Tuesday, April 2, 2013

You Can't Blame the Cavemen

Paleofantasy: What Evolution Really Tells us about Sex Diet and How we Live by Marlene Zuk is a response to what has been a common explanation for our modern habits, that we have not evolved to fit our modern world, that, as far as genes are concerned, we are still cavemen. This theory purports that we were once perfectly suited to our environment, clubbing or spearing animals, collecting rare pieces fruit and mating polygamously. Our current lifestyle, which includes lots of flour, sugar and commitment, is supposedly unnatural, so it's no wonder we're fat and depressed.

Well, it was fun while it lasted. Not that my wife ever bought it when I blamed my inner caveman for my tendency to overeat Little Debbie snack cakes and lose concentration around women in heels. But according to Zuk the whole theory is just wrong. Her attack is three-pronged: 1) we were never "in balance" with nature; 2) evolution is often more rapid than we realize; and 3) we often misread anthropological discoveries to promote non-scientific agendas.

She is, unfortunately, pretty convincing. She shows a Paleolithic environment that's not only as varied as our own but is rapidly changing. There was no caveman diet, no caveman way of life. Rather, there were many. And as people spread they found even more ways to live.

She also demonstrates, with guppies, crickets, snakes and toads, how quickly evolution can happen. Far from taking millions of years, new traits can appear in as little as a few years. Male crickets newly introduced to the Hawaiian Islands, for instance, lost the ability to chirp in just five years because their chirping was attracting killer flies. Many other studies showed changes in species occurring in similar short time spans and even new species emerging in as little as 2,000 years, a microsecond compared to our usual conception of evolutionary time. Thus, the concept that we haven't had time to evolve out of our caveman ways may be entirely flawed.

Finally, Zuk blames our own biases and the biases of paleoanthropologists and popular science writers, showing how we see in the fossil record and in the behavior of apes what we want to see, excuses to promote or critique certain ways of life, to hold onto certain gender stereotypes. She shows how far more significance is given to certain discoveries than they really deserve and how they become part of the modern mythology.

No one can claim that Zuk didn't do her homework. At times it seems as though she questions every casual remark made by a pop science writer who has taken on the subject of paleoanthropology. But Zuk is not stuffy or disdainful, opting instead for wry if occasionally mocking. Paleofantasy is also chock full of science, revealing study after study. All in all, it has one of the highest ratio of laugh lines to footnotes in all of science writing.

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