Audio Article: Babies can tell who has close relationships based on one clue: saliva

MIT neuroscientists have identified a specific signal that young children and even babies can use to determine whether two people have a strong relationship and a mutual obligation to help each other: whether those two people kiss, share food, or have other interactions that involve sharing saliva. Read the article: https://news.mit.edu/2022/babies-relationships-saliva-0120