Even baboons can learn how to live peacefully. Conciliatory behaviour can be socially transmitted, at least in olive baboons (Sapolsky and Share, 2004) , and macaques (de Waal and Johanowicz, 1993). Moreover, such pacifist behaviour within the troops can be enduring.
The macaque study involved mixing juveniles of 2 species, quarrelsome Rhesus monkeys and another easy-going stumptail monkeys. The stumptail monkeys have a "hold-bottom" ritual whre they hold their opponent's hips as a gesture of reconciliation after fights while the rhesus monkeys rarely make up after a fight. In the mixed groups (dominantly stumptails), the "hold-bottom" ritual became ingrained in the rhesus monkeys, so much so, that even when separated from the stumptails, they showed three times more reconciliation than normally shown by their kind. Where is the love, you may ask?
The oilve baboon (Papio anubis) study in Kenya occurred by happenstance when aggressive males were wiped out by bovine tuberculosis from contaminated meat at the garage dump of a tourist lodge, since refuse eaters were also the more aggressive members of their troops. So the cohort was then made up of less agressive individuals. In a typical baboon troop, new adolescent males join the troops and face the wrath of the highly aggressive dominant males, but for this cohort, the atmosphere was one of a "relaxed" dominance hierarchy and physiological measurements showed less stress among the low-ranking males as well. Compared to other troops, this so-named "Rainforest troop" was less aggressive, more friendly and enjoyed low stress levels.
de Waal FBM, Johanowicz DL (1993) Modification of reconciliation behavior through social experience: An experiment with two macaque species. Child Dev 64: 897–908. abstract
Sapolsky RM, Share LJ (2004) A Pacific Culture among Wild Baboons: Its Emergence and Transmission. PLoS Biol 2(4): e106
de Waal FB (2004) Peace Lessons from an Unlikely Source. PLoS Biol 2(4): e101