Lorenzo Warby touches on some of the social and demographic issues that David Friedman discussed the other day:
US Birth Rates from 1909-2008. The number of births per thousand people in the United States. The red segment is known as the Baby Boomer period. The drop in 1970 is due to excluding births to non-residents.
Graph by Saiarcot895 via Wikimedia Commons
Cities are demographic sinks. That is, cities have higher death rates than fertility rates.
For much of human history, cities have been unhealthy places to live. This is no longer true: cities have higher average life expectancies than rural areas. But they are still demographic sinks, for cities collapse fertility rates.
The problem is not that more women have no children, or only one child, making it to adulthood. Such women have always existed, though their share of the population has gone up across recent decades.
The key problem is the collapse in the demographic “tail” of large families. Cities are profoundly antipathetic to large families, and have always been so. This is particularly true of apartment cities — suburbs are somewhat more amenable to large families, though not enough to make up for the urbanisation effect.
While modern cities do not have slaves and household servants who were blocked from reproducing as ancient cities did, various aspects of modern technology have fertility-suppressing effects. Cars that presume a maximum of three children, for instance. An effect that is worsened by compulsory baby car-seats. Or ticketing and accommodation that presumes two children or less. There is also the deep problems of modern online dating. Plus the effects that endocrine disrupters and falling testosterone may be having.
These effects also extend to rural populations: falling fertility in rural populations is far more of a mystery than falling fertility in urban populations. How much declining metabolic health plays in all this is unclear. Indeed, futurist Samo Burja is correct, we do not really understand the “social technology” of human breeding.
Be that as it may, cities as demographic sinks is a continuation of patterns that go back to the first cities.
Matters at the margin
There are factors at the margin known to make a difference. Religious folk breed more than secular folk, though that is in part because rural people are more religious and city folk more secular.
Educating women reduces fertility. This is, in part, an urbanisation effect, as more education is available in cities. It is also an opportunity cost effect — there is more to do in cities, both paid and unpaid.
Education increases the general opportunity cost of motherhood, by expanding women’s opportunities. This also makes moving to cities more attractive. Women having more career opportunities reduces the relative attractiveness of men as marriage partners, reducing the marriage rate.
Strong cultural barriers against children outside marriage can reduce the fertility rate, by largely restricting motherhood to married women. This makes the fertility rate more dependant on the marriage rate.
Educating women makes children more expensive, as educated mothers have educated children. Part of the patterns that economist Gary Becker analysed.
