Darwin’s delight: By comparing the genomes of humans, chimps, macaque monkeys, and orangutans (pictured clockwise), scientists discovered that the ancestor to the great ape lineage, which includes humans, underwent a burst of evolution about 12 million years ago. Charles Darwin (pictured lower right), born 200 years ago today, would have been proud.
Macaque, Scott Liddell; Orangutan, Tom Low; Chimpanzee, Aaron Logan; Charles Darwin, Julia Margaret Cameron
Regions of DNA prone to duplication may have played a vital role in human evolution.
About eight to twelve million years ago, the evolutionary ancestor to humans, chimpanzees, and orangutans appears to have undergone a burst of evolution, driven by duplicated sequences of DNA. This mechanism of genetic change, which has only recently come under scientific scrutiny, may have endowed primates with an evolutionary flexibility that drove the development of different great ape species, including humans.
When a stretch of DNA is mistakenly duplicated, extra copies of the gene or genes within that region are added to the genome; those genes can then mutate separately. "Duplications are really important from an evolutionary perspective because they add a lot of variation to the genome," says Tomas Marques-Bonet, a scientist in Evan Eichler's lab at the University of Washington, in Seattle, who led the research. "These regions are rapidly evolving."
Most estimates of genetic similarity between humans and other primates have focused on single-letter changes to the genome as the primary basis for evolutionary change. But scientists are now discovering the importance of structural changes to the genome, which include deletions or duplications of segments of DNA between 1,000 and 100,000 letters in length. These regions are flanked by repetitive stretches that are thought to trigger errors in the cells' DNA replication process, resulting in duplicated genes.
"It's only recently that we have had the sequence data and the genomic tools to study this and understand its role in evolutionary history," says George Perry, a scientist at the University of Chicago, who was not involved in the research. The chimp genome was released in 2005, and the orangutan and macaque genome projects are ongoing. In addition, scientists can now create custom-designed gene microarrays to quickly detect a large number of specific duplications.
Marques-Bonet and his colleagues analyzed the genome sequence of four primate species: humans, chimpanzees, orangutans, and macaques. Humans, chimps, and orangutans descend from the African great ape lineage, sharing a common ancestor about 12 million years ago, while macaques, classified as old-world monkeys, split from the common primate lineage more than 25 million years ago. Comparing areas of DNA duplication in the genome sequence, researchers found a burst in the rate of duplications right before orangutans split from the tree, and a second burst before chimps and humans diverged, according to research published today in the journal Nature. This increase happened even as rates of single-letter changes decreased.
Scientists are hesitant to speculate about precisely how the acceleration in the rate of duplication arose in the human and chimp lineage, and how it affected human evolution. For example, it's not yet clear whether the duplications that occurred during this time period conferred an evolutionary advantage on their bearers. "We think that duplications make the genome more dynamic," says Marques-Bonet. "But having a dynamic genome creates both sides of the coin: these rearrangements can be beneficial, or they can be linked to disease." Recent research shows that duplications in the human genome play a role in a variety of diseases, including autism, schizophrenia, and mental retardation.
Detecting structural changes in the genome could bring new diagnoses.
Chunks of shuffled DNA in the human genome could underlie many diseases.
just gimmie a con(in)clusive explanation
ok. lemme make some sense of this.. a couple billion years ago after the earth happened to be formed and fit just the right equalities for a life to flourish, some gooey mess held the key of dna and sprouted forth with the capability for life as we know it today.
-i'm a lil shaky on the foundations but hold with me a minute..]
so billions of years pass and we've got the diversity of life on this planet from animal to fauna and the existence of apes in trees. yay!
fast forward some 12 or so million years ahead and you say that humans as decadent as we are today are simply the natural evolution of animals over time, or that specific animal, over time.
question one, why don't we see similar examples of evolution across the spectrum of species held by this planets ecosystems? maybe we lack the sophistications to recognize such progress?
question two, and this is a bit involved; characteristics move generationally, so how many total changes make the difference between homo erectus and homogorillimus and could those evolutions total the differences held between us during the time span given? don't forget about ice ages and catastrophies.
i watched WGBH or PBS last night talking about creationism vs evolution and both forget about the holy ghost middle ground no-mans' land ascertion that pieces of them all total the sum answer.
('d never say trust me, but i know what's wrong)
oh, and what about Mendel and his beans? only purposeful cross breading or manipulation can create the kind of drastic differences that chance stumbles upon.
i'm glad i don't get paid for this- it wouldn't be as fun.
When did this matter become truth? There are no less holes today than when Chuck made his Origin of Species assertion. I suspect he would change his mind if he knew today what he lacked back then. I am sorry that you feel comfortable believing you came from an ape, but I much prefer to believe that I came from an intelligent Creator! BTW. Try telling Dr. Tomas Marques-Bonet that his work is a "nice piece of evolution" and let me know if he's insulted.
Science, USC-91, is based in large part, on collecting enough experiential evidence to support a premise, a statement of fact. Although there's no denying that in the beginning something created matter, which after a billion years of evolution gave rise to life here on this planet, no one has been able to describe, at least in reasonably 'intelligent' terms anyway, how that process actually takes place. It's still quite inexplicable, and, therefore, still a mystery to even to the most 'enlightend' thinkers of our times. I am always open to all sides of an argument just as long as the debate stays reasonably 'intelligent' and well informed. Yes I have read Michael Behe's, 'The Edge of Evolution', and found it interesting, just as some well constructed theological arguments can add to the equation. The trick here in this particular situation, is, however, being able to make your case without resorting to meer sophistry or blind adherence to a lot of allegorical Biblical dogma.
Re: Huh? Proof in the pudding.
The proof that evolution has a large component of randomness in it, is the very existence of people like USC-91.
An intelligent creator/designer would not create loonies.
But a stochastic evolutionary process always produces a subpopulation of suboptimal individuals. It's a bell curve distribution after all...
Looks like this thread has been hijacked by some creationist loons. Why oh why does America, the most scientifically advanced country on the planet, harbour such an anti-scientific public? From climate change to evolution there seems to be no end to the lunacy that pours forth from these guys who would clearly be quite at home in the dark ages. Not literally, I mean, these guys wouldn't have the slightest idea of how to survive once you take em out of their heated homes, comfortable SUVs, and fast food, all products of science and technology. I suppose its partly the fault of scientists who somehow became isolated from the public and not engaged enough with them.
...loons? Such contempt. Has liberal been stripped from liberalism just as freedom has been stripped from academic freedom? If the Good News we preach is hidden behind a veil, it is hidden only from people who are perishing. Satan, who is the god of this world, has blinded the minds of those who don’t believe. They are unable to see the glorious light of the Good News. They don’t understand this message about the glory of Christ, who is the exact likeness of God (2 Cor 4:3-4). Yes, that is a Bible quote! Read it sometime. I too was blind.... one thing is for certain. The Nazi Holocaust was all about eugenics and 'natural selection.' If we reject a higher authority, a creator, and remove all faith, then we are left with no moral absolutes. There is no right or wrong. This is entirely consistent with the ideas of evolution. Still want to be ape-man? I don't. Don't get me wrong. I love all people, flaws and all... and so does my Creator. After all, He did die for all of our sins (including the ones that nailed Him to the cross, the one who betrayed Him, those who mocked Him, and yours). No comment will be forthcoming. You are in my prayers, and my defense is in His hands now.
One thing that we certainly don't want here, USC-91, is someone trying to hijack this forum with the kind of religious blather which your promoting. Try picking up a copy of 'The Jesus Dynasty' by James Tabor, then follow it up with 'Misquoting Jesus' by Bart Ehman, then polish off Michael Baigent's, 'The Jesus Papers.'
If after that however, you still feel the need to postulate any further, please feel free to go to your local church and bear witness. You will have our complete and unrepentant blessing.
I think your attack on creationism is a little hypocritical in the way you state your case.
Evolution has never been verified as true or even a viable form of origin of species. It has too many flaws and holes to be anything but a theory (although a colorful theory though). Creationism has not been proven either though for equalization, but placed side by side, there is far more evidence of the claims of creationism than evolution.
I for one think both should be kept out of school teaching for these reasons, or both presented side by side for all to see the relations and characteristics presented by both camps.
Attacking one side or the other is not scientific by any means and scientific investigation should be the rule here instead of the hateful ramblings which I sense from your ill-informed opinions.
Bottom line is both are theories and should be treated with the respect and investigated as such without the hate or unscientific condemnation which I often see.
Are we asking the right question ?
I agree that there are too many looney comments, but shouldn't we be asking the fundamental question (no matter what side you're from) which is HOW does gene or DNA duplication create new genetic information ? Whether the quantity of this activity is high (burst) or not....Where is the knock down proof (looking for a scientifically reproducible formula) that this explains HOW one can add to the DNA molecule and thus explain macro evolution. I've been reading materials from the ID camp, and either they're ignoring the evidence, or there isn't an obvious enough answer to satisfy their Biologists. Anybody have any comments on that ?
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phoenix
172 Comments
ode to homo eructus
From the great apes we slowly ascended,
Taking our place on the evolutionary tree,
The human race was clearly intended,
To be much more intelligent you see,
But we wage wars and die from diseases,
Pollute our planet and cause so much pain,
I guess we were just never intended,
To be perfect that much is quite plain.
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