Abstract
The centrality of the social world in human life is nowhere clearer than in the extreme dependence of children on their caregivers. Infants not only require that their caregivers provide for all of their physical needs, they also need a deep affective bond to learn about their physical and social world—to be able to explore, form relationships with others, to act both independently and collaboratively. This bond also scaffolds learning about language, how to interpret others’ behavior, and how to pursue joint projects. Human sociality generally begins with the infant-caregiver relationship. Like so many features of human life, attachment has both continuities and discontinuities with other animals. The extreme evolutionary investment that our species has made in the capacity to learn complex interactions with the physical and social world is evident in the prolonged dependence of human offspring. Even in the simplest forms of human life, children do not produce more than they consume until their late teens. The human investment of relational resources in complex capacities begins with the caregiver-infant relationship, which ramifies throughout individual and collective lives.