Comments on the article by A. H. Eagly and W. Wood (see record 1999-05337-002) which examined the origins of sex differences in human behavior. Eagly and Wood argued that social structural theory can explain the origin of psychological sex differences. The present article discusses conceptual problems which render Eagly and Wood's theory implausible. The authors see the social structuralists' dualistic interpretation of the origin of human traits as untenable and note that it results from a misunderstanding of what drives the evolution of adaptations. It is also noted that social structuralists' contention that humans do not have evolved psychological sex differences is implausible, because their implicit assumption that the sexes have not faced different adaptive problems over evolutionary history is not true. The authors point out that social structuralists neglect empirical evidence supporting the hypothesis that behavioral sex differences are mediated by hormonal influences.