No....hair was originally for temperature regulation a long time ago in humans. Currently, after evolution, and with new technological advances, hair is not used anymore. It's just dead cells that we humans use for our looks. Our hair basically has no function now.And no, the hair does not shield you from the sun's UVA UVB radiation. That's what melanin does inside your skin cells, guarding your cells' nucleus from the radiation coming from sunlight.