Mailbag: Thick skulls and diet

Re: <a href=http://johnhawks.net/node/15421”>”Hard headed science”</a>:

Although genetics undoubtedly play a part in the thickness of the skull bone, there is another parameter that more often than not is overlooked by anthropologists. That parameter is nutrition. Modern man is overfed on calories but malnourished on micronutrients. Soft tissues always evolve to their fullest, but the hard tissues, i.e. bone, are much more dependent on nutrition and physical work-load. Compared to the skulls of its ancestors, the skull of modern man is thinner, smaller, narrower, the eye sockets tend to be rounder and there tends to be insufficient space for the teeth in the mouth. It seems reasonable to me that in so far as the shape of the skull, it is the phenotype thats changed, not the genotype.

Nutrition can make a difference, but the variation in skull thickness during the last 2 centuries is very minor compared to the amount of difference between Homo erectus, Neandertals and us. The thinning also preceded any significant shift from hunting and gathering to agriculture. There has been further thinning after agriculture, so that we can’t attribute the shift to a straightforward diet change.