Ah, demography. It seems like such a mild-mannered, uncontroversial topic until you start to look at related movements and policies: eugenics, China’s “One-Child” policy, and forced-sterilization in India. Most recently, demographic change made international news when the United Nations declared that, sometime shortly after 2000, half the world’s population would be living in cities. This is a result of both natural births within cities, and urban in-migration. There is some disagreement about the exact year in which humanity passed the 50%-urban mark, partly because of rough statistics, and partly because of disagreements about what ‘urban’ means. Details aside, however, what matters is that there is a significant, ongoing shift of the entire human population towards living in cities.

Two key authors on demography were Warren Thompson and Kingsley Davis. Thompson was an early observer of large-scale demographic changes. Better sanitary urban infrastructure reduced epidemics, and around 1900 the death-rate in cities dropped below the birth-rate for the first time in human history. From 1900-1910, Progressive-Movement activists promoted hygiene, at the same time that the germ theory of disease was formally recognized and validated by Koch’s winning of the Nobel Prize (1905).

In 1929, Thompson recognized that two shifts were going on, especially in industrialized countries. By the ‘teens, death-rates had dropped significantly, especially among children; bringing up the average life-expectancy. Thompson called this the First Demographic Shift. The immediate result was a spike in population growth. But even by the 1920s, families began to realize that most, if not all of their children were now likely to grow to adulthood; and so they started choosing to have fewer children. This was certainly true on both sides of my family in the change between by great-grandparents (six to eight children) and my grandparents, who had two children respectively. Thompson called this drop in birth-rates the Second Demographic Transition. I means that as public hygiene and health regimes get implemented, populations initially spike but then level off after about a generation.

Kingsley Davis’s career began later; he published in the 1950s and 1960s. For us, his most important article is “The urbanization of the human population,” published in the general-interest Scientific American journal in 1965. Davis describes an “extended-S” pattern of urbanization, where the massive shift happens during the moment of industrialization:



Today, we seem to be facing a Third Demographic Transition: rapid decline in population with an associated rise in median age. The good news is that women are becoming more educated worldwide, feeling more entitled, and pursuing more fulfilling lives (with partners or without). Furthermore, children born after 1960 are under far greater financial and temporal stress. The ratio of median income to median living-costs has shifted against younger generations across the world; so birth-rates have now dropped significantly in wealthier countries. In Japan, Spain, and Italy this is already causing macro-economic problems; capitalism was designed for growth, not for stability let alone shrinkage. Environmentalists may be viewing this as good news, but I am unsure about the overall consequences given the number of variables involved.

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