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Jul 23 2011

Neanderthals and the beauty of science

A common creationist debating tactic is to sneer at science, saying something like “It changes all of the time! Scientists can never make up their mind, and often times they’re wrong! Why would you want to trust something that admits it could be wrong?”
And my response is usually to laugh, because that’s precisely what makes science so wonderful. We don’t stick with some dogmatic book even when faced with mountains of contrary evidence. We’re constantly trying to figure out where we’re wrong, so we inch closer and closer to an understanding of reality that’s based on…well, reality. Finding out we were wrong and correcting that mistake is the beauty of science.

I bring this up because a recent news story illustrates this perfectly to me. You may have seen the story circulating that non-African humans are part Neanderthal. Yes, some Neanderthals and Homo sapiens interbred back in the day!

At first I was a little confused, because I thought we had established this in May of 2010 when the Neanderthal genome paper by Svante Paabo’s group came out. But this new paper serves as a confirmation of that work, since it avoids one of the main criticisms of the study – that the human and Neanderthal DNA were cross contaminating each other. This new research only looked at human DNA, and compared it to the Neanderthal sequence. What they found was that about 9% of the X chromosome has a Neanderthal origin in non-African humans.

But if I go back to just April of 2010, everything was different. I was taking my 500 level Evolution class at Purdue, about to graduate. Our final project included downloading mitochondrial DNA sequences of humans, Neanderthals, and other apes to determine if humans and Neanderthals had interbred. From that data alone, the conclusion was an obvious “no.” And that’s what all prior knowledge had said up until that point.

I remember one of the last questions on the project being to explain how new information could potentially change this viewpoint. We needed the whole genome before we could definitively say Neanderthals and humans didn’t interbreed! Mitochondrial DNA is only a tiny part of the whole genome. We need more information because we’re so closely related. And what if only Neanderthal males were the ones mating with humans? Then no Neanderthal mitochondrial DNA would be passed on at all!

One year later, and my professor has to totally redo his lesson plans.

And that’s what makes science awesome.

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