However, man is homeothermic, i.e. thanks to a sort of internal thermostat, his body is able to maintain itself at a temperature which changes little from day to day: from 36°C at night, it may rise to 37.5°C during the middle of the day. Man's ability to adapt to cold is soon overtaken when the internal temperature of the human body falls below 35°C, his metabolism slows to a dangerous level, and death ensues once it falls below the fatal level of around 25°C.

However, some degree of tolerance to cold has been observed. Any person who is exposed for a long time to great levels of cold develops mechanisms which compensate for the temperature and allow the outer envelope of the body to cool down beyond normal, thus creating a sort of buffer zone; this automatic cooling reduces the blood flow to the skin, fat layers and superficial muscles. We have all experienced violent shivering and the involuntary trembling of our muscles - which are merely uncontrollable and typical reactions designed to generate heat for a body which has cooled down too much. Nevertheless, the struggle to heat up again is costly in terms of energy and can be fatal to someone who is suddenly exposed to extremes of temperature. This is why, after 2 or 3 weeks of exposure to the cold, that the body adapts by reducing this expenditure of energy by turning down its thermostat by a few tenths of a degree. After 74 days on the Arctic ice-floes, the internal body temperature of the two Belgians, Alain Hubert and Didier Goetghebuer could fall as low as 35.5°C when resting.

Lowest Recorded Temperature -91°C at Vostok station (Russian) 1997

These automatic mechanisms which regulate our temperature do not amount to much, though, compared to the significant progress which has been made in recent decades by the chemical industry in developing new fibres. These fibres perform so well and are so revolutionary that polar explorers today can virtually dress in a second skin. However, like the clothes of yesteryear, these new fabrics still have to comply with the immutable rules concerning the way we dress (roomy clothes, not too tight against the skin, etc.) which have always been observed by the men and women who venture into latitudes such as these.