Background: Sexual dimorphism in stature and weight is the outcome of boys and girls responding differently to environmental cues, and may have fitness advantage because of the interaction between size-related survival and size–related obstetric complications and fertility.
Hypotheses: Living standard and health affect size dimorphism; Variations in size dimorphism are due to differential responding by boys and girls to environmental cues; Size dimorphism will be greater where population average height and weight are greater.
Methods: We characterized size dimorphism in the CDC2000 database from age 0-20. We correlated 161 countries’ a-gross domestic product, b-life expectancy (LE), c-population average size with adult M/F ratio in height and weight per country. We correlated M/F height and weight ratio in 44 present-day preindustrial societies with LE, total population and density.
Results: Size dimorphism appears and disappears at minipuberty and then is established when the boys enter puberty. Stature and weight M/F ratio correlate with the LE (r=.572**, =.262*, resp.) and average M (r=.519**, =.523**) and F height (r=.183*, p=0.019, r=.299**), but not with the GDP. In 44 preindustrial societies, size dimorphism correlates positively with average M (r= .410*) but not F height, weight dimorphism correlates with the tribal population (r=-.534*).
Conclusions: Minipuberty is associated with adult-type size dimorphism. Size dimorphism is established during puberty. In industrial societies but not in preindustrial societies LE and living standards positively correlates with size dimorphism. Female’s growth is more resilient to negative health effects. Size dimorphism is greater where human size is greater.
