Social Learning And Culture In Capuchin Monkeys
A growing body of evidence has broken the stereotype that only humans have culture by showcasing cultural variation between social groups in other species. However, less is known about whether animals can have a “cumulative culture,” which happens when we make progress on what previous generations have learned.
One theory as to why we have not observed much cumulative culture in animals is that animals may be less capable of learning from observing others (“social learning”) versus from their own experiences (“individual learning”). This study set out to explore whether it is true that non-human primates rely more readily on individual learning rather than social learning, relative to humans who accumulate culture through social learning.
The subjects for this study were fourteen capuchin monkeys housed in the Edinburgh Zoo. Capuchin monkeys were chosen because evidence of traditions has been found in wild capuchin social groups. Additionally, these animals have large brains, are good at using tools, and live in relatively tolerant (rather than combative) social groups.
Monkeys had the opportunity to voluntarily engage with a touchscreen computer for a chance to earn extra food rewards, and they could stop participating at any time. In stage A of the study, the screen showed an information trial where one of two shapes was chosen — by the monkeys themselves for the individual learning group, versus by a human experimenter for the social learning group) — followed by a random outcome of either a reward (“win” condition) or no reward (“lose” condition). Next was a test trial, in which the monkeys were given the option to either choose the shape that was previously selected in the information trial (“stay” response) or choose the other shape that was not chosen in the information trial (“shift” response).
Choosing the same shape as in the information trial was rewarded with food only if that shape had resulted in a “win” in the information trial. Similarly, choosing the alternative shape was rewarded with food only if the previously-chosen shape had resulted in a “lose” in the information trial. Stage B of the study was essentially the same, but with three shapes to choose from in each trial rather than two, and fewer participants (only seven subjects who did exceptionally well on stage A qualified for stage B).
The researchers found that capuchin monkeys performed better, on average, for win trials (they correctly chose to “stay” with the same shape in 74% of win trials) versus lose trials (they correctly chose to “shift” to a different shape in 39% of lose trials). The researchers attributed the low accuracy on lose trials to an overall tendency of the monkeys to repeat the selection from the information trial (“stay”) regardless of the outcome. The bias towards choosing to “stay” with the information trial selection was maintained even in stage B, which included two alternatives to the “stay” selection rather than just one.
Information source — that is, being in either the social versus individual learning condition — was not found to be a significant predictor of how well monkeys performed in the trials. This indicates that capuchin monkeys, a non-human animal species, rely on social learning as readily as individual learning. Similarly, past studies have found that young capuchin monkeys in the wild prefer observing more skillful nut-cracking over less skillful nut-cracking, suggesting they may discriminate between behaviors that lead to more successful outcomes and pick up on them through social learning. However, because the monkeys faced significant challenges with the “lose-shift” scenario, the researchers argue there is not enough evidence to suggest these animals possess cumulative culture.
It is important to note that the monkeys in this study were housed in a zoo environment — not in the wild — and that the social learning condition required them to learn from observing a human experimenter rather than someone from their own species and social group. Nevertheless, the results shed interesting light on the psychology of capuchin monkeys.
Studies like this can help animal advocates break stereotypes that only humans rely on social learning and that only humans have culture in the first place. Advocates can also call for more studies that allow non-human subjects to voluntarily engage with trials and for more studies that are rewards-based rather than punishment-based. Finally, more research is needed to investigate differences and similarities between human and non-human social learning styles to better understand how culture operates in each.