, thus retaining their diversity. Hence the conclusion: we went close to extinction.

OF course there is the possiblility that it's all a freak matter of chance, or that people were so damned mobile that they never were truely genetically isolated from any of the others. Neither of these two conclusions are very likely, because we are relatively different (skin color etc), and it does roughly correspond to geography; it seams there was indeed a good bit of isolation, enough to diverge recognizably at least. So still, we're probably very closely related, and came close to extinction.

you can so quantify diversity!!!!

[Anonymous Coward]

If geneticists needed to discuss gene diversity in some sort of quantifiable measure, it would eliminate their ability to discuss relevant topics. Unless you are referring to a specific sample of genes, you can't quantify the diversity.

Leave it to an anthro major to pull out bullshit like that.

Meanwhile, in the scientifc world, diversity has a specific technical meaning that can be measured using "H," or entropy, from Claude Shannon's information theory -- which is similar the measure of entroy in physics.

H(p) = - sum[i=1..X] (pi * log pi)

Just take Shannon's equation, plug in allele frequencies for the population (maybe use log base 4 for 4 base pairs?) and presto, a quantity of diversity

Re:you can so quantify diversity!!!!

[Inexile2002]

But you have no concrete values to plug into 'p'. Why the hell go through the trouble of using an exacting formula when you're talking about inexact data? And if you have specific samples, you don't need to talk about diversity since you can talk about the specific genetic differences.

Sheesh! I work with enough bean counters all damn day, I don't need them here too.

Answer = Time

[abbamouse]

I teach this data (prior studies) as part of my lecture on Race in Politics (I like to disabuse my students of the notion that race is a useful biological marker or indicator of genetic variance). Here are the answers from my reading of other studies:

1. Chimps have remained a distinct species filling their ecological niche for far, far longer than homo sapiens. Genetic changes have had more time to accumulate.

2. The 2000 indidivuals from whom we all descend didn't have kids that continued in isolation from the others in that group. Rather, they interbred continuously, meaning that what genetic variance they had was them passed around to all of their descendants over time. There were more than 2000 chimps, presumably, and they tended to split off and diverge more rapidly afterwards due to the fact that their habitat is more likely to split into isolated "islands" over time. (Humans can exist in many habitats, even with Stone Age tools).

3. "The Urge to Merge" -- Every time two previously isolated groups of humans make contact, they start to mate. This results in the little variance we do have being shuffled around even more, further reducing average variance.

Athleticism

[Anonymous Coward]

So why is it that Europeans and Asians are not as athletic as Africans? Europeans and Asians also tend to be shorter. There may be a few exceptions to this of course.

Re:Athleticism

[Reaper9889]

Wouldn't you be more athletics if you run 15 km to school and back each day you think? That really happend cause the few nr. of schools down there.

Goats are Full of Lactose

[MonkeyBoyo]

Goats don't produce lactose in their milk.

From the Ontario Goat Milk Producers' Association

Many people with cow milk allergies can drink goat milk because it contains a different kind of protein. Goat milk has 13% less lactose than cow milk, and 41% less than human milk.

A possibility

[kramer2718]

IANAG (I am not a geneticist), but a possibilty could be that the groups of Chimps refered to in the article could have been found in zoos and taken from completely different locations/lineages.
If the group of two thousand that survived happened to be lucky enough to have come from the same approximate lineage, they would not have an large amount of genetic diversity compared to the much larger group of chimps (which would then be sampled fairly randomly for inclusion in zoos).

70,000 years only? When did we settle in aus?

[Anonymous Coward]

I thought that was 100,000 to 200,000 years ago. SO how did we get to austrailia before getting out of arfica.

Could it be that there were many out of arfica events? SOme went east to asia and aus etc and there was little genetic variation until a second migration 70K yeas ago that fed europe and the US?

Read these papers...

[sonamchauhan]

The Bible is correct.

Read this post discussing these papers/articles:


Paper #1) Danish and Middle East population could have diverged 4,500 years ago
----> Fits with the Biblical description of human dispersion occuring after the flood (around 4,500 years ago as well).

Paper #2) 20 times faster observed mtDNA Mutation Rate
----> Genetic bottlenecking can be approximately just 150,000/20 = 7,500 years old. Fits Biblical description of "bottlenecking" down to Noah's family 5,000 years ago.

Paper #3) 1 male root lineage / 3 sub-lineages / only 1 of these 3 has 7 sub-sub-lineages that populate the world outside of Middle East and Africa.
----> Remarkable fit with Biblical story of Noah, his 3 sons, and the 7 descendants of only one of the 3 sons ("Japeth") populate the rest of world. The other 2 sons and their descendants populate the Middle East and Africa.

Skin Color

[Quill_28]

Being nice and white, it there any physical advantage for having light skin?

It seems physically(not trying to get in a social debate) that dark skin would only be advantageous(you don't burn as bad), less skin cancer?

Ideas either way.

Re:Skin Color

[afreniere]

Being nice and white, it there any physical advantage for having light skin?

It seems physically(not trying to get in a social debate) that dark skin would only be advantageous(you don't burn as bad), less skin cancer?

Ideas either way.

I believe those with darker skin need more sunlight to produce enough Folic Acid and Vitamin D. Thus the adaptation to lighter skin when we moved North to the Cloudy Continent.

-Ansel.

Re:Skin Color

[Anonymous Coward]

Two current theories of the reason for dark skin:
1- Melanin absorbs UV, thus providing some protection against somatic mutations (ie. cancers, burns)
2- Melanin is rather toxic to bacteria. Because some insects (and maybe other organisms, I'm unsure) make of use of it in immune responses to infection, some have suggested that humans may as well.

Because both UV and infectious microorganisms are found in higher doses and larger quantities in sunnier and more humid regions, it is suggested that having melanin-rich skin is extremely useful.

Why do caucasians and asians have lighter skin? Perhaps because they inhabit regions deprived of sunlight compared with equatorial areas (as you travel away from the equator, the intensity of the sunlight becomes progressively lower, because it has to travel further through the atmosphere to reach the surface). Sunlight is necessary for the photosynthesis of active vitamin-D which is an essential nutrient, therefore, the lighter the skin, the more vitamin-D is available.

Caucasians and light-skinned asians probably had to make a trade-off between cancer/infection protection and sufficient nutrient synthesis

Re:Skin Color

[Anonymous Coward]

When a population doesn't use a trait over evolutionary significant time (eg, humans in Scandinavia & melanin), there tend to be mutations that disrupt the trait. Folks with these mutations die in Nairobi but survive in Oslo.

This is why melanin tends to track with latitude.

Apparently, one can also track a culture's acquisition of fire and pottery by the size of their teeth - fire means less wear on teeth, so they can start out smaller, and pottery+fire=soup, so you don't need teeth at all.

The is all according to my anthro prof, CL Brace. I understood how folks got new, useful traits, but I didn't understand how folks *lost* useless traits until I heard this.

If you follow the Bible...

[dunedan]

then yes we were close to extinction at least twice.

Funny how evidence that could *easily* be used to support religion is always seen as new insight into our current scientific theories. Even if it doesn't always fit right.

Re:If you follow the Bible...

[Cackmobile]

except it does. funny how religious people never need evidence to back their theories. Just the bible

New Find Shows Modern Humans in Africa 160k YrsAgo

[Cy Guy]

The article says the discoverers think the find in Ethiopia supports the "Out of Africa" hypothesis, and that the bones are similar enough to modern huimans to be classified as Homo sapiens but a different (ancestral) subspecies Homo sapiens idaltu - idaltu meaning "elder" in the local tribal language.

An curious thing about the find is that the sculls were found but without the bodies, or even the jawbones. Other evidence indicates they some of the sculls may have been used in a ritual, or possibly be the victims of cannibalism.

Your Sig

[sig cop]

Self-referential sigs are passe.

Reading the Headline...

[Master of Transhuman]

one hopes...

Probly within a single troop diversity would drop

[Szplug]

Even if it started out high. I think male chimps move between troops, so the 'within a single troop' bit was just to make a point; but, probably the diversity within any given troop is maintained by contact with others further afield. Whereas humans maybe at one point were only one or a few troops.

You RTFA.

[balaam's ass]

It is a mystery to me how this rant got modded "3, Insightful". How about "-2, Pathetic"? How did we get off the topic of genetic diversity and onto the topic of offensive, ignorant rants against Christianity? In fact, neither article says says anything about the Bible or religion at all. With a title like "RTFA", you'd think he'd have something to say about one of the articles. Next time, RTFA yourself, and please read "Important Stuff:" before you post, mmmK?

Just read

[Cackmobile]

That relatd story on Supervolcanoes. Quite scary. I really believe if it did blow civilisation would break down. You see in places where things go wrong how quickly we reverse back to mob mentallity/survival of the fittest. Imagines this on a worldwide scale. This is why we need to expand to other planets. If its happened before, it can happen again.

Why keep all our eggs in one basket, so to say. Its very well then that we have the article about nanotube production so we can finally get off this planet with the help of a space elevator.

Earth, what a shit hole. from Alien Resurrection i think.

Sensationalist reporting?

[20_ooodbye]

It's a bit of a leap from saying that all currently alive humans appear to be descended from a population of 2 000 individuals to saying there were only 2 000 of us left at that time.

Surely itâ(TM)s just as likely that one population of 2 000 superseded the rest of the humans about at the time

Re:That would be the Masai. (admittedly -partly -O

[dvk]

> Having lived with a Jewish roommate, i can remember the look of horror on her face as she tried to interpret it into kosher food concepts.

Uhm... IANAR(abbi), but what's there to interpret with such difficulty? Animal blood is not kosher. Period. Presense of a milk in the mix is irrelevant, then.
(Now, if blood WAS kosher, then the question would also be simple: does it count as "meat" product or not?).

Then again, that's probably why I'm not a Rabbi :)

Clones?

[charlieo88]

Wait till the Raelians read this. Yet another news cycle of supremely ugly people trying to make exact copies of themselves. Yeaash!

This is NOT new.

[Evil Pete]

OK came to this topic a bit late so dont know if anyone will see this, but ...

This bit of "news" has been well known for years. Though I think the figure mentioned previously was a population of "less than 10 thousand". I guess the figure of 2,000 is a refinement.

I am amazed however that they don't mention the most likely culprit for this catastrophe. There was a volcano, sorry I don't remember the name, that exploded 70,000 years ago ... biggest eruption in the last 100,000 years I believe ... surely more than just a coincidence.

Re:That would be the Masai. (admittedly -partly -O

[Anonymous Coward]

I think the horror was not over whether it was legal or not, but the sheer overload of prohibitions.

Blood prohibition and not mixing dairy and meat.

Re:That would be the Masai. (admittedly -partly -O

[Grishnakh]

Which is why people should just dispense with such superstitious nonsense and what whatever they want.

Although I can't imagine mixing blood and milk (sounds worse than putting ketchup on a chocolate cake), but I reject the idea because of my own opinion, not because some stupid book says it's bad, mmmmkay.