Adjustment to Cold of Bushmen in the Kalahari Desert

¹ From the Applied Physiology Laboratory, Transvaal and Orange Free State Chamber of Mines, Johannesburg, South Africa

A study has been made of the cold adaptation of Kalahari Bushmen under natural conditions at an air temperature of 10°–12°C. A completely ‘wild’ Bushman had a fall in total heat content, measured by change in core and surface temperatures, similar to Europeans. Core temperature fell more than in the Europeans, but the surface temperature fell less. The subjects were exposed, naked, at rest at an air temperature of 12°C for 2 hours. Surface temperatures of another Bushman sleeping under a cloak beside his fire were followed from 10 p.m. until 6 a.m. at 12°–13°C air temperature. Air temperature over the trunk under the cloak was in the thermoneutral zone, i.e. about 26°C, but extremities were less well protected; consequently, extremity temperatures fell more than trunk temperatures during the night. The Bushman, like the Australian aborigine, makes good use of fire, so that the average Globe thermometer reading at the feet, nearest the fire, was 24.4°C and at the head, 17.2°C, even when the Globe thermometer reading fell to 12°C away from the fire. The Kalahari Bushman has, in his own primitive manner, produced a microclimate during the coldest part of the day which is near the thermoneutral zone, hence his adaptation is an intellectual one, not a physiological one, in that he has developed thermal barriers.