Wednesday, July 16, 2008

DNA of humans and chimps 98% the same...

DNA of humans, chimps have 45,000,000 differences!

That wasn’t the subtitle of the August 17, 2006 Houston Chronicle article on the similarity of human and chimpanzee DNA, but it could have been. There are 3 billion letters in the human DNA genome, and they are 98.5% similar with chimps. DNA is fantastically complex, and the math yields 45 million differences. But of course the Chronicle article stated, “DNA of humans, chimps is 98% the same.”

Most of the “science” in the article was based on the unproven assumption that chimps and humans have a common ancestor. It would have been nice if they had explained how the DNA could have tens of millions of changes in only a few million years (according to their theory), as well as how it kept changing at the same pace throughout the human population without us veering off into multiple species. Or if it changed at a rapid pace, why did it do so for some and not others? And how did the males and females just happen to evolve similarly and simultaneously?

And where are those missing fossils? Shouldn’t the archeological finds be teeming with transitional fossils? Instead, we find explosions of fossils.

All life on earth, from bacteria to human beings, have at last 25% of DNA in common. The DNA of a nematode worm is 75% similar to that of humans. They could have mentioned that our DNA is 30% similar to bananas. But it is the differences that matter.

Nearly all cars have 4 wheels. That doesn’t mean they were genetically related, just that the designers have a model that works well so they replicate it. Perhaps next time the Chronicle will have headlines stating that “chimpanzees and humans are both carbon based life forms” or “Houston is hot in the summer.”

This is just another example of how our biases influence reporting.

Posted on July 15, 2008, by Neil on his 4simpsons blog. The blog is excellent. Check it out.

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