Abstract

Man evolved as a hunter-gatherer, and the invention and spread of agriculture was followed by changes in diet, the environment and population densities which have resulted in globally high prevalences of anaemias due to nutritional deficiencies of iron, folate and (locally) vitamin B12, to infestations by hookworm and schistosomes, to malaria, and to the natural selection for the genes for sickle-cell diseases, beta-thalassaemias, alpha-thalassaemias, glucose-6-phosphate dehydrogenase deficiency, ovalocytosis and possibly (locally) elliptocytosis. The present explosion of population is driving an expansion of agriculture, especially the cultivation of rice, and this has led often to disastrous increases of transmission of malaria, schistosomiasis and other diseases, to widespread chemical pollution, and to degradation of the environment. Anaemia, as the commonest manifestation of human disease, is a frequent consequence. The urgent need for increased food production is matched by the urgent need for assessment and control of the health impact of agricultural development.