Human mothers commonly receive help from others to support their children, an unusual reproductive system known as cooperative breeding. Because cooperative breeding is not a trait shared with other great apes, its emergence in the human lineage marks a significant departure in reproduction and parenting, which has far-reaching consequences for the life history, sociality, and demographic success of our species. This chapter first defines cooperative breeding and establishes those characteristics that distinguish humans from other cooperative breeders. To unravel the evolutionary puzzle of cooperative breeding, the benefits of helping to mothers and offspring, why helpers help, who helps, and what helpers do are then reviewed. The discussion then turns to the question of why humans become cooperative breeders. Because humans provide food, shelter, and protection not just to infants but also to juveniles, humans expand the range of helping behaviors beyond those observed in other cooperative breeders, which has implications for many other aspects of sociality. Cooperative breeding has much to offer as a framework for conceptualizing the cooperative nature of humans and to explain our derived life history of early weaning, high fertility, and the long developmental period during which juveniles benefit from both receiving and giving help.

This chapter offers a cultural epidemiology of digital communities, describing how these groups emerge, bond, and come to develop shared embodied experiences. We argue that online communities, while seemingly novel and often “strange," can offer insights into fundamental mechanisms of human sociality albeit on an unprecedented speed and scale due to specific affordances of cyberspace. After framing this argument, we outline a noncomprehensive anthropological survey of online communities of interest. Our hope is to provide a model for how online communities grow to share interphenomenal experiences despite lack of face-to-face interaction, and how this might inform our understanding of ordinary social cognition.