"It's a boy!" screamed the headlines celebrating the birth of China's 1.3 billionth person on 6 January this year. While China's latest star made the news, elsewhere that day, as on any other, 200,000 new arrivals went unnoticed by all but their joyful families. The population clock never stops ticking--there are already 6.4 billion of us and the latest estimates predict around 9.3 billion by 2050. Yet back in 1900, world population was just 1.6 billion. So what has driven this period of startling growth?
"In many ways, the 20th century was the century of population--it saw an extraordinary expansion in numbers," says Carl Haub, a demographer at the US Population Reference Bureau. "The simple reason for this was the widespread improvement in conditions--life expectancy increased while, particularly in the developing world, birth rates remained high."
Haub is describing the start of the 'demographic transition'. This theoretical model proposes that all countries begin with high birth and death rates--so populations remain stable--but as a result of economic and social development, they end up with both low birth and low death rates, again leading to stable populations. In reality, however, while such patterns do exist, the process is complex, and there are very few places where stability has yet been achieved.
Before this transition began, Europe's agrarian economy meant large numbers of children were preferred, as they provided a workforce for family-run farms. As Thomas Buettner of the UN Population Division explains, the lack of healthcare and poor sanitation meant that "mortality rates were out of control"--so despite high birth rates, population grew very slowly. But the scientific breakthroughs of the Enlightenment of the late 18th century, as well as the economic progress of the Industrial Revolution, transformed society and changed the face of the world.
Urbanisation was a key part of this transformation. "If you go back 250 years, some European towns existed, but they were extremely unhealthy places where there were more deaths than births," says Tim Dyson of the London School of Economics. "Towns at this stage of development are known as demographic sinks--they consume people. But as conditions improve, death rates fall and urban populations begin to grow."
Dyson estimates that in this pre-transitional phase, just ten per cent of people lived in towns; he now puts the proportion at 70-80 per cent. Urbanisation had positive economic benefits--not least the concentration of consumers that facilitated the rise of modern capitalist societies.
Crucially, population growth was relatively slow in Europe--it took from 1650 to 1950 for Europe's population to expand from roughly 100 million to around 400 million, by which time population growth was slowing down. …