We’re a gloomy lot, with many of us insisting that there’s nothing we can do personally about global warming, or that the human race is over-running the planet like a plague.

But according to leading ecologists speaking this week in Albuquerque at the annual meeting of the Ecological Society of America, few of us realise that the main cause of the current environmental crisis is human nature.

More specifically, all we’re doing is what all other creatures have ever done to survive, expanding into whatever territory is available and using up whatever resources are available, just like a bacterial culture growing in a Petri dish till all the nutrients are used up. What happens then, of course, is that the bugs then die in a sea of their own waste.

One speaker in Albuquerque, epidemiologist Warren Hern of the University of Colorado at Boulder, even likened the expansion of human cities to the growth and spread of cancer, predicting “death” of the Earth in about 2025. He points out that like the accelerated growth of a cancer, the human population has quadrupled in the past 100 years, and at this rate will reach a size in 2025 that leads to global collapse and catastrophe.

But there’s worse. Not only are we simply doing what all creatures do: we’re doing it better. In recent times we’re doing it even faster because of changes in society that encourage and celebrate conspicuous and excessive consumption.

“Biologists have shown that it’s a natural tendency of living creatures to fill up all available habitat and use up all available resources,” says William Rees of the University of British Columbia in Vancouver, Canada. “That’s what underlies Darwinian evolution, and species that do it best are the ones that survive, but we do it better than any other species,” he told me prior to the conference. Spreading humans

Although we like to think of ourselves as civilised thinkers, we’re subconsciously still driven by an impulse for survival, domination and expansion. This is an impulse which now finds expression in the idea that inexorable economic growth is the answer to everything, and, given time, will redress all the world’s existing inequalities.

The problem with that, according to Rees and Hern, is that it fails to recognise that the physical resources to fuel this growth are finite. “We’re still driven by growing and expanding, so we will use up all the oil, we will use up all the coal, and we will keep going till we fill the Petri dish and pollute ourselves out of existence,” he says.

But there’s another, more recent factor that’s making things even worse, and it’s an invention of human culture rather than an evolved trait. According to Rees, the change took place after the second world war in the US, when factories previously producing weapons lay idle, and soldiers were returning with no jobs to go to.

American economists and the government of the day decided to revive economic activity by creating a culture in which people were encouraged to accumulate and show off material wealth, to the point where it defined their status in society and their self-image.

Rees quotes economist Victor Lebow as saying in 1955: “Our enormously productive economy demands that we make consumption our way of life, that we convert the buying and use of goods into rituals, that we seek our spiritual satisfaction and our ego satisfaction in consumption. We need things consumed, burned up, worn out, replaced and discarded at an ever-increasing rate”.