On Evolutionary Fitness

Kevin Drum is wondering whether or not avocados are good for you. That got the ineveitable health/diet comment thread going, and one of the commenters opined:

Just eat what tastes good in moderation. Our appetite and taste in food has evolved over centuries to maximize our fitness to survive.

That’s not quite correct. Our appetites and tastes in food have evolved over eons, not centuries, and for nearly all our evolutionary history, food was often difficult to get. Our tastes therefore evolved to insure we would pig-out whenever we encountered foods rich in fats and carbohydrates; it was imperative for our ancestors to build up fat deposits on their bodies so as to increase the probability of surviving the next, inevitable period of scarcity.

For any given individual, a lot has to do with genetics of course, but for many people, the sad truth is that eating what you like best with regularity — even in so-called “moderate” amounts — is not consistent with optimal health*. If you want to maximize your physical well-being, when it comes to eating you most definitely should pay attention to our species’s evolutionary history. And that translates into minimizing the consumption of processed carbohydrates, moderating the consumption of overly fatty meats (leaner protein sources, of course, are highly consistent with several million years of human evolution and should be eaten), and mostly eschewing dairy products. Oh, and eat lots of plants. I’ve never heard a bad thing about avocados.

*For the record, I personally have never been able or willing — at least until very recently — to even approach anything resembling a health-optimizing diet, and I certainly don’t pass judgment on anybody who is similarly inclined. When it comes to utility maximization, who the hell am I to say that being fairly spry at age 92 is worth living a life largely devoid of desserts and pizza? And again, some people have DNA that apparently allows them to live lives of extreme gastronomic excess with few ill effects. Winston Churchill was Prime Minister into his eighties.