My research focuses on the evolution of social and sexual behavior in taxa ranging from arthropods to humans. My interests center on the evolutionary adaptiveness of contingent responses of animal and human minds to challenges associated with sexual reproduction and social living. My nearly continuous studies of the sexual selection system of the sierra dome spider, Neriene (=Linyphia) litigiosa (Linyphiidae), are now in their 40th year. These studies are unique in that they integrate field and lab work, include experimental manipulations of factors affecting sexual decision-making in nature, consider the effect of a probable sexually transmitted disease on the structure of the mating system as well as individual variation in male and female mating decisions, and address seldom examined issues of how processes of male-male competition and female choice co-evolve and interact to form a "whole" mating system. See: McCullough et al. 2016 for a clear discussion of the latter issue. I involve graduate and advanced undergraduate students in all my research, and spend a good deal of time advising students on their own projects.