Lice, sweat and a lost gene reveal when humans shed fur and dressed
For most of our history as a species, people went naked, probably for at least 90,000 years before anyone invented clothes. Working out when fur vanished and garments arrived has pushed researchers towards odd evidence, from a broken keratin gene to the family tree of lice, including one kind that seems to have come from gorillas.
Among roughly 5000 living mammal species, only a handful are effectively bare, such as elephants, whales, walruses and naked mole rats, and humans are the only primate on that short list. Homo erectus, which appeared about 1.6 million years ago, was the first hairless member of our genus. The favourite explanation is cooling: moving from shady forest to open savanna and chasing game raised the need to shed heat, and less hair plus more sweat glands did the job. Nina Jablonski suggests that efficient sweating also let the brain, our most heat-sensitive organ, grow dramatically larger.
Genetics adds detail. A keratin-related gene called KRT41P appears to have stopped working in our lineage about 240,000 years ago. Once the fur was gone, dark, melanin-rich skin protected against ultraviolet light, and paler skin later evolved outside the tropics so the body could still make vitamin D. Rival ideas exist: sexual selection might explain why men carry more coarse terminal hair, and a parasite theory notes that ancestors living in groups around 1.8 million years ago made humans the only one of 193 primate species with fleas.
Lice offer a clock. The human pubic louse descends from the gorilla louse, splitting off 3.3 million years ago, implying our ancestors were already largely hairless by then. Body lice, which live in clothing, branched from head lice much later; a 2010 study put habitual clothing between 83,000 and 170,000 years ago, likely in Africa before migration into colder lands.
Adornment may have come first, with body decoration traced to 77,000 years ago in South Africa. Fitted garments needed fine stone blades and eyed needles, skills of the Cro-Magnons who reached Europe around 35,000 years ago, while Neanderthals relied on loosely draped skins. Figurines from the southern Levant hint at fabric clothing 11,700 to 10,500 years ago, and the oldest surviving woven cloth is Egyptian linen from 5000 BCE.
Source: Prehistory of nakedness and clothing
