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“When in Rome, do as the Romans do” runs the familiar advice. When you visit a different culture you are going to fit in with the locals quicker if you are ready to adopt their habits, however different those may be from how you carried on back home. Our new research on wild vervet monkeys in South Africa has revealed that a willingness to conform to what all those around you are doing when you visit a different culture is a disposition shared with other primates.


To test this we first provided groups of wild vervet monkeys with a box of maize corn dyed pink and another dyed blue, and made the blue corn taste repulsive. The monkeys soon learned to eat only pink corn. In the same way we trained other groups to eat only blue corn. We then took the corn away for months until a new crop of infants were ready to take their first solid food, and then offered the pink and blue corn with no nasty taste in either. Sure enough, the adult monkeys stuck to the preference they’d learned earlier. The question was, what would the new, naïve infants do? In fact, all but one of them began to eat only the colour their group preferred, even though within their easy reach was a perfectly edible, different coloured pile of corn. Some infants even sat on that, to eat the colour that all the monkeys around them were eating! The other infant’s low ranking mother dare only take the ‘wrong’ local corn colour and that is also what her infant ate. This part of our experiment has shown how strong the effects of copying your elders can be in our wild primate relatives.



Our surprising “when in Rome …” discovery came when the male monkeys began to migrate between groups, which is something they naturally do to search for mating opportunities beyond their original family. By luck, some males moved from groups where it was the norm to eat pink corn, to others where monkeys instead ate blue. Others switched from blue to pink corn groups. What would they do? We found that of the ten males who immigrated in this way, all but one switched from their original learned preference to the new local norm either immediately, or as soon as higher ranking resident monkeys moved away and gave them a free choice.


Our results show that that learning from others rather than by one’s own efforts is a more potent force in shaping wild animals’ behavior than has been recognized. This ‘social learning’ can make infants ‘blind’ to food types that are right before their eyes, channeling them to the maternal diet; and it can make migrants even overturn their existing habits to conform to local norms. Our human ‘when in Rome’ dispositions likely have ancient evolutionary roots.

“Potent social learning and conformity shape a wild primate’s foraging decisions” by Erica van de Waal, Christèle Borgeaud and Andrew Whiten is published in Science, 6131, 483-485, 2013. See:

Dr Erica van de Waal –

videos of the study on:

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