Chimp genome now mapped

[Soxy]

Linkage

Very cool. Although, I thought we shared more than 96% of our genetic material with them. Learn something every day (woohoo! I don't have to learn any more today). Yesterday I learned we share 90% of our genetic make-up with the rat. Isn't science awesome? (The correct answer is yes. . .)

 

Chimp genome mapped out

96% of gene material matches humans'; differences may shed light on diseases

 

By Peter Gorner

Tribune science reporter

Published September 1, 2005

 

Humans and chimpanzees share 96 percent of the same genetic material yet are profoundly different creatures, a mystery scientists hope to begin to unravel with Wednesday's announcement that the genes of humanity's closest cousin have been cataloged.

 

Publication of the complete chimp genome, marked by a celebratory issue of the journal Nature, is viewed by scientists as a landmark event that will lead to a better understanding of how the human genome has evolved and to insight on diseases that people get but chimpanzees rarely suffer, including cancer and Alzheimer's.

 

It long has been speculated that humans and chimps diverged from a common ancestor 6 million to 7 million years ago, a relative eye-blink in evolutionary terms. Their genes are quite similar, as are certain behaviors, posing a direct challenge to humans' uniqueness.

 

"Humanity's special place in the cosmos is one of abandoned claims and moving goalposts," primatologist Frans B.M. de Waal wrote in Nature, citing 40 years of studies showing that humans are not the only animals who hold close family bonds, play power politics and form alliances, make and use tools, or engage in warfare.

 

The scientific value of the chimp genome, researchers said, lies in the subtle differences. Data are now at hand that can be used to figure out what makes us human, they said.

 

`Narrows the search'

 

"This genomic comparison dramatically narrows the search for the key biological differences between the species," said the study's senior author, Dr. Robert Waterston, chair of genome sciences at the University of Washington School of Medicine in Seattle.

 

Nature asked Wen-Hsiung Li, a pioneering genetic evolutionist at the University of Chicago, to write a commentary on the work.

 

"Because the genomes are huge--3 billion base pairs of DNA--the differences in molecular terms are quite a lot," Li said. "Most of them probably will not be biologically significant, but some may be crucial. Our task now is to identify those that are meaningful and prove it in the laboratory."

 

Comparison of the human and chimp genomes reveals that their genetic sequences are directly comparable over 96 percent of their lengths, and these regions are 99 percent identical.

 

Out of the 3 billion base pairs of DNA in each genome, about 35 million differ, of which as many as 3 million may lie in crucial protein-coding genes.

 

The number of genetic differences between a human and a chimp is about 60 times less than that between a human and a mouse and about 10 times less than between a mouse and a rat--but it is about 10 times more than between any two humans.

 

Sixty-seven geneticists formed the Chimpanzee Sequencing and Analysis Consortium and share authorship of the main Nature paper.

 

Most of the work of sequencing and the assembling the chimp genome was done at the Broad Institute of the Massachusetts Institute of Technology and Harvard University and the Washington University School of Medicine in St. Louis. More work was done at U.S. institutions and others in Israel, Italy, Germany and Spain.

 

The chimp DNA came from a male named Clint, who died last year of heart failure at the relatively young age of 24 at the Yerkes National Primate Research Center in Atlanta.

 

Tarjei S. Mikkelsen, an MIT graduate student of such promise that his elders honored him by making him senior author of a major paper, said researchers will be studying genetic changes that may be related to such human-specific features as walking upright on two feet, a greatly enlarged brain and complex language skills.

 

Key distinctions already made

 

Among the discoveries so far is that three key genes involved in inflammation appear to be deleted in the chimp genome, perhaps explaining some of the known differences with humans in respect to the immune inflammatory response.

 

On the other hand, humans appear to have lost function of the caspase-12 genes, which produce an enzyme that may help protect other animals from Alzheimer's disease.

 

"The sequencing of the chimp genome is a historic achievement that is destined to lead to many more exciting discoveries with implications for human health," said Dr. Francis Collins, director of the National Genome Research Institute, which funded the project at a cost he put at $20 million to $40 million.

 

"It has become clear that comparing the human genome with other genomes of other organisms is an enormously powerful tool for understanding our own biology."

 

The researchers warn against the breeding of transgenic chimps, as is often done with mice, and called for more effective policies to protect chimps in their wild habitat.

 

"We hope that elaborating how few differences separate our species will broaden recognition of our duty to these extraordinary primates that stand as our siblings in the family of life," they wrote.

[FlaSoxxJim]

It's actually 96% to 99%+ shared DNA, depending on how the comparison is made, so we're still brothers removed by a measly 6 million years.

 

Yes, Science Rocks Hard!

 

Science!

[FlaSoxxJim]

Ah, here's the reference from the piece posted:

 

Comparison of the human and chimp genomes reveals that their genetic sequences are directly comparable over 96 percent of their lengths, and these regions are 99 percent identical.

 

So basically, if the 4% dissimilarity in sequence runs ands up amounting to non-coding regions ("junk DNA", although the jury is again out on whether there is such a thing), then the older dogma that there is 99% similarity in the coding sequences between chimps and humans holds true.

[jasonxctf]

but i believe in intelligent design....

 

 

[JUGGERNAUT]

Perspective is fundamental to understanding.

 

What signifigance is there to the fact that there is a 4% differential between our genome & that of a chimp's? None. The fact taken by itself is irrelevant. You would be a fool to suggest that this 4% is the same as say a 4% differential in the price of oil.

 

The signifigance then lies in RELATION to differentials of other species. There is less than a 10% differential between humans & fruit flys. Or put another way less than a 6% differential between fruit flys & chimps. When you list the characteristics & attributes between a fruit fly & a chimp it's a VAST difference. Probably on par with the VAST difference in characteristics & attributes between a chimp & a human.

 

Is this kind of understanding taught in public schools? Doubtful. They are mostly Darwinists afterall. Any understanding that threatens their narrow vision is attacked with zeal reminiscent of militant Islamic fundamentalists.

Is Darwinism a religion? It sure acts like one :rolly

Edited September 4, 2005 by JUGGERNAUT

[Heads22]

Not much of a connection, butttt......

 

 

"'Thank the Lord'? That sounded like a prayer. A prayer in a public school. God has no place within these walls, just like facts don't have a place within an organized religion. "

[FlaSoxxJim]

Is Darwinism a religion?

No, it isn't.

 

And I actually largely agree with the rest of your post, other than the science-bashing.

 

A value of 10% or 4% or 1% difference in overall genetic sequence taken by itself in a vaccuum is not particularly meaningful. What becomes meaningful is when genes coding for specific proteins are taken from various source organisms and compared to one another. Highly conserved genes, like that encoding for p53, can be used as informative sources of information concerning the chronology of divergence of evolutionary lineages. We share an astounding amount of similarity on those regions with those species we diverged from very recently, i.e, the other great apes. we share much less similarity with more distantly related taxa such as fruit flies and corn plants.

 

Without this kind of comparative genomic technology, we might be tempted to again believe that all our intellect and accomplishments makes it impossible that we're still really great apes. Really. really smart animals, but animals nevertheless.

 

Older paraphyletic (splitting the descendants of a common ancestor) classification schemes artificially put human and a some prehistoric Homo spp. groups into the family Homidae, while placing the rest of the great apes (gorillas, chimps, orangutans) into the family Pongidae. More current systematics relegates the Pongidae to subfamily status (Ponginae), and puts all of us together as the extant great apes in family Hominidae. Systematic revisions like this are largely done when the comparative genetic work indicates. In this case, the taxonomic 'lumpers' have done us all a favor by reminding us that we're still just smart, naked apes.

 

Back to the % genetic similarity issue. What we don't yet have much of a handle on is how important gene suites and gene clusters are at making us so dffferent from our nearest evolutionary relatives. Even though the blueprints in humans and Bonobo chimps are so as similar as two slightly different editions of a school textbook, somehow our translational machinery for making proteins out of these blueprints is squeezing more information out of the same blueprints. Novel gene products seem to emerge when some information from gene A is translated along with some information from gene B and gene C, etc. basically, our DNA regulatory mechanisms are more different than a gross value of 1% or 4% or 10% would seem to sugggest.

Edited September 6, 2005 by FlaSoxxJim

[Heads22]

Nerd.

[FlaSoxxJim]

Nerd.

But I get the babes. The really, really nerdy babes.

[JUGGERNAUT]

No, it isn't.

 

Novel gene products seem to emerge when some information from gene A is translated along with some information from gene B and gene C, etc.  basically, our DNA regulatory mechanisms are more different than a gross value of 1% or 4% or 10% would seem to sugggest.

<{POST_SNAPBACK}>

 

Some would say militant religions are made up of people who ignore facts in hopes that they will go away so that they can adhere to their own paradigms. Darwinists seem to fit the bill.

 

I do not see where my post demonstrates any science-bashing. I acknowledge that natural selection played a primary role in man's evolution. I'm reading a book now that actually compares the development stages of embryos & fetuses to other organisms. The similarities are so astounding that you could make the argument that man's evolutionary past can be visibly seen during reproduction.

 

But in comparison that past represents 9 months of a 72 yr life expectancy. There is little scientific evidence to support natural selection as the predominant influence beyond birth.

 

The research suggesting a multiplicity function to genes in humans is equally astounding. That's why the article was termed software of life. If you think of in terms of object oriented programming, the common genes represent the data structures & the software is represented by the methods. It appears the same data structure in humans has many times more methods.

 

What I will admit & it's not really been discussed yet in the thread is that ID is too complex to teach at an elementary level. You need at least a college level understanding of calculus, molecular biology & chemistry to make sense of these findings. So I don't forsee an ID class for the average kid.

 

ID can not even be introduced into a class on evolution until the class as covered RNA, DNA, the human genome, the neural net including the brain. Such stuff is usually not covered in K-9. The only impact in K-9 would be a subjective one. Natural selection would no longer be assumed as the primary influence for mankinds super-cognitive abilities. Super in comparison to everything else.

[FlaSoxxJim]

The similarities are so astounding that you could make the argument that man's evolutionary past can be visibly seen during reproduction.

Ontogeny recapitulates phylogeny?!?

 

When was that book written?

[JUGGERNAUT]

http://www.uchospitals.edu/ - findings on frequency of mutation in humans.

 

http://www.sciencedaily.com/releases/2005/...50111170714.htm

Humans Are A 'Privileged' Evolutionary Lineage

 

Lahn: "The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented. Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."

 

www.sciencedaily.com/search/?keyword=Bruce+Lahn&topic=all&dates=1995&dates=2005&sort=relevance

[FlaSoxxJim]

http://www.uchospitals.edu/ - findings on frequency of mutation in humans.

 

http://www.sciencedaily.com/releases/2005/...50111170714.htm

Humans Are A 'Privileged' Evolutionary Lineage

 

Lahn: "The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented. Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."

 

www.sciencedaily.com/search/?keyword=Bruce+Lahn&topic=all&dates=1995&dates=2005&sort=relevance

Thanks.

[Balta1701]

http://www.uchospitals.edu/ - findings on frequency of mutation in humans.

 

http://www.sciencedaily.com/releases/2005/...50111170714.htm

Humans Are A 'Privileged' Evolutionary Lineage

 

Lahn: "The making of the large human brain is not just the neurological equivalent of making a large antler. Rather, it required a level of selection that's unprecedented. Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."

 

www.sciencedaily.com/search/?keyword=Bruce+Lahn&topic=all&dates=1995&dates=2005&sort=relevance

I looked through those links you've given us, and I must say, hopefully without being edited in the future by the moderators, I think you're heavily misinterpreting the conclusions of the group you're citing.

 

If I understand your argument correctly, you're saying that the person's research implies that there is a greater rate of mutation appearing within human development than within other species, something you're using to argue as evidence of the unique place of humans.

 

However, I believe you are ignoring the key point...in particular through your selection of the text you quoted in this post. From the same article, I believe this excerpt sums up the problem with your reasoning:

 

Researchers examined the DNA of 214 genes involved in brain development and function in four species: humans, macaques (an Old World monkey), rats and mice. (Primates split from rodents about 80 million years ago; humans split from macaques 20 million to 25 million years ago; and rats split from mice 16 million to 23 million years ago.)

 

For each of these brain-related genes, they identified changes that altered the structure of the resulting protein, as well as those that did not affect protein structure. Only those genetic changes that alter protein structure are likely to be subject to evolutionary selection, Lahn said. Changes in the gene that do not alter the protein indicate the overall mutation rate – the background of random mutations from which evolutionary changes arise, known as the gene's molecular clock. The ratio of the two types of changes gives a measure of the pressure of natural selection driving the evolution of the gene.

 

Researchers found that brain-related genes evolved much faster in humans and macaques than in rats and mice. Additionally, the human lineage has a higher rate of protein changes than the macaque lineage. Similarly, the human lineage has a higher rate than the chimpanzee lineage.

 

"For brain-related genes, the amount of evolution in the lineage leading to humans is far greater than the other species we have examined," Lahn said. "This is based on an extensive set of genes."

 

They argue that a significant fraction of genes in the human genome were impacted by this selective process. The researchers estimate there may have been thousands of mutations in thousands of genes that contributed to the evolution of the human brain. This "staggering" number of mutations suggests that the human lineage was driven by intense selection process.

What the author is in fact saying is that there is a normal background rate of mutation, given by the rate of mutations that do not affect the phenotype. There is also a rate of mutations in proteins that are expressed in the phenotype of the organism. These two rates are identical.

 

What the authors of this paper have found is that when a beneficial mutation did appear in human brain development, it was adopted with extraordinary speed. In other words...there was an incredibly huge selective advantage for a proto-human which posessed a larger and more developed brain.

 

This is in fact no where near an argument for ID...it does show that human evolution has occupied a unique place in recent history in that there was some sort of extraordinary selective pressure towards larger brains for proto-humans. It does not say that the mutation rate in those genes was found to be different.

[JUGGERNAUT]

This is in fact no where near an argument for ID...it does show that human evolution has occupied a unique place in recent history in that there was some sort of extraordinary selective pressure towards larger brains for proto-humans.  It does not say that the mutation rate in those genes was found to be different.

<{POST_SNAPBACK}>

 

You won't find many researchers mention the term ID. The term is simply too hot an issue right now for any researcher to risk such media pressure. Instead they will make use of terms suggestive of ID like "blueprint", "unique", "priviledged", "enormous", "exceptionally" "complex", "software", etc.

 

I would do the same thing if I were in there shoes. Use words that are strongly suggestive of an intelligent design but including references to natural selection.

 

Lahn: "Human brain evolution required a major overhaul of the genetic blueprint."

 

Vastly accelerated evolutionary changes in humans is a stark contrast to the belief that natural selection takes eons of time & the selective process at work in other species. It remains a mystery as to why this happened.

Edited September 8, 2005 by JUGGERNAUT

[Balance]

The main problem with ID is that its fundamental underlying precept is that some intelligent power (and make no bones about it, each and every proponent of ID believes that the intelligent power is God, usually the Christian god) set up all the laws of nature which led us to this point in the history of the universe. That, in and of itself, is not scientifically testable. You can gather as much information as you want about the natural world, you can study what those natural laws are, you can use them to infer other information, but you can't ever get to a point where it's possible to scientifically prove that God... excuse me, an Intelligent Designer set up the rules.

 

You can believe whatever you want to believe about why the laws of nature are what they are. Just so long as that doesn't interfere with the scientific study of those laws.

[Balta1701]

You won't find many researchers mention the term ID.  The term is simply too hot an issue right now for any researcher to risk such media pressure.  Instead they will make use of terms suggestive of ID like "blueprint", "unique", "priviledged", "enormous", "exceptionally" "complex", "software", etc.

 

I would do the same thing if I were in there shoes.  Use words that are strongly suggestive of an intelligent design but including references to natural selection.

 

Lahn: "Human brain evolution required a major overhaul of the genetic blueprint."

 

Vastly accelerated evolutionary changes in humans is a stark contrast to the belief that natural selection takes eons of time & the selective process at work in other species.  It remains a mystery as to why this happened.

No, it does not. Vastly accelerated human evolutionary changes simply argues that there was a strong selective advantage to the increased brain size and complexity of humans. That is written throughout the papers that you are trying to cite. In fact, the papers you are choosing to cite have no problem attaching a basis in selection for changes you are claiming are impossible.

 

Secondly...you are clearly failing to define your timescale very well here. We are talking about vast changes in the human genome yes...over a period of 25 million years. This is more than enough time. We are talking about hundreds of thousands, if not millions of generations in there, depending on the average lifespan of each organism.

 

You say that researchers using words like "complex, enormous, exceptionally" are somehow arguments that prove they really want to talk about ID? First, I would ask whether or not you have spoken to those people and actually know that this is what they mean, and you are not just reading additional meaning into it. Secondly, if the answer is no, and you have not in fact spoken to that particular research group and found out that is the case, how is it you can infer from his language that he really is talking about ID in 1 case but really does not mean the words he is writing when he talks about how dramatic of a selective advantage there must have been for those traits to be adopted?

 

Finally...you say it is a mystery exactly why that happened...on this point I must actually agree with you, because there is not yet any scientific consensus about exactly what the main driving force behind the dramatic expansion of the proto-human mind was. Some would say it was driven by the diet. Some would say it was driven by tool use. I would argue communication is the biggest driving factor. But the fact that there is debate going on in an issue at present is clearly not a reason to suddenly toss all of that discussion out the window and point towards an unknown, unexplained, and unprovable designer.

[JUGGERNAUT]

<{POST_SNAPBACK}>

 

You have nailed it. I view ID to mean Intelligent Design but the majority of the 64% polled view it as Intelligent Designer. All I've advocated is that spontaenous mutation & natural selection alone do not account for human evolution. Darwin himself stated the same thing when asked about the human eye. He used the word "absurd" at that notion.

 

Recent research suggests our brains played a prominent role in the evolution of the eye. Other researchers believe they have found the genes that played a prominent role in regulating our brain sizes. I've never heard any one suggest that 25 million years is plenty of time to explain the vast development of the human brain. That is why these findings are so profound.

 

With respect to an Intelligent Designer the connection lies in QT. The wacky crazy world of Quantum Theory has led to physics converging with philosophy as we now have to confront a world that seems to defy laws of space & time. This has led to strange theories of alternate universes, ghosts in the machine, realization of a spirit world, & God as the ultimate observer. A Grand Unifying Theory lends itself to intelligent design.

 

So inevitably any discussion of QT involves a discussion of God. The question then is should QT be taught in K-9? That's a tough question. Traditionally you were grounded in CM before you learned about QT. But many believe you can teach the philosophical constructs of QT early on & leave the math until later. I tend to agree with that.

Edited September 8, 2005 by JUGGERNAUT

[knightni]

Honestly, I find it tough to believe that life on earth just spontaneously happened.

 

There had to have been some sort of help somewhere.

 

God? Aliens?

 

You can't just spontaneously have something "occur".

 

It's highly improbable.

[Soxy]

You have nailed it.  I view ID to mean Intelligent Design but the majority of the 64% polled view it as Intelligent Designer. All I've advocated is that spontaenous mutation & natural selection alone do not account for human evolution.  Darwin himself stated the same thing when asked about the human eye.  He used the word "absurd" at that notion.

Perhaps, and I think that this is the central tenent of evolution/natural selection/etc that the human eye (which, I agree, is not the most efficient design) is not done evolving? And that in a million years or so the design might be radically different? Or the brain differently organized?

 

I think you're missing the point of evolution--evolution says there is no FINAL product. We will continue to evolve as long as we exist on the planet, thus any unefficient designs will be streamlined through natural selection, propogation of the fittest, etc. . .

[knightni]

The earth tilted "just so" and JUUST the right distance from the sun to keep life alive.

 

Oxygen/Nitrogen/Carbon Dioxide levels in a perfect amount for breathing.

 

Even if there was evolution, the beginnings of life are pretty unlikely.

 

I've never seen my breakfast combine into a living organism all on it's own.

 

Anything humans do on earth scientifically is just an adjustment of what is already here.

 

Nothing new has been created on this earth by humans.

Edited September 8, 2005 by knightni

[Balta1701]

You have nailed it.  I view ID to mean Intelligent Design but the majority of the 64% polled view it as Intelligent Designer. All I've advocated is that spontaenous mutation & natural selection alone do not account for human evolution.  Darwin himself stated the same thing when asked about the human eye.  He used the word "absurd" at that notion.

Seriously...who exactly cares what Darwin thought was "Absurd"...Darwin didn't have the full story. He didn't have an understanding of genetics, how traits were inherited, or mutation itself. That doesn't mean that we can't trace essentially a complete lineage of the modern mammalian eye back through time. (Read both part 1 and part 2 here)

 

Recent research suggests our brains played a prominent role in the evolution of the eye.

How exactly is this unexpected? The evolution of a more complex brain would allow easily for the evolution of a more complex eye able to send more complex signals to that more complex brain, and the selective advantage of a more complex eye to a creature that is trying to avoid predators on an African plain should be obvious to almost everyone.

 

With respect to an Intelligent Designer the connection lies in QT.  The wacky crazy world of Quantum Theory has led to physics converging with philosophy as we now have to confront a world that seems to defy laws of space & time.  This has led to strange theories of alternate universes, ghosts in the machine, realization of a spirit world, & God as the ultimate observer. A Grand Unifying Theory lends itself to intelligent design. 

 

So inevitably any discussion of QT involves a discussion of God.  The question then is should QT be taught in K-9?  That's a tough question.  Traditionally you were grounded in CM before you learned about QT.  But many believe you can teach the philosophical constructs of QT early on & leave the math until later.  I tend to agree with that.

What you refer to as strange theories I refer to as eminently practical theories to explain observed behaviors. I see nothing magical in viewing the universe as a series of vibrating strings that move in 12 dimensions, and I don't consider it to be a logical conclusion of it at all.

 

And secondly...and more importantly...a grand unifying theory may lead itself to a discussion of a God, but it does not in any way lend itself to intelligent design in the way you suggest. It may be possible to argue that there was a God who set the laws of the universe and constants of the universe to what they currently are (again here I would say this is just a cop out - saying that because science doesn't yet have a full explanation a God must be the cause, but that's a side point)...but nothing in quantum mechanics, a unified field theory, or any of the other models you present suggest in any way that there is a designer who is willing to interfere with the laws of the universe in order to give rise to "Intelligently designed" species. In fact, it would probably argue even stronger that if there were a designer...he did his designing 15 billion years ago and left it alone, because why else would he have founded a universe based on constant, unchanging laws...thereby providing a strong arguement against your other points about the "Uniqueness" of the human animal.

[Balta1701]

Honestly, I find it tough to believe that life on earth just spontaneously happened.

 

There had to have been some sort of help somewhere.

 

God? Aliens?

 

You can't just spontaneously have something "occur".

 

It's highly improbable.

Ok, now here is 1 key point...we're confusing 2 issues. Evolution of Life through Natural Selection of inhereted characteristics says absolutely nothing about the origin of life on Earth or anywhere else. So this is now a totally separate issue from anything dealing with evolution.

 

Evolution based on natural selection only matters once you have a being which is capable of passing on genetic material to its offspring. Without that, Natural Selection doesn't matter.

 

On the second issue...I would say that yes, in fact, you can spontaneously have something just "Occur", if you have an input of energy from an outside source such as the sun. When a large amount of energy is released and absorbed by another system, it must be either released or stored in something. On this planet, it has been stored as information.

 

While we do not yet have a full explanation for how life on Earth first evolved...that doesn't mean there is no answer to that question. At some point in my lifetime, we may very well have a good answer to it.

[knightni]

Okay, you can spontaneously have an explosion occur if gases build up somewhere...

 

But it is HIGHLY improbable that the rocks, debris etc. from that explosion can just happen fall into place so that it creates a planet that is 100% perfect for living organisms.

[Balta1701]

The earth tilted "just so" and JUUST the right distance from the sun to keep life alive.

 

Oxygen/Nitrogen/Carbon Dioxide levels in a perfect amount for breathing.

 

Even if there was evolution, the beginnings of life are pretty unlikely.

 

I've never seen my breakfast combine into a living organism all on it's own.

 

Anything humans do on earth scientifically is just an adjustment of what is already here.

 

Nothing new has been created on this earth by humans.

Actually...oxygen levels have varied significantly throughout geologic time. The first appearance of significant levels of oxygen on Earth didn't happen until roughly 2.3 billion years ago give or take an Eon or two. Prior to that, the Earth had a reducing atmosphere - if you put iron out in the atmosphere, it would not have rusted. It probably would have been loaded with CO2 at times.

 

In fact, the Earth may also have completely frozen over several times, leading to a massive increase in CO2 in the atmosphere as it was pumped up through volcanic activity.

 

Oxygen/nitrogen levels have varied significantly through even more recent geologic time. About 400-300 million years ago, the oxygen level of the earth appears to have been much higher...as high as 30-40% at some times. There is good evidence for this in the fossil record...evidence for massive wildfires fed by the higher oxygen levels, life forms that evolved which were not processing oxygen as efficiently.

 

The Oxygen level may in fact have taken a catastrophic drop right around the time of the End-Permian mass extinction...the worst mass extinction in Earth's history. It may have even dropped below 10%. There is also evidence for this...species that were adapted to harsh environments, such as reptiles which lived at high elevations, were some of the most successful organisms at surviving the die off.

 

Now we're something like 22% oxygen...and that is the perfect level for us. Why? Not because it was designed for us, but because our species evolved in a world with 22% oxygen. Our bodies were designed to survive in 22% oxygen because that is what we were living in. In fact, you can probably see evidence of selection on the human body based on atmospheric pressure...for example, there are villages in Kenya where you can knock on every door and find a marathon champion at each one. Why? It may very well be that their bodies have adapted to lower oxygen at higher elevations, and when you put those bodies at a lower elevation, they suddenly find their bodies loaded with oxygen.

 

As the Mesozoic and Cenozoic preceded, the oxygen level gradually began to recover as a new equilibrium was established between land plants and animals.