I've been following a mostly paleo diet recently (which along with my workout regimen has been great). I heard this interview today on NPR with Daniel Lieberman; he's an evolutionary biologist who teaches at Harvard and has a new book out. Very cool insights about how our bodies are out of sync with modern foods.
Pretty long so I'm just going to highlight the part about paleo.
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Pretty long so I'm just going to highlight the part about paleo.
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Quote:Quote:
LIEBERMAN: I'm not a - a bit of a skeptic about the Paleo diet. One of the things that's interesting about the health movement today is that just as there is a lot of polarization in American in terms of politics and class, that's also happening with how we use our bodies. And it used to be that only rich people could afford to be unhealthy and overweight and inactive, and now it's, it's almost reversed and there are a lot of well-off educated people who are now really interested in using their bodies better and they're exercising and they're running marathons and they're trying various kinds of diets.
And one of them that's become very popular recently, of course, is the Paleo diet. And I think that the Paleo diet has some germs of truth to it. It is true that an evolutionary perspective does help us understand that there are certain foods for which we're better adapted and they're other foods for which were less adapted. But the Paleo diet also has a kind of simplistic approach to this question, almost creating a bunch of rules that don't necessarily make any sense from an evolutionary perspective. After all...
GROSS: So before you describe some of those roles, what's the diet?
LIEBERMAN: So, people who eat the Paleo tend to, they avoid all cereals and grains. They eat a lot of fat and meat because they have a, there's a notion that lots - our ancestors ate huge amounts of meat.
GROSS: And then there is the pre-farming era, so there's no grains yet.
LIEBERMAN: That's right. Which is actually not true, because we know from various archaeological sites that hunter gatherers, when they had grains available to them, did eat grains in probably very large quantities - although not, of course, as much as farmers. They tend to avoid milk products because after all, we evolved to drink milk only when we're young and not to drink milk when we're older after weaning. Many of them avoid legumes - things like peanuts, etcetera, which were not eaten by hunter-gatherers. At least so they think.
So it's a kind of diet by analogy. If hunter-gatherers ate it, it must be good and if we eat it - if it's more recent than hunter-gatherers, it must be bad. And you can, of course, quickly appreciate that some of that logic is a little bit flawed because just because something is recent doesn't mean it's bad. And just because something is old doesn't mean it's good. And furthermore, hunter-gatherers didn't evolve necessarily to be healthy. They evolved to have lots of babies and health was only selected for in so far as it helped people have more babies. That's after all, what natural selection's really about.
And hunter-gatherers, in fact, aren't always healthy. There's I think a kind of a little bit of romanticism applied to hunter-gatherers. And there's also no one kind of hunter-gatherers. After all, our ancestors who are hunter-gatherers lived in environments as diverse as the African savanna to and rainforests and in the Arctic and everywhere else, they managed to eke out a living in all kinds of different habitats. And there was no one Paleo diet, there were many Paleo diets. And so it's a complex problem.
GROSS: And probably they didn't live to celebrate their 80th birthdays very often.
LIEBERMAN: Well, actually, you'd be surprised.
GROSS: Really?
LIEBERMAN: So hunter-gatherers have very high infant mortality rates. You know, it varies from population to population and the data aren't great, but maybe between 30 and 50 percent rates of infant mortality. But once they survived childhood, they actually tended to live reasonable long and healthy lives. And it was - actually the origins of farming that caused health to really decline in that respect. So farmers also have high infant mortality rates. But farmers also have high mortality rates in general and people started dying younger and becoming shorter. So farming really was initially a very bad thing for the human body in terms of longevity and nutrition and health. Of course, it was great for increasing the number of offspring people were able to have.
But to return to the Paleo diet, the thing about the Paleo diet is that there was also some truth to what some of the Paleo diet proposes. I mean, it is true that much of what we eat and do in our modern life we're poorly adapted for and the Paleo diet does go some of the way toward correcting that, but I'm not sure I agree with everything they say.
GROSS: Well, because it's going too far?
LIEBERMAN: In some respects. For example, there's a big debate going on about fats and what kinds of fats are healthy and we've been hearing for years now that saturated fats are evil and unsaturated fats are healthy. But some hunter-gatherers eat a lot of saturated fats. And so some Paleolithic diet proponents believe that you should just have as much saturated fat as you want. And there are various arguments for and against that but that's an experiment that I, for example, am not willing to undergo, is to eat as much saturated fat as I'd like. There are still scientific arguments about what ratios of fats are the best and what's the right fat. And in fact, I think even asking what's the best is often problematic because again, what's the output parameter you're interested in? You know, are you interested in living longest or being more vigorous or having more offspring? Remember, that what natural selection cared about the most was how many offspring you had who then survived to then have offspring themselves. So just because hunter-gatherers may eat certain diets doesn't mean that they're going to, that's the same kind of diet that's going to promote health in a modern context.