National income inequality predicts cultural variation in mouth to mouth kissing

Christopher D Watkins,Max Korbmacher,Samuela Bolgan,Jeanne Bovet,Marco Antônio Corrêa Varella,Danielle Wagstaff,Agnieszka Żelaźniewicz,Ana Maria Fernandez,Juan David Leongómez

doi:10.1038/s41598-019-43267-7

Abstract

Romantic mouth-to-mouth kissing is culturally widespread, although not a human universal, and may play a functional role in assessing partner health and maintaining long-term pair bonds. Use and appreciation of kissing may therefore vary according to whether the environment places a premium on good health and partner investment. Here, we test for cultural variation (13 countries from six continents) in these behaviours/attitudes according to national health (historical pathogen prevalence) and both absolute (GDP) and relative wealth (GINI). Our data reveal that kissing is valued more in established relationships than it is valued during courtship. Also, consistent with the pair bonding hypothesis of the function of romantic kissing, relative poverty (income inequality) predicts frequency of kissing across romantic relationships. When aggregated, the predicted relationship between income inequality and kissing frequency (r = 0.67, BCa 95% CI[0.32,0.89]) was over five times the size of the null correlations between income inequality and frequency of hugging/cuddling and sex. As social complexity requires monitoring resource competition among large groups and predicts kissing prevalence in remote societies, this gesture may be important in the maintenance of long-term pair bonds in specific environments.

Highlights

Romantic mouth-to-mouth kissing is culturally widespread, not a human universal, and may play a functional role in assessing partner health and maintaining long-term pair bonds
Many relationship behaviours and expressions of romantic attachment contribute to maintaining durable pair bonds, which are important to understand given that threats to pair bonds may affect health and wellbeing
Not a human universal, romantic kissing is observed in a wide variety of cultures[11] and being perceived as a good kisser can enhance a person’s desirability as a partner

Summary

Introduction

Romantic mouth-to-mouth kissing is culturally widespread, not a human universal, and may play a functional role in assessing partner health and maintaining long-term pair bonds. The pair bonding hypothesis posits that, as an expression of love that strengthens romantic attachment, kissing plays a functional role in monitoring and maintaining long-term relationship quality[14]. Consistent with this hypothesis, kissing frequency and satisfaction with kissing are related to relationship quality while having a partner who is a good kisser predicts relationship quality at twice the size of the relationship between sexual satisfaction and relationship quality[17]. This would extend prior research by suggesting that the value attached to kissing as a mate assessment cue is greater in high pathogen ecologies (i.e., to accept or reject a partner) even if it is used sparingly in these environments

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