Story by Christen Brownlee
It’s certainly no secret that our species is skilled at procreating.
By the end of October this year, humans will hit a major milestone: An estimated 7 billion of us will occupy the planet. By 2100, the total will probably reach more than 10 billion, according to UN demographers.
The latest population projections came as a bit of a surprise, says Amy Tsui, PhD, MA, director of the Bill and Melinda Gates Institute of Population and Reproductive Health. Until May of this year, projections had estimated that the population would level off at around 9 billion in 2050. While previous models incorporated a trajectory that had birth or fertility rates worldwide following the downward trend begun in the 1970s, explains Tsui, the new estimates show the pace isn’t guaranteed.
“Fertility hasn’t steadily declined in high-fertility countries as much as expected,” she says, especially in sub-Saharan African countries such as Niger and Mali. “It doesn’t take much with fertility for a population to continue to grow.”
That’s because momentum can continue to drive population numbers up, even if the growth rate itself drops. “It’s like compound interest on savings in a bank,” Tsui explains. “Once you have births in a population, those people reach childbearing age and have births themselves.” If momentum picks up, she explains, more births translate into more youth—a group that bears much of the brunt of slow economic development and public health problems.
“The only sustainable population growth in the long term is zero. The question is how we get there.” —Stan Becker
While Niger and most of its sub-Saharan neighbors have started to recognize the value of slowing population growth and are actively implementing measures to do so, that’s not the case everywhere. Ugandan president Yoweri Museveni, whose country has a birth rate of about 6.5 children per woman, is encouraging birth rates to stay high. “He believes that the population should grow because it’s an important market opportunity—the more people you have, the more consumers you have,” Tsui says. “But he ignores the costs in getting there.”
One visible sign of unrestrained growth is immigration tensions, says Duff Gillespie, PhD, a professor in Population, Family and Reproductive Health (PFRH). Most of the rampant growth is occurring in Southern Hemisphere countries that can ill afford it, where economic and educational opportunities are slim and poverty is harming health. Many of those disenfranchised people are now seeking opportunity in wealthy Northern Hemisphere countries, much to the chagrin of some people there.
“It is definitely going to be a challenge to get the socioeconomic development in the South that the North has enjoyed for some time, and to do it as quickly as possible,” Gillespie says.
The easiest way to prevent population growth from causing severe problems is to put a stop to it, says Stan Becker, PhD, a PFRH professor. “The only sustainable population growth in the long term is zero,” he notes. “The question is how we get there.”
One proven solution is improving education, especially for girls and women, explains Becker. Education typically leads to later marriage and viable careers, giving women options other than being housewives and mothers. That’s been the case in the BRIC countries—Brazil, Russia, India and China—which have all experienced unprecedented economic growth in the last few decades, as well as lower birth rates.
Another obvious solution is providing access to contraception, he adds.
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