Scent of a father: Paternal body odors boost interbrain synchrony.

Olfactory cues are ancient signals and mammalian young utilize maternal body odors (BO) to form a bond to their habitat in the absence of the mother, strengthen associative learning, and grow a social brain. Whether infants respond to their father's BO and how paternal BO impact their brain maturation is still unknown. Utilizing ecologically-valid paradigms with dual-electroencephalography recordings, we measured infant-father and infant-stranger interbrain synchrony during naturalistic interactions and assessed the effects of paternal BO. Infants show greater interbrain synchrony with father compared to a stranger male. Paternal BO increase infant-stranger interbrain synchrony and enhance the father-typical positive arousal, providing evidence that infants process their father's odor and can invoke his presence in his absence. Fathers contribute to brain maturation by enhancing cross-hemisphere connectivity in alpha rhythm that sustains attention regulation during stimulating social interactions. Paternal olfactory cues can invoke infants' associative learning and may push the development of more complex neural and behavioral competencies.