to classify — the Sodas and Khoras and the nomadic Udejas and some members of the 

 Bhils — representing on the whole elements akin to European varieties. The Middle 

 Eastern — North African deserts contain folk of Caucasian, i.e. European affinities 

 belonging principally to the Mediterranean variety; such are the Ruwala Bedouin and 

 the Tuareg. There is also in this N. African desert region a fringe of Negro peoples. 

 The Kalahari contains the Southern Bushmen, who, on blood group and other data, 

 should be considered of Negroid affinity. In the desert strip called the Namib, Negros 

 of the Ovambo tribe are to be found. In or near the South Western deserts of N. 

 America there are American Indians (like the Hopi) as also in the Atacama desert. 

 The Australian desert may be regarded as uninhabited in its main central area yet 

 there are many tribes such as the Arunta who endufe the rigours of a desert climate. 

 A handful of Europeans in Australia also experience quite severe desert conditions. 



This sketchy description shows sufficiently that, where the desert heat load has 

 to be endured, the human species in all its varieties, Negro, Mongoloid, European, 

 Australian, has the physiological capacity to deal with it, even allowing that many of 

 the peoples mentioned have probably not come into desert conditions by choice and 

 that the populations are often nomadic and in many cases only semi -permanently in 

 these regions. The ethnological data gives strong a priori grounds for supposing that 

 the human physiological make-up does not itself constitute a primary or major bar to 

 the greater penetration and development of desert regions. Nevertheless, there is a 

 considerable adjustment needed, as will be shown, for existence in these conditions, 

 even for short periods, and a knowledge of these can contribute much to successful 

 and more extensive human activity in these parts of the world. 



2. The Discomfort of Desert Conditions 



Stimulated by the requirements of ventilating engineers, considerable investiga- 

 tion has been made in Europe and America on the relation between ambient condi- 

 tions and subjective impressions of warmth so that for individuals living in these 

 countries, these can be stated with some precision (Bedford, 1948). This is usually 

 and conveniently done in terms of the American Effective Temperature scale which 

 enables one to specify the subjective effect of any combination of wet bulb, dry bulb 

 and air movement (and radiation) as a single temperature. When the effective tem- 

 perature exceeds 70°F, many people in temperate climates move out of the 'comfort 

 zone' and above 75°F the majority will complain of the discomfort. Such figures refer 

 to people lightly clothed, sedentary, in the summer; in winter, tested in the same way, 

 these levels will be found to be too high, that is, there is an increased tolerance to 

 heat in the summer showing the existence of an acclimatization process. It is to be 

 expected therefore that individuals who have lived for long periods in hot climates of 

 the world would show a similar increase in subjective tolerance. Native-born white 

 Australians, according to the recent investigations of Drysdale (1951), can tolerate 

 without undue discomfort an upper limit of warmth as high as 80°F effective tem- 

 perature. At such temperatures the skin may be quite moist but there are few com- 

 plaints on this score. Results in other hot places (Iran, Singapore, India) generally 

 confirm these high limits though in some cases differences in clothing may have 

 been operative in the tests. 



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