Evidence from four lemur species that ringtailed lemur social cognition converges with that of haplorhine primates

Many haplorhine primates flexibly exploit social cues when competing for food. Whether strepsirrhine primates possess similar abilities is unknown. To explore the phylogenetic origins of such skills among primates, we tested ringtailed lemurs, Lemur catta, for their ability to exploit social cues while competing for food. We found that in two contexts ringtailed lemurs spontaneously approached food out of their competitor's view. To assess whether these skills are related to the relatively complex social structure seen in ringtailed lemurs or shared more broadly across a range of strepsirrhines, we then compared ringtailed lemurs to three lemur species with less complex societies in the same food competition task (N=50 lemurs). Although all species skilfully avoided food proximate to a competitor in a pretest, only ringtailed lemurs performed above chance in the food competition task that required subjects to avoid food that an experimenter was facing in favour of one that he was not facing. We also compared all four species in a noncompetitive gaze-following task. Ringtailed lemurs were again the only species that looked up more frequently when an experimenter gazed into space than when an experimenter gazed forward (although at relatively low frequencies). These results are consistent with the hypothesis that ringtailed lemurs have undergone convergent social-cognitive evolution with haplorhines, possibly as an adaptation for living in the largest and most complex social groups among strepsirrhines. Results are discussed in terms of lemur cognitive evolution as well as the social intelligence hypothesis.