Tuesday, March 3, 2009

Why People Who Don't Understand Evolution Shouldn't Write Science Books

Recently I started listening to Why Beautiful People Have More Daughters by Alan S. Miller and Satoshi Kanazawa. It's about evolutionary psychology, a relatively new field which seeks to answer questions about human behavior under the assumption that there is a strong genetic component to behavior and that adaptive behaviors have evolved. So we can understand modern psychology by examining the conditions under which our ancestors evolved, namely a hunter-gatherer social unit, small in number (~30-40 individuals) living in savanna conditions.

There's some value in this approach, to be sure, and the book starts out all right, by discussing possible types of bias that people can fall into. Both involve confusing the way things are with the way things should be. The authors call these the naturalistic fallacy, in which people believe that because that's the way it is, that inherently makes it morally correct (e.g., nature is harsh and unforgiving so human societies should be harsh and unforgiving). The moralistic fallacy is the opposite, believing that things are the way you think they should be (e.g., all races and genders should be treated with equal respect and given equal rights, therefore there are no significant differences in measurable capacities such as intelligence or athletic ability between genders or races). But then the authors state blithely that they're not going to fall into either trap by simply not discussing the way things should be, but by sticking to the facts. Which is dumb. You don't have to explicitly talk about they way things should be to commit either fallacy. But hey, whatever. I let that slide and kept listening.

What made me press the eject button was the bit where they actually start talking about how evolution works. This snippet from an interview with Kanazawa basically restates the position from the book:

In fact, we’re not playing catch up; we’re stuck. For any evolutionary change to take place, the environment has to remain more or less constant for many generations, so that evolution can select the traits that are adaptive and eliminate those that are not. When the environment undergoes rapid change within the space of a generation or two, as it has been for the last couple of millennia, if not more, then evolution can’t happen because nature can’t determine which traits to select and which to eliminate. So they remain at a standstill. Our brain (and the rest of our body) are essentially frozen in time — stuck in the Stone Age.

That may sound reasonable on the surface. The problem is, it's flat out wrong. It's utterly, horribly, unmistakably wrong.

First of all, evolution in the strictest biological sense simply means change. Specifically it's a change in the makeup of the gene pool of an interbreeding population over time. Natural selection is just one way in which the number and types of genes in a population can change. It's a powerful mechanism, no doubt, but it's not the only mechanism. There's also a little thing called genetic drift, which is basically the effect of chance on changes in gene distributions. For those with any statistics in their background, you can think of it as sampling bias.

The point is, even if in an idealized model in which no selection were acting on a population, it would still continue to evolve. But besides that, there has been a torrent of recent research demonstrating that not only has human evolution not ground to a halt, it has actually accelerated. Check out this post on John Hawks' excellent blog regarding the increasing rate of genetic change in human populations.

Anyway, when someone is writing a book about how evolution affects behavior, they need to demonstrate a basic working understanding of evolution. By completely failing to do so, so early in the book, the authors actually saved me a fair amount of time. Why should I listen to someone ostensibly trying to teach me about a subject that they don't even have a basic grasp of?

I didn't even get to the explanation of why beautiful people supposedly have more daughters, but based on what I'd read so far, I be a lot less credulous about any claims they make.

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