Ehrlich's argument was counterfactual, even when he made it. And it is that very same counterfactual and dire forecast that has informed legislative efforts to set up a bureau of population control and motivated demographers to suggest a one-child policy (a policy that has tragically been forced upon the Chinese population).

But why was Ehrlich wrong? Zubrin explains that,

... every mouth comes with a pair of hands. Well, if that was all there was to it, there'd be a wash—the more people, the less people—it'd be the same amount [of resources] per person. But it's better than that, because you see, every mouth not only comes with a pair of hands, it comes with a brain. And the more people there are, the more inventors there are and inventions are cumulative. And furthermore, the more people there are, the larger the market is therefore the easier it is to find investment to initiate new technologies into action...

Ehrlich, it seems, had understood human beings primarily as consumers—a veritable cancer upon the earth, rather than cultivators—creative, productive, and innately precious. Throughout his lecture and eponymous book, Zubrin explores the tentacles of Ehrlich's misguided predictions and the implications of this anti-humanism.

It is, Zubrin explains, this very anti-humanism that has motivated racist eugenics campaigns in the U.S. and genocidal population-control programs around the world. In quieter ways, this suspicion about humanity also provides the foundation for modern tirades against nuclear power, pesticides, biotech foods, and industrial development.

Ironically, anti-humanistic hype is so far off the mark that it is actually plummeting fertility rates that pose some of the largest social and policy challenges in our day. Jonathan Last delves into the details with his book (and lecture) What to Expect When No One's Expecting.

Census numbers merely outline the results of a million personal decisions—they hardly prescribe or proscribe reproduction. And the rather bizarre and tragic update on Octomom's story suggests that huge families shouldn't be an end in and of themselves.

But every time someone quizzes me on my grandparent's bedroom decisions, I just smile a little and tell them about my grandpa's favorite saying: "There's always room for one more." I happen to think he's right.