Thursday, 5 September 2013

Human sexual dimorphism (fat-free mass difference between men and women) is greater than generally believed - similar to gorillas!


Extracted from a review article by David A Puts of Penn State University - "Beauty and the Beast: mechanisms of sexual selection in humans." Evolution and Human Behavior 2010; 31: 157-175. Words in square brackets [ ] are my editorial additions, three dots ... represents a cut. References are omitted. Bold emphases have been added.  


Men are larger, stronger, faster, and more physically aggressive than women - and the degree of sexual dimorphism in these traits rivals that of species [such as gorillas and common chimpanzees] with intense male contests.

1. The relatively modest 8% stature [height] dimorphism  in humans... and a difference of about 15-20 % in body mass might suggest that male contests are reduced compared with our closest [primate] relatives. However... this is partly because women are unique among primates in having copious fat stores.

2. When fat-free mass is considered, men are 40% heavier... and have 60% more total lean muscle mass than women.

3. Men have 80% greater arm muscle mass and 50% more lower body muscle mass...

4. ...The sex difference in upper-body muscle mass in humans is similar to the sex difference in fat free mass in gorillas..., [which are] the most sexually dimorphic of all living primates. (...)