ABSTRACT
I n evolutionary terms, successful reproduction ultimately means produc ing offspring that are themselves successful at reproducing. Proximately, this requires integration of many complex systems. Appreciating the com plexities of these proximate mechanisms gives one a better understanding of the magnitude of selection pressures that have shaped them. This is important because those same selection pressures also shaped physiolog ical responses to the environment-mechanisms that maximize future reproductive opportunities by minimizing costly reproductive effort when environmental conditions for reproduction are temporarily poor. This paper describes the role of the environment, and especially the social environment, i n shaping reproductive processes, and i t emphasizes the importance of reproductive failure as a means to control the t iming of reproduction. We begin by summarizing some of the proximate mecha nisms that must be integrated to produce successful offspring i n an attempt to illustrate the magnitude of selection pressures that shaped them. We then describe how and w h y these same proximate and ultimate mechanisms promote reproductive failure i n a manner that ultimately maximizes reproductive success. Our final message concerns the need to address the role of the social environment i n clinical approaches to human reproduction and infertility.
