Will Malthus Be Right?

By Niles Eldredge

Malthus was right. So read a car bumper sticker on a busy New Jersey highway the other day, and it got me thinking about the Rev. Thomas Malthus, the English political economist who gave the "dismal science" its nickname. His "Essay on the Principle of Population," published in 1798, predicted a gloomy future for humanity: our population would grow until it reached the limits of our food supply, ensuring that poverty and famine would persistently rear their ugly faces to the world.

The most casual cruise on the Internet shows how much debate Malthus still stirs today. Basically, the Pollyannas of this world say that Malthus was wrong; the population has continued to grow, economies remain robust--and famines in Biafra and Ethiopia are more aberrations than signs of the future. Cassandras reply that Malthus was right, but techno-fixes have postponed the day of reckoning. There are now 6 billion people on Earth. The Pollyannas say the more the merrier; the Cassandras say that is already twice as many as can be supported in middle-class comfort, and the world is running out of arable land and fresh water. Despite a recent slowdown in the growth rate, the U.N. Population Division expects the world population to reach 9.5 billion by the year 2100.

What's missing from the debate is an understanding of the changing relationship between humanity and nature. For it is how humans fit into the natural world that will settle whether Malthus was right or wrong. He was wrong in 1798. But if he had been writing 10,000 years earlier, before agriculture, he would have been right. And were his book being published today, on the brink of the third millennium, he would be more right than wrong. Let me explain.

Malthus cared about only one species: ours. And, ecologically speaking, ours is an unusual species. With the invention of agriculture 10,000 years ago, we became the first species in the 3.7 billion-year history of life not to be living as small populations off the natural fat of the land. Taking food production into our own hands, we stepped outside the local ecosystem. All but a few cultivated plants became weeds, and all but a few domesticated herds, pets and game animals became pests and vermin.

In short, we declared open war on the very local ecosystems that had until then been our home. As preagricultural hunter-gatherers, we humans held niches in ecosystems, and those niches, resource-limited as they always were, had indeed kept our numbers down. Estimates vary, but a figure of roughly 6 million people on Earth at the beginning of agriculture is reasonable. By 1798 the population reached 900 million. Agriculture altered how we related to the natural world and, in liberating us from the confines of the local ecosystem, removed the Malthusian lid in one fell swoop.

So, when he wrote 200 years ago, Malthus was wrong. He did not see that nations are not like ecosystems, that people could expand into new regions and, with the burgeoning technology of the Industrial Revolution, become vastly more efficient at producing food and wresting raw materials from Earth.

But something else is going on, and I think Malthus may have sensed it coming. As long ago as 1679, Antoni van Leeuwenhoek (the Dutch inventor of the microscope) speculated that the limit to the human population would be on the order of 13 billion--remarkably close to many current estimates. For our position in the natural world is once again undergoing a sea change. We are not the first nor are we the only species to spread around the globe, but we are the first to do so as an integrated economic entity. Other species maintain tenuous genetic connections, but no direct ecological connections, among their far-flung members. We, in contrast, are exchanging more than $1 trillion of goods and services among ourselves globally every day.

This means that in an economic--if not a political--sense, we have become a single, enormous population. The system in which we are living, extracting our energy and other supplies, is global: the totality of Earth's atmosphere, its waters, its soils and crust, and all its living things. This is the sum total of all the world's local ecosystems--ecosystems we have allowed to decay as we have chosen (quite successfully!) to live outside them.

We have converted woodlands and prairies to farmland virtually all over the globe. Our cities, suburbs and malls have paved over natural communities, and pollution and overfishing are rapidly destroying our rivers, lakes and oceans. As these ecosystems go down, we are losing perhaps 30,000 species of animals and plants a year, out of perhaps 10 million total species, even though we still deeply rely on at least 40,000 species for food, shelter, clothing and fuel. We rely on natural products to replenish genetic diversity in our crops and to produce new medicines. We rely on pristine ecosystems to replenish oxygen, regulate water cycles, control erosion, cycle essential nutrients and restock critical fisheries. We still need these things to sustain life--our life. The irony is that our rampant success in living outside the world's ecosystems has put them all, and thus ourselves, in jeopardy.

The tide is running back toward Malthus. We are emerging from a 10,000-year vacation from nature still not fully realizing that our own survival hinges on reducing the damage we do to Earth's natural systems. We may not drive ourselves to the complete oblivion of biological extinction, but I fear that the Malthusian specters of famine, warfare and disease will rise in the comparatively short run (the next few centuries), coupled with an accelerating loss of human cultural diversity and, ultimately, quality of life.

Unless. We can, I think, find the inner will to wake up to our current situation, to see the grimmer outlook around the corner and to choose to do something about it. We can stabilize our numbers and temper our patterns of consumption. We can work to stem the tide of ecosystem destruction and species loss. We can, in short, see ourselves for what we have become: the first global economic entity, a fascinating state arrived at through no end of cleverness but a state that is ultimately limited by the health and productivity of the natural system in which we live. We can, if we choose to do so, prove Malthus' direst prognostications wrong.

Niles Eldredge is a paleontologist at the American Museum of Natural History. His book The Triumph of Evolution is due out early next year