Chris Kresser published a podcast and transcript yesterday of an interview with Mat Lalonde. The theme of the interview was "What Science Really Says About the Paleo Diet." Now, I'm not one to get caught up in the science of paleo. I do paleo because eating unprocessed whole foods works for me and so does avoiding grains. But, somehow this point from Lalonde (and it's not the first time I've heard it) has gotten under my skin.
We evolved over millions of years without consuming the foods that became readily available only after the advent of agriculture. Hence, we???re not adapted to these foods. But this assumes that a species isn???t adapted to a food because it???s never consumed it. And if you look at the evolutionary record, that???s incorrect. There are plenty of examples throughout evolution where species discover novel sources of food and thrive on them.
There are a few paragraphs discussing this point further so it's worth listening to the interview or reading the transcript.
Is Lalonde's argument valid? If not, where's the science that shows we're not adapted to foods we've never consumed?
asked bySol (5828)
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on June 14, 2012
at 01:33 PM
By definition, a species cannot adapt to something to which they've never been exposed. pre-existing favorable conditions in a species, upon exposure to new stimuli, are called exaptations.
But Lalonde's point is still salient: there are certainly things we may have no problem consuming despite not having evolved according to their pressures. That being said, major dietary transitions like the one from primarily tree-dwelling herbivores to mixed omnivory take a long time and a lot of selection pressure. One good reason for that is gut length (shortest in obligate carnivores, longest in obligate herbivores). That humans have by far the shortest gut length (adjusted for size) of any primate indicates we've adapted considerably more than any other primate to eating meat, for example.
Adapting to grains is a similar difficulty. Without the gut length we've lost, we're less able to endogenously process the phytic acid and other "antinutrients" coating the seeds of grains. As grains are simply domesticated grasses, and grasses evolved for wind-disbursion instead of consumption and redeposition (pooping), getting past their evolved defenses requires some amount of coevolution. In the case of humans, we used our brains to bypass this evolutionary necessity by inventing fermentation, soaking, and other traditional processing methods.
Not a clear answer, I know, and lacking citations, I also know. But I hope this at least helps paint a clearer picture. If I have time later I'll edit with some links c:
on June 14, 2012
at 01:50 PM
I think all he's really saying is that just because you didn't necessarily adapt to consume those foods due to evolutionary pressures does not mean that you can't tolerate them or that they are per se unhealthy.
Mat is about the quality of the science. He's not saying it's wrong, just that saying "we didn't adapt to it so we shouldn't eat it and it makes us sick" is logically insufficient.
P.S. Mat Lalond is the fucking man.
on June 14, 2012
at 01:41 PM
Yes, his argument is valid.
Looking at evolutionarily novel foods gives you a good place to start your examination of whether a food is beneficial or harmful. And indeed, many if not most neolithic foods will be problematic for many people. However, Mat's point is that simply saying a food is newer on the evolutionary scale is not the end of the discussion. You must look to the "harder" sciences such biology and chemistry to understand what happens to those foods and your body once you consume them. Once you do that, you find there is a stronger argument that can be made for avoiding some neolithic foods, such as wheat, than other foods, such as potatoes.
on October 10, 2012
at 11:13 PM
Dr. Mike Eades wrote a recent blog post about a preliminary study about the inflammatory effects of eating old vs. new foods.. As the study authors note, the study is far from definitive, but I hope there will be larger and better studies along this line of inquiry.