Abstract

Of the 3831 breeds or breed varieties of ass, water buffalo, cattle, goat, horse, pig, and sheep believed to exist or to have existed this century, 618 (16%) are estimated to have become extinct. Of the 3213 existing breeds, 475 (15%) are defined as rare. Worldwide, the horse is the species most differentiated into breeds and the water buffalo the least. Breed biodiversity varies markedly between continents, being greatest in Europe and least in South and Central America and Oceania. In the countries of the Old World, numbers of breeds are correlated with human population and with land area, implying that conditions favoring growth in human population also favor diversification of breeds. Peripheral and remot countries have the highest ratios of breeds per million people, implying that remoteness can also promote diversification. Breed extinctions have been most thoroughly documented in Europe and the former U.S.S.R., where the richest countries have lost the highest proportions of their breeds, implying that agricultural development is hostile to breed diversity. Data are particularly lacking from the developing world, and the Global Data Bank for Domestic Livestock of the Food & Agriculture Organization of the United Nations has been set up to collate census and production information.