We have just as much hair all over our bodies as chimpanzees or monkeys or any other furry primate. Most of it is just very short and light. It's called "vellus hair" or "peach fuzz". I think it's bizarre that most of our thick hair is on the tops of our heads. Imagine if dogs looked like that! On second thought, maybe it's better if you don't imagine that.
Research shows that we humans lost all our body hair through evolution about a million years before somebody finally figured out how to purchase clothes at one of the first primitive Walmarts.
One theory says that we lost our all body hair in an attempt to avoid parasites like ticks, fleas, and lice, and that we've only kept the hair on our heads because other people think it's pretty. As proof, consider that you haven't seen many bald pregnant women.
There is a very special kind of louse that only lives in human clothing. DNA tests indicate that it evolved from a louse that only lives in human hair, and that this happened about 42,000 to 72,000 years ago. So, that's probably roughly when clothes first went on sale. There are no special lice that live in any form of footwear, so DNA testing cannot solve the troubling mystery of exactly at what point in the past Hello Kitty themed socks were invented.