The popularity of the Paleo Diet brings a slew of debunking attempts from dietitians and academics answering the call of their vocation to save the world from the big Paleo Diet debacle.
It motivated evolutionary biologist Marlen Zuk to write a book (see my post) and it apparently motivated Christina Warinner to show up at a TEDx to offer her own debunking, this time from an archaeological point of view.
Christina presents herself as an Archaeological Scientist who studies the health and dietary history of ancient people using bone chemistry and ancient DNA. She then proceeds to call the Paleo Diet “one of the fastest growing diet fads” that “has no base in archaeological reality”.
Every student of science knows that it is impossible to prove anything with certainty and what scientists do, at the most, is assemble more and less dubious facts to tell a story that will hopefully make sense. This framework should be all the more intuitive when reconstructing historical phenomenon, in this case diet, is at stake. This is the reason no scientist can claim to offer certainty regarding ancient diets, no matter what his professional credits are or how confident he or she sounds.
The first myth that Warinner tries to debunk “as an archaeologist” (just to make sure we didn’t miss the introduction) is that “humans are evolved to eat meat and Paleolithic peoples consumed large quantities of meat”.
She begins by stating: “human has no known anatomical, physiological, or genetic adaptations to meat consumption”. Even in the contest of a TEDx lecture this is a very bold statement for a scientist to make. In plain language it means that there is not even a controversy that she is aware of about the fact in question. That preposterous, incorrect statement alone would have been sufficient to convince me not to waste any further time on this lecture. I would have left it at that had I not read Paul Jaminet and Richard Nikoley‘s posts, urging their readers to stay for the second, better half. Traversing my way to the second half I had to hear that our digestive track is not adapted to eating meat (could it be that she hadn’t read Aiello and Wheeler 1995 or Milton 1987?) and that we have a generalist dentition with molars that are built to shred fiber and not to cut meat and so on and so forth.
I would have loved to see Peter Ungar’s reaction to her statement regarding dentition. Peter Ungar is The best known teeth expert among current physical anthropologists. His reputation got him a million dollars to build a “Biting Machine” to test the suitability of ancient teeth to handle different types of food. Here is a video (18:50 minute) in which you can see Ungar’s machine and hear him state that unlike our predecessors, our teeth are evolutionary adapted to handle meat. In a 2004 paper he stated with appropriate scientific cautiousness: “meat seems more likely to have been a key tough-food for early Homo than would have USOs “[tubers, M.B]. I would also love to see Mchenry’s reaction to the statement that we have big molars. McHenry developed the Megadontia Quantient and shows that in relative terms our molars are less than half the size of our evolutionary predecessors. I will leave it to you to judge how this state of scientific knowledge regarding teeth and gut can be reconciled with a statement denying any “known anatomical, physiological or genetic adaptation to meat consumption” and specific statement about the inadaptability of our dentition to handle meat.
The lecture continues with arguments of like quality and a straw man here and there. To be fair the lecture does also contains some better quality arguments (regarding the validity of isotopic N15 collagen studies for example), which I do not agree with but are still presented in a more professional manner.
The second half in which she recommends basically natural and fermented foods make more sense but I couldn’t miss the fact that the word “meat” is not mentioned even once which makes the whole thing looks too legit vegetarian to my taste.
In my forthcoming lecture at AHS13 I intend to present the current state of scientific knowledge regarding Palaeolithic nutrition as I see it. Yes, it is inevitably going to be judged as biased by some but by god I hope that the scientific quality of the presentation will not be as easily dismissible as this one is.
As I said in the previous post, Paleo Diet success can be attributed to more then its intellectual finesse so debunking its scientific basis is of little short term practical consequence but still, one would hope that future scientific critique of its basis be done in a manner that can contribute to the improvement of its efficacy in the long term.
Aiello LC, Wheeler P (1995) The expensive-tissue hypothesis: The brain and the digestive system in human and primate evolution. Current Anthropology 36(2): 199–221.
Milton K (1987) Primate diets and gut morphology: Implications for hominid evolution. In: Harris M, Ross EB, eds. Food and evolution: Toward a theory of human food habits. Philadelphia: Temple University. pp 96–116
Ungar P (2004) Dental topography and diets of Australopithecus Afarensis and early Homo. Journal of Human Evolution 4: 605–622.
McHenry HM (2009) Human evolution. In: Ruse M, Travis J, eds. Evolution: The first four billion years. CambridgeMA: Harvard University Press. pp 256–28