Increased life expectancy may mean lower fertility
8 February 2008
One of the benefits of postindustrial life is that it is largely free of the fear of early mortality. However, a curious side-effect of this confidence seems to be a dramatic reduction in birthrates.
Writing in the latest edition of 'Science', Professor Ruth Mace (UCL Anthropology) draws a clear correlation between increased life expectancy and lower fertility in cities.
Professor Mace attributes this trend to over-investment in our offspring: "Having a larger family maximises reproductive success but goes hand in hand with lower levels of investment per child. In contrast, when the cost of family building is raised, the opposite occurs: More has to be invested in each offspring to enable them to go on to reproduce, and simulations have shown this can lead to a more prosperous society."
Historical and evolutionary demographers are broadly agreed that the cost of raising a child in the city involves enabling it to compete with its peers for marriage, employment and the means to support a family, all of which create a competitive environment that ultimately leads to a reduction in birthrates.
"Education introduced a new mechanism through which children could compete for future employment opportunities. School also adds pressure on parents to present adequately fed and dressed offspring for public scrutiny. Culturally acceptable levels of parental investment then rise," explains Professor Mace.
Ultimately, argues Professor Mace: "These conditions have led to a situation in which 'runaway parental investment' is driving levels of investment in each child higher and higher and thus fertility lower and lower."
To find out more about Professor Mace's research and to read the paper in full, use the links at the top of this article.