1.8 Million-Year-Old Skull Suggests Three Early Human Species Were One

ananyo writes "A 1.8 million-year-old human skull dramatically simplifies the textbook story of human evolution, suggesting what were thought to be three distinct species of early human (Homo habilis, Homo rudolfensis and Homo erectus) was just one. 'Skull 5', along with four other skulls from the same excavation site at Dmanisi, Georgia, also shows that early humans were as physically diverse as we are today (paper abstract)."

Comments

Obligatory creationism troll.

[Anonymous Coward]

What! Science says that there were three different species of humans, now it says that there was only one. See. Scientists keep changing their mind. How could you put your faith in them? Put your faith in Jesus, God and read the bible instead. The truth in bible doesn't change over time, unlike science. Creationism triumphs over evolution once again.

Re:Obligatory creationism troll.

[flyneye]

No no, Homerus Scientificus. He tends to believe any piece of bone he finds still has meat on it. mmmmmmmmmmm

Re:Obligatory creationism troll.

[Empiric]

I was just scrolling by, minding my own business; when I saw your little faux passe about the truth in the Bible not changing over time.

You actually didn't address his statement at all. While it's fun to talk about how many books there were, and how many changes there may have been, it actually doesn't make any more difference to the truth of the content than book editions today, or how many may be rejected by a publisher covering the same topic. Far from "whimsical", the criteria, determined at absolute minimum, by people deeply engaged in the topic at the time, was largely consistency with the baseline, most-trusted documents. If the writing lacks consistency with those, or even internally with itself, by any criteria it should be rejected--and that is precisely the basis by which they were. Christians tend to believe that the bible accurately transmits the essential truths of the religion due to the historical guidance of God, but your argument doesn't even rise to being a valid criticism of, say, the most mundane topics such as the creation and selections of a textbook on physics.

And, the notion that the essential truths to be conveyed was selected based on political considerations is highly implausible, as the core was selected by Irenaeus before 200 AD, well before the Catholic Church had notable political power to "protect" by your fanciful notion of "political" motivations. Since you didn't present even the barest notion of some political gain to be had even theoretically, by means of some relevant theological conclusion that could be "manipulated", how about you make something up now, to fill in your argument that much, at least?

If you can name an essential difference in actual doctrine (analogous to presuming wildly varying accepted understandings of physics because of physics books typos or consolidations) that one would derive differently based on the history of the documents, that is, the "truths" that are proposed to be there, to make your argument relevant, then do so and we'll take it from there.

Here'e the problem

[jbmartin6]

A nice example of the problems with using a point in time technique like taxonomy and applying it to an extended period of time. There's no single point where one species transforms into another, this is a very slow process. Any given sample, depending on where it is on the timeline, could belong to two different species. All the homo this and homo that is pretty much a waste of time, or so it seems to me.

Re:Here'e the problem

[G3ckoG33k]

It is not exactly like that. It is rather that any given sample along one line, regardless where it is on the timeline, belongs to only one and the same species, regardless of evolutionary change! A new species is _only_ formed when one line is split into two lines. And even more surprising, to many, then is that neither is the same species as their ancestor, for solely technical reasons.

Re:Here'e the problem

[jbmartin6]

You are correct, I think I should have clarified by saying that the point on the timeline where a new species is formed is entirely arbitrary, and an individual at that point is wholly compatible with some number of generations to either side.

Re:Here'e the problem

[brunes69]

The true definition of species is a group that can and do inter-breed to make offspring. So, the line actually *IS* very clear cut... as soon as a mutation occurs that branches one set so they can no longer reproduce with the other, it is a new species. The problem is, determining that point in history using only archeology is very difficult and full of guesswork. Even if you have the DNA from all 3 sides of the tree, we aren't adept enough yet to be able to look at two pieces of DNA and say "yes these two could reproduce and make viable offspring", vs. "yes these two could reproduce but their offspring would all be sterile". That is when you form a new species.

Re:Here'e the problem

[TapeCutter]

A new species is _only_ formed when one line is split into two lines.

Yes, but pinpointing the "split", is quite a problem. You don't need fossils to show this 'problem', it can be seen in what are known as "ring species" that are alive today.

Basically one species spreads both directions along a circular geological boundary. Despite the fact that all individuals along the expanding route can breed with the different races on either side of them, when the two expanding ends of the population meet at the other side of the boundary, they have become distinct species that can no longer interbreed. There is no point along the genetic line where the species forked, yet fork they did since each "end" of the route is a different species.

Another more linear example (like the fossil record) are the changes that occur as a species expands it's range up a tall mountain, there's a continuum of slight genetic variations from the species at the bottom of the mountain to the (different) species at the top. Again, there is no point on the genetic continuum where it can be said the species "split".

Re:Here'e the problem

[Hognoxious]

The true definition of species is a group that can and do inter-breed to make offspring.

It's not as simple as that.

So, the line actually *IS* very clear cut... as soon as a mutation occurs that branches one set so they can no longer reproduce with the other, it is a new species.

What mechanism do you propose for causing the same (or at least compatible) changes in all the group at the same time? It's pretty unlikely to happen by chance.

Re:Here'e the problem

[brunes69]

Normally what causes the group to become differentiated is not a matter of "all at the same time". Groups become differentiated because they stop cross-breeding outside the group, due to either environmental or social barriers. Over time, these isolated groups develop their own mutations that are specific to them. And over an even longer period of time, they would not be able to reproduce with animals in the other group. It's no different than the process that resulted in humans evolving different feature sets in different regions of the wold, because of isolation... if humans had remained isolated and never developed technology, then eventually we would have split into many different species.

1.8 Million-Year-Old Skull Suggests ...

[mrwolf007]

Man, the real story here is the skull.

It dont really care what it suggests, the mere fact it was talking is creepy...

Re:1.8 Million-Year-Old Skull Suggests ...

[mrwolf007]

Actually i was just poking fun at the title, for claiming "1.8 Million-Year-Old skull Suggests ..." instead of reading "Scientists studying 1.8 million year old skull suggest ...".

Re:1.8 Million-Year-Old Skull Suggests ...

[znrt]

ok, thanks, guys.
to my skull: woosh!

Re:The Problem

[Arancaytar]

Yeah, yeah, sure. We've become such an awful species now, compared to the enlightened past when slavery and genocide were considered a-ok.

Stuff we know and stuff we assume

[cripkd]

I really have question and then it's not ironic or rethoric.
How do scientists know, when it comes to any prehistoric animal or human skeleton, when an individual becomes to a new species, to some sort of missing link or just-split subspecies, and not just a slightly different individual belonging to a known species?
I mean how do they know when a lightly larger bump on a skull is not normal variation and it's for sure a new species where all individuals will have that bump?
What puzzles me is that we find like 0.00000000001 of all living individuals from that time and species and yet we know it's relevant.

Re:Stuff we know and stuff we assume

[gd2shoe]

How do scientists know, when it comes to any prehistoric animal or human skeleton, when an individual becomes to a new species, to some sort of missing link or just-split subspecies, and not just a slightly different individual belonging to a known species?

When it permits them to publish a paper.

No, I'm serious. When I was in school, the best lecturer in the department was almost canned because the department didn't want to give him tenure. Their excuse? (among other things) He didn't publish enough.

The pressure to publish is enormous, often to the detriment of real science.

Re:Stuff we know and stuff we assume

[rasmusbr]

I think they look at the complete picture and make their best guess based on all the evidence that they have and the best models that they have. The species concept is also inherently fuzzy. I'm not a biologist, but I've been told it can be fairly hard to tell if two living organisms are of the same species or not. Obviously, we should not expect perfect certainty about individuals that died 2 million years ago.

Scientists never really know anything, because knowing something with full certainty is an absurd idea. When it comes to the distant past our best hope is to be able to paint a rough picture. Of course, advances in chemistry and physics may make it possible to analyze fossils at the molecular and atomic level and find out all sorts of amazing things about them that were previously thought impossible, but even then the whole detailed picture will always elude science.

Creationists love this, but the problem with biblical creationism and Islamic creationism is that if there was a global flood 4000 years ago there would still be a global flood today, because there is nowhere for the water to go. Also, the moon missions would have crashed into the firmament that holds the flood gates to the waters beyond when they orbited the moon since the moon is attached to the firmament. It's funny that there are grown men that hold on to early iron age beliefs about the cosmos...

Re:Stuff we know and stuff we assume

[MightyMartian]

Short answer... They don't, not directly anyways. What they do use is techniques like comparative anatomy to determine if a substantial morphological differentiation in existing closely related species similar to those found in fossils represent two different species. But really, the idea of species is somewhat a convenience even in extant populations.

Re:Does this support creationism?

[abdullah]

No, but It highlights that more scientific rigor is needed around evolution theory, something like this http://www.youtube.com/watch?v=xoMAp8Q7nZM supports creationism

Re:Maybe an anomaly

[Patch86]

That's pretty much the problem for the whole field. There are so few complete specimens (we're talking dozens, rather than hundreds) and they're generally so diverse geographically and chronologically that is becomes very difficult to say whether something was "species wide" or just individual variance. So you find a 4 foot tall skeleton on an island and you might be tempted to say "I've found a new miniature-species of human!", conveniently forgetting the fact that you only have one skeleton and dwarfism is a relatively common feature of the only human population we have a good sample of (modern us). That skeleton could have been the only 4 foot tall adult within a 100 mile and 100 year radius, and yet there's no way of telling unless you can find more specimens that agree or disagree. And those specimens may simply not exist to be found.

I've always found fields like archaeology & palaeontology particularly fascinating for this reason. It's one of the few areas of science where there will be some things that simply CANNOT be known, because no evidence has survived of it and we can't ever study the past directly. It is one of the only areas of modern study where there is a real sense of mystery that will never and can never be lifted. Every little discovery we make is like finding a single piece of a 100 million piece jigsaw- you learn something, but the balance of things not known is still colossal.

Offspring of a mule

[gd2shoe]

We like to think that it's clear-cut. When it's not, we quibble over just how to redefine "clear-cut".

http://en.wikipedia.org/wiki/Mule#Fertility

It seems we may be at the very tail end of Horse/Donkey differentiation.

(Yes this is an assumption on my part, but I doubt there's good reason to think otherwise. A case to demonstrate this for more than two generations is probably too statistically unlikely to ask for. It might conceivably be possible to get Donkey genes into the Horse population with a couple of really lucky generations. IANAG)

Re:Offspring of a mule

[brunes69]

I don't see how this contradicts the traditional definition of a species. Mules are infertile. Therefore they would not survive as a species in the first place if it were not for human breeders. They would just be essentially one-offs that happened occasionally in the wild, and die off. This is how evolution works; the mule would not be a successful species evolutionarily speaking.

Re:Offspring of a mule

[gd2shoe]

You didn't read the link, did you. Some female mules are not infertile. It's just incredibly rare.

If a fertile female mule mated with a horse and produced a fertile female offspring, it could lead to convergence between one donkey and the horse population. Even assuming I know what I'm talking about (I've made a number of genetic assumptions), the odds of this are extraordinarily unlikely... but baring a particularly good reason why not, it is technically possible. Saying that it doesn't work because they're different species would be begging the question.

Jesus wasn't white

[tepples]

God's own son wasn't especially white. The Bible makes it clear that he looked like a typical Galilean Jew; otherwise, he would have found it a lot harder to mix with crowds.

Day-age creationism

[tepples]

Yeah, I'm with you. I believe in day-age creationism, that the "days" of Genesis 1 correspond to periods up to billions of years. The Bible makes it clear in 2 Peter 3:8 that time periods from God's point of view aren't necessarily literal, and before the emergence of Homo on the sixth creative day, God's was the only point of view. Even English has idioms like "the good old days" and "back in the day". This and God's use of evolution as a tool show no big conflict between Genesis and the fossil record.

Re:Day-age creationism

[MightyMartian]

A *literal* interpretation of Genesis conflicts explicitly with the science. I think it's important to point out that the poster you're responding to clearly does not interpret Genesis literally.

I have absolutely no debate, save perhaps on philosophical grounds, with a Christian who accepts the age of the universe, the Earth and with evolution. Obviously any kind of theistic evolutionist is going to assert that God guides the process to one degree or another, but providing they're not claiming there is scientific evidence to that effect, then really, they accept as I do that humans, and indeed all life evolved from a common ancestor.

Re:Day-age creationism

[Camel Pilot]

If God uses evolution as a tool ... Then this alleged Being is not Good and Omnipotent. Darwin when he fully started to understand that ramifications of his theory remarked that:

"What a book a Devil's chaplain might write on the clumsy, wasteful, blundering low & horridly cruel works of nature!"

What sort of God would use evolution, lubricated with the blood, guts and unrelenting cruelty, as a means to bring about his favored species or race? Just doesn't make any sense.

Nevertheless Genesis is a earth centered creation story... told from a species centric position. I can't believe anyone would give it any stock or think it has some resemblance to reality. The one thing we do know is that the earth wasn't created first with the stars created at a latter date.

Surprise

[PopeRatzo]

I never knew before reading Slashdot how many "tech nerds" really hate science.

I wonder how many of them are angry because they couldn't cut it.

Re:Surprise

[MightyMartian]

Some things can be accepted with a high degree of certainty. It strikes me that it is almost certain that all life evolved from a common ancestor. It also strikes me as almost certain that the Earth and the other planets condensed out of a cloud of gas and material orbiting the young Sun. It also strikes me as certain that the observable universe was once very hot and very dense and began to expand and cool about 13.5 to 13.7 billion years ago.

There is not Truth in science, but there is something like provisional truth.

Re:Surprise

[MightyMartian]

Calling something "provisionally true" is hardly a trap. It recognizes the high degree of certainty while still suggesting that it, like any "fact", can be altered by future evidence.

Simply put, some things are known with a such a high degree of certainty that it would be all but impossible that it would be outright overthrown. We know, as much as ever can be known, that stars are fueled by fusion reactions. That's not to say that the picture is completely clear, or that as-of-yet unobserved phenomena are not at play, but the theory is so well grounded in our understanding of physics and in observation that we do not expect it to be ever overthrown. Enlarged, yes, perhaps even subsumed into some new theory of matter/energy interactions, quite likely.

It's rather like Newtonian mechanics. It would be incorrect to call them outright wrong, since, for most non-relativistic calculations (like, say, putting a probe in orbit around Jupiter), they work very very well. While certainly supplanted by GR, they remain a useful simplification for most real world applications.

Damned few scientific theories have been outright overthrown. I suppose a few, like alternative theories of continent formation and movement, have been pretty much eliminated by the theory of continental drift, but generally a theory is the product of a considerable amount of effort to explain the data by numerous researchers, sometimes in different fields. Thus a theory is almost always fairly rigorously built, debated and modified. It may ultimately be "wrong" in the same way that Newtonian mechanics is technically wrong, but in that case it is almost always subsumed into a larger theory.

I would put Linnaean taxonomy in the same category. It clearly is an antecedent, probably the major antecedent, to Common Descent, but in and of itself, isn't always strictly "right" (look at the debates of how many hominid species there might have been), but is still a useful taxonomical system, and has readily been adapted and altered by new evidence from extant and extinct species.

Re:Surprise

[MightyMartian]

Do you actually think theories like plate tectonics or Proto-Indo European were developed at the margins? They may have initially been developed by researchers who, by the mere fact that they posited theories, were in the minority, but their success didn't come because the researchers dared to develop a new model, but because ultimately their models best explained observation, and just as critically, made further predictions as to what we ought to find if we went looking.

There's this great myth in science, perhaps promulgated by the likes of Popper, that science is a series of revolutions terminating periods of retrenchment and even inactivity. But an actual analysis of science demonstrates that for every "eureka!" moment, there are probably a hundred slow steady research programs that work towards modest goals, and its the sum of those programs' (successes and failures) that builds towards new understanding.

Sad comment on the "science" ....

[fygment]

5 skulls leading to pronouncements on the species and its evolution?!

5 of several tens or hundreds of thousands is not statistically significant.

This is why creationism can survive, because it at times makes as much sense as the extraordinary extrapolations tossed out by scientists.

Make it right. Demand that the scientists also share possible margins of error (in this case HUGE).

Re:Sad comment on the "science" ....

[koan]

Science has a tendency to correct it's self, creationism does not, you see that's the trap of religion, in order to be valid it must remain unchanged.

Because if you change it.... =)

Re:Sad comment on the "science" ....

[Bite The Pillow]

The article has a few quotes from opposing viewpoints essentially calling bullshit.
Science will not change because of one data point or one opinion unless it is bulletproof, which almost never happens. The real problem is reporting, where data is simplified once for the reporter, again by the reporter, again by the headline, and probably once each by the editor and reader.
Go read the article, note both sides being represented, and admit how you simplified one person's report to mean all of science, and come back here to apologize for exactly the thing you are whinging about.

Re:The Problem

[flyneye]

Put on some Speed Stick and you wouldn't be so awful.
I'm just delighted to be able to explain the ridge brow, knuckle draggers I've had to cover for all my life.
Of course these species are one. Still are! As are Homerus Erectus,(average hominids) Gluteus Rex,(species attracted to elected office) Rattus Habilis,(law enforcement and judicial hairy lizards) various mamosauruses (double breasted rod suckers) and ptero shrews( pinchy face complainers).
I can't get down the street for herds of them making nuisances of themselves all day long. We need a hunting season...

Re:Does this support creationism?

[__aaltlg1547]

Both proponents of creationism and anthropologists agree that all living humans must have one common male ancestor at some point. They Y-MRCA (most recent ancestor of all y-chromosomes, and the guy who had it) is estimated to have lived sometime between 140,000 and 300,000 years ago. That would probably make him H. sapiens because sapiens has been around for about 200,000 years. However, we can't be sure. If the oldest date is right, he might have been h. heidelbergensis.

Re:Maybe an anomaly

[Patch86]

That's sort of my point. It's idiotic to say that we can never reach the bottom of the ocean- that's just an engineering problem. And while it's possible that it could be a "never" for humans travelling to other stars, never is indeed a very long time.

But history is different. Barring time travel, if evidence for something hasn't survived, there is simply no way of knowing it. There might have been a really interesting species existing somewhere once with some really fascinating features and which could tell us a lot about evolution in its relative species. But fossils only form in really specific circumstances, and even once they're formed they only survive if they're left undisturbed. What if the local geography is fossil unfriendly, and not a single member of the species has left remains to be found today? We will simply never know it existed. And I mean properly never. It is knowledge that is lost to us and cannot ever be obtained. Similarly, want to know what language was spoken by the people of stone age Britain? Tough, you can't- they didn't write it down, and there is quite literally no way for you to know. Ever.

That's what's so mysterious and fascinating about it.

Re:Obligatory WTF

[MightyMartian]

They aren't separate species because 1. Interbreeding produces fertile healthy young, 2 the genetic distance between human populations is very small.