Can Population-Level Laterality Stem from Social Pressures? Evidence from Cheek Kissing in Humans

Abstract

Despite extensive research, the origins and functions of behavioural laterality remain largely unclear. One of the most striking unresolved issues is the fact that laterality generally occurs at the population-level. Why would the majority of the individuals of a population exhibit the same laterality, while individual-level laterality would yet provide the advantages in terms of improving behavioural efficiency? Are social pressures the key factor? Can social pressures induce alignment of laterality between the individuals of a population? Can the effect of social pressures overpass the effect of other possible determining factors (e.g. genes)? We tested this important new hypothesis in humans, for the first time. We asked whether population-level laterality could stem from social pressures. Namely, we assessed social pressures on laterality in an interactive social behaviour: kissing on the cheek as a greeting. We performed observations in 10 cities of France. The observations took place in spots where people of the city meet and greet each other. We showed that: a) there is a population-level laterality for cheek kissing, with the majority of individuals being aligned in each city, and b) there is a variation between populations, with a laterality that depends on the city. These results were confirmed by our complementary data from questionnaires and internet surveys. These findings show that social pressures are involved in determining laterality. They demonstrate that population-level laterality can stem from social pressures.

Kissing Right? Absence of Rightward Directional Turning Bias During First Kiss Encounters Among Strangers

“…Specifically, those whose cultural customs include social kissing may have established a head-turning direction when kissing non-romantic partners. This is supported from research by Chapelain et al (2015) which found that head-turns for social cheek kissing varied by regions in France, but that the direction was almost unanimously followed by members from each region.…”

Embraces are lateralized in spider monkeys (Ateles fusciceps rufiventris)

“…The face‐embrace recorded in our group involves direct and initial contact of the cheeks. Data from humans indicates side biases for kissing behavior but these studies introduce additional variation in the term with “kiss” that is not captured in our data set (Chapelain et al, ; Ocklenburg & Güntürkün, ; Sedgewick & Elias, ; van der Kamp & Canal‐Bruland, ). It is possible that certain social greeting gestures vary among groups of spider monkeys in a similar way that cheek kissing varies in humans in which some cultures kiss once on one side of the cheek, while others kiss on both sides, and others preferring to kiss directly onto the lips.…”

Social Risk Dissociates Social Network Structure across Lateralized Behaviors in Spider Monkeys

“…For example, female sexual risk taking within certain communities is associated with greater risk of male aggression towards them [28,29]. Contact and partner variables have also been examined in the literature on social touch laterality in human kissing [30][31][32][33][34] and embracing [35,36], although these studies have not framed their findings in the context of risk, which may be an avenue in the future to connect these two streams of research.…”