A new study marries, so to speak, economics and kissing. The study is:
“National Income Inequality Predicts Cultural Variation in Mouth to Mouth Kissing,” Christopher D. Watkins, Juan David Leongómez, Jeanne Bovet, Agnieszka Żelaźniewicz, Max Korbmacher, Marco Antônio Corrêa Varella, Ana Maria Fernandez, Danielle Wagstaff, and Samuela Bolgan, Scientific Reports, vol. 9, article no. 6698 2019. (Thanks to Tony Tweedale for bringing this to our attention.) The authors explain:
Romantic mouth-to-mouth kissing is culturally widespread, although not a human universal…
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)…. When aggregated, the predicted relationship between income inequality and kissing frequency was over five times the size of the null correlations between income inequality and frequency of hugging/cuddling and sex.
Here is some numerical detail:
