Does target animacy influence manual laterality of monkeys? First answer from northern pig-tailed macaques (Macaca leonina)

Hand preference during bimanual coordinated task in northern pig-tailed macaques Macaca leonina

In humans, handedness is one defining characteristic regardless of cultures and ethnicity. Population-level right handedness is considered to be related with the evolution of left hemisphere for manual control and language. In order to further understand evolutionary origins of human cerebral lateralization and its behavioral adaptation, standardized measures on hand preference are required to make reliable comparison in nonhuman primate species. In this study, we present the first evidence on hand preference during bimanual coordinated tasks in northern pig-tailed macaques Macaca leonina. The classical TUBE task was applied to examine hand preference among nine individuals from Tianjin Zoo of China. We recorded and made analysis on both frequency and bout data on manual laterality. The results consistently show that subjects displayed strong individual hand preferences, whereas no significant group-level handedness was found. There were no sex and age significant differences on both direction and strength of hand preference. The M. leonina preferred to use the index finger to extract the baited food inside the tube. Our findings fill the knowledge gap on primate handedness, and efficiently affirm the robustness of the TUBE task as one efficient measure of hand preference in primates.