Hand preference predicts behavioral responses to threats in Barbary macaques

Abstract

The structure and functioning of the brain are lateralized—the right hemisphere processes unexpected stimuli and controls spontaneous behavior, while the left deals with familiar stimuli and routine responses. Hemispheric dominance, the predisposition of an individual using one hemisphere over the other, may lead to behavioral differences; particularly, an individual may be programed to act in a certain way concerning hemispheric dominance. Hand preference is a robust estimator of hemispheric dominance in primates, as each hemisphere controls the opposing side of the body. Studies have found links between hand preference and the exhibition of behaviors in contexts such as exploring and manipulating objects. However, little is known whether hand preference predicts behavioral variations in other ecologically relevant contexts like predation. We investigated the relationship between hand preference and behavioral responses to two types of predator models in captive Barbary macaques (Macaca sylvanus) (n = 22). Besides, a nonpredator novel object was included as control. We found 91% of the macaques to be lateralized with no group‐level bias. A higher rate of tension and focus (behavioral response) behavior was found in predator contexts than in the novel object condition. Unlike their right‐hand counterparts, individuals with a strong left‐hand preference elicited frequent focus and tension behavior toward the predator models. Additionally, the behavioral response varied with predator type. We also found an interaction effect between hand preference and predator type. Our study suggests that hand preference can reliably predict behavioral variations in the context of potential predation. While these results are consistent with lateralized brain function, indicating lateralization a neural mechanism of behavioral variation, the interaction effect between hand preference and predator type elucidates the importance of context‐specificity when investigating laterality noninvasively. Future research on other nonhuman primates using the current framework may provide insights into the evolution of laterality and underlying behavioral predispositions.

Behavioral, physiological, and genetic drivers of coping in a non-human primate

“…Therefore, we revised our sample size for the behavioral part of coping from 32 to 30 individuals. In addition, even if two predators could elicit responses from monkeys quite differently (see 54 ), we decided to combine their data for each phase (at the individual level) to tackle the low occurrences of some of the variables. Three experimenters coded the behavioral coping videos, and inter-rater reliability was calculated.…”

“…The current study uses a multidisciplinary framework to investigate the coping behavior of long-tailed macaques ( Macaca fascicularis ), a group-living NHP species. We conducted ecologically relevant predator exposure experiments repeatedly (see 53 , 54 ) to assess coping styles. Encounters with predators can be unpredictable and uncontrollable, following the definition of a stressor, 1 which forces individuals to cope with the situation.…”