176 Superlongevity Without Overpopulation forced by changing tastes resulting from improved education. The revenue vs. expense equation for extra children further shifts toward having fewer offspring as populations become urbanized. Children cost more to raise in cities and can pro- duce less income than in the country. Fertility  declines  for  another  reason:  As  poorer  countries become wealthier, child mortality falls as a result of improved nutrition, sanitation, and health care. Reduced child mortal- ity in modern times can come about even without a rise in income. People in poorer countries are not stupid; they adjust their childbearing plans to reflect changing conditions. When child death rates are high, research has shown that families have more children to ensure achieving a given family size. They have more children to make up for deaths, and often have additional children in anticipation of later deaths. Families reduce fertility as they realize that fewer births are needed to reach a desired family size. Given the incentives to have fewer children as wealth grows and urbanization proceeds, reduced mortality leads to families choosing to reduce family size. Economic policy helps shape childbearing incentives. Many of the same people who have decried population growth have supported policies guaranteed to boost childbirths. More than that, they boost childbearing among those least able to raise and educate children well. If we want to encourage people to have more children, we should make it cheaper for them to do so. If we want to discourage fertility, or at least refrain from pushing it up, we should stop subsidizing it. Subsidies include free education (free to the parents, not to the tax-payers), free child health care, and additional welfare payments to women for each child they bear. If parents must personally bear the costs  of  having  children,  rather  than  everyone  else  paying, people will tend to have just the number of children for whom they can assume financial responsibility.