[quote]“Nothing in biology makes sense except in the light of evolution”
– T.G. Dobzhansky[/quote]
The basic concept of a Paleo-like diet is that our bodies are genetically best adapted to utilize the foods we evolved to eat, and that humans (and ergo, the human genome) evolved over a few million years as hunter-gatherers. Agriculture did not appear on the human landscape until between ten to fifty-thousand years ago. Although most reliable estimates place the appearance of agriculture at closer to the ten thousand year mark, even using the maximum fifty-thousand year estimate yields a similar outcome — not nearly enough time for our genotype to evolve sufficiently to cope with the introduction of these new, agriculturally-grown (read, grain) foodstuffs.
The most prevalent source of calories for our Paleolithic ancestors of 50,000 years ago would have been lean meat. The fatty parts would have been favored (as it offered more “bang for the buck”), however, since wild game is very lean, the average fat intake would have been relatively low. Our genes are cued to respond favorably to a much higher fat intakes, however.
Dairy, too, would not have been consumed until just a few hundred generations ago, when livestock was initially domesticated. Lactose intolerance is an extreme symptom of our genotype’s having not yet evolved to handle this novel food. I take an agnostic approach when it comes to dairy, though, as many people do tolerate it well, and (in the raw form at least) dairy does provides a multitude of healthful benefits.
Ultimately, the genes we inherited from our Paleolithic ancestors now determine what our optimum diet should consist of. These same genes — virtually identical to those of our ancestors harbored some 50,000 years ago — evolved according to the environment (including food varieties that were available to them) in which those ancient ancestors evolved. And although our ancestors did not eat just one single diet — but rather, ate various diets, depending on geography, ecologic niche, season and glaciations — these various diets did, however, share some of the following, universal characteristics:
The available carbohydrate sources were:
- Plants, leaves
- Roots and tubers
- Nuts (could be considered a fat source as well)
The available protein and fat sources were:
- Wild animals of all sorts (including muscle tissue, fat, organs, brain and marrow). However, the total amount of fat, and the fatty-acid composition of that fat, was different than that found in modern domestic animals.
- Fish and seafood
It can be argued, as well, that the carbohydrate content and load for the modern version of the fruits/berries (and to some extent, vegetables, as well) is much different that that available to our ancestors. This is a minor point of contention, though I do tend to agree. One can, however, avoid problems here by limiting the ingestion of these foods. The same can be said for opting to eat grass-fed meat when possible and where available. I am a realist, though, and will always opt for taking care of the major worries before attempting to fix the minor stuff. See my thoughts on the 80/20 rule, here.