Because most philosophies that frown on reproduction don't survive.

Saturday, September 03, 2005

Marriage Demographics & Fertility

It's been a really busy couple weeks at work, but I ran across an interesting article and some stats I'd like to take a closer look at:

I found this brief essay on historical demography on the MIT website. It's interesting in that it both dispels some common myths about how pre-birth control societies worked at a demographics level, and also gives us some insight into NFP, natural law, and fertility.

Since Malthus wrote about the dangers of population growth back in 1798, it's been one of the standard enlightenment myths that back in the "bad old days" people bred like rabbits until there wasn't enough food to go around and then were cut back by plagues and famines. (They also, if 1980s movies can be believed, never took baths...) The only other alternative, Malthus imagined, would be to encourage the lower classes not to breed, or else practice infanticide.

However, as the MIT essay discusses, when people went back and starting doing studies of parish registries from medieval and renaissance Europe, it became clear that this was by no means the case. Instead, what we find is that people based their decision to marry upon economic circumstances.

This should hardly be surprising, given that people living before 1800 were generally no dumber than people born afterwards, and before the advent of artificial birth control, people understood very clearly the connection between sex and childbirth.

Thus, in western European societies where the oldest son inherited, oldest sons were much more likely to marry than younger sons. And people married later or earlier based upon their ability to support a family. During much of European history men married at 26-29 and women at 23-25, while 20-30% of the adult population never married. (Among the more affluent class, women tended to marry much earlier, though men still often did not marry till their late 20s or even early thirties.)

In the period leading up to the industrial revolution (throughout the 1700s and early 1800s) marriage ages began to fall until men were often marrying in their early twenties and women were marrying in their late teens. Much of this was a result of the rapidly increasing productivity and relative prosperity resulting from the agricultural innovations of the 1700s.

Settlers in the Americas tended to marry even earlier, and the percentage of the population that married was much higher, perhaps to a great extent because there were more available resources for an able bodied young family to go out and support themselves.

Moving into the 20th century, the trend of more and more of the population marrying (and doing so younger and younger) increased up until the 1960s, when the percentage of never married adults began to increase again.

This table shows the number of never married adults as a percentage of the total adult population from 1900 through 2003. The percentage of never married adults declines dramatically from 40% in 1900 to 23% in 1960. Some of this is the result of declining age at first marriage. Age at first marriage declined from 26 to 23 for men and 22 to 20 for women between 1900 and 1960. The effect of this downward trend in marriage age would have been exaggerated by the fact that the average lifespan in 1900 was shorter than in 1960, and so a greater percentage of adults were under 25 in 1900 than in 1960. However, this can't account for all of the change. Significantly more people either married very late or did not marry at all in 1900.

While some of this may have been by personal preference, it seems likely that most of the difference was the result of adults deciding that they could not afford to have a family.

Since 1960 the percentage of never married adults has risen back up to about 30%. This is a result of both a rising age at first marriage (now 27 for men and 25 for women) and more people never marrying. However, the choice never to marry is now often a lifestyle rather than an economic choice, and the rate of sexual activity among the unmarried and never married has skyrocketed since 1960.

On the one hand, it seems very much a good thing that modern economic circumstances have made marriage possible for nearly anyone who wants to marry and can find a suitable partner. On the down side, the advent of artificial birth control seems to have increasingly separated the linkage of marriage and childbirth in people's minds. While once upon a time people who could not afford to have children did not get married, it is now quite common to marry first and then decide when it is affordable to have children. Since a two income married family without children provides both the savings of communal living and unprecedented income potential, married childless couples often face a significant economic sacrifice when choosing to have children. Thus, for those not ideologically or emotionally motivated to begin childbearing, childless marriage is increasingly becoming the preferred option.


Daniel Williams said...

I can't access the MIT historical demography essay. could you repost the link?

Darwin said...


Thanks for bringing this to my attention. It took some googling around, but this seems to be a copy of the original PDF:

Daniel Williams said...

Thank you!