An adult male peacefully resting on a rock early in the morning.

Credit: Catherine Markham, Ecology and Evolutionary Biology Dept., Princeton University

Laurence Gesquiere of Princeton University explains how higher social ranks in baboons can come at a price.

Credit: National Science Foundation, Princeton University
Images Courtesy of: A. Catherine Markham and Jeanne Altmann of Princeton University

An adult male mate-guarding a fertile female (note the sexual swelling) during a sexual consortship. Successful mate guarding allows the male to maintain exclusive access and to obtain any fertilizations. This involves the male following the female closely, being vigilant and fighting off any males that might disrupt the consortship.

Credit: Jeanne Altmann, Ecology and Evolutionary Biology Dept., Princeton University

Two adult male baboons fighting at very close range. The one on the left is giving a threat by staring and raising his eyebrows, perhaps also slapping the ground; the one on the right exhibits a classic fear grimace, perhaps accompanied by a scream. Such a grimace also bares the male's teeth, reinforcing the reality that even a lower-ranking male can inflict debilitating, potentially lethal damage in a contact fight. Each male seems to be both lunging and pulling back from an attack, exhibiting the common ambivalence about actually engaging in physical combat that has the potential to lead to puncture wounds.

Credit: Jeanne Altmann, Ecology and Evolutionary Biology Dept., Princeton University

The researchers' work is described in the July 15, 2011 issue of the journal Science.

Credit: Copyright AAAS 2011