Is it useful to view the brain as a secondary sexual characteristic?

Gregory F. Ball, Jacques Balthazart, Margaret M. McCarthy

Research output: Contribution to journalReview articlepeer-review

32 Scopus citations


Many sex differences in brain and behavior related to reproduction are thought to have evolved based on sexual selection involving direct competition for mates during male-male competition and female choice. Therefore, certain aspects of brain circuitry can be viewed as secondary sexual characteristics. The study of proximate causes reveals that sex differences in the brain of mammals and birds reflect organizational and activational effects of sex steroids as articulated by Young and collaborators. However, sex differences in brain and behavior have been identified in the cognitive domain with no obvious link to reproduction. Recent views of sexual selection advocate for a broader view of how intra-sexual selection might occur including such examples as competition within female populations for resources that facilitate access to mates rather than mating competition per se. Sex differences can also come about for other reasons than sexual selection and recent work on neuroendocrine mechanisms has identified a plethora of ways that the brain can develop in a sex specific manner. Identifying the brain as sexually selected requires careful hypothesis testing so that one can link a sex-biased aspect of a neural trait to a behavior that provides an advantage in a competitive mating situation.

Original languageEnglish (US)
Pages (from-to)628-638
Number of pages11
JournalNeuroscience and Biobehavioral Reviews
Issue numberP4
StatePublished - Oct 1 2014


  • Female competition
  • Organizing effects of steroids
  • Sex differences
  • Sexual differentiation
  • Sexual selection
  • Sexually differentiated gene expression

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience


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