Most visible human variation is complicated. Height, skin tone, hair texture and facial structure each involve many genes contributing small effects, which is why they vary continuously rather than falling…
Almost every emotional display a person produces can be manufactured. Smiles, frowns, gestures, tone of voice, posture — all of them are under some degree of voluntary control, which is…
There is a category of biological feature that only makes sense as a leftover, and the third molars are the most familiar example.
They appear late, typically in the late…