The Yaghan People
Amazing, heartbreaking info from Wikipedia: The Yahgan may have been been driven to this inhospitable area by enemies to the north, but were famed for their complete indifference to the bitter weather around Cape Horn. Although they had fire and small domed shelters, they routinely went about completely naked in the frigid cold and biting wind of Tierra del Fuego, and swam in its 48-degree waters. They would often sleep in the open completely unsheltered and unclothed while Europeans shivered under their blankets. A Chilean researcher claimed their average body temperature was warmer than a European's by at least one degree. But the Yahgan, who never numbered more than 3000 individuals, could not survive contact with white man's diseases; they allegedly became sick immediately if the missionaries persuaded them to put on some clothes. In the 1920s some were resettled on Keppel Island in the Falklands in an attempt to preserve the tribe, as described by E. Lucas Bridges in Uttermost Part of the Earth (1948), but continued to die off. The last full-blooded Yahgan died in 1999.