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Total fertility rate

SALT LAKE CITY — "Jon & Kate Plus 8" and "19 Kids and Counting," two reality television shows on the TLC network, played a part in catalyzing James Lee's descent into the darkest abyss of mental illness.

Promised voyeuristic entry into the hustle-and-bustle routines of inordinately large families desperately seeking to mobilize handfuls of often-uncooperative young children, millions of viewers faithfully flocked to "John & Kate" and "19 Kids." The phenomenal popularity tortured Lee's psyche because from his mindset he perceived the shows as glorifying large families in an already overpopulated world.

After years of his haranguing TLC and its parent network Discovery Channel — including a 2008 protest outside Discovery Channel's Maryland headquarters that ended with his arrest after he initiated a public disturbance by throwing large amounts of cash into the air — Lee recently reached his breaking point and returned to the Discovery Channel offices one last time. With a loaded gun in hand and explosives strapped across his body, he stormed the building and took three hostages. Following four hours of tense negotiations with law enforcement, a police sniper shot and killed Lee without injuring his captives.

If innocuous television programming drove Lee to terroristic behavior, then he clearly suffered from some form of mental illness. However, Lee's professed belief that the world is overpopulated and as a result on the brink of ecological disaster is a familiar refrain among academics dating back at least as far as 1798 and Thomas Malthus's seminal "An Essay on the Principle of Population."

And therein lies an issue for debate — with 6.9 billion humans already calling earth home, are there too many people or can the third rock from the sun still sustain more population growth?

Two camps of thinkers generally exist on the topic, neither of which will ever agree with the other. Joel Kotkin, an expert on urban development and author of "The Next Hundred Million: America in 2050," is representative of the optimists who view population growth as a potential springboard to greater societal achievement. Contrary to Kotkin, Stanford professor Paul Ehrlich believes that humanity long ago blew past an appropriate threshold of global population — a decidedly Malthusian viewpoint that's especially popular within academia and among scientists.

One of Kotkin's favorite metrics for forecasting a nation's future economic viability is fertility rate, measured in terms of live births per adult woman. Replacement-rate fertility is 2.1 births per female, the level at which a country can maintain its current population before factoring in immigration. Kotkin believes that a low fertility rate such as Japan's 1.2 births per woman is troubling because there inevitably will come a time when too few young adults exist to replace retirees in the workforce. The flip side to that coin, though, is how high fertility rates like Afghanistan's 5.5 will prove to be immensely problematic until the country has the framework in place to sustain such intense growth.

"More and more I've become convinced that there's just something missing from societies with low numbers of children in them," Kotkin said. "If you go to a city and you hardly see any kids you begin to wonder, 'What is the very nature of that society?'

"And I think the opposite side of it is that you don't want everybody in India having 12 kids. You want some sort of a golden-mean solution, which is a sustainable population."

The fertility rate in the U.S. is holding steady at 2.06, slightly below replacement level. But because of immigration, the U.S. Census Bureau projects that the country's current population of 310 million will surpass 400 million by 2040. Kotkin believes that, thanks to its abundance of land and natural resources, America will parlay that population growth into a new golden era.

"I think the world of the mid-21st century will have three dominant countries: India, China and the United States," Kotkin said. "Be that as it may, India is so impossibly poorer than the United States. … The United States is just blessed with more space and more fertile land and more fresh water. These are all very positive things."

Kotkin loathes the brand of environmentalism that encourages lower birth rates to lessen the detrimental impact of human existence to earth's ecology because of the long-term consequences of falling fertility rates.

"The current green movement, which pretty much dominates politics right now (believes) that if we actually had fewer people we'd be much better off, that if people stopped having kids we'd be much better off," Kotkin said. "The problem with that is, just as overpopulation can be a danger, having a skewed population of many more elderly than young is a problem because of the issue of sustainability. …

"Environmentalists are considered progressives, but actually they're some of the biggest reactionaries out there in that they have very little confidence in the ability of human beings to adjust or adapt. And so they tend to do these straight-line projections. They don't understand that we could use resources better, we could find substitutes for some of these resources, and we might find a whole bunch of new resources. This idea just does not occur to them."

Unlike Kotkin, Ehrlich believes less is always better when it comes to the number of people on earth. For more than 40 years he has advocated the social benefits of performing vasectomies on as many males as possible, and he frequently references having had a vasectomy after the birth of his first and only child.

"The media don't talk about it, but every person you add to the population disproportionately adds more (carbon dioxide) to the atmosphere," Ehrlich said. "That's not really a surprise; we've known for more than a century that it was likely, and for at least 30 or 40 years that it was happening. …

"What your optimal population size for the moment is depends on a lot of assumptions, but I would say (it's) 1.5 to 2 billion, which is about the number of people there were when I was born (in 1932)."

This year Ehrlich coauthored "Humanity on a Tightrope," his 32nd book. But his fame in academic circles dates back to 1968 when he penned "The Population Bomb," in which he predicted rampant starvation in the 1970s and 1980s if the global population continued spiraling upward undeterred. The tome remains one of the most enduringly polarizing books of its era, skewered by Intercollegiate Review as one of "The 50 Worst Books of the Century."

Even though the dire forecasts of "The Population Bomb" never came to fruition, Ehrlich remains defiantly unapologetic.

"I have total support from the scientific community (and) I've had total support from Stanford University," Ehrlich said. "The fact is that a bunch of innumerate morons like vilifying me (and) it gives them pleasure, I'm glad for them to have the pleasure.

"Scientists live by their reputation with their peers and with really smart people, and my peers have been totally supportive. I've got every gong the scientific community can deliver and I have basically nothing but friends, so it doesn't bother me even slightly."

He isn't losing any sleep, either, over the implied rejection of his work by people like Kotkin or David Brooks, the New York Times columnist who wrote an op-ed piece generously praising "The Next Hundred Million."

"Neither Kotkin nor Brooks has the first clue about how the world works," Ehrlich said recently. "They're very smart and totally ignorant, and any scientist can tell them that."