Is body hair a functionless vestige?

Hair on the head can serve as a sexual cue.Hair around the genitals and joints (such as armpits) can serve to prevent chafing. That sort of skin irritation can lead to infection and other difficulties.Thin body hair can still act as a partial barrier against insects, or again prevent chafing with clothing. (more modern clothing won't chafe even without hair, but older clothing probably would.)