Armpit hair

Sometimes we say things before we think them through properly. Me and a friend were pondering over why we have armpit hair. I suggested it comes from when we were cavemen and it would warn us if we had gotten to close to the fire. Apparently this was a stupid comment, similar to my friends theory on her mobile phone interfering with her brain waves. My friend explained we probably have them due to us evolving from apes, so our body hair are remnants of monkey ancestors. His theory seems to make more sense. 

Or maybe we have hair to protect us from the harsh signals from technology such as mobile phones. So all you baldies should invest in a tinfoil hat!!