Nutritional factors in human dispersals

Nutrition can be defined as the biochemical network by which diet affects expression of genes giving rise to phenotypes that are able to successfully respond to environmental challenges, such as those resulting from dispersal to new habitats. A virtuous circle is generated between genes and diet via optimal nutrition, which provides metabolic support for the development of functions that in turn allow better exploitation of food resources in the new habitat. The present contribution will test this hypothesis by nutritional analysis of three sequential dispersals of Pleistocene hominins, which were accompanied and made successful by a dramatic expansion in brain size and function. Such anatomical/functional changes are likely to be related to specific mutations, but can be maintained across generations by the essential contribution of dietary factors since they are very expensive of both the energy and quality content of the diet. The importance of access to 'nutritionally dense' food, essentially meat, marks the forest to savannah transition, while that to a 'brain-specific diet', essentially a maritime pattern of food chain, seems distinctive of the inland to coast dispersal and of more recent out of Africa long-distance dispersals.