Viewpoint on Food and Population

On January 24, 2004, Mark submitted a letter to Mother Earth News about population and construction, two topics he’d read about recently in that publication. An editor there quickly informed him that his letter would be published and then invited him to write an outline for a Viewpoint piece about the issue of food supply and fertility. Mark happily took the magazine up on this opportunity, and soon afterward his outline was approved. He was provided a contract and, upon submission, was paid a $100 honorarium for his views, which came in at six words shy of the imposed 1,500 word count. The magazine never published the piece. It appears here in its entirety.

According to Kermit the Frog, it’s not easy being green. Indeed, individuals and societies certainly seem to have difficulty acting in ways that are ecologically appropriate and sustainable. But the difficulty almost always lies not in the actions themselves so much as our ways of thinking. Ideas color our world, and some ideas box in the options we allow ourselves to consider. One way to expand that box is to learn how the world actually works. The more we understand nature’s principles, the more we see how humans are not separate from nature but part of it, and how it can be effortless to harmonize with our neighbors in the community of life instead of hurting them.

While the ecologically minded tend to promote this kind of thinking, we’re not immune to its implications. Even many green thinkers remain oblivious to certain key natural principles. The price of this unawareness is a cap on their potential to generate positive change. To remove that cap, we must remove the misunderstandings. The natural principle that is perhaps most misunderstood, by green and ungreen alike, and to the most dangerous global effect, is one of the fundamental tenets of ecology: the relationship between food and population size.

Green thinkers tend to be good at explaining how human population growth fuels environmental and social problems. Yet far too often, population growth is thought to be an independent variable, a given that we can do nothing but respond to. In fact, population growth has its own clearly identifiable — and modifiable — causes. We will respond effectively to population growth only once we understand these causes, and the limiting factor is food availability.

The relationship between food and population was (in)famously discussed by Thomas Malthus in the late 18th Century. Claiming that food production increases arithmetically (i.e., 1, 2, 3, 4, 5) while population increases geometrically (i.e., 1, 2, 4, 8, 16), Malthus concluded that food production can never match population growth, causing misery for many who must go without. Malthus was doubly wrong. Technological advances have allowed humans to beat the arithmetical increase of food production. More importantly, populations cannot grow faster than their food supply.

Charles Darwin developed his theory of biological evolution in part by spinning out the implications of Malthus’ claims. If all offspring of all living things were to survive, populations would, indeed, increase geometrically, and the world would be quickly overrun — but this never happens. Food resources are limited, and individuals compete for them. Those better able to get the resources tend to leave the most offspring. Populations don’t increase geometrically — they evolve while staying relatively stable in size, because limited food availability checks geometric increase. Malthus got the details wrong, but he was right in posing a fundamental relationship between food and population. It took Darwin and the further development of evolutionary theory and ecological science to provide the details and reveal the true food/population relationship — one of the key drivers of the very process of life.

In both observation and theory, ecology confirms that population size is a function of food supply. Most well known, perhaps, is how fur-trapping records from the Hudson’s Bay Company show the population cycles of Canada lynx and its prey, the snowshoe hare. Cycles arise from the basic relationship between predator and prey, i.e., a population and its food. As lynx eat hare, the hare population goes down. At some point, there aren’t enough hare to go around, and the lynx population goes down. With fewer predators, the hare population rebounds. Finally, with more hare available to eat, the lynx population increases, and the cycle becomes poised to repeat. Standard population models confirm this dynamic, a simple negative feedback loop, much like a thermostat that keeps a room’s temperature around a given set point. In ecology, the set point is a population’s carrying capacity — the size at which a population can be indefinitely maintained with cyclic fluctuations.

Carrying capacity is an often misunderstood concept. The stable population level isn’t some inherent constant for each species. It is affected by the availability of food, the presence of competition for food, how a population’s abilities compare to its competitors, and other factors. In other words, carrying capacity is a measure of how large a population can be sustained in a given environment.

The idea of carrying capacity is usually badly misapplied when it comes to humans. Some people attempt to determine “the” carrying capacity for humans, hoping to have a guideline for where we should level off our global population. They mistakenly imagine carrying capacity to be an absolute constant. Others, though, entirely reject carrying capacity and the cyclical population dynamic as inapplicable to humans, because we are able to influence our food supply. This, however, does not exempt us from the laws of ecology. Increasing food production doesn’t allow us to sidestep our carrying capacity — it literally increases it. Indeed, since carrying capacity is so strongly tied to the availability of prey, growing more food means increasing our carrying capacity by definition.

Green thinkers tend to be good at explaining how we can’t increase food production indefinitely. Not only is the Earth finite, but we risk reducing biodiversity to a point where ecosystems collapse, and our food sources along with them. Yet with so many starving people in the world, we often hear about the need to increase food production enough to eliminate hunger. Ideally, this would be done through greater agricultural efficiency — getting more food out of the same area rather than expanding into new farmland. Regardless, such pleas correctly reject Malthus’ ratios, only to undermine themselves by perpetuating his other error. They assume that starving populations grow faster than their food supply, that increasing food production to catch up with their numbers will solve their hunger, and that we can stop increasing food production once all hunger is eliminated. This simply cannot work.

Cultural factors can potentially reduce fertility, but nothing can change the biological reality that food availability sets the maximum fertility rate. No population grows faster than its food supply. The idea that this can happen is a myth. Living things — including humans — can be made only from other living things. Even starving populations, though they have less food per person than well fed populations, only grow if their food supply increases first.

As described by author Daniel Quinn, perhaps the most transformative thinker on the subject, we are in a “food race” in which escalation is just as futile as in an arms race. Every win on the food side is answered by a win on the population side. More food may alleviate hunger for some people in the here and now, but it causes population growth, ensuring the certainty of chronic hunger for that many more people in the future. As population grows, disease and malnutrition worsen. When the ecological limits of global food production are eventually hit, supplies will crash, causing a maximum number of hungry people to suffer even more than they do now, and also endangering countless previously well-supplied people. It’s rather like throwing gasoline on a fire to put it out, imagining that a liquid of low temperature will cool it off but ignoring that gasoline fuels the very flame to be extinguished. In the end, there is simply no way to achieve a stable population by growing more food, just as there is no way to achieve any kind of sustainability through growth.

Many propose cultural modifications — development, education, birth control — as the solution to high fertility. This scenario involves great effort producing ever more food, followed by great effort implementing cultural treatments for the inevitably resulting population growth and related escalations of social and ecological problems — not to mention that the treatments themselves may yield unintended negative consequences. These cultural factors may have a role to play, but relying on only them means falling into the general trap of control-based thinking which ecological movements must counter. Chronic problems despite great ongoing effort indicate that mere symptoms are being addressed rather than root causes. Such an approach denies natural principles and so provides only stopgaps, not solutions.

Align with natural principles, though, and lasting solutions flow, generating positive and healthful results with ease. Once the principles of food and population are acknowledged, it will be no more thinkable for us to participate in the vicious cycle of the food race than it is for us to bother trying to build a perpetual motion machine. Stabilizing — or even reducing — food production may seem daunting and inhumane, but only our lack of understanding makes it seem so. By truly understanding these principles, they’ll become as second nature to us as the fact that the world is round, and we’ll find it effortless to live by them. What’s difficult is denying them. What’s difficult is constantly increasing food production. What’s difficult is dealing with the problems growth causes. What’s easy is not letting these problems happen in the first place — as long as we’re willing to learn how.