While some human hairs can be argued to serve various purposes, such as protecting the head
from the sun, or sexual signaling, or reducing friction during sex (pubic hairs), the underarm hairs are not located
to keep us warm, nor to protect us from the sun, or even to be visible at a distance. The only plausible purpose
appears to emit odors or pheromones. They do this efficiently. Only one in ten shaved armpits are described as
odorous 24 hours after washing, while nine out of ten unshaved armpits are described as odorous (Shelley, Hurley &
Nicols, 1953, as cited in Stoddart, 1990, pp. 66-67). The concentration of hairs here, served by multiple apocrine
glands, must be an adaptation for the production and dissemination of odors. [para 7]
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