Social environment elicits lateralized behaviors in gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes).

Abstract

The influence of the social environment on lateralized behaviors has now been investigated across a wide variety of animal species. New evidence suggests that the social environment can modulate behavior. Currently, there is a paucity of data relating to how primates navigate their environmental space, and investigations that consider the naturalistic context of the individual are few and fragmented. Moreover, there are competing theories about whether only the right or rather both cerebral hemispheres are involved in the processing of social stimuli, especially in emotion processing. Here we provide the first report of lateralized social behaviors elicited by great apes. We employed a continuous focal animal sampling method to record the spontaneous interactions of a captive zoo-living colony of chimpanzees (Pan troglodytes) and a biological family group of peer-reared western lowland gorillas (Gorilla gorilla gorilla). We specifically focused on which side of the body (i.e., front, rear, left, right) the focal individual preferred to keep conspecifics. Utilizing a newly developed quantitative corpus-coding scheme, analysis revealed both chimpanzees and gorillas demonstrated a significant group-level preference for focal individuals to keep conspecifics positioned to the front of them compared with behind them. More interestingly, both groups also manifested a population-level bias to keep conspecifics on their left side compared with their right side. Our findings suggest a social processing dominance of the right hemisphere for context-specific social environments. Results are discussed in light of the evolutionary adaptive value of social stimulus as a triggering factor for the manifestation of group-level lateralized behaviors.

Social environment elicits lateralized navigational paths in two populations of typically developing children

“…A recent study by Quaresmini, Forrester, Speizio, and Vallortigara (2014) aligns most closely with the evolution of social lateralization studies that indicate a preference to keep conspecifics proximally situated with a left visual field advantage during spontaneous natural behaviors. Observational focal sampling of spontaneous social behaviors in a family group of western lowland gorillas (Gorilla gorilla gorilla) and in a colony of captive zoo-living chimpanzees (Pan troglodytes), revealed group-level biases in both gorillas and chimpanzees (trend) for keeping conspecifics proximally situated to the left side of the focal individual compared with the right side.…”

“…In the first instance, a bias to keep conspecifics on the left side inherently provides an advantage for viewing social stimuli with the left visual field. The left visual field would provide the most efficient route to the right hemisphere for processing identity, intention and Quaresmini et al, 2014). Additionally, a bias of the left visual field/right hemisphere has been reported in recognizing faces and facial expressions in both apes (Morris & Hopkins, 1993) and humans (De Renzi, Perani, Carlesimo, Silveri, & Fazio, 1994;Kanwisher et al, 1998).…”

“…Each navigational path was equal to one frequency point. In line with Quaresmini et al (2014), to ensure that the relative presence of the social partner was influencing the positioning of the focal subject, we adopted an approximate distance of less than 3 m or less between the child being observed and the social partners.…”

Context-dependent lateralization of trunk movements in wild Asian elephants

“…Lateralized behaviour is known to be especially pronounced in relation to socially significant objects as compared to other types of stimuli (e.g., Forrester et al, 2014a;Karenina et al, 2013;2017;Quaresmini et al, 2014). For example, both human children and feral horse foals prefer to keep conspecifics on their left side, but show no side bias when choosing a position relative to inanimate objects (Forrester et al, 2014a;Karenina et al, 2017).…”

Hand preference in fast-moving versus slow-moving actions in capuchin, Sapajus spp., and squirrel monkeys, Saimiri sciureus

“…Rogers, 2009). Indeed, there is now much evidence that these features affect manual preferences in both apes and human children (Forrester, Quaresmini, Leavens, Mareschal, & Thomas, 2013;Forrester, Quaresmini, Leavens, Spiezio, & Vallortigara, 2011;Forrester, Quaresmini, Leavens, & Vallortigara, 2012;Quaresmini, Forrester, Spiezio, & Vallortigara, 2014).…”