“Paleo” diet trends holding that the healthiest way to eat is to avoid the ground grain products that were unavailable to our pre-modern ancestors have grown enormously in popularity over the past few years. But Laura Miller, channeling evolutionary biologist Marlene Zuk, says it’s total nonsense to think these products haven’t been around long enough for our bodies to evolutionarily adapt to them:
The most persuasive argument Zuk marshals against such views has to do with the potential for relatively rapid evolution, major changes that can appear over a time as short as, or even shorter than, the 10,000 years Cordain scoffed at. There are plenty of examples of this in humans and other species. In one astonishing case, a type of cricket Zuk studied, when transplanted from its original habitat to Hawaii, became almost entirely silent in the course of a mere five years. (A parasitical fly used the insects’ sounds to locate hosts.) This was all the more remarkable because audible leg-rubbing was the crickets’ main way of attracting mates, literally the raison d’etre of male crickets. The Hawaiian crickets constitute “one of the fastest cases of evolution in the wild, taking not hundreds or thousands of generations, but a mere handful,” Zuk writes. Adjusted to human years, that amounts to “only a few centuries.”
There are human examples, as well, such as “lactase persistence” (the ability in adults to digest the sugar in cow’s milk), a trait possessed by about 35 percent of the world’s population — and growing, since the gene determining it is dominant. Geneticists estimate that this ability emerged anywhere from 2200 to 20,000 years ago, but since the habit of drinking cow’s milk presumably arose after cattle were domesticated around 7000 years ago, the more recent dates are the most likely. In a similar, if nondietary, example, “Blue eyes were virtually unknown as little as 6000 to 10,000 years ago,” while now they are quite common. A lot can change in 10,000 years.
Grinding and cooking grain is a practice that goes back perhaps as far as 30,000 years. By contrast, brussel sprouts appear to be just a few hundred years old and until the 16th century Native American populations were the only people eating tomatoes or hot peppers. None of which is to say that adopting a paleo diet won’t “work.” Any sufficiently stringent, somewhat arbitrary set of dietary restrictions is likely to lead you to snack less and be more mindful of what you’re eating. But the paleo concept is a marketing gimmick that doesn’t have much basis.