People josh about shin mange. Josh all you will (and you will), but it could very well be a major evolutionary imperative of the humanoid species. Call it "follicular Darwinism."
Mankind, as it evolves, is becoming less hirsute. This is clearly because hairier men are less inclined to procreate, lest they suffer the pain of forcible depilation by probing, year-old fists. Hairless men, on the contrary, can procreate with impunity. Thus, the smooth-skinned male lives to pass on his glabrous genes, while the man-yaks are slowly, inexorably outnumbered.
I demand this be taught in high schools across the country immediately. Especially in Kansas, which seems extra willing to embrace new ideas.