Fears of a "population explosion" were widespread in the 1950s and 1960s, but the 1960 book The Population Bomb and its author brought the idea to an even wider audience.
Tactics (in an anti-vegan context):
Oversimplifying of the truth
Overlooking patriarchy and inequality
Conflating overpopulation with overconsumption
Omitting the “second population explosion” of “livestock” animals
Not that human population growth is a non-issue, but redirecting a conversation about the high material cost and waste output of animal agriculture to human overpopulation, as people so often do, is a diversion tactic that oversimplifies a complex issue. And continuing to support animal agriculture while worrying about overpopulation is illogical.
Human impact on the natural environment = Population x Affluence x Technology
Overconsumption seems to be the root of the problem, not number of births. Here's why:
Back in 1999, scientists warned that 16 percent of the world's population was consuming some 80 percent of its natural resources – and inequality has already worsened since then.
With few exceptions, the highest-consuming nations (richer countries) have steady or declining birthrates while the lowest-consuming nations (poorer countries) have the highest birth rates.
Consumption grows as countries gain wealth, not number of people. So what is as the heart of our overconsumption?
The second population explosion
Globally, "livestock" animals outnumber humans many times over, and have for a long time. In the 1976 BBC segment, the Vegan Society's Erika Cooke explained:
Many people are turning to veganism today because so many more could be fed if we ate plant food direct instead of feeding them to animals first, thus increasing the chance of world famine... The number of animals deliberately bred by man now outnumbers him; this adds up to a second population explosion which we must stop if we are going to feed people.
Unfortunately, we've continued going in the wrong direction since then. Today, in the US and in many wealthy countries, farmed animals consume the most water, land, corn, soy, wheat, and antibiotics and produce the most bodily waste, water pollution, and arguably the most GHGs. (Stats/sources here.)
2018 research published in PNAS found that that farmed “poultry” today make up 70% of all birds on the planet, and 60% of all mammals on Earth are “livestock” (while 36% are human and just 4% are undomesticated/free-living).
Explains Guardian journalist George Monbiot, “Human numbers are rising at roughly 1.2% a year, while livestock numbers are rising at around 2.4% a year. By 2050 the world’s living systems will have to support about 120m tonnes of extra humans, and 400m tonnes of extra farm animals.”
We can't just somehow lower the human population and continue clearing land and consuming resources like we are either, because it wouldn't make much of a dent – especially if we continue eating animal-based diets.
Writes Fred Pearce in YaleEnvironment360, published at the Yale School of Forestry & Environmental Studies:
“I do not deny that fast-rising populations can create serious local environmental crises through overgrazing, destructive farming and fishing, and deforestation. My argument here is that viewed at the global scale, it is overconsumption that has been driving humanity’s impacts on the planet’s vital life-support systems during at least the past century.”
Note that although he doesn't come out and say it, the drivers named are all entirely or mostly due to animal consumption.
Economic & political forces
Considering that fertility tends to decline with wealth, perhaps we're letting patriarchy and inequality off the hook when people say we just need to "reduce the number of humans" and everything will be okay, steaks and all.
According to 10 Reasons to Rethink Overpopulation (a publication of the Population and Development Program at Hampshire College):
Fears of overpopulation are pervasive in American society. From an early age we are taught that the world is overpopulated and that population pressure is responsible for poverty, hunger, environmental degradation and even political insecurity. If we don’t get population growth under control now, the argument goes, our future is in danger.
Conventional wisdom, however, is not always wise. Placing the blame on population obscures the powerful economic and political forces that threaten the well-being of both people and the planet. It leads to top-down, target-driven population control programs that undermine voluntary family planning and women’s reproductive rights. It reinforces racism, promoting harmful stereotypes of poor people of color. And it prevents the kind of global understanding we need in order to reach across borders to work together for a more just, peaceful and environmentally sustainable world.
The advancement of eugenics is another horrific aspect of overpopulationist rhetoric that can't be overlooked. Per the Vegan Feminist Network, as long as the human procreation discussion is framed "as a choice argument grounded in pseudo-concern for the fate of the planet and economics, the movement ignores a far more serious threat... the advancement of eugenics, the belief that the human gene pool can and should be improved through selective procreation and forced sterilization."
The discussion also generally obscures the number one way through which we needlessly and dramatically amplify our global impact, which is animal consumption. Overconsumption in wealthy nations, especially meat and dairy consumption, needs to be centered in conversations about overpopulation rather than trivialized or altogether omitted in favor of oversimplified anti-natalist solutions.
There’s a population crisis all right, but probably not the one you think (The Guardian)
10 Reasons to Rethink 'Overpopulation' (Population and Development Program at Hampshire College)
Consumption Dwarfs Population as Main Environmental Threat (YaleEnvironment360)
World's wealthiest 16 percent uses 80 percent of natural resources (CNN, 1999)
Vegans, Procreation, and "Overpopulation," Oh My... (Vegan Feminist Network)
Of Breeders, MOOs and Overpopulation: Eugenics in the Animal Rights Movement (Vegan Feminist Network)
Go Vegan in Response to Overpopulation (All Creatures)
Planet of the Cows (IEEE Spectrum)
I’m an environmental journalist, but I never write about overpopulation. Here’s why. (Vox)
Is the way we think about overpopulation racist? (The Guardian)
Should Leftists and Vegans Embrace Antinatalism? (Vegan Vaguard)
Humans just 0.01% of all life but have destroyed 83% of wild mammals – study (The Guardian)
The Problem with "Overpopulation" (Mexie)
Change Your Diet, Change Our Destiny? (Environment Reports “Food Matters” Series)
We need to stop eating meat to save our planet (Marco Springmann)