This piece is part of my “Arguments” series. In this collection of posts, I examine and respond to some of the most common arguments used to defend the exploitation of animals or to criticise veganism.
These articles are not intended to be exhaustive treatments of each topic. Rather, they are designed as practical reference pieces, helping readers reflect on these arguments more carefully and respond to them in a thoughtful, informed way.
You can find other entries in this series here.
The Claim
This argument suggests that if humans stopped consuming animal products, farmed animals would continue breeding unchecked and eventually overwhelm ecosystems. The implication is that eating animals is necessary to prevent an ecological crisis.
At first glance, this may sound like a practical concern rather than a moral defence. However, it rests on a misunderstanding of how animal agriculture functions.
Farmed animals do not reproduce freely or naturally at scale. Their populations are tightly controlled by human breeding decisions through artificial insemination, selective breeding, and production planning (1). The number of cows, pigs, chickens, and other farmed animals in existence is determined almost entirely by market demand.
If demand falls, production falls as well.
The Short Answer
Farmed animals would not overpopulate the planet if people stopped eating them, because their numbers are controlled by human breeding, not by nature.
Cows, pigs, and chickens exist in such large numbers only because they are deliberately bred to meet consumer demand. If demand for animal products falls, fewer animals are bred into existence.
Farmers do not continue producing animals without a market for them. Supply follows demand. A gradual shift toward plant-based diets would lead to a gradual reduction in breeding, not a sudden ecological crisis.
This argument misunderstands how animal agriculture works. Overpopulation is created by human decisions, and it is reduced by changing those same decisions.
The Detail
Supply Follows Demand
Animal agriculture operates within market systems. Farmers breed animals because there is a financial incentive to do so. If consumer demand for meat, dairy, and eggs decreases, fewer animals are bred into existence (2).
This is how agricultural markets function across industries. When demand for a product declines, production contracts accordingly.
We have already seen this dynamic in practice. In several countries, per-capita meat consumption has stabilised or declined in recent decades, and production has adjusted in response (3). Farmers do not continue breeding animals at a loss indefinitely. Even in systems supported by subsidies, long-term overproduction without demand is economically unsustainable.
The overpopulation concern assumes that farmed animals would continue to be bred even if there were no market for their bodies. That would require producers to absorb enormous financial losses for no reason, and there is no economic incentive for them to do so.
Farmed Animals Are Not Wild Populations
It is also important to distinguish between farmed animals and wild species.
Farmed animals exist in such large numbers precisely because humans intentionally breed them at scale. For example, tens of billions of chickens are raised annually worldwide, not because of natural population growth, but because of industrial breeding systems designed to maximise output (1). If those breeding practices slow down, the population declines accordingly.
This differs from discussions about wild animal population management, which involve complex ecological considerations. Farmed animals are not self-sustaining wild populations that would suddenly be released into ecosystems if people stopped eating them. They are part of tightly controlled agricultural systems.
If society gradually reduced its reliance on animal agriculture, breeding would gradually decrease as well.
Transitional Questions
Some people raise a more nuanced version of this concern – they ask what would happen during a transition period if demand dropped significantly.
In reality, dietary change tends to occur gradually over decades rather than overnight (3). A shift toward plant-based diets would likely lead to incremental reductions in breeding rather than an abrupt collapse of animal agriculture. There is no realistic scenario in which the entire global population goes vegan overnight.
In addition, some animals currently in production systems could live out their lives without being replaced at the same scale. The idea that billions of animals would suddenly be released into the wild does not reflect how agricultural supply chains operate in the real world.
A Question of Responsibility
Ultimately, this argument inadvertently highlights an important ethical point:
The only reason these animals exist in such large numbers is because humans deliberately breed them for consumption. Their existence is not a natural inevitability – it is the result of human economic decisions (1, 2).
If we are concerned about overpopulation, the most direct solution is not continued slaughter, but reducing the demand for animal products over time, and therefore stopping the breeding of these farmed animals, which creates these populations in the first place.
Summary
Farmed animal populations are determined by human breeding practices and market demand. If demand for animal products declines, production declines with it.
The concern that animals would overpopulate the planet assumes that farmers would continue breeding animals without economic incentive, which is highly unlikely.
Rather than justifying continued consumption, this argument highlights how tightly controlled and human-driven animal agriculture actually is.
Bibliography
- Food and Agriculture Organization of the United Nations. Tackling Climate Change Through Livestock: A Global Assessment of Emissions and Mitigation Opportunities. FAO, 2013.
https://www.fao.org/3/i3437e/i3437e.pdf - United States Department of Agriculture. Livestock and Poultry: World Markets and Trade. USDA, various editions.
https://www.fas.usda.gov/data/livestock-and-poultry-world-markets-and-trade - Our World in Data. “Meat and Dairy Production.”
https://ourworldindata.org/meat-production
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