Nutritional ecology of pastoralists in dry tropical Africa.

African pastoralists inhabit a variety of environments within tropical arid to semiarid regions. Ecological and cultural factors as well as economic opportunities and constraints influence the amounts and types of foods available. The preferred staple of all pastoral populations is milk from livestock. Pastoral diets are low in energy, but apparently adequate in protein. Growth in children is slow until late adolescence when height approaches the 50th percentile of reference data. Adult pastoralists are correspondingly tall and lean. Maintenance of high human numbers within the economy is a common strategy among a variety of pastoralists. The result is that pastoralists appear to be near the lower threshold of reasonable nutritional status at most times. This occurs despite marked variation in such elements as livestock and human numbers, diet composition, and activity patterns.