A skull and a picture of British naturalist Charles Darwin are pictured in a museum at Down House, Bromley, Kent on February 12, 2009. Darwin moved into Down House, in 1842. He conducted experiments and research there for 40 years.
(Carl de Souza/AFP)Photos (1 of 1)
New experiments push evolution in ways Darwin never expected
Column: Advances in DNA research enhance basic concepts of evolution.
By Robert C. Cowen | Columnist for The Christian Science Monitor/ February 18, 2009 edition
Science columnist Robert C. Cowen discusses what Charles Darwin didn't know and when he knew it.
Science columnist Robert C. Cowen
As scientists celebrate Charles Darwin’s 200th birthday this month, it’s worth considering what Darwin did not know. He hadn’t a clue about genetics or DNA. That knowledge has extended Darwin’s evolution research to include the fundamental information that underlies our planet’s organic life. He also knew nothing of combinatorial chemistry in which robots carry out thousands of simultaneous experiments. This modern technique has enabled scientists to explore the formation and evolution of the first living cells.
David Deamer at the University of California in Santa Cruz is one of those scientists. At the annual meeting of the American Association for the Advancement of Science (AAAS) that ended Monday in Chicago, he explained why he thinks the origin of life on Earth is the result of combinatorial chemistry – millions of simultaneous “experiments” operating on a global scale. He described how his laboratory mimics that era in an array of thousands of individual compartments in which different molecule mixtures undergo reactions. He noted that critics doubt that the right molecules would randomly come together to jump-start life. But, he added, the possibility that combinatorial chemistry provided millions of opportunities for this to happen on primitive Earth “gives us a better way to think about the probability of life emerging from this process.”
While Darwin knew nothing of DNA, modern geneticists readily admit that they have a lot to learn, too. Research published in the journal Nature on Feb. 12 (Darwin’s birthday) illustrates this point. Evan Eichler at the University of Washington in Seattle and colleagues have taken a fresh look at genetic changes that shaped the emergence of humans and modern apes from their common ancestors 8 to 12 million years ago. It turns out that change due to mutations in individual genes, which drives much evolution, had slowed down. Instead, those ancient ancestors were undergoing a burst of duplication of whole swatches of their genomes. This resulted in mix and match rearrangements of DNA that led to significant structural changes in the animals themselves.
This research gives a new perspective on the question of why humans differ strikingly from close ape relatives with whom they share so much of the same genome. The difference at the level of genetic information now appears to lie in the mix and match rearrangements of genetic duplication. The researchers say they discovered “striking examples of gene-containing duplications within the gorilla and chimpanzee that are absent in the human lineage.”
Meanwhile, Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany shared the latest results from Neanderthal DNA research at the AAAS meeting. Neanderthals appeared about 300,000 years ago. Yet their DNA shows common roots with humans reaching back at least 880,000 years. Also Neanderthals and humans share a gene called FOXP2 that is related to speech, suggesting that Neanderthals may have been able to speak. Other genetic differences suggest that humans and Neanderthals did not interbreed.
Darwin’s concept of evolution through natural selection of inheritable changes is the overarching theme of biology today. Yet modern researchers, who know so much more than Darwin did about the history and mechanism of those changes, have only begun to explore the theme’s full implications.
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Comments
2. John | 02.19.09
Would this be the same Lloyd Pye who believes modern humans are a result alien intervention or alien interbreeding? The same Pye whose “Starchild Skull” proved to be human after mitochondrial DNA testing by two independent labs. All Pye’s claims are totally unsubstantiated by any evidence and thus should be viewed with skepticism.
3. Ken | 02.19.09
“Evolution takes base fundamentals and builds on them…advantageous traits built up over millions of years rarely go away”
A large brain has proven to be highly advantageous.
4. Gary | 02.20.09
Human chromosome 2 contains a fusion of two chromosomes found in other great apes. This elegantly explains the decrease in chromosomes from 48 to 46. See Proc Natl Acad Sci USA 88(1991):9051-55.
5. James Bowden | 02.20.09
A larger brain, has the most unique factor with increasing brain power, the species ‘cheats’ evolution, or at least has options not available in other more primitive brains, instead of fight or flight responses you add a third, ‘choice’ the ability to choose how to survive, can quite possibly be so successful that more and more resources, get pumped into growing the brain, exponentially increasing the species survival rate. our brains are no more or less powerful than the when the first humans walked the earth. with time brain evolution has slowed, but has been replaced by our brains direct handy-work ‘technological evolution’ starting very slow, with growth rate unimaginable to the person from only 100 years ago. Evolution starts us of, but now science can continue the evolution, with genetic engineering we can use our brains to evolve the species to our own goal.
6. Rafinki | 02.20.09
“As scientists celebrate Charles Darwin’s 200th birthday” …it might be more worthwhile to remember that he was able to form logical theory’s for what he was able to observe in the world around him. Granted that we have better scientific ways of measuring DNA in more and more amazing ways, still in furthering on Darwin’s theory on the origin of the species it doesn’t appear we are any closer to breaking new ground with a more pronounced understanding that the scientific community can readily agree on.
I have never read any of Pye, but from what Steven wrote, it may turn out to be the revelation of our species.
Imagine for a moment a time line beginning with a species that grew and evolved to a certain point experienced a *sudden explosion of genetic manipulation*, then tried UNSUCCESSFULLY to explain away the obvious tampering with our genetic makeup with more and more complexity… and one day when scientists are able to manipulate our own DNA to the same extent that we observe in ourselves, a light bulb appears above the head of a brainy scientist who announces “Hey you know it kind of looks like someone was mucking around with our DNA…probably ALIENS”. And humanity rewards him by celebrating his birthday. The End.
7. Robert | 02.20.09
Gradual change versus rapid change? Stephen Jay Gould called the phenomenon “punctuated equilibrium” well before researchers found the means by which it occurs. As pointed out in the essay above there are TWO processes which enable evolutionary change. One is gene mutation which, in the aggregate, over long spans of time, produces adaptive change to fill biological niches created by typically gradual environmental change. The other, only recently discovered, is manifested by a kind of master switching process that produces “a burst of duplication of whole swatches of … genomes” fostered by sometimes more rapid environmental change (such as the global warming we are now witnessing). Some creationists insist that this is all god’s m.o., but the evidence indicates that natural, observable processes are sufficient to drive all of it, and any attempt to insert a deity into the mix “should be viewed with skepticism.” Those who have difficulty grasping this would do well to read, and understand, any of Gould’s books, such as The Panda’s Thumb, or The Flamingo’s Smile.
8. Bjørn Østman | 02.20.09
Steven, PZ Myers has an excellent post about how chromosome numbers change:
http://scienceblogs.com/pharyngula/2008/04/basics_how_can_chromosome_numb.php
“Why have we not witnessed the continued evolution of other simian groups over the past several million years”
Because we haven’t been around to observe it. But as much as we can infer from phylogenetics and comparative genomics, other simian groups did evolve significantly in the past several million years.
9. taxadvice | 03.09.09
the loss of a chromosome in humans versus the great apes was discovered as a fused second chromosome in humans. you can read details on it here. http://en.wikipedia.org/wiki/Chromosome_2_(human)
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1. Steven | 02.18.09
I have found Lloyd Pye’s book very interesting on this subject. It seems that Darwin’s Origin of the Species pre-dated the discovery of the “Cambrian Explosion”, and as a result, Darwin’s theories are somewhat debunked. Also, the fact that Simians have 48 chromosomes while humans have 46, with humans having few of the “survival” traits of the apes left makes me wonder whether there were any outside genetic manipulations going on. Lloyd Pye talks about all of this in his book “Everything You Know is Wrong: Origins”. I thin he is on to something; how else can we explain that within a very short period, apes lost all of their strength due to environmental factors, with strength being replaced with larger brains. What environmental factors could have driven that over such a short period? How did we lose chromosomes? Why have we not witnessed the continued evolution of other simian groups over the past several million years, with rather the genetic foundations becoming stronger, not varying? There is almost no way to explain it without coming to the conclusion that we were genetically manipulated. Even this article hints that over a short period “ancient ancestors were undergoing a burst of duplication of whole swatches of their genomes. This resulted in mix and match rearrangements of DNA that led to significant structural changes in the animals themselves.” This doesn’t sound right if you think of Darwin’s theories. But if true then its hard to believe that this happened in nature. Evolution takes base fundamentals and builds on them…advantageous traits built up over millions of years rarely go away