Chronic traumatic encephalopathy (CTE) among football players; the antlers of the Irish elk; the feathers of the male peacock. They’re all examples of the results of sexual dimorphism: gender-specific traits associated with sexual selection. In very simple terms, the peacock’s feathers, the Irish Elk’s antlers, and the football player’s brawn, all signal the female of the species that this male has enough testosterone to maintain physical health despite producing these features, and would therefore make a good genetic father for her children.
Generational repetition of selection for a specific trait—the male with the biggest display of feathers, antlers, or muscles—reinforces the trait. Feathers, antlers, and muscles become larger, more pronounced.
Nor are sexual selection traits limited to the male of the species. For example, large mammaries signal the male that the female is likely to be a good nurturer of children (although that is probably secondary when the footballer looks at the cheerleader).
In the southern United States, the match between football players and cheerleaders is a cliché. Footballers and cheerleaders seem to go together in some sort of natural order—selecting mates for brawn and beauty; breeding with one another to produce more brawn and beauty. It’s not a coincidence that the prettiest girls are cheerleaders and vice-versa. Both brawn and beauty are reinforced and exaggerated over the generations.
The late-twentieth-century trend toward school consolidation kept the footballer-cheerleader (F-C) gene pool large enough to prevent the inbreeding that occurs among smaller gene pools. However, as multiple generations of footballers and cheerleaders (F-Cs) and their offspring attend the same schools, some recessive genes are likely to be expressed.
The F-C example of sexual dimorphism may be in part responsible for the decline in the United States of education in general and science-technology-engineering-math education in particular. The success of the F-Cs, the relaxing of academic standards for them, the diversion of money to sports teams, and the designation as nerds (or worse) of non-F-Cs who do excel in academics all serve to push down academic standards.
Let’s not overlook the lesson of the Irish Elk. There is a strong hypothesis among biologists and paleontologists that the female elks’ selection for large antlers preserved and exaggerated this trait to the point that males’ antlers became a burden that the males could not support, both physically and, more basically, the males’ metabolism and ability to maintain homeostasis.
Is there a lesson, here? Yes. Will it make a difference? That depends on how readers’ react and whether it penetrates their perceptual filters.
For more, consider reading Darwin’s “The Descent of Man, and Selection in Relation to Sex,” and the following article from the National Academy of Sciences:
For a broader, and less detailed treatment, try:
Registered Curmudgeon, scientist, skeptic, humanist, and writer.