There is evidence that in women high levels of testosterone are associated with more sexual partners and more permissive sexual attitudes. If a similar relationship holds true for men, the higher basal testosterone levels of divorced and unmarried men may be caused by this relationship rather than by testosterone's effect on dominance striving.

Emotion-science without basic brain-science is only superficially satisfying. Dynamic systems approaches to emotions presently provide a compelling metaphor that raises more difficult empirical questions than substantive scientific answers. How might we close the gap between theory and empirical observations? Such theoretical views still need to be guided by linear cross-species experimental approaches more easily implement in the laboratory.

Heritability is not a measure of the relative contribution of nature vis-à-vis nurture, nor is it the phenotypic variance explained by or because of genetic variance. Heritability is a correlative value. The evolutionary and developmental processes associated with human culture challenge the use of “heritability” for understanding human behavior.

The facial expression of pain is the end product of a complex process that is, in part, emotional. The evolutionary study of facial expression must account for the social nature of human consciousness and should address the questions of why empathy exists, the adaptive importance of empathy, and whether facial expression is a mechanism of empathy and second-person consciousness.