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Richard Dawkins: Universal DNA Code Is 'Knockdown' Evidence of Evolution

October 19, 2009 – Evolutionary biologist Richard Dawkins was on Grounds Friday to discuss his new book, "The Greatest Show On Earth: The Evidence For Evolution," which lays out more than a dozen lines of argument and evidence in support of evolution. Dawkins gave a quick introduction to every one of those lines of evidence (each gets a chapter in the book), speaking to a standing room only audience in the Gilmer Hall Auditorium. (Scores more were turned away after the room filled.)

The most compelling evidence of all, Dawkins explained, comes from molecular biology – the fact that DNA code is universal among all living things, with all creatures sharing identical segments of code.

Dawkins, recently retired from his position as the Charles Simonyi Professor of the Public Understanding of Science at Oxford University, is perhaps most famous (and certainly most controversial) for his 2006 international bestseller "The God Delusion." In it, he makes the case for the improbability of the existence of a supreme being, and, more provocatively, that religion is not only wrong, but evil, a position that defines so-called "New Atheists."

But on Friday, Dawkins skipped any attack on religion, sticking to the subject matter in his latest book. However, he did express palpable scorn for those who believe the young-earth creationist view that the earth is less than 10,000 years old, a view that 40 percent of Americans (and 28 percent of Brits) agree with, according to a Gallup poll Dawkins cited.

Since the earth is actually 4.6 billion years old, Dawkins said, the magnitude of error in the young-earth creationist view is equivalent to thinking North America is 8 yards wide. Such a magnitude of false belief would be disabling in practically any other field, Dawkins quipped, noting that a plumber wouldn't be able to connect his pipes and do his job if his measurements were off by such a factor.

Dawkins' new book is an attempt to better muster the evidence for evolution, in hopes of changing the "disturbing" opinion of some who subscribe to the creationist view. While Dawkins acknowledged that there was little use in trying to argue with the most dyed-in-the-wool creationists (responding to a student who asked how best to join the fight against the creationist view), he suggested that the most persuasive tactic is to drop the truculence and share the fascinating ways that evolution can explain the natural world.

Dawkins himself did so with a mix of wry humor and a wide-eyed appreciation for the power of the idea of evolution.

The most convincing evidence for evolution comes from considering the similarities between so many living creatures, Dawkins explained.

Charles Darwin himself was quite aware of the striking similarities in the skeletons of various mammals, such as the wings of a bat and the fingers of a human hand, Dawkins explained. The bat's wing is composed of five sets of bones that support the flesh draped between them. Compared to the bone structure of a human hand, the bats' five wing bones are quite elongated in proportion to his body, but there is a striking similarity in the number and arrangement of the bones that makes it plain, Dawkins said, that they are two versions of the same thing. The same 'five-finger' outline is even evident in the skeleton of a winged dinosaur, the pterodactyl, that lived more than 65 million years ago.

While Darwin was limited to observing such qualitative sameness among species, a similar lesson is much more discretely apparent in comparisons of the genetic code of various creatures.

To begin with, it's striking that all life, from plants and animals to bacteria, viruses and fungi, rely on the same DNA coding mechanism to carry the biological instructions guiding how the creature is put together, Dawkins noted. What varies from one animal to another is not the code's structure or mechanism, but the individual genes.

Thanks to the Human Genome Project and similar projects that have uncovered the gene sequences of other animals, such as the chimpanzee, scientists can now compare the code among different species. They can be textually compared, like a Biblical scholar might compare two scrolls containing the book of Genesis. When every letter of two gene sequences is compared, scientists find whole 'sentences' and 'paragraphs' of identical DNA 'text.'

In the future, as ever-increasing computing power will enable a proliferation of genome sequencing, scientists will be able to make detailed DNA comparisons about the evolutionary relatedness of every species to every other. There is already enough such DNA comparison evidence to prove beyond doubt that all living things have shared ancestry, Dawkins said. This textual proof of the common ancestry of all living things is "knockdown evidence" of evolution.

Dawkins' talk was sponsored by U.Va.'s Department of Biology.

— By Brevy Cannon

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