The past 30 years have seen a sea change in the study of sexual selection in primates. With few exceptions–such as Goodall's work on chimpanzees and DeVore's on baboons–the earlier work usually consisted only of descriptive field studies giving such crude social and ecological parameters as group size, age and sex composition, preferred food species, and whether reproduction was annual or not. The literature was often dull and justified only by the phylogenetic closeness of the species studied to ourselves.

Now we have studies of male paternity using DNA analysis, experimental analyses of the attractiveness of female swellings, comparative work on sexual dimorphism in size across various primates characterised for intensity of sexual selection, comparative studies of the primary sex ratio in primates and studies of sperm competition as well. On the theoretical side, we have passed well beyond the initial model linking sex differences in variance in reproductive success to sex differences in parental investment. We now have theory regarding reproductive skew, sex-antagonistic genes and sex-antagonistic selection, female choice biased toward daughters, and extra-pair and sperm competition as major variables in sexual selection. This is the new world that the present volume introduces us to. What follows is one person's selective summary, meant to highlight the key findings. Much is left out, of course, and there are certainly some important results that I have overlooked.