honestly, when I read 'anaerobic' I am thinking less about modern anaerobic life forms that are involved in fermentation (some of which can even survive in an oxygen environment) and more about chemosynthetic organisms that live around volcanic vents and base their entire metabolism on hydrogen sulfide.
these are the anaerobes of the Archean era, the ones that were killed off by the onrush of oxygen that the photosynthetic life forms brought with them and forced down into the oxygen-less cracks of the Earth
If you can draw a direct line between chemosynthesis of hydrogen sulfide and the oxygen-based metabolism that keeps me upright, then I am all ears.
I will give this a careful response tonight, but "modern" anaerobic life is ancient anaerobic life. That is what I mean by unchanged. I will post what I am reading about the commonality of fermentation, sulphide reducing, and oxygen respiration later when I get a chance to review it again. Also IIRC the oxygen respiration was initially there to protect the anaerobic from oxygen. The theories on how all this came about are fascinating.
Can you give an example of such an unchanged gene? Some genes related to DNA handling proteins should be a good example. How unchanged they really are between archae, bacteria and a few lines of eukaroytes? Any references?
Because I'm under the impression, that even though the genes work pretty much the same (as they have to, since chemical stucture of DNA and the information coding are the same), the DNA sequences have actually changed quite a bit, actually about as much as it could have changed without breaking the functionality.
If you have an online link to something which discusses the difference of genes doing identical functions in archae, bacteria and eukaryotes, and includes actual quantative data about the difference, I'd be thrilled.
I'll have to look tonight for one of the specific things in commonality I've been reading about but my initial response is that unchanged and changed as much as possible without breaking functionality is the same thing. By unchanged I mean unchanged functionality.
I don't have any online links. What I've been reading are the Nick Lane books I mentioned in an earlier link. I have purchased a large library of technical books on the subject but was reading Nick Lane's first.
Of course there has been drift in the DNA sequences of letter errors which as you know is used to approximate length of time between two samples. But far more than the proteins coded for is the very process itself of DNA, RNA, manufacture of proteins, etc. which are casually accepted that this complex cellular machinery, which is mind boggling in how sophisticated it is, was in place as far back as we can obtain fossils, nearly three billion years ago, and has remained unchanged to this day yet with evolution we talk about and see the changes that took place with everything constructed of the cells.
That the cells are so sophisticated we still don't know much about how they work and so perfect they have made up all life in ever changing forms for over two billion years without changing themselves I find hard to believe can be accepted so casually. My original point was that very few people understand that this is what has happened. The universality of life based on the same cell workings from the beginning of time is just not something that we are exposed to.
How would that make it less mind-boggling? It just relocates the problem. Does it somehow make more sense to think that life had a few billion more years to evolve on some other planet than just 1.5 billion years here on earth? I'm not trying to be pedantic here, I'm genuinely curious as to how you'd think "space" is a better explanation...
It means it provides for more possibilities of being engineered than initially coming together on its own in the initial anaroebic world. By it I mean the long list of extremely complex biochemical cellular mechanisms that all life work on.
What are those possibilities? I don't know. But I'm having a problem seeing this amazingly complex machinery fall together from nothing. We laymen can understand increasing complexity. That the most complex of all hasn't changed for billions of years but just has been that way as far back as we can determine is even harder to understand and accept than gradually increasing complexity over time.
Because of course every gene in existence can be traced back to a few, possibly even just one, orignal gene (or soup of short pieces of xNA, or whatever the first successful drop of self-replicating chemical soup was like).
Had I not just read in depth enough to know how mistaken you are, I would have believed this statement from you. It represents the increasing complexity I said most people understand to have occurred.
In actuality, the complex functionality and genes that enable it are nearly unchanged. Nothing like what you portray here.
I said essentially drown. The point was that oxygen using life didn't crowd out anaerobic life, the oxygen produced by clorophyll based life forced it to places with still no oxygen or killed it. If drowning doesn't do it for you as an analogy instead of disrupted enzyme production, then I'm glad everyone was able to see the technically correct explanation.
My point was made and clear to readers however. I was responding to the oxygen using forcing out anaerobic life.
There's no hard and fast cutoff of how much oxygen is too much or too little.
There actually is. Below 15%,as you point out at the end, is too little to support oxygen breathing life. I guess will cause problems is one way of putting it.
As levels rise there will be more wildfires and the less oxygen-tolerant organisms will struggle, as levels fall the more oxygen-reliant organisms will have problems.
The study this statement is based on has some problems. Your statement has been commonly accepted scientific lore but the actual forests bursting into flame thing is based on one experiment with pieces of paper of various wetness.
Oxygen levels are believed to have been at 35% during dinosaurs and other gigantic life such as dragonflies, etc.
"All current life was set in place nearly three billion years ago". Absolutely not - your view of the history of biology is very warped. Study more biology itself to realize what 'current life' actually looks like.
well I am reading on biology, and I did ask biologists to correct me if I was wrong, but I would not say between 2.1 billion and 2.7 billion years for eukarytes instead of saying nearly three billion years is warped.
Also I clearly denoted that the basis of life I was referring to was the unchanged cellular mechanisms universally shared by life for those nearly three billion years.
a) How long should we have expected that first billion years of evolution to take?
You misunderstand my point. My point was that a large list of extremely complex cellular operations is known to exist three billion years ago and hasn't changed since in every life form that ever existed. That is was perhaps optimal at that point, or that a billion years is a long time, isn't the point. The point is that this is extremely complex biochemical machinery that is mind boggling to even imagine how this somehow came together.
I am more inclined to think it came from space than anything.
b) You should rephrase "not gaining new and more complex capabilities" to say "at the cellular level". At higher levels, progress has been phenomenal. (How much smarter are you than a single-cell organism?)
Yes, but every one of those cells in that phenomenal progress are the same workings as three billion years ago. Have groups of cells specialized to greater macro capabilities? Yes. But even there the basis are in much more primitive life forms. My point is people see the more complex macro capabilities and don't realize that it all operates unchanged in every life form for three billion years, and we have no idea how those incredibly genius mechanisms somehow came together to make life what it is.
The origin of cellular machinery is indeed impressive, but unfortunately "I can't believe it could happen by natural causes in a billion years" tells us a little about the speaker's beliefs, and nothing at all about what actually happened.
well it is my opinion. "I can't believe it" uses the word belief, doesn't it. Also I said I was not religious and have no beliefs. My internet record is long and well documented, and when I say something you can bank on it.
As to why not much new has been added to that machinery since, maybe we have more basis for speculation. Competition from all-new "designs" is probably impossible, because the necessary building blocks would probably be oxidized, or digested by current organisms, before it could bootstrap itself into a new cell type. For variants on what we have, evolution is not a reversible process, so we can't expect cells to undo part of their history and try something else, any more than birds would evolve back into dinosaurs and go then forward again down a different path.
That something that complex, and by complex I mean that people are still trying to figure out how this stuff works, became solid and fundamentally unchanged three billion years ago is undeniable. I personally can't believe that complexity could even sort itself together from various biochemical variants, then at the furthest point that we can gain fossil records and perform genetic analysis, became optimal and all this amazing coming together just stopped for three billion years apparently because nothing more was helpful.
So we're probably stuck with consideration of add-ons to the current machinery. But there's no guarantee that something nifty would happen in that regard within any bounded period of time. Evolution doesn't provide organisms with things just because they are needed or would be useful. Possibly cellular evolution has reached a "local maximum" on the fitness landscape, from which there is no easy jump to something better.
I believe there is feedback to embryo development in the same channel that instincts and behavior are inherited, but I don't know what that process is and obviously no one else does either. but it's of great interest to me and that's why I'm doing this reading. That the feedback impacts structural development in the embryo level development seems clear. Cellular mechanisms are lost, and haemoglobin and clorophyll are specializations that impact the cellular operations, and the operations do vary, such as sulphur reducing, etc. But they are all variations on a complexity that I assure you people think came about later, not three billion years ago.
And who knows... some of the past jumps may not have
And since "more complex" generally means "more expensive in terms of energy consumption", any mutations in that direction could quite likely have been a survival *disadvantage*.
I agree with that, but what I'm saying is that the common perception of evolution is that life gets more complex by "evolving" but the most complex machinery of cells has stayed unchanged for three billion years, and that all life forms, from bacteria to yeast to fungus to plants to animals have the same cell machinery, the stuff we just figured out like the DNA helix just a few decades ago.
I don't think very many people have any idea everything has the same cellular basis of life for past three billion years, every life form that ever existed. Maybe biologists just operate knowing this but the rest of us have no idea. I just read it myself in the past month, and I've read a lot of science in my lifetime.
Is not that every living thing died, but that very few survived, and those very few could had common recent mutations (i.e. resistence to cold around ice ages) that could be misinterpreted as ancient genes as found in different species.
Those things would be the Archaea with all our existing complex life infrastructure existing in frigid cold and hydrothermal vents deep under sea, and in earth heated sulphur lakes and high saline lakes. They were able to survive and pass on to us life.
what I find interesting about the article is the layering effect of life. how the anerobic life got pushed out by the oxygen breathers and relegated to living in the cracks. good for us, but an extinction event for them. there have been many big extinctions, and each allowed some hardier form of live to make it to the next expansion. we are in a current extinction event (holocene), and have started to worry about an asteroid or some such wiping us out.
even that worry over our own 'extinction' bumps up against any number of religious beliefs, even if they seem to have an unrealistic timescale of tens of years, when any historical events have been separated by millions of years.
I'm a programmer but just happen to be reading Nick Lane's books on this. If I get something wrong please biologists jump in and correct me.:)
I only read a page or two a day (first "Oxygen", and now "Power, Sex, Suicide" - and yes, that's all based on oxygen). But the revelation I had yesterday was that anaerobic bacteria essentially drown in oxygen, just as we would suffocate with too little oxygen, which by the way is not that much below the historic percentage of atmosphere for last several hundred million years of 21%. Dropping below about 15% of atmosphere would kill all oxygen breathing life.
So anaerobic life which ruled the world didn't get pushed out by oxygen breathing life, it got pushed "out", or down into stagnant places rather, by oxygen, which was created by photosynthesis. Almost all the oxygen over.1% of the atmosphere was created by photosynthesis in plant life.
And what became of that anaerobic life in the sea with.1% oxygen? It exists to this day in our cells, which are in the same salt water of the sea in our body and exposed to.1% oxygen delivered by hameoglobin in the blood. It also exists in our intestines among other places with little oxygen, such as bottoms of swamps.
The kicker? People talk of evolution and they have no idea. All current life was set in place nearly three billion years ago. Every complex thing you ever read about in the human body cells is in every cell of every life form for almost three billion years.
DNA, RNA, mitochondria, conversion of glucose to storage of energy in ATP molecules using an extremely complex 12 step process, manufacture of the same proteins with ribosomes, fermentation to create energy without even that.1% of atmosphere oxygen when necessary (such as our muscles which fermentation kicks in when needed and creates a byproduct lactic acid which eventually causes cramps), respiration using haemin which is haemoglobin in blood and clorophyll in plants, everything was set almost three billion years ago.
Nothing has evolved, it has only specialized.
The bigger question is how this complex machinery of life developed in the first billion years of Earth amidst massive meteor impacts. People can call it what they want, but knowing that all life that has ever existed has existed essentially unchanged from three billion years ago defies explanation of "evolving" in first one to two billion years to the amazing complexity of how cells work and then staying pat for almost three billion years and only losing capabilities, not gaining new and more complex capabilities as one assumes from casual science study and reading.
I am not religious and do not consider religious arguments against evolution as anything but pedantic handwaving, but what we call evolution is really rather trivial specialization implemented by the ancient common embryo genes.
I could go on and I'm probably leaving out even more stuff that took my breath away when I read it but people have no idea the ancient universality of all life forms from the same unbelievably complex cell from three billion years ago.
Is a captcha not enough of a barrier? I've never seen a website that actually banned @gmail addresses. I'm curious, and highly surprised.
The phpBB version 2 Captchas are broken, they are automatically identified by bots. I checked on the new version of phpBB and #1 I don't like the new features and #2 a new Captcha system was still being perfected.
I have posted through the years on Captcha and the phpBB is trivially simple but there are others on other sites that are so non-trivial I quite frankly can't read the letters. There are good Captchas whose letters overlap but are still plainly readable, however it's my understanding from posts through the years that algorithms measure a density or signature of Captchas for anything widespread enough to make the effort and thus "break" those Captchas as well. It would narrow it down quite a bit though.
In the end however, there are armies of people available to type in any human required entry that bots send their way and use to complete the registration so I don't see that as a solution to unending spam registrations and postings if they were allowed through.
You would not believe what I have blocked and continue to add to blockings and I still get two to three spam registrations per day. Someone depending on Captcha alone would be inundated or perhaps don't care I don't know.
The spam registrations and ultimately postings are quite sophisticated and cannot be detected by content, only by identifying links as "bad" using some service. Most sites that use services to stop spam registrations beyond Captcha also depend on those sites listing by IP address.
Using an IP address to determine the content of a message is a bad idea anyway.
and what are your suggested alternatives to blocking website spammers? I block by IP address because the only thing coming to my website from certain areas of the world is spam.
Right, the reply to your post was asking why the male organelles were discarded. The answer is that the nuclear DNA is persisting at the expense of the mitochondrial DNA and that this relationship came about because it is beneficial to the offspring.
No, the nuclear and mitochondria DNA are symbiotic. Mitochondria is essentially a bacteria that is incorporated in cells. It has its own DNA, replicates separately within the cell, etc.
Nuclear DNA is kept from degrading by the merging of male and female DNA, which is one survival technique. Bacteria survive without degradation by splitting rapidly, but within a cell the mitochondria stays there and degrades from oxidation over time. The survival mechanism was for female to preserve an unused mitochondria in eggs and store inactivated. The female mitochondria is then used for the mitochondria in the offspring.
The short answer is that aged degraded mitochondria doesn't survive well in generations and only the mechanism that preserved it unused survived. The two nuclear DNA's merging is just as important in that mechanism to keep nuclear DNA viable, but its the stored unused mitochondria DNA by females that establishes sex.
Oxygen by Nick Lane is an excellent, eye opening book. I'm moving on to another one of his and books by others on this subject.
It's a bit of both. In order to prevent the more independent organelles which have DNA from fighting for the right to live on in the successor and thereby potentially damage the cell, one of the sets of organelles must be discarded from the sex cells. The descendants of the genes that do this are more likely to have healthy offspring and pass it on to the next generation. This is the theory why in most organisms that have sex, one of the genders' sex cells will discard the organelles. Once this convention is established, genes that can gain numbers or other advantages at the cost of the healthiness of the organelles are selected for because there is no detriment to the offspring.
But nuclear DNA from both are used. Only mitochondria DNA is used from only one parent. That establishes the female.
And why should it last any longer after 100 generations of egg production and 30 years of dormancy than it would last after 100 generations of sperm production and no dormancy? It isn't like the eggs aren't duplicates in the first place - the difference is when they form.
Oxidation from respiration. The female mitochondria is inactive and undamaged from oxidation.
The mechanism for passing on pure mitochondria was to preserve it in a female egg, thus arose the need for sexes.
While an interesting idea, I'd like to see some proof that mitochondrial preservation was the primary driver behind the need for sexes. Could not hermaphroditic organisms employ the same mechanism to protect mDNA, assuming such protection is even necessary?
It does in some species. However no species that attempted to reproduce with actively used mitochondria survived.
Again, this and much else about cells, such as DNA-RNA and other quite complex cellular mechanisms that we read about, is universal in all life.
No argument there. The question is WHY is it conserved, and are all elements of this truly important, or do they just happen to come together?
I think the only thing that can truly answer these questions are experiments - not conjecture about mechanisms. Sure, you have to start with a hypothesis, but you can't stop there.
Nick Lane (English professor and science writer) in his book Oxygen cites a 1999 Nature article by Oregon Health Science University that male mitochondria in cattle is tagged with protein ubiquitin in embryo and marked for destruction. So as is known with Drosophila larvae, male mitochondria in embryo is actively destroyed.
Reason again is mitochondria from males is from active cells where mitochondria DNA is damaged over time by oxidation, much more than nuclear DNA due to converting oxygen and their DNA is unprotected. Mitochondria in females eggs are stored early, not active, and passed on as pristine as possible.
While male mitochondria could work, nothing survived that tried it.
There's a lot of sampling bias there. His paternal mDNA was discovered only because it was defective. It's quite possible there are a large number (though small percentage) of people carrying paternal mDNA who are never discovered because there's no reason to look.
The maternal mitochondria lineage is universal in all life, not just humans. I agree this one example doesn't prove anything, but I wasn't aware of it and had nothing to do with the statement.
First, by saying that maternal mitochondria lineage is nearly universal, that means that male lineage isn't found to speak of in any samples of life when studied unless species is known to use both. A small percentage that's always missed? Possible, of course. Some studies of mouse mitochondria DNA suggest male is present in proportion to sperm to egg mitochondria, 1 in 1000 to 10,000, too low to detect.
Second, Nick Lane (English professor and science writer) in his book Oxygen cites a 1999 Nature article by Oregon Health Science University that male mitochondria in cattle is tagged with protein ubiquitin in embryo and marked for destruction. So as is known with Drosophila larvae, male mitochondria in embryo is actively destroyed.
Reason again is mitochondria from males is from active cells where mitochondria DNA is damaged over time by oxidation, much more than nuclear DNA due to converting oxygen and their DNA is unprotected. Mitochondria in females eggs are stored early, not active, and passed on as pristine as possible.
While male mitochondria could work, nothing survived that tried it.
Interesting. Do you have a citation for this study where they actually grew embryos to term using male and female-originated mitochodria and determined that it actually made a difference?
I'm not quite sure why the DNA in the mitochondria would be any more aged and defective than the haploid genome in the sperm in the first place. It is true that eggs in a woman are essentially formed early vs sperm forming late, but that applies to all DNA in the sperm and not just the mitochondria.
Maybe you're right and that it is this way for a reason. However, having a nice argument doesn't really translate into proof...
hi there, I won't go into a lot here, as much as necessary if you follow up, but all life with nucleus and mitochondria (most everything but bacteria) uses female mitochondria exclusively in offspring.
Your point about the other DNA being aged in both male and female is true, but nucleus DNA is protected by a protein cover. The DNA of mitochondria, a cell within a cell, is like bacteria and has no protective protein covering. Bacteria get around this by dividing rapidly. The mechanism for passing on pure mitochondria was to preserve it in a female egg, thus arose the need for sexes.
Again, this and much else about cells, such as DNA-RNA and other quite complex cellular mechanisms that we read about, is universal in all life. That was quite eye-opening.
You present a false choice. Evolution is a well studied and documented fact. A fact that in no way disproves god. It's only 'contested' by people who don't even understand their own theology and history of their book.
I did not mean to present it as a forced pick of one or the other. It was a play on the words thank god for sexes, or evolution, or both:), take your pick.
Does the book specifically mention the maleness of the mitochondria being the problem, or is it more that the cell it came from just completed a rather long race?
yes, the book addresses both. It's not that the mitochondria is used and damaged by the sperm, but rather that the copy from the male used to make the sperm is used and damaged, the older the male the more damaged.
The female mitochondria is preserved unused in the egg and universally used as the mitochondria in cells in the offspring. That is why in DNA analysis you can track the maternal lineage with the mitochondria DNA.
I think based on studies cited in the book if they tried to continue this experiment for three or four generations it would peter out.
I'm reading Oxygen by Nick Lane, and recreating with male mitochondria is a universal no no. Even worms while forming excrete the male mitochondria from the gametes used to form it.
The male mitochondria passed on is aged and defective, the female mitochondria an unused preserved version.
In other words, there's a reason it doesn't work the way it's being forced to work. That's why we have sexes. Thank God or evolution, your choice.
Who cares if people use more addresses ? We are going to run out of IPv4 anyway and it will happen 'fast' or faster.
You're missing the point. These are criminals. They do things that make it hard to stop them. Operating from a wide range of addresses makes it harder to stop them.
As a secondary effect, they are trying to force to ipv6 ASAP because they will be impossible to stop then.
As a side effect, those who own a rare resource can make money. These addresses are used to make money until someone is willing to pay even more for the addresses.
Should this unrestricted ipv6 be put into place, ip addresses lose all of their sale value but provide infinite IP addresses to attack from.
The people here seem to be network types that only care about their routers, but what will happen is teh United States and other western countries will be forced to set up a secure network for the public to keep out the hordes of attackers.
And yes, I know proxies in the US are used also, and I block them too.
The idea was that if regions had their own range you could just agregate everything in that region (use 1 large IP-block to represent many smaller ones). For example an other continent.
This would safe memory and CPU-time on routers.
It was a nice idea, but it doesn't work in real life. In real life large networks span the globe and similair problems.
Thanks for the explanation. ARIN and the other geographical assignment areas work fine. I increasingly see an ipv4 split between continents but still is pretty good at 255.255.128 or so.
I see the ipv6 people here are pretty rabid but I'm not joking. They're crazy if they think the rest of us are going to allow IP attacks from anywhere in a gazillion addresses.
The rest don't know it yet, but they will when all hell is unleashed on them by the attackers who must be giggling about this. In fact, the number of IP ranges keep being added to former USSR is amazing. Do you have any idea how many address ranges are assigned to Latvia, for example. just to pick a very small country with an amazing range of addresses generating spam attacks.
Slashdot Mirror
honestly, when I read 'anaerobic' I am thinking less about modern anaerobic life forms that are involved in fermentation (some of which can even survive in an oxygen environment) and more about chemosynthetic organisms that live around volcanic vents and base their entire metabolism on hydrogen sulfide.
these are the anaerobes of the Archean era, the ones that were killed off by the onrush of oxygen that the photosynthetic life forms brought with them and forced down into the oxygen-less cracks of the Earth
If you can draw a direct line between chemosynthesis of hydrogen sulfide and the oxygen-based metabolism that keeps me upright, then I am all ears.
I will give this a careful response tonight, but "modern" anaerobic life is ancient anaerobic life. That is what I mean by unchanged. I will post what I am reading about the commonality of fermentation, sulphide reducing, and oxygen respiration later when I get a chance to review it again. Also IIRC the oxygen respiration was initially there to protect the anaerobic from oxygen. The theories on how all this came about are fascinating.
rd
Can you give an example of such an unchanged gene? Some genes related to DNA handling proteins should be a good example. How unchanged they really are between archae, bacteria and a few lines of eukaroytes? Any references?
Because I'm under the impression, that even though the genes work pretty much the same (as they have to, since chemical stucture of DNA and the information coding are the same), the DNA sequences have actually changed quite a bit, actually about as much as it could have changed without breaking the functionality.
If you have an online link to something which discusses the difference of genes doing identical functions in archae, bacteria and eukaryotes, and includes actual quantative data about the difference, I'd be thrilled.
I'll have to look tonight for one of the specific things in commonality I've been reading about but my initial response is that unchanged and changed as much as possible without breaking functionality is the same thing. By unchanged I mean unchanged functionality.
I don't have any online links. What I've been reading are the Nick Lane books I mentioned in an earlier link. I have purchased a large library of technical books on the subject but was reading Nick Lane's first.
Of course there has been drift in the DNA sequences of letter errors which as you know is used to approximate length of time between two samples. But far more than the proteins coded for is the very process itself of DNA, RNA, manufacture of proteins, etc. which are casually accepted that this complex cellular machinery, which is mind boggling in how sophisticated it is, was in place as far back as we can obtain fossils, nearly three billion years ago, and has remained unchanged to this day yet with evolution we talk about and see the changes that took place with everything constructed of the cells.
That the cells are so sophisticated we still don't know much about how they work and so perfect they have made up all life in ever changing forms for over two billion years without changing themselves I find hard to believe can be accepted so casually. My original point was that very few people understand that this is what has happened. The universality of life based on the same cell workings from the beginning of time is just not something that we are exposed to.
rd
How would that make it less mind-boggling? It just relocates the problem. Does it somehow make more sense to think that life had a few billion more years to evolve on some other planet than just 1.5 billion years here on earth? I'm not trying to be pedantic here, I'm genuinely curious as to how you'd think "space" is a better explanation...
It means it provides for more possibilities of being engineered than initially coming together on its own in the initial anaroebic world. By it I mean the long list of extremely complex biochemical cellular mechanisms that all life work on.
What are those possibilities? I don't know. But I'm having a problem seeing this amazingly complex machinery fall together from nothing. We laymen can understand increasing complexity. That the most complex of all hasn't changed for billions of years but just has been that way as far back as we can determine is even harder to understand and accept than gradually increasing complexity over time.
Because of course every gene in existence can be traced back to a few, possibly even just one, orignal gene (or soup of short pieces of xNA, or whatever the first successful drop of self-replicating chemical soup was like).
Had I not just read in depth enough to know how mistaken you are, I would have believed this statement from you. It represents the increasing complexity I said most people understand to have occurred.
In actuality, the complex functionality and genes that enable it are nearly unchanged. Nothing like what you portray here.
They don't "drown" in oxygen.
I said essentially drown. The point was that oxygen using life didn't crowd out anaerobic life, the oxygen produced by clorophyll based life forced it to places with still no oxygen or killed it. If drowning doesn't do it for you as an analogy instead of disrupted enzyme production, then I'm glad everyone was able to see the technically correct explanation.
My point was made and clear to readers however. I was responding to the oxygen using forcing out anaerobic life.
There's no hard and fast cutoff of how much oxygen is too much or too little.
There actually is. Below 15%,as you point out at the end, is too little to support oxygen breathing life. I guess will cause problems is one way of putting it.
As levels rise there will be more wildfires and the less oxygen-tolerant organisms will struggle, as levels fall the more oxygen-reliant organisms will have problems.
The study this statement is based on has some problems. Your statement has been commonly accepted scientific lore but the actual forests bursting into flame thing is based on one experiment with pieces of paper of various wetness.
Oxygen levels are believed to have been at 35% during dinosaurs and other gigantic life such as dragonflies, etc.
rd
1.7~2 Billion years ago: probable endosymbiosis of prokaryote into eurkaryotic cells, forming mitochonria.
actually mitochondria enabled the formation of eukarytes.
"All current life was set in place nearly three billion years ago". Absolutely not - your view of the history of biology is very warped. Study more biology itself to realize what 'current life' actually looks like.
well I am reading on biology, and I did ask biologists to correct me if I was wrong, but I would not say between 2.1 billion and 2.7 billion years for eukarytes instead of saying nearly three billion years is warped.
Also I clearly denoted that the basis of life I was referring to was the unchanged cellular mechanisms universally shared by life for those nearly three billion years.
rd
a) How long should we have expected that first billion years of evolution to take?
You misunderstand my point. My point was that a large list of extremely complex cellular operations is known to exist three billion years ago and hasn't changed since in every life form that ever existed. That is was perhaps optimal at that point, or that a billion years is a long time, isn't the point. The point is that this is extremely complex biochemical machinery that is mind boggling to even imagine how this somehow came together.
I am more inclined to think it came from space than anything.
b) You should rephrase "not gaining new and more complex capabilities" to say "at the cellular level". At higher levels, progress has been phenomenal. (How much smarter are you than a single-cell organism?)
Yes, but every one of those cells in that phenomenal progress are the same workings as three billion years ago. Have groups of cells specialized to greater macro capabilities? Yes. But even there the basis are in much more primitive life forms. My point is people see the more complex macro capabilities and don't realize that it all operates unchanged in every life form for three billion years, and we have no idea how those incredibly genius mechanisms somehow came together to make life what it is.
The origin of cellular machinery is indeed impressive, but unfortunately "I can't believe it could happen by natural causes in a billion years" tells us a little about the speaker's beliefs, and nothing at all about what actually happened.
well it is my opinion. "I can't believe it" uses the word belief, doesn't it. Also I said I was not religious and have no beliefs. My internet record is long and well documented, and when I say something you can bank on it.
As to why not much new has been added to that machinery since, maybe we have more basis for speculation. Competition from all-new "designs" is probably impossible, because the necessary building blocks would probably be oxidized, or digested by current organisms, before it could bootstrap itself into a new cell type. For variants on what we have, evolution is not a reversible process, so we can't expect cells to undo part of their history and try something else, any more than birds would evolve back into dinosaurs and go then forward again down a different path.
That something that complex, and by complex I mean that people are still trying to figure out how this stuff works, became solid and fundamentally unchanged three billion years ago is undeniable. I personally can't believe that complexity could even sort itself together from various biochemical variants, then at the furthest point that we can gain fossil records and perform genetic analysis, became optimal and all this amazing coming together just stopped for three billion years apparently because nothing more was helpful.
So we're probably stuck with consideration of add-ons to the current machinery. But there's no guarantee that something nifty would happen in that regard within any bounded period of time. Evolution doesn't provide organisms with things just because they are needed or would be useful. Possibly cellular evolution has reached a "local maximum" on the fitness landscape, from which there is no easy jump to something better.
I believe there is feedback to embryo development in the same channel that instincts and behavior are inherited, but I don't know what that process is and obviously no one else does either. but it's of great interest to me and that's why I'm doing this reading. That the feedback impacts structural development in the embryo level development seems clear. Cellular mechanisms are lost, and haemoglobin and clorophyll are specializations that impact the cellular operations, and the operations do vary, such as sulphur reducing, etc. But they are all variations on a complexity that I assure you people think came about later, not three billion years ago.
And who knows... some of the past jumps may not have
And since "more complex" generally means "more expensive in terms of energy consumption", any mutations in that direction could quite likely have been a survival *disadvantage*.
I agree with that, but what I'm saying is that the common perception of evolution is that life gets more complex by "evolving" but the most complex machinery of cells has stayed unchanged for three billion years, and that all life forms, from bacteria to yeast to fungus to plants to animals have the same cell machinery, the stuff we just figured out like the DNA helix just a few decades ago.
I don't think very many people have any idea everything has the same cellular basis of life for past three billion years, every life form that ever existed. Maybe biologists just operate knowing this but the rest of us have no idea. I just read it myself in the past month, and I've read a lot of science in my lifetime.
rd
Is not that every living thing died, but that very few survived, and those very few could had common recent mutations (i.e. resistence to cold around ice ages) that could be misinterpreted as ancient genes as found in different species.
Those things would be the Archaea with all our existing complex life infrastructure existing in frigid cold and hydrothermal vents deep under sea, and in earth heated sulphur lakes and high saline lakes. They were able to survive and pass on to us life.
what I find interesting about the article is the layering effect of life. how the anerobic life got pushed out by the oxygen breathers and relegated to living in the cracks. good for us, but an extinction event for them. there have been many big extinctions, and each allowed some hardier form of live to make it to the next expansion. we are in a current extinction event (holocene), and have started to worry about an asteroid or some such wiping us out.
even that worry over our own 'extinction' bumps up against any number of religious beliefs, even if they seem to have an unrealistic timescale of tens of years, when any historical events have been separated by millions of years.
I'm a programmer but just happen to be reading Nick Lane's books on this. If I get something wrong please biologists jump in and correct me. :)
I only read a page or two a day (first "Oxygen", and now "Power, Sex, Suicide" - and yes, that's all based on oxygen). But the revelation I had yesterday was that anaerobic bacteria essentially drown in oxygen, just as we would suffocate with too little oxygen, which by the way is not that much below the historic percentage of atmosphere for last several hundred million years of 21%. Dropping below about 15% of atmosphere would kill all oxygen breathing life.
So anaerobic life which ruled the world didn't get pushed out by oxygen breathing life, it got pushed "out", or down into stagnant places rather, by oxygen, which was created by photosynthesis. Almost all the oxygen over .1% of the atmosphere was created by photosynthesis in plant life.
And what became of that anaerobic life in the sea with .1% oxygen? It exists to this day in our cells, which are in the same salt water of the sea in our body and exposed to .1% oxygen delivered by hameoglobin in the blood. It also exists in our intestines among other places with little oxygen, such as bottoms of swamps.
The kicker? People talk of evolution and they have no idea. All current life was set in place nearly three billion years ago. Every complex thing you ever read about in the human body cells is in every cell of every life form for almost three billion years.
DNA, RNA, mitochondria, conversion of glucose to storage of energy in ATP molecules using an extremely complex 12 step process, manufacture of the same proteins with ribosomes, fermentation to create energy without even that .1% of atmosphere oxygen when necessary (such as our muscles which fermentation kicks in when needed and creates a byproduct lactic acid which eventually causes cramps), respiration using haemin which is haemoglobin in blood and clorophyll in plants, everything was set almost three billion years ago.
Nothing has evolved, it has only specialized.
The bigger question is how this complex machinery of life developed in the first billion years of Earth amidst massive meteor impacts. People can call it what they want, but knowing that all life that has ever existed has existed essentially unchanged from three billion years ago defies explanation of "evolving" in first one to two billion years to the amazing complexity of how cells work and then staying pat for almost three billion years and only losing capabilities, not gaining new and more complex capabilities as one assumes from casual science study and reading.
I am not religious and do not consider religious arguments against evolution as anything but pedantic handwaving, but what we call evolution is really rather trivial specialization implemented by the ancient common embryo genes.
I could go on and I'm probably leaving out even more stuff that took my breath away when I read it but people have no idea the ancient universality of all life forms from the same unbelievably complex cell from three billion years ago.
rd
Is a captcha not enough of a barrier? I've never seen a website that actually banned @gmail addresses. I'm curious, and highly surprised.
The phpBB version 2 Captchas are broken, they are automatically identified by bots. I checked on the new version of phpBB and #1 I don't like the new features and #2 a new Captcha system was still being perfected.
I have posted through the years on Captcha and the phpBB is trivially simple but there are others on other sites that are so non-trivial I quite frankly can't read the letters. There are good Captchas whose letters overlap but are still plainly readable, however it's my understanding from posts through the years that algorithms measure a density or signature of Captchas for anything widespread enough to make the effort and thus "break" those Captchas as well. It would narrow it down quite a bit though.
In the end however, there are armies of people available to type in any human required entry that bots send their way and use to complete the registration so I don't see that as a solution to unending spam registrations and postings if they were allowed through.
You would not believe what I have blocked and continue to add to blockings and I still get two to three spam registrations per day. Someone depending on Captcha alone would be inundated or perhaps don't care I don't know.
The spam registrations and ultimately postings are quite sophisticated and cannot be detected by content, only by identifying links as "bad" using some service. Most sites that use services to stop spam registrations beyond Captcha also depend on those sites listing by IP address.
ipv6 is a spammers nirvana.
rd
Using an IP address to determine the content of a message is a bad idea anyway.
and what are your suggested alternatives to blocking website spammers? I block by IP address because the only thing coming to my website from certain areas of the world is spam.
rd
How much spam actually is originating through gmail?
From my perspective of a small website, if I drop the ban on *@gmail.com I start getting spam registrations within minutes.
So experiment away.
Right, the reply to your post was asking why the male organelles were discarded. The answer is that the nuclear DNA is persisting at the expense of the mitochondrial DNA and that this relationship came about because it is beneficial to the offspring.
No, the nuclear and mitochondria DNA are symbiotic. Mitochondria is essentially a bacteria that is incorporated in cells. It has its own DNA, replicates separately within the cell, etc.
Nuclear DNA is kept from degrading by the merging of male and female DNA, which is one survival technique. Bacteria survive without degradation by splitting rapidly, but within a cell the mitochondria stays there and degrades from oxidation over time. The survival mechanism was for female to preserve an unused mitochondria in eggs and store inactivated. The female mitochondria is then used for the mitochondria in the offspring.
The short answer is that aged degraded mitochondria doesn't survive well in generations and only the mechanism that preserved it unused survived. The two nuclear DNA's merging is just as important in that mechanism to keep nuclear DNA viable, but its the stored unused mitochondria DNA by females that establishes sex.
Oxygen by Nick Lane is an excellent, eye opening book. I'm moving on to another one of his and books by others on this subject.
rd
It's a bit of both. In order to prevent the more independent organelles which have DNA from fighting for the right to live on in the successor and thereby potentially damage the cell, one of the sets of organelles must be discarded from the sex cells. The descendants of the genes that do this are more likely to have healthy offspring and pass it on to the next generation. This is the theory why in most organisms that have sex, one of the genders' sex cells will discard the organelles. Once this convention is established, genes that can gain numbers or other advantages at the cost of the healthiness of the organelles are selected for because there is no detriment to the offspring.
But nuclear DNA from both are used. Only mitochondria DNA is used from only one parent. That establishes the female.
rd
And why should it last any longer after 100 generations of egg production and 30 years of dormancy than it would last after 100 generations of sperm production and no dormancy? It isn't like the eggs aren't duplicates in the first place - the difference is when they form.
Oxidation from respiration. The female mitochondria is inactive and undamaged from oxidation.
The mechanism for passing on pure mitochondria was to preserve it in a female egg, thus arose the need for sexes.
While an interesting idea, I'd like to see some proof that mitochondrial preservation was the primary driver behind the need for sexes. Could not hermaphroditic organisms employ the same mechanism to protect mDNA, assuming such protection is even necessary?
It does in some species. However no species that attempted to reproduce with actively used mitochondria survived.
Again, this and much else about cells, such as DNA-RNA and other quite complex cellular mechanisms that we read about, is universal in all life.
No argument there. The question is WHY is it conserved, and are all elements of this truly important, or do they just happen to come together?
I think the only thing that can truly answer these questions are experiments - not conjecture about mechanisms. Sure, you have to start with a hypothesis, but you can't stop there.
Nick Lane (English professor and science writer) in his book Oxygen cites a 1999 Nature article by Oregon Health Science University that male mitochondria in cattle is tagged with protein ubiquitin in embryo and marked for destruction. So as is known with Drosophila larvae, male mitochondria in embryo is actively destroyed.
Reason again is mitochondria from males is from active cells where mitochondria DNA is damaged over time by oxidation, much more than nuclear DNA due to converting oxygen and their DNA is unprotected. Mitochondria in females eggs are stored early, not active, and passed on as pristine as possible.
While male mitochondria could work, nothing survived that tried it.
rd
There's a lot of sampling bias there. His paternal mDNA was discovered only because it was defective. It's quite possible there are a large number (though small percentage) of people carrying paternal mDNA who are never discovered because there's no reason to look.
The maternal mitochondria lineage is universal in all life, not just humans. I agree this one example doesn't prove anything, but I wasn't aware of it and had nothing to do with the statement.
First, by saying that maternal mitochondria lineage is nearly universal, that means that male lineage isn't found to speak of in any samples of life when studied unless species is known to use both. A small percentage that's always missed? Possible, of course. Some studies of mouse mitochondria DNA suggest male is present in proportion to sperm to egg mitochondria, 1 in 1000 to 10,000, too low to detect.
Second, Nick Lane (English professor and science writer) in his book Oxygen cites a 1999 Nature article by Oregon Health Science University that male mitochondria in cattle is tagged with protein ubiquitin in embryo and marked for destruction. So as is known with Drosophila larvae, male mitochondria in embryo is actively destroyed.
Reason again is mitochondria from males is from active cells where mitochondria DNA is damaged over time by oxidation, much more than nuclear DNA due to converting oxygen and their DNA is unprotected. Mitochondria in females eggs are stored early, not active, and passed on as pristine as possible.
While male mitochondria could work, nothing survived that tried it.
rd
Interesting. Do you have a citation for this study where they actually grew embryos to term using male and female-originated mitochodria and determined that it actually made a difference?
I'm not quite sure why the DNA in the mitochondria would be any more aged and defective than the haploid genome in the sperm in the first place. It is true that eggs in a woman are essentially formed early vs sperm forming late, but that applies to all DNA in the sperm and not just the mitochondria.
Maybe you're right and that it is this way for a reason. However, having a nice argument doesn't really translate into proof...
hi there, I won't go into a lot here, as much as necessary if you follow up, but all life with nucleus and mitochondria (most everything but bacteria) uses female mitochondria exclusively in offspring.
Your point about the other DNA being aged in both male and female is true, but nucleus DNA is protected by a protein cover. The DNA of mitochondria, a cell within a cell, is like bacteria and has no protective protein covering. Bacteria get around this by dividing rapidly. The mechanism for passing on pure mitochondria was to preserve it in a female egg, thus arose the need for sexes.
Again, this and much else about cells, such as DNA-RNA and other quite complex cellular mechanisms that we read about, is universal in all life. That was quite eye-opening.
rd
You present a false choice. Evolution is a well studied and documented fact. A fact that in no way disproves god. It's only 'contested' by people who don't even understand their own theology and history of their book.
I did not mean to present it as a forced pick of one or the other. It was a play on the words thank god for sexes, or evolution, or both :), take your pick.
rd
Does the book specifically mention the maleness of the mitochondria being the problem, or is it more that the cell it came from just completed a rather long race?
yes, the book addresses both. It's not that the mitochondria is used and damaged by the sperm, but rather that the copy from the male used to make the sperm is used and damaged, the older the male the more damaged.
The female mitochondria is preserved unused in the egg and universally used as the mitochondria in cells in the offspring. That is why in DNA analysis you can track the maternal lineage with the mitochondria DNA.
I think based on studies cited in the book if they tried to continue this experiment for three or four generations it would peter out.
rd
I'm reading Oxygen by Nick Lane, and recreating with male mitochondria is a universal no no. Even worms while forming excrete the male mitochondria from the gametes used to form it.
The male mitochondria passed on is aged and defective, the female mitochondria an unused preserved version.
In other words, there's a reason it doesn't work the way it's being forced to work. That's why we have sexes. Thank God or evolution, your choice.
rd
Who cares if people use more addresses ? We are going to run out of IPv4 anyway and it will happen 'fast' or faster.
You're missing the point. These are criminals. They do things that make it hard to stop them. Operating from a wide range of addresses makes it harder to stop them.
As a secondary effect, they are trying to force to ipv6 ASAP because they will be impossible to stop then.
As a side effect, those who own a rare resource can make money. These addresses are used to make money until someone is willing to pay even more for the addresses.
Should this unrestricted ipv6 be put into place, ip addresses lose all of their sale value but provide infinite IP addresses to attack from.
The people here seem to be network types that only care about their routers, but what will happen is teh United States and other western countries will be forced to set up a secure network for the public to keep out the hordes of attackers.
And yes, I know proxies in the US are used also, and I block them too.
rd
The idea was that if regions had their own range you could just agregate everything in that region (use 1 large IP-block to represent many smaller ones). For example an other continent.
This would safe memory and CPU-time on routers.
It was a nice idea, but it doesn't work in real life. In real life large networks span the globe and similair problems.
Thanks for the explanation. ARIN and the other geographical assignment areas work fine. I increasingly see an ipv4 split between continents but still is pretty good at 255.255.128 or so.
I see the ipv6 people here are pretty rabid but I'm not joking. They're crazy if they think the rest of us are going to allow IP attacks from anywhere in a gazillion addresses.
The rest don't know it yet, but they will when all hell is unleashed on them by the attackers who must be giggling about this. In fact, the number of IP ranges keep being added to former USSR is amazing. Do you have any idea how many address ranges are assigned to Latvia, for example. just to pick a very small country with an amazing range of addresses generating spam attacks.
rd