Paleo Diets

In July, Scientific American ran an article, Human Ancestors Were Nearly All Vegetarians, by Rob Dunn of the Department of Biology at North Carolina State University.

I found it to be a well-balanced article on the subject of how our pre-historic ancestors ate. Here are some particularly interesting excerpts:

“…And so if you are serious about eating a really old school paleo diet, if you mean to eat what our bodies evolved to eat in the “old” days, you really need to be eating more insects.

“But, we know our human digestive systems DID evolve to deal with agriculture and the processing (fermenting and cooking) of food.…some human populations evolved extra copies of amylase genes, arguably so as to better be able to deal with starchy foods…several human populations independently evolved gene variants that coded for the persistence of lactase (which breaks down lactose) so as to be able to deal with milk, not just as babies but also as adults.

“So, what should we eat? The past does not reveal a simple answer, ever. …The recent adaptations of our bodies differ from one person to the next, whether because of unique versions of genes or unique microbes, but our bodies are all fully-equipped to deal with meat (which is relatively easy) and natural sugars (also easy, if not always beneficial), and harder to digest plant material, what often gets called fiber.”

Even though I appreciate this article, and think it is useful for people to send to their paleo-eating friends, I don’t agree with the assumption that if we knew exactly what our ancestors ate (and it was consistent throughout time) it could override today’s nutrition science. Not everything our ancestors ate was necessarily optimal and we can only know what was and what wasn’t by examining different eating patterns using modern methods.

That said, I would be elated if paleo-eaters gave up their chicken legs and spare ribs for insects in an attempt to eat more naturally. More power to them!

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9 Responses to “Paleo Diets”

  1. Dave Rolsky Says:

    The whole paleo diet fad seems to be based on what should be a really obvious fallacy (but apparently isn’t). Just because our ancestors ate X does not mean that we should X.

    Unless there’s some overwhelming evidence I’m not aware of, there’s no reason to think that our pre-agricultural diet led to absolutely optimal health. And that’s not even taking into account the fact that our lifestyle is entirely unlike a paleolithic hunter/gatherer’s lifestyle.

    And of course, this also ignores the fact that hunter/gatherers around the world lived on a huge variety of diets, depending on their local fauna and flora.

    How could anyone possibly think that they can come up with an optimal diet from prehistoric evidence? And who could possibly think that there is such a thing as an optimal diet?

  2. Tyler Says:

    Your comment, “I don’t agree with the assumption that if we knew exactly what our ancestors ate (and it was consistent throughout time) it could override today’s nutrition science.”, is a straw man. The author of the article never makes such a claim, instead:

    “So, what should we eat? The past does not reveal a simple answer, ever. The best we can hope for is that it might shine a useful but flickering light into the darkness of our understanding”

    Evolutionary considerations can help us understand the sorts of foods our bodies are well adapted to eat and since adaptations towards foods not present in our ancestral diet is unlikely…it can help us understand what sorts of foods we shouldn’t be eating as well.

  3. Jack Norris RD Says:

    Tyler,

    > Evolutionary considerations can help us understand the sorts of foods our bodies are well adapted to eat and since adaptations towards foods not present in our ancestral diet is unlikely…it can help us understand what sorts of foods we shouldn’t be eating as well.

    What you say above is what I’m disagreeing with. We already know enough about nutrition that if we find out that our ancestors ate pattern X, that tells us nothing about whether pattern X is a healthier way for us to eat than the patterns we already know to be healthy.

  4. Amy Says:

    Tyler wrote:
    “[…] since adaptations towards foods not present in our ancestral diet is unlikely…it can help us understand what sorts of foods we shouldn’t be eating as well.”

    This does not follow because not every (novel) food necessarily requires genetic adaption for successful healthy digestion.
    In my opinion, Paleo diets are largely based on an elaborate naturalistic fallacy: Evolution does not select for life- or healthspan beyond successful reproduction, so arguing for presumed prehistoric diets for optimal health is, in itself, unfounded.

  5. Tyler Says:

    “What you say above is what I’m disagreeing with. We already know enough about nutrition that if we find out that our ancestors ate pattern X, that tells us nothing about whether pattern X is a healthier way for us to eat than the patterns we already know to be healthy.”

    Tells us nothing? Evolutionary considerations and nutrition science should be used, together, to develop a consist theory of nutrition. I don’t understand why one would view different bodies of evidence as antagonistic just because they may in some cases arrive at different conclusions. The differences, as typically done in science, should be resolved to build a consist theory. Evolutionary biology provides context, meaning and insight into every area of biology….why would nutrition science be any different?

    “This does not follow because not every (novel) food necessarily requires genetic adaption for successful healthy digestion.
    In my opinion, Paleo diets are largely based on an elaborate naturalistic fallacy: Evolution does not select for life- or healthspan beyond successful reproduction, so arguing for presumed prehistoric diets for optimal health is, in itself, unfounded.”

    This is based on a false dilemma, its not “either/or”. I said that it can help us understand, not that it uniquely determines what should and shouldn’t be eaten. Furthermore, its more about “food types” than any old new food. A new fruit is likely to pose a problem to humans because it will be structurally similar to other fruits, but a new food type yet to be consumed? Its very likely to be poorly utilized at first.

    As for your assertion on natural selection, its not accurate. In a species with a long developmental period, like humans, there would be selection pressure to exist beyond your last year of reproductive viability. After all, who is going to raise the child? Furthermore, your grandchildren carry a significant amount of your genetic material as well so their survival is evolutionary important too. Not surprisingly you find that monopause in women is well timed, it stops their reproductive viability while still giving them sufficient time to raise their last children.

  6. Jack Norris RD Says:

    Tyler,

    I will try to make my point one final time.

    There’s nothing that we are going to discover about historical diets that should change someone’s eating habits without first testing it against the patterns we already know to be healthy. Of course, this is just my opinion.

  7. Jason Says:

    As far as I know, every serious paleo advocate believes “There’s nothing that we are going to discover about historical diets that should change someone’s eating habits without first testing it against the patterns we already know to be healthy.” Can any of the commenters link to a top paleo advocate (say, the speakers at the Ancestral Health Symposium) who believes otherwise? Who doesn’t believe in the importance of nutrition science? Their blogs and books are filled with analyses of studies.

    What I find most annoying about the previous posts is that it’s clear the posters have done zero research into the issue before issuing forth with critical opinions. So many people (paleo-ers included) do the same thing to vegans. Why not try to be better than that and do a little research before starting the criticism?

  8. Idan Says:

    jason :

    If you read any of their blogs and book then you should notice they only use studies that somehow , Sometimes in a very very strange way – support their “eating like prehistoric is best” belief .

    They do very little to look at the body of scientific evidence in any objective way .
    Their legume and whole grain smear campaign shows this in the best way.

    Their bias makes their points very hard to take it seriously.

  9. Bertrand Russell Says:

    >Their bias makes their points very hard to take it seriously.

    Sounds like … every other place that pushes a specific diet. (Except Jack and Ginny — the exception that proves the rule.)

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