Lower birthrates and longer life lead to «population aging» which is most rapid in the developed world. The median age here rose from 28.2 in 1950 to about 35 close to the end of the century. In less developed countries the median age at present is only around 22.

The fear of population aging leads governments to introduce policies which aim at inducing people to have larger families (banning contraception and abortion, offering financial aid for women with babies, etc.)

At the same time many people still fear that global population growth will overwhelm the capacity of economies, and destroy the global ecosystem. Since Thomas Robert Malthus many economists believed that the growing number of people would make land increasingly scarce, and the rising food prices would leave the growing population starve.