Social neuroendocrinology : Effects of social contexts and behaviors on sex steroids in humans.

In this paper we provide a critical review of research concerned with social/environmental mechanisms that modulate human neuroendocrine function. We survey research in four behavioral systems that have been shaped through evolution: competition, partnering, sex, and pregnancy/parenting. Generally, behavioral neuroendocrine research examines how hormones affect behavior. Instead, we focus on approaches that emphasize the effects of behavioral states on hormones (i.e., the "reverse relationship"), and their functional significance. We focus on androgens and estrogens because of their relevance to sexually selected traits. We conclude that the body of research employing a reversed or bidirectional perspective has an incomplete foundation: participants are mainly heterosexual men, and the functionality of induced shifts in neuroendocrine factors is generally unknown. This area of research is in its infancy, and opportunities abound for developing and testing intriguing research questions.