This may seem like a trifling distinction from what is already known, but people in both the paleo and vegan camps hold false notions. There is the ridiculous notion held by some people that one day we humans can evolve into pure vegetarians if we would just eat veggies for an eon or two. I've also heard paleo leaders state that we haven't yet evolved to eat grains, because it's too new to our diets. This line of thought displays a fundamental misunderstanding of evolution. Allow me to demonstrate why we will never evolve into vegetarians, and why we will never develop the ability to fully tolerate Neolithic foods.
Reproduction and the Phenomenon of Random Variation
Consider siblings. They come from the same genetic heritage, but have vastly different genetic expressions. My own brother is taller and heavier and has much lighter skin than I do. This is pretty easy to understand. Genes vary slightly in the offspring of all species, and that variation is random. This is true for all life on earth, even bacteria.
The reason that a species changes over time (evolves) is because certain small variations give certain genes an advantage at reproducing. To be clear, the 'success' or 'strength' of a gene depends entirely on it's ability to reproduce, and to reproduce at a higher frequency.
So unless meat-eating genes cause certain death before sexual maturity (reproduction), natural human vegetarians will never exist. And since grain consumption does not affect rates of human reproduction, those celiac genes won't disappear either.
The last paragraph here is absolutely key. For the negative effects of any environmental pressure to have any effect on evolution, it must be sufficiently deleterious to impact survival before and/or during fecundity or reproductive fitness and/or success in general.
ReplyDeleteThis is doubly offset by medicine. If we're able to keep people alive and marginally fertile through drugs and surgery, despite chronic sickness, there is no sufficient adaptive pressure to effect evolutionary change relating to those illnesses.
Since grain consumption doesn't kill people (in the short-term), archaeological evidence of its use in the Paleolithic will always be anecdotal irrelevant footnotes. Conversely, the short-term survival benefit of the carbs in grain may have increased survival to fecundity in extreme circumstances. This would result in a prediction of a population increase for agricultural societies along with simultaneous declines in general health. Shocker! The 4-6 inch decrease in average height at the beginning of widespread agriculture demonstrates this prediction.
People can crank out kids by subsisting on Pepsi and peanut butter pretzels. That doesn't mean they're evolutionarily recommended food sources.
I believe in The Primal Blueprint Mark mentions that grains can cause infertility (and a recent Friday success story illustrates this). But for most, it likely does not. More likely we'll be capable of genetically engineering humans to be immune to such biochemical "errors" that grains cause in the fairly near future. Much easier to skip the R&D and just buy more meat, but hey, who am I to stunt human re-evolution.
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