The human adaptability project of the International Biological Programme (HA-IBP) is but one of seven sections of the programme, which has as its overall theme ‘the biological basis of productivity and human welfare’. The peculiar emphasis of HA-IBP is upon Homo sapiens. Under this project a daring inter-disciplinary attempt has been made to explore interactions between man and his natural environment on a world-wide scale. Publication of the resulting data has proceeded in both ‘horizontal’ and ‘vertical’ directions; thus, ‘horizontal’ reports have covered varied aspects of adaptability in a single type of habitat such as the circumpolar territories, while ‘vertical’ reports have compared and contrasted smaller bodies of data collected on peoples living in a wide variety of environments–urban and rural, primitive and civilized, with exposure to extremes of heat, cold and high altitude.

The present volume is a ‘vertical’ analysis of data on human physiological work capacity. Among the substantial body of research workers attracted to HA-IBP were an industrious cohort of exercise physiologists – men and women with a particular concern for the measurement of physical activity and the determination of physiological work capacity. Such an expertise has obvious relevance to both the general theme of human ecology and the specific study of the biological basis of productivity. Some of the participants were investigators with a long-standing interest in human anthropology, but quite a proportion were city-dwellers who had not previously ventured far outside the urban environment.