Popu Ion Societies

A the end of 2003 the human population crossed a historic, but so far little noticed, threshold: more than 50 per cent of the world’s people now live in a country or a region in which fertility is below 2.1 children per woman, the level conventionally regarded as indicating long-run replacement of the population (see boxes 1 and 2) [1]. A convenient way to illustrate this is to plot a curve that indicates for each level of fertility the percentage of the global population living in places where fertility is below this level (figure 1). In 2003 the curve cuts the 50 per cent line at 2.1 children per woman (green curve). To put it simply, one half of the human population has fertility below replacement level and the other half above. The curves plotted in figure 1 mostly present the fertility level country by country. However, because of their huge size, China and India are treated differently. The two Asian giants make up 21% and 17% of the total world population, and each of their regions is plotted separately. Thus the provinces of China and the states of India are treated as equivalent to nations elsewhere (see box 3) [2]. More than half of the global population lives where fertility is below replacement level