Too many people for too little land," David Attenborough said last week, makes it "barmy" to send food to Africa, before going on to say that he wants to "start a debate about overpopulation". Stephen Emmott, author of overpopulation bestseller Ten Billion, says he wants to start a debate too. What insights does each bring to this debate? Attenborough says, "Humans are a plague." Emmott says, "I think we're fucked." It sounds as if they're inviting someone else with less to lose to step forward and say something disgraceful.

Let's get one thing straight from the start. There is no population explosion. The rate of population growth has been slowing since the 1960s, and has fallen below replacement levels half the world over. But what about the other half? That's where population is exploding, right? Well, actually, no. The UN Population Division's world fertility patterns show that, worldwide, fertility per woman has fallen from 4.7 babies in 1970–75 to 2.6 in 2005-10. As Peoplequake author Fred Pearce puts it: "Today's women have half as many babies as their mothers … That is not just in the rich world. It is the global average today."

Attenborough's overpopulation thesis is, therefore, flawed. But even if the whispering naturalist were right, even if there were a population explosion, it would still be inhuman to say that there are too many humans on the planet. You can say there are too many people in a lift ("eight persons max") but not on Earth. To wish to reduce the number of living, breathing humans on this planet is an obscenity.

Today's overpopulation hysteria is not a patch on what it was a hundred years ago, however, when mainstream intellectuals such as HG Wells, WB Yeats, Virginia Woolf and DH Lawrence were proposing not just sterilisation but actual extermination. Back then, there were fewer people in Britain, of course, but many more of them were homeless. It was thought that homelessness came from there being too many people. It was a population problem. Simple as that. But then voters – as opposed to intellectuals – realised that homelessness was caused not by too many people crowding too small a country, but by too few people owning too much land.

In came social housing and down – spectacularly – went urban homelessness. It's never gone away, but neither has it returned to anything like it was. And the era of notorious doss houses the Spike and the Peg came to an end thanks to extending democracy to cover land ownership and land use.

As with shelter then, so with food now. Today's population panic goes on as if the Earth's temperate grasslands are straining under the weight of supporting voracious humans rather than voracious Big Ag. "We've run out of farmland," shriek op-eds and talking heads. "We're already at the limit. The population is booming, but every last hectare of prime arable land is already taken!"

Taken by what? According to the National Corn Growers Association, 30% of US corn ends up as fuel ethanol, while 5% is grown as corn syrup for junk food sweeteners and fizzy pop. Ain't it grand that we'd sooner say there are too many human beings in the world than too much Coca-Cola, Honey Nut Cheerios or Special K?

Food security and ecological sustainability are impossible without democratic control of land. Only through land nationalisation can we introduce the connected landscapes, smart cities and wildlife corridors that will let ecosystems bend, not break. As with homelessness a century ago, the problem facing a population of 7 billion is not too many people crowding too small a piece of land, but too few people owning too much world.