by Daniel Kane » Sat Jul 06, 2013 7:32 am
Chewing in primates can be seen as a sign of irritation in the individual displaying the behaviour, or a threat (usually given after a direct stare or flashing of eyelids, and before a mock/full charge or a bite). Not wanting to anthropomorphise, but it can be difficult when the two species are 'closely related'! Like some people may grind their teeth in a stressful situation, these primates may well do the same. Then again, maybe there was food in its cheek-pouch and it was simply chewing this! From what I've learned working in a zoo a lot of primate behaviour is similar to human behaviour, which you may not find surprising.