There is currently considerable interest in animal teaching, including in primates. There are, at present, only three nonhuman species that fulfil Caro and Hauser's (1992)¹ functional definition of teaching, but none of these three species are primates. However, there is suggestive evidence of teaching in golden lion tamarins (Leontopithecus rosalia), in two contexts: food sharing and food calling.

The aim of this study was to investigate candidate teaching behaviour of golden lion tamarins in the food-sharing context by combining experimental and observational work in wild populations in Brazil, as well as the application of cutting-edge statistical modelling to facilitate the detection of teaching. Specifically, we test the hypothesis that food sharing is a form of teaching, whereby provision of novel food types to juveniles teaches them what foods to eat in the future.

We evaluate the evidence that food sharing fulfils each of Caro and Hauser’s¹ three criteria that behaviour qualifies as teaching if: a) it is costly or not beneficial to the tutor (self-evident in this case); b) it is modified in the presence of a naïve pupil; and c) results in learning in the pupil. Results show that adults transfer more novel food compared to familiar food to juveniles, and that this is not due to an increase in juvenile motivation to obtain novel food, supporting criterion b). Using Bayesian modelling, I assess whether receiving food in food sharing events has an effect on juveniles’ later foraging choices, and whether this effect persists into adulthood, thus assessing criterion c).