Cultural diversification also drives human evolution

The study, coordinated by the expert Rolando González-José from the Patagonian National Research Center (CENPAT-CONICET, Argentina), examines physical, genetic, geographical and climatic patterns affecting over 1,200 people from the Baniwa, Ticuna, Yanomami, Kaingang, Xavánte and Kayapó indigenous groups of the Brazilian Amazon and Central Plateau.

According to the experts behind the study, one of the most interesting results is the rapid rate of morphological change in the Xavánte, which is up to 3.8 times faster than in the other groups studied. The changes observed in the Xavánte -- who have larger heads, narrower faces and broader noses -- follow an integration pattern of human skull shape recently described in the literature. "This study demonstrates that when selection acts in the same direction as integration patterns, evolution is favoured," explain the researchers Mireia Esparza and Neus Martínez-Abadías, who co-authored another recent study on morphometric patterns and the evolutionary potential of the human skull ( see http://www.sciencedaily.com/releases/2011/12/111220102244.htm).

The study suggests that this divergence is also independent of the Xavánte's geographical separation from other population groups and differences in climate. According to the team of experts, the combination of cultural isolation and sexual selection could be the driving force behind the changes observed. To conclude their study, the authors hypothesize that gene-culture co-evolution could in fact be the dominant model throughout the history of the human evolutionary lineage.