Sunday, October 3, 2010

The Evolutionary Test

The so-called Paleolithic diet asks us to make our dietary decisions from an evolutionary point of view. It does not require that we simply copy a hunter-gatherer diet. (To do such a thing would be impossible in any case. There was not a single hunter-gatherer diet. There were many. They were different at different times and at different places.) Recapitulation is not the goal. Instead we are asked to consider the sorts of nutrients - both macro and micro - on which hunter-gatherers seemed to thrive and to incorporate these into our diet in the same proportions as did hunter-gatherers.

The Paleolithic diet also does not condemn all neolithic and modern foods. Rather it would have us consider carefully which we choose to eat. Of some of these "new" foods, it is not at all skeptical. If they are of the same sort as foods eaten by hunter-gatherers, this is good prima facie evidence that they are acceptable. But if some new food is unlike anything eaten in quantity by hunter-gatherers, it would have us be quite skeptical of it. Grains are of this sort, as are refined sugars. Even if we did not know of the pernicious consequences of these so-called foods, the Paleolithic diet would have us eschew them. It is possible, of course, that a new food unlike anything eaten by hunter-gatherers might eventually absolve itself. But the burden of proof would be high.

The Paleolithic diet thus imposes a kind of evolutionary test. Certain kinds of foods nourished us as we evolved into the creatures we are now. Eat foods of this kind, the Paleolithic diet tells us, and eat them in the same ratios as they were eaten by hunter-gatherers.

I find that this evolutionary test quite helpful. It can help to weed out dubious claims.

For example, nutritionists will often tell us that carbohydrate is necessary to our diet and that we should eat it many times a day. This is how we're supposed to keep up our energy levels. That's bullshit. Primates first climbed down out of the trees over 2 million years ago. We did so to hunt, and for millions of years we thrived on a diet high in animal protein and fat. Now, just how plausible is it that we need the energy burst that carbs provide every few hours? Not so very damn plausible at all. What kind of hunters would we be if we couldn't keep up a hunt for any length of time? Dead ones. Extinct ones.

The simple fact is that we can go for long periods with no carbs at all and still maintain our energy levels. And how is this possible? When we burn fat instead. When we are primed to burn fat (as we will be if we eat a low-carb, high-fat diet), we can access our own fat stores easily and without any drop in energy level.

Indeed the evolutionary test suggests that we need little or no carbohydrate at all in our diet. Early humans spread all over the globe and came to live in places that experience harsh winters. There would be nothing to gather in the winter months. There would be no plant-foods stored, for humans did not yet cultivate crops. Instead the only food supply would have come from the hunt. And we must suppose that the quality of that food would have been very high. It allowed us not only to simply live but to hunt another day. This means that it allowed us to thrive, for the only successful hunter is a healthy hunter.

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