Substitute Parents: Biological and Social Perspective on Alloparenting Across Human Societies

From a comparative perspective, human life histories are unique and raising offspring is unusually costly: humans have relatively short birth intervals compared to other apes, childhood is long, mothers care simultaneously for many dependent children (other apes raise one offspring at a time), infant mortality is high in natural fertility/mortality populations, and human females have a long post-reproductive lifespan. These features conspire to make child raising very burdensome. Mothers frequently defray these costs with paternal help (not usual in other ape species), although this contribution is not always enough. Grandmothers, elder siblings, paid allocarers, or society as a whole, help to defray the costs of childcare, both in our evolutionary past and now. Studying offspring care in a various human societies, and other mammalian species, a wide range of specialists such as anthropologists, psychologists, animal behaviorists, evolutionary ecologists, economists and sociologists, have contributed to this volume, offering new insights into and a better understanding of one of the key areas of human society.

Gillian Bentley is a biological anthropologist and reproductive ecologist and a Royal Society Research Fellow at University College London. Her prior work focused on explaining why different human populations occupying a range of environments have varying levels of reproductive hormones. She now directs projects that interface with reproduction and reproductive health, working with the migrant Bangladeshi community in London. Recent publications include Infertility in the Modern World: Present and Future Prospects, edited with C.G.N. Mascie-Taylor (Cambridge University Press, 2000).

Ruth Mace is Professor of Evolutionary Anthropology at University College London. She works on the evolutionary ecology of social and subsistence systems. Particular interests include parental investment, mainly in African populations but also in the UK, and also macro-evolutionary studies on the evolution of cultural diversity. Recent publications include The Evolution of Cultural Diversity: A Phylogenetic Approach, edited with C. Holden and S. Shennan (UCL Press, 2005).