Why do we have hair in our armpits, but not in our 'kneepits'?

We do have hair in our "kneepits." However, it has "thinned" considerably over the years.

We do not have Lymph Nodes in our knee pits that need to be kept warm by hair as we do in our arm pits!

The recess behind the knee is called the popliteal fossa.


Doesn't answer the question but I found it interesting!

It's probably a left-over from the days when scent was much more important. Nowadays we try to eliminate odour, where once we used it to convey status messages. The knees are usually further away from the detection zone and so wouldn't matter any more than the rest of the leg. The area at the top of the leg did matter, though, which explains the retention of longer thicker hair there. There is naturally hair over most of the body - even on a naturally bald head - and it varies in thickness and length quite a lot.