Robert VerBruggen of RealClearPolicy points us to a new paper by Jason Collins of the University of Western Australia and Oliver Richards of the Australian Treasury which argues that “the recent rise in the fertility rate in developed countries is the beginning of a broad-based increase in fertility towards above-replacement levels.” Robert writes:
We usually assume that evolution happens at a glacial pace, but it doesn’t always. Certainly, the slow rate of genetic mutation limits the speed at which a species can add entirely new features, but evolution can act quickly when it has existing variation to work with. For example, some wolves are tamer than others; if you breed the tamest wolves together for a few generations, they become noticeably more like dogs. Even in the natural world, a sudden shock to the environment can create incredibly rapid changes.
The various technological and cultural shocks that have reduced fertility levels have changed the playing field:
As the new paper demonstrates, there’s a significant correlation between the fertility of parents and that of their children, and much of this correlation is likely attributable to genetics. Depending on numerous variables, evolution might increase the fertility rate significantly in as little as two generations. And we shouldn’t ignore culture — like genes, it can influence fertility and is transmitted to some degree from parent to child.
In 2006, Phil Longman predicted that the coming decades would see ”the return of patriarchy” in the affluent market democracies:
A single child replaces one of his or her parents, but not both. Nor do single-child families contribute much to future population. The 17.4 percent of baby boomer women who had only one child account for a mere 7.8 percent of children born in the next generation. By contrast, nearly a quarter of the children of baby boomers descend from the mere 11 percent of baby boomer women who had four or more children. These circumstances are leading to the emergence of a new society whose members will disproportionately be descended from parents who rejected the social tendencies that once made childlessness and small families the norm. These values include an adherence to traditional, patriarchal religion, and a strong identification with one’s own folk or nation.
The obvious counterargument is that children born to fecund culturally conservative families might defect from the patriarchal way of life as they age. But this doesn’t rule out the possibility that these children will nevertheless have larger-than-average families.