Bad Health and Agricultural Origins
A few weeks ago on Jason Collins’s Evolving Economics blog there was a discussion of changes in human height assessed from skeletal remains. A well-known finding is that when humans started farming they became shorter, less robust, and exhibited numerous pathologies. The new foods were apparently not so good for us.
This decline in size and indicators of health occurred in the New World, in Europe, and in East Asia. While much of the literature is focussed simply on documenting this remarkable change in our biology, it seems to me that there are very interesting issues that ought to be examined more carefully. The conventional story is that shared nutritional deficiencies are responsible for the health decline, but recent popular nutrition literature seems to emphasize the toxicity of many of the new foods, particularly grasses. For an excellent scholarly summary see the excellent book by the Jaminets .
Did we adapt to the new diet over several millenia? If the culprits were simply carbohydrates it might be more difficult that coming up with simple solutions to simple toxins.
One of the go-to guys these days on human paleopathology is Clark Larsen at Ohio State University. I wrote him to ask about the current state of knowledge, and, with his permission, here is his summary:
- All are deficient in one or more essential amino acids (lysine for maize, millet, and wheat);
- None of the common domesticated cereals have adequate bioavailable iron;
- All are deficient in one or more vitamins: e.g., B1 (thiamine), B2 (riboflavin), C (ascorbic acid);
- All have links with malnutrition, immunosuppression, and susceptibility to a variety of pathogens rendering the individual prone to infection where the population derives the majority of calories/energy from plant domesticates;
- All are carbohydrates, creating circumstances that promote a cariogenic oral environment and dental caries, oral infection, and susceptibility to degenerative conditions in later life (e.g., cardiovascular disease, diabetes).
Clark suggested several reviews he has written recently [2,3] as well as the classic volume edited by Cohen and Armelagos.
In the Collins blog post cited above there is reported work by Tim Gage showing that there is recovery from the new diet. It is not clear from post who cited this, but at any rate Tim denies having written anything at all about health and the agricultural transition.
If the culprits on the different continents were simply cooked carbohydrates then we do expect roughly the same outcome everywhere, and Larsen suggests that this is so. On the other hand one notices hints of greater complexity in the literature. Caries and gum disease are prominent in North American collections and much less common in Europe. One anomalous European site shows a lot of caries, and the authors suggest that they must have had a lot of honey in their diet.
An easy test for region-specific adaptations comes to mind. New foods, especially cereals, introduced by the Atlantic Exchange after 1492 should have been difficult for the recipients, who were not adapted to plants from the other side of the ocean. I do not recall ever having seen a discussion of this, and it might make an interesting project. Maize spread rapidly in southern Europe and in Africa: did it cause trouble early on? Is it still causing trouble? The staple of the diet in much of southern Africa today is ground maize (“mealie meal”) but no one seems concerned. While maize is associated with iron deficiency in many places, iron overload is a health problem in Africa, perhaps from the widespread use of cast iron pots.
 P. Jaminet, S.-C. Jaminet, Perfect Health Diet: Four Steps to Renewed Health, Youthful Vitality, and Long Life, YinYang Press, 2010.
 C.S. Larsen, Biological changes in human populations with agriculture, Annual Review of Anthropology. (1995) 185–213.
 C.S. Larsen, Bioarchaeology: the lives and lifestyles of past people, Journal of Archaeological Research. 10 (2002) 119–166.
 M.N. Cohen, G.J. Armelagos, Paleopathology at the Origins of Agriculture, Academic Press Orlando, 1984.