Can Population-Level Laterality Stem from Social Pressures? Evidence from Cheek Kissing in Humans.
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.
UMR 6552 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Amandine
A
Chapelain
UMR 6552 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Pauline
P
Pimbert
UMR 6552 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Lydiane
L
Aube
UMR 6552 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Océane
O
Perrocheau
QDC, département R&D, 31000, Toulouse, France.
Gilles
G
Debunne
UMR 6553 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Alain
A
Bellido
UMR 6552 Université de Rennes 1-CNRS, Station biologique, 35380, Paimpont, France.
Catherine
C
Blois-Heulin
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005602:France; D007839:Functional Laterality; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012919:Social Behavior; D011795:Surveys and Questionnaires; D055815:Young Adult