There is an abundance of material dealing with agricultural practices in the tropics, in particular those described as involving 'shifting cultivation', and Spencer (1966) has recently covered the Southeast Asian literature. However research is only now beginning to emerge from that intellectual cul-de-sac in which attention has been focussed almost exclusively on crop and fallow cycles and interpretations have been influenced by assumptions about their essential immutability and relative inefficiency in the use of land and labour. As long ago as the 1930s and 19^0s anthropologists associated with the Rhodes-Livingstone Institute sought to abstract the sets of interconnections that exist between social relationships, ecological relationships, modes of belief, etc., while officers of the Northern Rhodesia Department of Agriculture attempted to evaluate the nature and effectiveness the same people's adjustment to their environment through their agricultural practices.