Among a troop of savanna baboons in Kenya, a terrible outbreak of tuberculosis 20 years ago selectively killed off the biggest, nastiest and most despotic males, setting the stage for a social and behavioral transformation unlike any seen in this notoriously truculent primate.Non-human culture has been demonstrated for many years, both in other primates and in non-primates. This is still an astounding discovery and natural experiment. Even though one expects the baboons to revert to "kind", it's easy to imagine how a reinforcing change in the evironment could reinforce the transformation and make it persistent.
In a study appearing today in the journal PloS Biology (online at www.plosbiology.org), researchers describe the drastic temperamental and tonal shift that occurred in a troop of 62 baboons when its most belligerent members vanished from the scene. The victims were all dominant adult males that had been strong and snarly enough to fight with a neighboring baboon troop over the spoils at a tourist lodge garbage dump, and were exposed there to meat tainted with bovine tuberculosis, which soon killed them. Left behind in the troop, designated the Forest Troop, were the 50 percent of males that had been too subordinate to try dump brawling, as well as all the females and their young. With that change in demographics came a cultural swing toward pacifism, a relaxing of the usually parlous baboon hierarchy, and a willingness to use affection and mutual grooming rather than threats, swipes and bites to foster a patriotic spirit.
Remarkably, the Forest Troop has maintained its genial style over two decades, even though the male survivors of the epidemic have since died or disappeared and been replaced by males from the outside.
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