Mothers and their babies are often said to share a deep, intimate connection

Mothers and their babies are often said to share a deep, intimate connection, but even so, this discovery is weird. Simply by looking and smiling at each other, moms and babies synchronize their heartbeats to within milliseconds of each other.

Researchers at Bar-Ilan University in Israel found that visible affection from their mothers had tangible physiological effects on three-month-old infants. Previous studies in animals have shown that social interactions between “attachment partners” can affect the animal infants’ bodies, but this is the first time such an effect has been observed in humans. Writing in Infant Behavior and Development, the researchers explain what they discovered:

Mothers and their 3-month-old infants were observed during face-to-face interactions while cardiac output was collected from mother and child. Micro-analysis of the partners’ behavior marked gaze, affect, and vocal synchrony episodes. Time-series analysis showed that mother and infant coordinate heart rhythms within less than 1-second lags.