The study of human reproductive ecology represents an important new development in human evolutionary biology. Its focus is on the physiology of human reproduction and evidence of adaptation, and hence the action of natural selection, in that domain. But at the same time the study of human reproductive ecology provides an important perspective on the historical process of human evolution, a lens through which we may view the forces that have shaped us as a species. In the end, all actions of natural selection can be reduced to variation in the reproductive success of individuals.

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Reproduction is among the most basic of human biological functions, both for our distant ancestors and for ourselves, whether we live on the plains of Africa or in North American suburbs. Our reproductive biology unites us as a species, but it has also been an important engine of our evolution. In the way our bodies function today we can see both the imprint of our formative past and implications for our future. It is the infinitely subtle and endlessly dramatic story of human reproduction and its evolutionary context that Peter T. Ellison tells in On Fertile Ground.

Ranging...

In social relationships--whether between mates, parents and offspring, or friends--we find much of life's meaning. But in these relationships, so critical to our well-being, might we also detect the workings, even directives, of biology? This book, a rare melding of human and animal research and theoretical and empirical science, ventures into the most interesting realms of behavioral biology to examine the intimate role of endocrinology in social relationships.

The importance of hormones to reproductive behavior--from breeding cycles to male sexual display--is well known. What this...