Hand preferences in coordinated bimanual tasks in non-human primates: a systematic review and meta-analysis

The evolutionary significance of hand preferences among non-human primates and humans has been studied for decades with the aim of determining the origins of the population-level tendency. In this study, a meta-analysis was conducted to statistically integrate data on hand preferences in non-human primates performing the tube task and other bimanual tasks to determine the presence and direction of manual laterality. Significant individual-level lateralization was obtained for these bimanual tasks. In non-human primates, 81% of the animals analysed showed right or left-hand preference performing the tube task, this figure being 88% for other bimanual tasks. No asymmetry was found at the population level, unlike in humans. Additionally, no preference in direction was found in either of the tasks, although a strong manual preference was found performing the tube task and other bimanual tasks. Species was studied as a variable moderator throughout the meta-analysis. These results emphasize the importance of standardized testing methodologies across species and institutions to obtain comparable data and fill the gaps in the taxonomy.