ScienceDaily (Mar. 17, 2009) — Adults of many animal species play a crucial role in the social development of youngsters. A new study reveals that the ratio of adults to young plays a much more important role in social development than the mere presence of adults.

Marie Bourjade, Alice de Boyer des Roches and Martine Hausberger of the University of Rennes 1, France, studied the effects of the adult-young ratios in naturally-formed groups of Przewalski horses on aggression rates and social cohesion of young horses. Previous studies led by the laboratory have shown that this ratio plays an essential role in song acquisition in songbirds (which has parallels with human language development) and so the authors sought to find a more general principle regarding the effects of adult-young ratios on social behaviour.