Cultural inheritance and diversification of diet in variable environments

Both cultural inheritance and cultural diversification of diets may play an important role in animal evolution. Here we studied how diet innovation and cultural change relate to cultural inheritance in a changing environment. We did this by studying diet cultures in group foragers adapting to environmental change through learning, and the consequences this has for diet differentiation between groups. We used an individual-based model of ‘monkeys’ that learn what to eat in a rich environment, and we changed resource species that are available in the environment. Relative to social influences on learning that arise spontaneously in groups, we found that more direct social learning, in the sense of observing another individual and copying what it eats, helps groups deal with high levels of environmental variability by generating greater group level incorporation of diet ‘innovations’ and enhancing cumulative cultural diet improvement. An important factor for the dual role of copying in diet innovation and cultural inheritance is how copying is mediated by foraging opportunities in the environment in the short term. During adaptation to environmental changes, groups diverge in diet. This is caused by differences in learning history and is increased when individuals copy each other, but this depends on migration. Furthermore, when groups live together in the same environment and compete for resources, diet differentiation is enhanced through what appears to be culturally mediated character displacement.