Human Population Through the Looking Glass

I can’t avoid this topic forever, not under the headline Peace with Nature. It is the intractable, controversial matter of the teeming numbers of human beings. How many more of us can the Earth sustain in this Anthropocene?

Only the most pig-headed science denier can dismiss environmental challenges that threaten our future, even our survival. Among the obvious are food insecurity and infectious diseases, soil erosion and desertification, air and water pollution, fossil fuels and global warming, animal and plant extinctions. It’s hard to dwell on them for long because our responses at best are puny against the tide. Besides, pessimism is not an attractive outlook.

Much can be blamed on world overpopulation. We are doubling every 49 years and will soon reach 8 billion. That is ratcheting up the impact of our insatiable appetites for consumption, which are reflected in an obsessive drive to constantly expand economies (as if no ceiling exists).

If everyone consumed resources like a medieval peasant, we would be far behind the curve. Billions of us still live that way, though never by choice. Wealth is not distributed in a bell-shaped curve. Raising prosperity for everyone to, say, an American level is unattainable on this finite planet: for some to be rich, many must stay relatively or absolutely poor. If this present state is manifestly unjust (who can deny it?), would a smaller population shrink the gap in wealth?

Population control is the hottest of hot potatoes. The liberty of choosing to have children and how many is a cherished human right. Woe betide the institution that coerces people into contraception or mandates sterilization.

Sanjay Gandhi tried during the 1975 ‘Emergency’ in India. The son of a prime minister led an aggressive program of shoddy vasectomies and tubal surgeries for mostly poor subjects in exchange for trivial incentives or were forced to comply. People pushed the policy back and his family became a tragic story. An authoritarian government succeeded in curbing growth of the Chinese population by limiting families to one child after 1979, but that policy relaxed too.  A distorted age pyramid had huge socio-economic implications and many girl babies were ‘missing’ before birth. Fortunately, family planning methods are freely accessible in many countries, although not enough. Private decisions in bedrooms have a bigger effect on birth rates than any government diktat or contraceptive.

As a young reader of Silent Spring and The Population Bomb, ecology and population created a frothy amalgam in my head. At that more idealistic age, I believed that the pair together with nuclear weapons made a triumvirate that threatened civilization. I then leaned into a career in reproduction research, hoping to help discover new contraceptive targets. To disable the sperm or egg before fertilization seemed (still seems) preferable to hormones for blocking ovulation or the more elusive goal of knocking out spermatogenesis. I became a Population Council (NY) research fellow, but drifted to profertility technologies, like my mentor Robert Edwards who pioneered fertility treatment with  IVF.

This is no small irony since I still fret about the ‘population problem’, although my original fear of human numbers and hopes for a technological fix were naive.  Family sizes in the West started to shrink at the end of the Victorian period when bumper crops of kids were grown. This shift occurred in tandem with declining infant mortality, revealing that people had the know-how to make reproductive choices before highly efficient contraceptives were developed after WWII. Men have traditionally called the shots at home but as women gained more authority and education, they chose smaller families, or started later, or remained childless. A trend that began in the West continues to spread globally.

The population anxiety of fifty years ago when the UN and grant agencies plowed money into research and fertility services has switched from fear of too many babies to too few for replacing people who die. Some countries, notably Japan, will have half the population by the end of the century, with huge social implications. They now try to hoist birth rates above the replacement threshold of 2.1 by offering incentives like free childcare services, and will welcome more immigration to offset population decline.

And yet the world population continues to climb while other countries catch up with the demographic shift. A recent paper in the Lancet offers a more optimistic forecast than the United Nations’ official projection. Instead of peaking at 10.9 billion by 2100, it reckons there will be only 9.7 billion of us in 2064. This small mercy doesn’t quash concerns about overpopulation, and there are no quick remedies, barring a global catastrophe. But sometime next century I believe new institutions will guide us through a painful and dangerous demographic transition to a much smaller population and more stable than ever in history.

That kind of flourishing worldwide requires peace between people and with nature. A more equitable society rolling over the lottery of being born rich or poor can offer a peace dividend and deliver environmental justice. A smaller population should draw from Earth’s limited bounty more sustainably with a lower impact on the environment. It will avoid impoverishing posterity and generational injustice.

Technology has been called a bane for conservation, but it also helps to live more gently with nature. But it can’t do the heavy lifting of giving 8-10 billion people a fairer share of prosperity. With a smaller population there is more to go round, but how much smaller for everyone to have a generous slice of pie that doesn’t cost the earth?

Ballpark averages of rich versus poor populations (or nominal GDPs per capita) show a 5-to 10-fold difference in wealth. Hence, for sustainability the world population should be no greater than a tenth of the present, about one billion or close to the number alive in the year 1800.

Maybe this speculation is pie in the sky. Optimism is in short supply and we are blind sighted by the narrow window of our own experience. But each successive generation experiences the world differently and sometime in the future people may look back aghast, wondering how their ancestors living in our time managed to muddle through. I think we will, just as people did in pandemics and wars of the past, because humans are experts at surviving and Earth is our only home. Gaia will be relieved when a post-Anthropocene era emerges with human numbers and appetites she can comfortably support.

Next Post: About Nostalgia



About Roger Gosden

British-born scientist specializing in reproduction & embryology. Career as professor & research director spanned from Cambridge to Cornell's Weill Medical College in NYC. Married to Lucinda Veeck Gosden, embryologist for the first successful IVF team in America. Retired early to Williamsburg, Virginia, to write and recover from 'nature deficit disorder'. Currently a visiting scholar at William & Mary.
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