Why do humans start getting body odor after they go through puberty?
In: Biology
Eccrine sweat glands are present from birth in humans and secrete sweat that is mostly water and functions in evaporative cooling, hence kids don’t seem to have body odor.
Apocrine sweat glands are found in the armpits and groin regions and become active in humans at puberty. These sweat glands secrete an oily substance containing lipids and proteins that through interactions with bacteria on the skin ( e.g bacteria digesting lipids), lead to the ‘smellness’ of adults (including body odor).
So it’s not the sweat that smells, it’s the action of bacteria on apocrine sweat gland that becomes prevalent after puberty. .
Why? Ultimately, the odors are meant to attract mates. Children (and young animals) have little odor, because it would attract predators and they have no need to attract mates at that age.
Fun fact: most east and southeast Asians and a significant percentage of native Americans have a gene that causes the apocrine glands to not secrete oils that bacteria like. So the bacteria don’t colonize their skin and they don’t get an unpleasant odor when they sweat. It’s called the ABCC11 gene.
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Basically (the way I was taught this at least) you have two major types of sweat glands, apocrine and eccrine. Sweat produced by eccrine glands is mostly water. Apocrine sweat is more oily and contains a whole bunch of other stuff (which I won’t get into). So bacteria can metabolize the components of apocrine sweat far more readily.
Apocrine glands (which are heavily concentrated in your pits and groin) are stimulated by sex hormones, the levels of which rise sharply during puberty. So you get an assload of oily sweat, which is then colonized by bacteria, who generate foul odors.
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