The olive baboon (Papio anubis) is among the largest species of monkey, together with a congener (P. ursinus) and the rainforest-inhabiting mandrills (Mandrillus sphinx). This baboon’s species name originates from the ancient Egyptian god, Anubis, god of the afterlife, who was depicted with a long canid-like snout. The protruding nuzzle of baboons gives them an atypical appearance for a primate, especially against the shield-like backdrop of a male’s face. Baboons have an incredibly varied diet, foraging for fruits, seeds, grasses, and leaves from the tops of trees to the ground. They opportunistically consume arthropods, especially ants and termites when in abundance, and have been documented hunting small mammals and even antelope such as dikdik and young gazelles. During the day, they move in troops of dozens to over a hundred individuals, and communicate via a complex vocal repertoire of grunts, shrills, jaw-claps, and visual signals such as facial expressions (grins, yawns, sticking the tongue out, and eye/ear/eyebrow movements). Baboons prefer to take refuge high off the ground at night to minimize predation from leopards and hyenas. At Mpala, troops would regularly climb up kopjes, cliffs, and fever trees by the river.
There is dramatic sexual dimorphism in the olive baboon, with males ~25% larger and heavier than females, also characterized by enlarged canine teeth that are displayed during competition between males. Interestingly, the tails jut out distally then droop steeply, almost as if broken, and in contrast to many other primates they are not used as prehensile appendages during arboreal locomotion.
In a troop’s dominance hierarchy, every baboon maintains a social ranking. Baboons of a higher rank benefit from having increased food resources during group foraging and greater reproductive success. Females remain in their natal groups and dominance is inherited, such that a high-ranking female’s offspring will attain a similar rank as her mother. Males instead disperse, challenging and usurping older males in neighboring troops. In some cases, two males form a coalition to outcompete a single larger, more dominant male. Females, likewise, often engage in close relationships and maintain subgroups within the troops, grooming and supporting each other during intragroup conflicts. Moreover, a single male and female within a troop sometimes form what is referred to as a “friendship,” where both parties groom each other and remain in close proximity, which may or may not escalate into future mating opportunities. These strong associations between baboons of the same and different sex create highly complex social dynamics within the troop.