In countries where large families are the norm, the urge to conform pushes people to have more children than they can economically support. And an effort to "keep up with the Joneses" leads people to consume ever more natural resources, a new economic model suggests.
Though neither idea on its own is new, combined they suggest the poorest nations are caught in downward spiral that will deplete resources and cause a population explosion, said co-researcher Partha Dasgupta, an economist at the University of Cambridge in the United Kingdom, who helped to develop the economic model. Technological changes and booming urban growth are unlikely to correct these trends, the model suggests.
However, the model and related study, detailed today (April 18) in the journal Science, do point to a way out of the cycle: Educating women in poorer countries can lead them to choose smaller families. [ Crowded Planet: 7 (Billion) Population Milestones ]
And not all scientists agree that population growth necessarily means environmental ruin, with one scientist saying that people will develop innovations so that overpopulation doesn't tax natural resources in an overwhelming way.
Conformity and consumption
Since Thomas Malthus wrote of exponential population growth in the 1800s, researchers have warned of a coming era of overpopulation and scarcity.
Paul Ehrlich, who co-authored the new study, warned that mass starvation and misery would come with overpopulation in "The Population Bomb" (Sierra Club/Ballantine Books, 1968).
The doomsday scenarios have yet to materialize. Still, with the world population slated to hit 9 billion by the year 2050, many scientists and others worry that unchecked population growth and increasing consumption of natural resources will cause dire problems in the future.
To see whether population growth and consumption would, in essence, self-correct naturally, the researchers looked at existing population trends in several developing regions, focusing on Sub-Saharan Africa, where the average woman has more than five children, and the average annual income is the equivalent of $1,200.
Several factors make large households the norm in this region, the researchers argue. The common practice of fostering children, communal land ownership and polygamy make it beneficial to men to have more children than they could support on their own. In addition, women's lack of education and lack of access to contraception fuel large families.
Conformity and social pressure also play roles.
Even as the economic pressures of urbanization favor smaller families, people's desire to conform to their neighbors' large families will keep family size up, the scientists argue. The natural desire to compete with neighbors pushes people to consume more resources.
As a result, poor nations may be headed toward scarcity that leads to mass migration from depleted villages, as well as other problems.
"These are not self-correcting phenomena," Dasgupta told LiveScience.
One way to combat the trend is to increase women's access to education and communication with the wider world.
People will always want to conform, "but as communication becomes cheaper, roads get built, TV comes, [then] your peer group — the ones you observe and want to emulate — expands," Dasgupta said.
For instance, family size in India dipped state-by-state after cable TV was introduced in each region, probably because TV shows depicted more modern outlooks on women and family, Dasgupta said.
Several other studies have shown that increasing women's education and access to contraception reduces family size, because educated women are likelier to buck societal pressure and choose smaller families, the study noted.
The idea that conformity could amplify the population growth is interesting, said John DeLong, a population ecologist at the University of Nebraska, who was not involved in the study.
But not everyone thinks population growth is a huge problem.
Very few demographers think the population could surge to 15 billion to 17 billion, as the authors suggest, said Elizabeth Hartmann, the director of the Population and Development Program at Hampshire College in Massachusetts.
In addition, some studies of Sub-Saharan Africa predict that population growth may not dramatically tax natural resources as people innovate more efficient methods of farming or provide more labor for conservation efforts, Hartmann told LiveScience.
The population scare ignores the complex reasons why birthrates are high there, she said.
"They're really diverting attention from the social and economic inequalities that cause both high birthrates and human suffering," Hartmann told LiveScience. "We're going to have those people in the population, so we need to plan for the addition of these people in environmentally sustainable and socially just and sustainable ways rather than just saying 'oh my god they're coming!'"
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