Sexual dimorphism

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Sexual dimorphism, aka severe gonochorism, refers to different appearance and behavior between the sexes within a species. A species with high sexual dimorphism has very noticeable difference between e.g. males and females. For example, the irish elk had such high sexual dimorphism that it was maladaptive, possibly being a major contributing factor in the extinction of the species.

Arguments on sexual dimorphism

Otto Weininger argued that in humans, the less sexually dimorphic the genders, the less of a problem female sexual liberation becomes. Whereas, if there is high sexual dimorphism in humans, female sexual liberation leads to agitation, domestic abuse against husbands, and corruption of the arts and science by feminine women only expressing vanity and seeking male attention.

The famous MRA Warren Farrell argued that in humans sexual dimorphism could lead to a fisherian runaway and extinction of the species if females continue to select for, "killer-hunter", type men with the advent of nuclear technology, though some think this is hysterical and overblown.

Causes of sexual dimorphism

Since males and females are mostly subject to the same survival selection, one would expect them to be very similar. Any dissimilarity must hence have a different origin than survival selection. One diver of sexual dimorphism may be sexual selection as proposed by Darwin (1858, 1871), i.e. that mate preferences evolved that shaped the phenotype for each sex differently often merely resulting in ornament rather than in functional changes. Sexual selection can result in runaway selection which can exaggerate the ornament and the mate preferences for it.

Another driver may be differential parental investment, i.e. that each sex has different sexual investment in the offspring and thus different mate preferences (e.g. women for a providing male) and is subject to different survival selection (e.g. pregnant women dying of different diseases and at higher rate than men). This mainly explains the dimophism in that women are choosy and men compete.

Sexual dimorphism and dimorphic mate preferences result in different kind of intrasexual competition for each sex, e.g. men competing with resources and physical power, and women competing merely in looks and with more gossip rather than physical power. Intrasexual competition, in turn can increase sexual dimorphism, e.g. by males evolving to be stronger and taller to achieve high status.

Dimorphic mate preferences

The most sexually dimorphic preference is for age with men of any age preferring young fertile, neotenous women while women prefer men of their own age or older.

Even though muscular bodies are nearly universally attractive to women, women do not care much about facial masculinity. Humans are substantially self-domesticated and therefore neotenous (meaning they retain youthful features) such that some facial neoteny is also attractive in men.

See also

• Facial Aesthetics: Concepts and Clinical Diagnosis
• Facial masculinity
• Estrogen Levels
• FWHR
• Height
• The Myth of Male Power
• Chad
• Stacy
• List of aesthetics