Human population growth has been a political and social hot potato for centuries -- and that potato just got reheated.

David Attenborough, renowned naturalist and documentary filmmaker, had the cheek to make the following statement: "We are a plague on the Earth. It's coming home to roost over the next 50 years or so," he said in a Radio Times interview.

"It's not just climate change; it's sheer space, places to grow food for this enormous horde," Attenborough said.

"Either we limit our population growth or the natural world will do it for us."

Threatening as this sounds, Attenborough insists it needs to be said. "[I]t's not an inhuman thing to say. It's the case. Until humanity manages to sort itself out and get a coordinated view about the planet it's going to get worse and worse."

Is Attenborough right? Maybe.

A Brief History of Population Growth

There's no denying that the human population has grown exponentially in recent decades. We saw our first billionth human in about 1804, according to The Telegraph. Our second billionth person showed up around 1927, or 123 years later. And we keep having babies -- number 7 billion arrived in 2011.

Warnings about the burgeoning human population go back as far as 1798, when Thomas Malthus published An Essay on the Principle of Population, in which he wrote:

"The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race.

The vices of mankind are active and able ministers of depopulation. ... [B]ut should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world."

Scary stuff indeed, and his observations -- dreadful though they be -- are echoed in Attenborough's more recent statements. Paul Ehrlich, too, in his 1968 bestseller The Population Bomb, make similarly dire warnings:

"The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate."

Yikes!

Keep Calm and Carry On?

It has to be acknowledged, however, the most alarmist positions are usually the first to be proven wrong. Yes, I'm looking at you, Mayan Apocalypse. Y2K. Comet Elenin. Large Hadron Collider ... ad nauseum.

Nothing like the global famine that Malthus and Ehrlich foresaw has happened (at least not yet), and Ehrlich himself admitted that his specific predictions were wrong: "In honesty, the scenarios were way off, especially in their timing (we underestimated the resilience of the world system)."

And such apocalyptic gloom will always prompt a backlash by people who insist that we just keep calm and carry on -- especially given the nature of what The New York Times calls "the bruising politics of reproductive health." Attenborough's comments are no exception: "Sir David is wrong," said Tom Chivers in The Telegraph.

"[B]illion number seven, for the very first time, took longer than the billion before it: back up to 13 years. Billion number eight is expected to take 15 years; billion number nine 19. Our population growth is slowing -– and may in my lifetime come to halt. ... [I]t looks like the world's population explosion is naturally stopping: there seems to be no need to force the issue."

Keep calm and carry on breeding.

The Depths of Human Suffering

But Chivers also noted the havoc our growing population is having right now, and will continue to have: "By all means be concerned about the impact of the human population on our planet: It is huge, and we are pressuring many species into extinction. But we do not, at the moment, seem to be in any danger of doing the same to ourselves."

The human population seem to be, in Chivers' view, the ultimate barometer by which we judge the planet's health. What he fails to understand is 1) we do not exist in isolation from our environment, and 2) simple numbers do not reveal the depths of human suffering caused by poverty, war, disease and all the other pains we are inflicting on ourselves right now, either directly or indirectly, as a result of the sheer numbers of human beings who are now struggling to survive on an increasingly crowded planet.

Alarmist? No. It's simply an understanding that no matter how clever or creative or resilient we fancy ourselves to be, we cannot provide a stable quality of living for the people we have right now. Adding another billion or two to the planet will inevitably make things harder and uglier and deadlier for many, many people -- and the other living things on which we depend.