More than fear: Contributions of biobehavioral synchrony and infants' reactivity to cooperative care.

We present two challenges to the fearful ape hypothesis : (1) biobehavioral synchrony precedes and moderates the effects of fear on cooperative care, and (2) cooperative care emerges in a more bidirectional manner than Grossmann acknowledges. We present evidence demonstrating how dyadic differences in co-regulation and individual differences in infants' reactivity shape caregivers' responses to infant affect.