Billed as "an exposé of pseudo-scientific myths about our evolutionary past and how we should live today," biologist Marlene Zuk's Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live aims to prove that the actual science of evolution is a lot more interesting than the popular myths it has inspired – especially that modern humans have strayed from the true path to fitness set out by our hunter-gatherer ancestors.
What's most exciting, according to Dr. Zuk, a biologist at the University of Minnesota, is new evidence showing that evolution in humans and all organisms can happen much faster than previously thought.
What inspired Paleofantasy?
The book came out of my interest in how much we're learning about the rate of evolution, and how that is eventually going to change the way a lot of people think about the operation of evolution. People seem to be fascinated with this idea that we're mismatched to our modern environments, and one of the ways that shows up is thinking about what to eat, because what we eat is a really important and personal decision.
What's the biggest genetic difference between us and our paleolithic ancestors?
The poster child for rapid evolution is our ability to digest milk products and dairy. Evidence now is pretty firm that the human genome changed in some populations 5,000 to 7,000 years ago in a way that allowed us to digest dairy products that we could not digest before.
So, yes, you could argue that 15,000 years ago humans would have done badly to try and drink milk or use dairy, but that's just not true any more.
The reason this came about is because of our co-evolution with culture. We were herding cattle 7,000 years ago, and people who were able to take advantage of milk past weaning were able to survive and reproduce better. So those genes got passed along.
And that's how selection works. There's no outside force that says, "Oh wait, we're perfect. Now it's all okay. Don't change."
What else can evolution tell us about modern diets?
It's not clear that we necessarily evolved to eat the best things for us. Evolution doesn't work like that. I think there's a really common perception that organisms kind of move along toward ever increasing perfection and eventually we end up in this state where we're perfectly in sync with our environment and anything that happens to move us off that peak is going to be a disaster. In actual fact, all organisms are this series of tradeoffs and compromises, and things that work well under some sets of circumstances and poorly under other sets.
What other examples of rapid evolutionary change have scientists discovered?
There's been a lot of research done in Canada looking at animals that are hunted and fished and the changes we now see in the gene pools of those animals: If you take out the largest, most mature members of a fish population and you do this generation after generation, in effect what you're doing is selecting for individuals that mature and are able to reproduce at a smaller size.
So over time you'll have a population of fish that are overall smaller, not just because you've removed all the big ones but because they're just not growing to the same size.
That's having a huge impact on fisheries worldwide. It's called fishery-induced evolution. We've changed the way the species appears. But were the fish perfect before? Not really. It depends on their environment.
The idea of evolution as purposeless recalls Richard Dawkins' concept of "unintelligent design."
Absolutely. Sometimes it's hard to comprehend that it's purposeless, and that also means that you're not going toward perfection. The population of salmon that matures at an earlier age is not more or less perfect than the population of salmon that matures at a later age, and they're not advancing toward anything.
You know, there are always those cartoons about the fish that's crawling onto the land and then becomes an amphibian and then a chimpanzee, and it always culminates with a human being either holding a gun or hunched over a computer, depending on what the cartoon is trying to say.
But really the joke is more insidious than that, because human beings are not an end point of evolution. They're not what evolution was aiming toward, and there isn't any support for the idea that we've gotten to here and if we do something bad things are going to change.