First, contemporary China where marriageable women are in short supply:
The Chinese government’s one-child policy, combined with a cultural preference for sons and technologies that permit selective abortion, have helped to create a large sex-ratio imbalance among young Chinese. For every 100 women in that group, there are now more than 120 men.Second, the US in the late 1960s when marriageable men were in short supply:
According to market models, the terms of trade in the Chinese marriage market should have shifted sharply in favor of women. And evidence suggests that young Chinese women and their families have in fact become much more selective in recent years.
They appear, for example, to focus more critically on the earnings potential of prospective mates. Because house size is often assumed to be a reliable signal of wealth, a family can enhance its son’s marriage prospects by spending a larger fraction of its income on housing. (Other families can follow the same strategy, of course, but when all families do so, the resulting homes are still reliable indicators of relative wealth.) Such a shift appears to have occurred.
For example, when Shang-Jin Wei, an economist at Columbia University, and Xiaobo Zhang of the International Food Policy Research Institute examined the size distribution of Chinese homes, they found that families with sons built houses that were significantly larger than those built by families with daughters, even after controlling for family income and other factors. They also generally found that the higher a city’s male-to-female ratio, the bigger the average house size of families that have sons.
In the United States, the end of World War II and the return of millions of troops set off the baby boom. In the second half of the 1940s, the population swelled by almost 14 percent, versus growth of less than half of 1 percent during the first half of the decade. By the mid-1960s, many of those babies were reaching the traditional marriage age.My skeptical nature holds me back from saying "this explains everything". But I do think the above is a significant factor in these sociological changes. We are victims of larger social forces that swirl around us, just as our ancestors on the African plains were subject to the preditor-prey ratios between lions/leopards and humans. Our cultural/mental world is powerful, but not all-powerful. Outside forces still rattle our chain.
At the time, it was American custom for women to marry men several years older than themselves. In a typical wedding in 1969, for example, the bride might have been born in 1947 and the groom in 1943. Because of that custom, women at the leading edge of the baby boom confronted a significant shortfall of potential marriage partners.
Economics teaches us that when there is excess demand for a good, its price rises. According to this model, excess demand for grooms should have caused the terms of courtship to shift in favor of men.
Before the 1960s, cultural norms encouraged celibacy before marriage. The breakdown of those norms has been widely attributed to the introduction of oral contraception, which gave women an unintrusive way to protect themselves against an unwanted pregnancy. The pill no doubt played a role — perhaps a very big one — but skeptics object that effective alternative forms of contraception had long since been available.
The supply-and-demand model bolsters the skeptics’ concerns. Biologists describe a fundamental asymmetry in the sexual strategies favored by males and females in vertebrate species. Males, whose sex cells are cheap to produce, tend to favor more transient sexual relationships, whereas females, for whom pregnancy and birth are far more costly, tend to favor greater commitment. The sexual revolution, which bent cultural norms toward male preferences, may thus be partly explained by the excess demand for grooms in the 1960s.