Of the 21 species of macaque monkeys, pigtailed macaques live in
societies that fall somewhere between the despotic and egalitarian

A dominant male and female run the show but conflict among
other monkeys is common, though rarely extreme. Most such conflicts end
with a third party intervening, usually in favor of one opponent. But
sometimes the most powerful monkeys literally stand between the two
combatants and, occasionally without even threatening them, impartially
resolve the conflict. It is this occasional policing that allows
pigtailed macaque society to be more diverse instead of breaking down
into warring cliques, according to new research.

By David Biello

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