Exploring the necessity of others in human evolution.

Abstract

“No mammal in the world has produced young that take longer to mature or depend on so many others for so long as did humans in the Pleistocene” (273). This fact, to Sarah Blaffer Hrdy, is an invitation to continue the “long argument” she began in 1991—Homo sapiens could only have arisen as a species, and proceeded to flourish, if they possessed a suite of mental abilities that both unite and separate us from the other Great Apes in ways that we are just now being to understand. Unlike many books that address the evolution of human behavior, this is not a book about competition and strife, but rather compassion and cooperation. Mothers and Others: The Evolutionary Origins of Mutual Understanding is, most of all, an attempt to describe and evidence the evolutionary emergence of emotionally modern humans. The “mothers” the title refers to are, mostly, mammals—what were the unique adaptations necessitated by the extreme dependence of mammalian offspring on their mothers for survival? The “others” are alloparents—Hrdy considers an alloparent to be any group member other than a parent who participates in the rearing of offspring. Hrdy evidences her argument that humans’ unique position among the Great Apes is a direct result of “mothers and others” by positing a series of logical questions, explaining why these questions are relevant to human evolutionary development, and then providing the best available evidence from historical and contemporary studies in animal behavior, primatology, neuroscience, cognitive psychology, human behavioral ecology, and cross cultural ethnographies. Key questions raised in her argument include: How did prosocial hunter-gatherers develop and flourish in ancient environments dominated by selfish apes? We know natural selection is not forward-looking—what was the initial benefit of prosociality? Directional selection pressure that favored empathy would have required immediate benefits; what are they (67)? Among the Great Apes, only humans exhibit spontaneous sharing and assistance (66). How did we develop from self-centered and hyper competitive chimpanzees? Hrdy believes we didn’t. In cognitive psychology, a “theory of mind” is defined as the ability to think about what someone else thinks. Hrdy prefers to use the term intersubjectivity as it places emphasis on a willingness to share in the emotional states and experiences of others—the foundation for humans’ advanced capabilities for mutual understanding (2). Anthropologists have itemized “unique” human attributes, but Hrdy claims these lists show our ignorance of our understanding of other species more than they express a