23. Bateman’s Principles and the Study of Evolutionary Demography

Over the last 40 years, investigators have been applying ideas from the body of theory known as sexual selection to the behaviour of humans, breaking exciting new interdisciplinary ground. The Darwin-Bateman Paradigm has been central to this endeavor, essentially the idea that males are more competitive over mates than are females, and that mating success affects reproductive success more strongly in males than in females. Less known among social scientists is the fact that biologists continue a vigorous debate over the validity of this paradigm. In this chapter I take social scientists into some of these issues, to see how and why the study of the operation of sexual selection on males and females has changed as a result of clearer theory and better methods. The simple takeaway message is that in many species gender roles are much less distinct than original investigations of the Darwin-Bateman paradigm might suggest. Applying some of the emerging insights to humans, we find a surprisingly limited general understanding about the extent and patterning of variability in reproductive success in either sex. Furthermore, success in the marriage or mating pool is associated with a range of reproductive outcomes, both positive and negative, for men and women. A new methodological approach is proposed for studying the effects of mating success on reproductive success which may help to sort through some of the extensive variation in our species. More generally, the chapter argues that an updated understanding of Bateman’s work might serve to guide evolutionary demographers today, just as Bateman’s original work steered research in the early days of sociobiology.