A while ago, I stumbled across an article that made me think twice about the evolution of human stature in terms of both natural and sexual selection. It wasn’t particularly well argued, but it did get me to think. One of the curiosities that popped into my head was the case of the African pygmies. They tend to be a fairly significant outlier, with an average height of adult men just under 5′ (59″). It’s imaginable that certain ecological contexts could confer phenotypic advantage to shorter individuals. It’s also imaginable that sexual selection for shorter individuals could also develop if there wasn’t significant ecological pressure for taller individuals. The latter would throw a wrench in the [all other things being equal] “women prefer taller men” assumption that’s floating around in the ether. Sorry to all you aspiring French dictators out there, but it doesn’t appear that there’s a group of women just over the horizon who all mysteriously prefer short dudes.
An article in Evolution and Human Behavior claims that sexual selection for a shorter stature was not a significant factor among the pygmies.
“our results demonstrate that stature influences mate choice in pygmies, and we argue that, if of any influence for sexual selection, mate choice should have favored tallness rather than shortness in our pygmy population. Consequently, this study establishes that sexual selection is a very unlikely candidate to account for the evolution of pygmies’ short stature.”
Height, particularly that of the sexually dimorphic (difference between men and women) remains a fascinating question. The stature dimorphism in humans averages about 15%, a significantly smaller difference than almost all other apes. The small relative difference would generally imply weak pressure on sexual selection via intrasexual selection (male-male competition), and intersexual selextiom (female mate choice). However, we still see a preference by women for taller men. Unfortunately, determining various selection pressures isn’t easy.
Translation: pygmy chicks didn’t develop a culture-wide crush on short men that drove evolution toward shorter stature.
What do you think? Is it just culture? Is women’s preference for taller men simply intersexual selection? If it can’t be explained by sexual selection, what bearing does height have on survival and reproduction? Is the preference simply a remnant from one or two or four or six million years ago when our ancestors lived in different social structures? Were taller men better hunters? Were they better defenders? Were they better at dominating other men? It’s almost a certainty that it’s a combination of pressures over a long period of time, and answering that question has implications for our understanding of nearly all things human.
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