Infant attachment behaviors reflect the parenting style of individual caregiver in common marmosets
Childrens physical, cognitive, and emotional maturation require adequate interactions and secure attachment with their primary caregivers. However, the causal relationships between parenting components and infant attachment behaviors remain unclear. New World monkey common marmosets provide an ideal model of human parent-infant relations because, like humans, infant attachment is shared among family caregivers, including parents and older siblings using intricate vocal communications. Combining the natural variations in parenting styles and subsecond-scale microanalyses of dyadic vocal and physical interactions, we demonstrate that marmoset infants signal their need by context-dependent call use and selectively maintain proximity with familiar caregivers. The infant attachment behaviors are individually tuned according to the caregivers parenting style; infants keep producing isolation calls when they are carried by rejecting caregivers and exhibit avoidance toward neglectful and rejecting caregivers. Family-deprived infants failed to develop such adaptive uses of attachment behaviors or age-appropriate autonomy and exhibited disorganized attachment behaviors. Thus, marmoset infants shape their ability to modulate their intricate attachment system depending on the caregivers attitude through early social interactions with their family caregivers. Demonstrating the significant similarity of the infant attachment system between marmosets and humans, these findings will pave a path to elucidating the neural mechanisms of the infant attachment system.