The target article examines the role of practice in the development of excellence in several domains that vary in the degree of innovation involved. The authors do not differentiate domains, but they discuss the development of specifically creative skills only in passing. This commentary presents evidence that practice plays a role in the development of musical composition, through an examination of the careers of Mozart and the Beatles.

Four aspects of Mazur & Booth's target article are discussed from a comparative perspective using teleost fish as a reference: (a) the relationship between aggression, dominance, and androgens; (b) the interpretation of the data in light of the challenge hypothesis; (c) the potential role of testosterone as a physiological mediator between social status and the expressionof male characters; and (d) the fact that metabolic conversions of testosterone may be important in its effect on aggression/dominance.

The fact that the female mammalian brain remains responsive to estrogens throughout life may open the way for other instigators of neuronal plasticity, making the female brain different from that of the male in its response to the actions of a number of hormones, to injury and to aging.

Data do exist to support the fact that the corpus callosum is relatively larger in women than in men. The corpus callosum is an integral part of the brain, and contrary to Fitch & Denenberg's examples of “pseudostatistics,” is not an extrinsic structure when determining its relative size.

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.

Howe et al. proposed that the “talent account” is not suited to explain exceptional performance in specific domains. Their conclusion that early experiences and deliberate practice are highly important for high levels of skill is supported by numerous studies on the acquisition of expertise. However, the two popular views they contrast (experts are born versus experts are made) do not seem representative of current theorizing. Models that integrate the effects of basic abilities and deliberate practice are more appropriate in light of the available evidence.

Using testosterone alone as a measure of dominance presents problems, especially when dominance is loosely defined to include a range of behaviors that may arise from multiple causes. Testosterone should be examined in relation to other hormonal and neurotransmitter factors, such as serotonin. Various hypotheses about the relationship between high and low levels of testosterone with serotonin and with impulse control are suggested for future study.

Mazur & Booth's target article presents strong evidence that social factors influence testosterone; however, the evidence for an effect of testosterone on dominance is considerably weaker. Although social and biological factors may interact, as suggested in the reciprocal model, findings in rhesus monkeys suggest that social factors may predominate. Finally, research is needed to evaluate whether androgens during early life influence later dominance.

Because the reciprocal theory of Mazur & Booth dominates the static basal model, given the evidence they present, it is worth considering the implications for women's equality, supposing it true. Testosterone might well give males a competitive edge, and hence higher status, creating an inequality that mere social legislation would be ill-suited to address. Further research on the role of testosterone is needed.

Although Howe et al.'s survey shows little evidence for the talent account, it is premature to conclude that individual differences in achievement can be attributed largely to training and early experience. Moreover, such an empiricist account has problematic social implications, especially in cultures in which effort is emphasized. The aptitude account is thus proposed as a third alternative.

Studies of testosterone's effect on dominance are confounded by the effects of dominance experiences on testosterone. Furthermore, antisocial behavior tends to originate prepubertally, when testosterone levels are the same for aggressive males, nonaggressive males, and females. It seems more parsimonious to view variation in testosterone as an effect of dominance-related mood states than to invoke a reciprocal model.

Developmental counts of axons in the splenium of the rat corpus callosum are compatible with the hypothesis that estrogen may be acting late in development to sculpt the female nervous system.

Sexual selection traditionally involves male-male competition and female choice, but in some species, including humans, sexual selection can also involve female-female competition and male choice. The degree to which one aspect of sexual selection or another is manifest in human populations will be influenced by a host of social and ecological variables, including the operational sex ratio. These variables are discussed in connection with the relative contribution of sexual selection and the division of labor to the evolution of human sex differences.

Mazur & Booth provide life scientists with an example of the multilevel biopsychosocial approach. Research paradigms have to become more flexible and multidisciplinary if we are to free ourselves from the nature–nurture dichotomy that we have long agreed was simplistic and shortsighted. I point out a variety of kinds of interactions that may be the next frontier for behavioral scientists.

The existence of natural talent becomes easier to see at extremes in performance. Practice alone could not account for the differences in performance that exist at the highest levels. Practice and other factors are no doubt important contributors to outstanding performance, but not enough to explain great creative works. Talent is essential.

This Response focuses on the strength of the testosterone (T) dominance relationship, the circumstances under which aggression accompanies dominance, the viability of the basal model, mediators and moderators of the T-dominance relationship, and the research that is needed.

In the animal literature, the concept of dominance usually links status in intermale encounters with differential reproductive success. Mazur & Booth effectively review the human literature correlating testosterone with intermale competition, but more profound questions relating this to male–female dynamics have yet to be addressed in research with humans.

Seen in its historical context, Mazur & Booth's (M&B's) target article may come to be viewed as a turning point in the study of the biological basis of human behavior in general, and dominance in particular. To facilitate further research, suggestions are offered for making the definition of dominance more precise. From an evolutionary point of view, the testosterone-dominance link may be as important in women as it is in men.

Howe et al. fail to provide evidence that practice is sufficient and ignore evidence of high ability before instruction. They unsuccessfully discount savants; provide weak evidence against heritability of music, criticize retrospective evidence selectively, using it when it supports their position; and ultimately both accept and deny talent. Finally, they conflate a scientific question with one of policy.

This commentary samples some of the major bodies of counterevidence omitted by Howe et al., including the strong relationship between IQ and academic excellence, the limited effects of early stimulation programs, and the measurement of musical aptitudes. The authors' selective review and analysis of the surveyed literature, especially studies of prodigies and in behavioral genetics, is discussed.