Reaching versus catching: flexible hand preference in ring-tailed lemurs

Compared to other primate taxa, hand preference in strepsirrhines has been poorly investigated and the available studies have often produced conflicting results. Thanks to their remarkable plasticity in foraging and postural habits, ring-tailed lemurs (Lemur catta) represent a key model species to examine manual lateralisation. We video-recorded 23 individuals hosted at four Italian zoological gardens during three food-related trials requiring different kinds of manual actions. We found a remarkable hand preference at individual level for grasping static food presented in a bowl, both when only one kind of food was offered (“food limited-choice” task) and when a mix of less and more palatable food items were available (“food large-choice” task). Conversely, most individuals did not show any hand preference for catching highly palatable food in motion (“catching” task). Moreover, the subjects not showing any hand preference engaged more frequently in bimanual actions (concurrent and symmetric use of both hands in catching food) than the subjects displaying a manual asymmetry. No detrimental effect on the task performance was recorded, indicating a high level of hand selection plasticity in Lemur catta. In conclusion, our findings show that ring-tailed lemurs can take advantage from a flexible manual strategy and highlight how ecological factors must be carefully evaluated when assessing hand preference in extant strepsirrhines.