Is that some ancient defense mechanism?

So, since odor is caused by bacteria digesting sweat, You can:

Reducing the level of bacteria is really a matter of cleanliness. To control the bacteria you should: wash with strong anti-bacterial soap

rofl…

“I shave both my armpits and my scrotum.”

“not having any nose hairs helps to produce the best boogiers”

you can read it here

As for smelling armpits, I have no idea.  Maybe it’s supposed to be some kind of bug repellant…lol…or girl 😉