Overpopulation is a dirty word.
Politicians talk about climate change and plastic pollution; conservationists preach of mass extinction and deforestation. We decry the erosion of our soils and contamination of our water.
But, heaven forbid, you suggest there are too many people. That’s a cardinal sin: it’s blaming the voter base. It’s questioning our core biological instinct. Life is good; people are even better.
That hasn’t stopped a daring few.
Back in 1798, Thomas Malthus — a cleric and scholar — was the first to preach the dangers of never-ending population growth. Writing in ‘An Essay on the Principle of Population’, Malthus explained that every increase in food production did not lead to increased nutrition, but ever more people. Agriculture was a Ponzi scheme. Eventually, Malthus predicted, humanity would reach the confines of our finite planet: the brick wall of famine and disease.
Yet nothing happened. The centuries passed and growth persisted.
As the 1970s approached, the message of Malthus was preached once more, notably in Paul Ehrlich’s ‘The Population Bomb’. Mass starvation awaited us. Hundreds of millions were to die. But the 1970s came and went.
Like the boy who cried wolf, the peddlers of overpopulation are branded doom-mongers. Critics of overpopulation point to innovations such as the green revolution and mechanised agriculture; they point to declining western birth rates. Some even suggest we should add more people. After all, if innovation is our salvation, then the more people, the more geniuses.
People aren’t the problem: they’re the solution!
Are they right?
What exactly is overpopulation?
Let’s define our terms.
Overpopulation: an increase in the number of people beyond the limits an environment can sustain.
It sounds simple enough. But there’s that little word at the end: sustain. What does sustainability have to do with overpopulation?
Picture a herd of deer living in a big field. There are no predators, so deer only die from disease, starvation and old age. Living amongst an abundance of food, the deer population gradually begins to grow. Slowly, year by year, it creeps up — each year adding more deer than the last.
Theoretically, as food becomes scarcer, the deer population should plateau, reaching an equilibrium with the landscape. But deer don’t just nibble the plants, as food gets scarcer: they eat them whole. By removing the plants from the ecosystem, the deer overeat — the ability of the grassland to sustain them plummets. With far more deer than the field can feed, the only way is down. The population plummets. This is called a bottleneck.
Sustainability, therefore, means having adequate resources to maintain a stable population into the future. However, this applies to a single location. If the deer managed to escape their field in the nick of time, that wouldn’t be sustainable. That is known as spillover.
In the real world, there is no field. Populations rely on entire ecosystems. The number of organisms of a species an ecosystem can sustain is known as the carrying capacity. For humanity, carrying capacity refers to the whole planet: making us the only species in the totality of Earth’s history to rely on the entire planet for our survival. Other species have fields to escape to, greener pastures. Having grown to fill our world, we have no place left to run.
If we, like the deer, damage the sustainability of the environment upon which we depend, our population will reach a bottleneck. Like Wile E. Coyote running off the edge of the cliff, sooner or later, gravity hits.
Except we haven’t fallen.
What happened?
Since humans first swung down from the trees, our ancestors were reliant upon the natural world. We ate what we could find. We kept what we could carry. When the year 8,000 BC rolled around, there were as few as 3 million humans in existence. That’s equal to the population of Athens today.
Having colonised the planet, we were reaching our carrying capacity. That should have been in it — the peak of the human story.
Then something strange happened. In a few scattered locations, groups of humans began planting foods and domesticating animals. Forest was cleared and turned into fields. Where once a panoply of carnivores and towering trees, soaring birds and scurrying mammals lived, now only the cows and nodding heads of wheat remained. We had expanded the carrying capacity of the land and grew our populations past the natural limit, but only through the destruction of everything else. The process early humans set in motion led to the destruction of 83 per cent of all wild mammals and half of all plants. Today, of all mammals on Earth, 96 per cent are livestock and humans.
Our hunting and gathering days were behind us. That door was closed: agriculture was born. The Malthusian trap was sprung, and the only way was up.
Lands ripe with people placed a heavy burden on the soil. Where once animal droppings and dead vegetation fed the earth, now it became barren. When the fertile valleys failed, people grazed the hills, chopping down the trees. The ground sloughed down the slopes; the wind blew soil into dust: civilisation collapsed. It was the same story the world over.
But, like the deer escaping the field, there were always new pastures for civilisation to cultivate. With each turn of the wheel, our crops and animals became more productive. Our technologies and techniques became more efficient. These advances further increased the carrying capacity of the Earth, and to the Malthusian beat, the population continued to rise. Biology demanded it.
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By the time 1800 rolled around, we were starting to hit the limits of traditional agriculture. Once again, we had reached the carrying capacity of our technological paradigm. And once again, we had a solution. But industrialisation and the second agricultural revolution were different. No longer was Man to be constrained by the strength of his shoulders or the thighs of his ox. Through machines, a single person could do the work of dozens, even hundreds. Malthus could never have dreamed of such innovation.
The population soared, passing billion after billion.
By the time man landed on the moon, even the tractor and modern cropping were beginning to see limited returns. Then the third agricultural revolution occurred: the green revolution. It involved the use of high-yielding varieties of wheat and rice, and the liberal use of chemical fertilisers, pesticides, fungicides and more. Where once we’d cleared the forests, now we took a chemical machete to the insects and pests. In the past 27 years, insect populations have seen a more than a 75 per cent drop. Effects on bees and other pollinators already portend disaster. Insects are essential to life on Earth: consuming other pests and providing food for higher organisms. Without them, humanity cannot survive.
But as insect populations fell, humanity boomed. Had the green revolution not occurred, hundreds of millions would have starved: as it was, five billion were born.
And the only way was up.
I can do this all-day
The devastation of animal life is nothing to worry about, according to the critics of overpopulation. They have faith in the power of innovation. We did it before, we’ll do it again, goes the mantra. But ecosystems are much like Jenga. Remove too many pieces, and the whole thing comes crashing down. At present, the tower is swaying.
Eagle-eyed readers will have also noticed a pattern to our innovation. The time between each cycle has been speeding up, and the effects have been increasingly dramatic. It was 9,000 years from the first agricultural revolution to the second, and only a few hundred until the third. Farming innovations that once arose by the century are now needed by the decade. The logic of population growth demands it. We are on a treadmill, and the speed is rising.
Once a simple tweak of the plough transformed agriculture. Today, such innovation wouldn’t make a dent. If we are to grow enough food for the predicted 11 billion or more, the modernisations of the green revolution won’t suffice either. We will need more.
But there is a broader question here. Is there a limit? Can we continue to get more and more from a single piece of land? After all, only so much sunlight hits the soil. Plants will only grow so quick. In a finite world, is it possible to increase production to infinity?
Furthermore, the past forty years have seen a third of arable land succumb to erosion and pollution. So, we’ll have to do more with less.
Take it to the limit
Think about everything you need in your daily life: phones, computers, cars, food, water, pencils and pens, tins for storing food, ovens and kettles, knives and forks. As civilisation has gone on, we’ve refined our tastes.
As Mark Twain put it:
‘Civilisation is the limitless multiplication of unnecessary necessities.’
No longer is a wooden bowl of stew enough. But this multiplication of necessities means we’re no longer only reliant on food for our carrying capacity. Unlike deer in the field, we need fossil fuels and copper wiring, nitrogen and phosphorus for fertilisers, and much more. The equation of human existence is a complicated business.
It’s also interdependent.
If we run out of fuel, copper, iron, cobalt, phosphorus or any one of the thousands of ingredients upon which we rely, industrial agriculture will grind to a halt. Like a chemical reaction, civilisation can be stalled by a single component: a limiting factor. Time will tell which runs out first.
Supersize earth
Consuming all these resources is an endless job. However, the burden isn’t spread evenly. Historically, kings and queens, emperors and dukes, were the beneficiaries of Man’s labouring in the fields. Banquets and monuments were erected in their honour. These lucky few were a rare breed. Today the differential is even more astonishing: split broadly between the West and the rest.
In different countries and social circumstances, people require radically different amounts of stuff to survive. Surviving without the internet in the West is increasingly impossible. For a farmer in Equatorial Guinea, the internet is next to useless (although smartphones are becoming more common).
By using the Earth as a measuring stick, we can compare these disparate consumption patterns. For instance, if all seven billion of us lived like the average Indian, humanity would only need the resources of Africa and Asia. Whereas if we adopted the Chinese lifestyle, we’d require a little over on Earth.
Meanwhile, the French live a little more extravagantly, demanding two and a half Earth’s worth of resources. But that’s nothing. If all of us lived the American Dream — muscle cars and hefty steaks — humanity needs to discover four more Earths!
Thus, as our consumption goes up, our resource footprint does too. One person does not equal another. An America is equivalent to four Chinese, 20 Indians or 250 Ethiopians. By increasing consumption globally, we could shrink our population in numbers and still become more overpopulated.
At present, the world’s richest half-billion are responsible for 50 per cent of carbon dioxide emissions. And the rest want a piece of the pie.
We’re acting like the deer in the field. In banking terms, it’s the difference between income and capital. Income is the Earth’s annual production. It is sustainability (although, at present, it still means environmental devastation). Capital is the savings in the bank. It is topsoil, mineral wealth, biodiversity, water aquifers, rainforests, and more. Like the wealthy socialite who inherits his father’s estate, we’re blowing the lot.
We’re spending tomorrow.
We’re eating the future.
It’s a long way down
After ten millennia of up and up and up, we’re faced with the dizzying prospect of down. There is some hope. Birth rates across the world are declining. Population growth is fizzling out. Forecasts by the UN predict that the population will level off at over 11 billion by 2100.
Yet during that time, consumption is hoped to skyrocket. Africa will see four billion people. The climate will warm. Production of significant resources will decline.
In his seminal lecture ‘Arithmetic, Population and Energy’, Professor Albert Bartlett dispassionately presented a table of population growth. In column one was everything that ‘made the population problem worse’. It included procreation, medicine, sanitation, scientific agriculture, and law and order. In the second column, was everything that decreases the population: abstention, contraception and abortion. But also, the four horsemen of disease, war, famine and pollution
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