QUANTITATIVE GENETICS OF SEXUAL DIMORPHISM IN HUMAN BODY SIZE

Area of Science:

• Evolutionary biology
• Human evolution
• Quantitative genetics

Background:

• Sexual dimorphism, the distinct differences between males and females of a species, is a common trait.
• Understanding the evolutionary pressures driving sexual dimorphism is crucial for evolutionary biology.
• Previous research suggested allometric responses to body size selection might explain primate sexual dimorphism.

Purpose of the Study:

• To predict the evolutionary rates of sexual dimorphism versus population means for human traits under selection.
• To evaluate the hypothesis that allometric scaling explains primate sexual dimorphism.

Main Methods:

• Utilized a classical dataset to model the effects of selection on human stature, span, and cubit.
• Calculated the predicted rates of change for population means and sexual dimorphism under equal selection intensity.
• Assessed the potential for selection on body size to generate sexual dimorphism in primates.

Main Results:

• Human population means for stature and cubit are predicted to evolve over 60 times faster than sexual dimorphism for these traits.
• Population mean of span evolves significantly faster than its dimorphism.
• Selection for larger body size can generate sexual dimorphism but is insufficient to explain primate patterns.

Conclusions:

• Sexual dimorphism in human stature, span, and cubit evolves at a very slow rate.
• Comparative studies of sexual dimorphism across human societies are unlikely to yield robust evolutionary insights.
• The allometric effect of body size selection is too weak to account for observed primate sexual dimorphism.