Nudity
The loss of body hair was one of a group of adaptations that are part of human evolution. Modern humans evolved in Africa from hunter-gatherers in terrain different from where hominins had lived before. There were fewer trees and more exposure to the sun. Sweat drying on bare skin cooled the body better when hunting for food, so less hairy hominins survived. Because the brain produces a lot of heat, better cooling of the body favors an increase in brain size. Early humans had learned to make tools and weapons, those with larger brains made them better. In adapting to running and carrying weapons, humans became fully upright. Another push towards being upright was that mothers had to carry their babies, who no longer had fur to cling to. Being smarter and having their hands free, humans could also make better tools. Being upright also reduced sun exposure except for the top of the head, which remained covered with hair. Longer head hair also covered the shoulders. Skin became darker as protection from the sun.