DNA testing: proof beyond reasonable doubt
A phrase in the March 2006 issue of Discover set off a train of thought that I'm surprised isn't more widely discussed. Instead of quoting the phrase right now, let me build the track for the train to reach it.
Almost everyone accepts that DNA testing can give proof of family relationships. If my sister and I each had a DNA test, the results would show that we're related--in other words, that we share a common ancestor. Indeed, we do: our parents. By the same token, if my cousin and I each had a DNA test, the results would again show that we're related, only more distantly. In other words, our common ancestors would be more distant. Indeed, they are: our grandparents.
This evidence is so strong that in a court of law, it overrides eyewitness accounts. If my father were to deny paternity (which he wouldn't, of course), and a DNA test showed otherwise, the court would accept the DNA evidence over my father's testimony. So far as I'm aware, nearly everyone accepts this procedure. As Gil Grissom has commented on CSI, people may lie, but DNA doesn't.
If a chimpanzee and I each took this same DNA test, it would show that the chimpanzee and I are related, only more distantly than my cousin and I are. In other words, our common ancestors are more distant. If a lemur and I took it, it would show that the lemur and I share an ancestor more distant than the chimpanzee and I have. If a grizzly bear and I took it, it would show that the bear and I share an ancestor more distant than the lemur and I have.
This is exactly the result that Charles Darwin would have predicted in 1859. Evolutionary biology, like all other legitimate science, allows scientists to make hypotheses, test them, and falsify or verify them. If anyone says, "Evolution isn't a science because we can't observe it," they're showing their ignorance of how science works.
Is the theory of evolution true? I would have to say that it is--not only by the standards of scientific proof, but by the American court standards of reasonable doubt. As Charles Siebert points out in the Discover article, evolutionary researchers use "DNA evidence as solid as that used to convict criminals" (37). It's unreasonable to ask for more than that.
Almost everyone accepts that DNA testing can give proof of family relationships. If my sister and I each had a DNA test, the results would show that we're related--in other words, that we share a common ancestor. Indeed, we do: our parents. By the same token, if my cousin and I each had a DNA test, the results would again show that we're related, only more distantly. In other words, our common ancestors would be more distant. Indeed, they are: our grandparents.
This evidence is so strong that in a court of law, it overrides eyewitness accounts. If my father were to deny paternity (which he wouldn't, of course), and a DNA test showed otherwise, the court would accept the DNA evidence over my father's testimony. So far as I'm aware, nearly everyone accepts this procedure. As Gil Grissom has commented on CSI, people may lie, but DNA doesn't.
If a chimpanzee and I each took this same DNA test, it would show that the chimpanzee and I are related, only more distantly than my cousin and I are. In other words, our common ancestors are more distant. If a lemur and I took it, it would show that the lemur and I share an ancestor more distant than the chimpanzee and I have. If a grizzly bear and I took it, it would show that the bear and I share an ancestor more distant than the lemur and I have.
This is exactly the result that Charles Darwin would have predicted in 1859. Evolutionary biology, like all other legitimate science, allows scientists to make hypotheses, test them, and falsify or verify them. If anyone says, "Evolution isn't a science because we can't observe it," they're showing their ignorance of how science works.
Is the theory of evolution true? I would have to say that it is--not only by the standards of scientific proof, but by the American court standards of reasonable doubt. As Charles Siebert points out in the Discover article, evolutionary researchers use "DNA evidence as solid as that used to convict criminals" (37). It's unreasonable to ask for more than that.
posted by Thomas Wright at 14:39
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