NPR recently picked up a story on “the paleo diet” moving more mainstream. The basic idea behind the paleo diet is that evolution has shaped our metabolic processes to fit a certain kind of diet, and by and large, we are not regularly consuming that diet these days. Hence we have massive problems with obesity, hypertension, diabetes and cancer.
There are certain strengths to this approach. It is definitely the case that our diet today has far more high-fat, high-sugar resources in particular, and far-less fiber. And taking an evolutionary approach to human health and wellness is something I can happily support. But you have to take evolutionary findings seriously if that is the case, and not just trumpet your own cause.
I have several specific problems with the paleo diet approach.
1) There is no singular paleo diet
This first is that attached definite article–the. Our ancestors have occupied large parts of the Old World for hundreds of thousands of years, and our direct ancestors span an even larger geographic range. Early modern humans acquired different kinds of food using different kinds of technology in different places. The diet of terminal Pleistocene Homo sapiens was not a uniform plate…diet varies across time and space.
2) We did not stop evolving 15,000 years ago, we began evolving faster
The second issue I have is that the paleo diet approach assumes there is some point in our past at which we were eating what we were supposed to. This point is generally placed sometime prior to when we really began to screw things up with agriculture, sometime more than 10,000 years ago. Back then, when we were still subsistence foragers, we were as God Darwin intended–natural, primitive and in balance with nature. Except that we weren’t.
More importantly, agriculture, and more specifically, the population boom that preceded and accompanied the transition to agriculture accelerated human evolution. The increase in population sizes supported by stable food production created added fuel in the form of genetic variability for natural selection to act on. Much of that selection likely acted on the changing dietary ecology of humans. Put simply, we have been evolving alongside our dietary change.
3) The world can’t support 7 billion hunter-gatherers
This is a point brought up last year in a story by…NPR. Hunter-gatherer populations live at a low density because they are dependent on the natural production and balance of ecological systems. Such systems, and the (paleo) food they produce, cannot feed 7 billion people…several orders of magnitude more than existed 10,000 years ago.
Clearly, the pace of change in our diet over the past 150 years brought about by the industrial revolution and transportation technology is something on a different scale. We have been eating meat for two million years, but nothing early hominins ate in the environment likely had the kind of fat density as an industrially raised cow. I am happy to be intelligently critical of some of the really terrible things we do in the context of food production and consumption…but the paleolithic does not offer us a clear and obvious solution to our contemporary problems.
