Social tolerance mediates social learning in wild red-fronted lemurs (Eulemur rufifrons) and ring-tailed lemurs (Lemur catta)

Social learning is widespread in the animal kingdom, allowing individuals to acquire information from conspecifics. Because such learning often follows the social network within a population, species with different social structures and tolerance levels may show distinct learning trajectories. We tested this in four groups of wild, egalitarian red-fronted lemurs (Eulemur rufifrons, N = 34) and three groups of wild, hierarchically organized ring-tailed lemurs (Lemur catta, N = 35) using a social diffusion experiment with feeding boxes. We also conducted a co-feeding test of social tolerance. The feeding boxes could be opened by either lifting or pushing the box. In experimental conditions, we trained a demonstrator in one of the two techniques; in control conditions, no demonstrator was trained. More red-fronted lemurs learned to open the box than ring-tailed lemurs, and they learned faster. Both species preferred the lifting technique, but when pushing was the seeded technique, most red-fronted lemurs adopted it, whereas ring-tailed lemurs did not. Order of acquisition diffusion analysis showed that in both species, social learning followed the social network and was more likely than individual learning. Social tolerance predicted the proportion of learners within a group, with red-fronted lemurs being more tolerant than ring-tailed lemurs. In a similar vein, in the more tolerant red-fronted lemurs, scrounging occurred much more often than in the less tolerant ring-tailed lemurs. Scrounging might also have driven the preference for lifting technique in red-fronted lemurs but not in ring-tailed lemurs. Our results show that tolerance facilitates social learning and that information spreads along social network pathways. Most importantly, our results show that these effects vary across species with different social structures. Together, this suggests that social tolerance can drive group-specific behaviours and may play a key role in the evolution of cultural traits.