Final answer:
Humans lost most of their body hair around a million years ago mainly for thermoregulation and to avoid parasites, with clothing adoption much later.
Step-by-step explanation:
Humans lost most of their body hair about a million years ago, a significant milestone in human evolution. One of the main reasons for this loss is believed to be thermoregulation, which allowed early humans to control their body temperature more efficiently in the hot savanna climate.
The presence of numerous sweat glands in humans, much greater than in other primates, supports this hypothesis. An additional theory suggests that the loss of body hair was an adaptation to reduce the burden of parasites, such as lice. Intriguingly, humans did not adopt clothing immediately after losing their body hair.
Research indicates that humans started wearing clothes substantially later, around 170,000 to 190,000 years ago, leaving a long period of adaptation to the environment without the benefit of garments.