On my desk sits a stack of manila folders. Each one contains an essay that argues, essentially, that all of our problems -- especially the environmental ones -- are caused by one thing: overpopulation. We get a lot of this sort of thing. Most of it comes from a guy named Frosty Wooldridge, who has beaten the population drum for years. But we also get letters from other folks, usually after a story about water or sprawl or immigration, emphatically demanding that we wake up and address the root of all evils: There are just too many people.

In this issue's powerful cover essay, Chuck Bowden finally does it for us. It's only a sentence or two, but it feels like a punch in the gut. Not that you populistas out there should get too excited: We're not about to become the Overpopulated Country News.

On one level, of course, the populistas are correct. An increased number of people will generally increase the strain on the environment. In one of the essays on my desk, Bromwell Ault of the Center for Public Conscience writes: "Population is a process of silent and powerful geometric increase," which entails "that for every added unit of population we lose one acre of land to the various development projects such growth requires." In other words: For every person added to a place, there is a directly proportional impact to the environment.

The appeal of this equation lies in its simplicity. As Wooldridge dramatically writes: "It is possessed of that same beautiful, and sometimes deadly, precision that we find in E=mc2 and a2+b2=c2." Yet that same simplicity is the equation's underlying flaw, for it leaves out the most important variable: consumption. Indeed, a more pertinent equation would be this: The more we consume, the greater the environmental impact.

And, contrary to what some might believe, consumption is not directly proportional to population. An average family of four in Mexico City, for example, lives on a much smaller piece of land and consumes considerably less than a similar family in a McMansion on the exurban fringe of Phoenix, complete with green lawn, three cars, big-screen television and a high-calorie fast-food diet. Each "population unit's" consumption level is determined by its own set of variables -- societal and individual values, culture, land-use regulations, wealth, economic systems, etc.

We will not curtail our consumption by stopping the flow of people from Mexico to the United States. In an age when Colorado shoppers buy apples from New Zealand and a single hamburger patty is amalgamated from cow parts grown and processed in several different countries, it should be obvious that keeping people on one side of a political boundary does not confine their impacts to that side of the line. Not that we've ever been able to keep people on one side of a border -- as Bowden points out, neither a border wall nor a police state can stifle the migratory urge.

It is indeed frightening to watch the national and global population clock race forward. But that is not the only or even the most important issue at hand. More important than how many of us there are is how we choose to live, both as individuals and collectively. And that requires acts of conscience and human innovation and will, none of which can be contained by a simple equation.