Early concepts of intimacy: Young humans use saliva sharing to infer close relationships

Ashley J. Thomas*, Brandon Woo, Daniel Nettle, Elizabeth Spelke, Rebecca Saxe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Across human societies, people form “thick” relationships characterized by strong attachments, obligations, and mutual responsiveness. People in thick relationships share food utensils, kiss, or engage in other distinctive interactions that involve sharing saliva. We found that children, toddlers, and infants infer that dyads who share saliva (as opposed to other positive social interactions) have a distinct relationship. Children expect saliva sharing to happen in nuclear families. Toddlers and infants expect that people who share saliva will respond to one another in distress. Parents confirm that saliva sharing is a valid cue of relationship thickness in their children’s social environments. The ability to use distinctive interactions to infer categories of relationships thus emerges early in life, without explicit teaching; this enables young humans to rapidly identify close relationships, both within and beyond families.
Original languageEnglish
Pages (from-to)311-315
Number of pages5
Issue number6578
Early online date20 Jan 2022
Publication statusPublished - 21 Jan 2022
Externally publishedYes

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