31-01-2014

Men and dogs in prehistoric times

Evolutionary biology aims at studying the processes and mechanisms generating biodiversity, based on the understanding of the genetic basis of the difference among species (divergence) as well as within every species (variation, polymorphism). Recently, researchers of the Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) participated in two interesting studies that tell us stories about men and dogs in prehistory.

The first study, directed by Carles Lalueza-Fox and published in Nature, is a genomic study of a man who lived in León 7.000 years ago. One of the most astonishing results is that he had dark skin, darker than present Europeans, but his eyes were blue, indicative of a nord-european phenotype. It was thought that white skin was related to the latitude and less insolation of European countries compared with Africa. However, the hominid studied had dark skin, despite his ancestors had lived in Europe for thousands of years. The results of this study suggest that changes in skin pigmentation may not be related to latitude but to diet. Thus, in the Neolithic men ate less meat and therefore the intake of vitamin D was reduced. In this context, having a clear skin is an advantage because it allows vitamin D synthesis under sunlight influence.

The second study refers to the relationship between men and domestic dogs. In the study participated several research groups from USA, China and several European countries, including researchers of the Institute of Evolutionary Biology Belén Lorente-Galdós, Óscar Ramírez and Tomás Marquès-Bonet. To identify genetic changes underlying dog domestication and reconstruct their early evolutionary history, the researchers generated high-quality genome sequences from three gray wolves, one from each of the three putative centers of dog domestication, two basal dog lineages (Basenji and Dingo) and a golden jackal as an outgroup. Analysis of these sequences supports a demographic model in which dogs and wolves diverged through a dynamic process involving population bottlenecks in both lineages and post-divergence gene flow. In dogs, the domestication bottleneck involved at least a 16-fold reduction in population size, a much more severe bottleneck than estimated previously. The study narrowed the plausible range for the date of initial dog domestication to an interval spanning 11–16 thousand years ago, predating the rise of agriculture. This suggests that the earliest dogs arose alongside hunter-gathers rather than agriculturists.

Marta Alegret (Universitat de Barcelona)

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