Throughout human history people have occasionally faced the problem of too many mouths to feed, whether in a family, tribe, city or other social group. Then around 300 years ago we started to wonder whether humanity itself might someday number more than the world could feed.

When Thomas Malthus published his theory that population multiplies much faster than the food supply in 1798, humanity had just about reached 1 billion after tens of thousands of years of slow increase. He predicted inevitable famines, but improvements in agriculture increased food supplies and allowed faster population growth.

The following two centuries brought advances in communication that made the burgeoning number of people obvious to just about everyone. By the time Paul Ehrlich published his alarming “The Population Bomb” in 1968, the world hosted 3 billion people and was adding another billion every 14 years.

Ehrlich, a butterfly scientist who grew up in South Jersey (Maplewood), again predicted mass starvation. And once again, advances in agriculture avoided famines and let people multiply faster — adding a billion every 12 years by the turn of the century. Having repeated the failure by Malthus to take into account the human capacity to find technological accommodations to population growth, Ehrlich was easily and widely dismissed.

But in starting to look beyond the challenge of merely feeding everyone to all other needs, Ehrlich was a pioneer who is now having the last laugh.

For example, although we’ve gotten a lot better at producing food and putting it into us, we’re not even close to doing an adequate job of handling what’s left when it comes out of us as human waste. Earth is a cycle of organic material in which new animals and plants repurpose matter that used to be part of others, yet even in advanced nations we consume immense amounts of that material and turn it into pollution that is dumped into the nearest waterway.

Potential shortages already are anticipated in many things, including drinking water, many metals, wood and agricultural land. For 12 metals there currently is no known substitute. Shortages can result from the increasing rarity of a material as demand for it rises and it is used up, or simply because what’s left isn’t as readily available. As Ehrlich said, whatever is “degrading the capacity of the environment to support the population” would eventually be a problem.

Many people think that climate change is the greatest challenge facing mankind at this point. To the extent that it is caused by people, though, it too is just another product of the size of the human population. Greenhouse gases produced by people were inconsequential before there were a billion of them and before their numbers required large amounts of energy produced by fossil fuels. As with the supply of food, the supply of energy will rely on technology to ensure there is enough without reducing the environment’s capacity to support us.

Note that all of these challenges inherent in population at current and greater levels are physical. Since man does not live by bread alone, there are many others related to fulfilling the existential human needs of each individual. Psychologist Erich Fromm suggested these include: relating to others, being free and able to create, feeling rooted and at home in the world, identifying as oneself as well as a part of groups, and being sufficiently oriented to plan where we want to go and how to proceed. On top of these needs are the quality-of-life desires. Much modern strife seems to derive from increasing struggles to satisfy these needs and desires of self-aware, thinking beings.

The non-physical challenges of high population are so complex and resistant to measurement that even speaking meaningfully about them is difficult. A strong case could be made, for example, that since humans are the most capable life form on Earth, billions more of them is a positive that could help the species overcome serious threats. It can be argued just as plausibly that the law of supply and demand also applies to humans, and their super-abundance devalues them as surely as it does starlings, squirrels and dandelions.

We created 7.7 billion of us alive today without much thought for the benefits or consequences. Now we are inescapably tasked with organizing ourselves in the most life-affirming, least destructive way.

Fortunately, I think our still relatively feeble powers of understanding and guiding life will be substantially bolstered — even outweighed — by the large scale forces of life acting through us. It’s already happening.

Worldwide people are having fewer offspring. It already takes a little longer — about 14 years now — to add another billion to the global population and by mid-century it’s expected to take 20 years, according to the U.S. Census Bureau. Some social scientists credit the birthrate decline to better economic circumstances or more urban living where “the bonds of religion and family often get replaced by friends and co-workers,” as two population-decline authors recently put it. But I have trouble imagining potential parents deciding they don’t need children with so much social contact available in the city, or that more family resources are necessarily a reason to have fewer children rather than more. I think most of this reversal of human population growth is taking place outside of our awareness or intention, which suggests that it derives from our instincts.

The same probably goes for our growing aversion to unnecessarily wasteful or destructive habits of many kinds. Long before we determine they are unsustainable, we feel and suspect as much because at bottom we know there are billions of others who might behave likewise.

With so many potential threats to continued human development and even existence posed by our shear numbers, the demands of organizing and operating life on Earth have become nearly the biggest challenge for the species.

Meeting that challenge will require us to succeed at something even more fundamental — blending our growing power to understand and direct our lives into the far older and larger flow of life that produced us and all else on Earth.

Email editorial page editor Kevin Post at or call 609-272-7250.

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