"A vegan world can feed more humans," is one of those absurd less = more vegan arguments — like that "veganism increases dietary variety" — that only makes sense when you consider a certain kind of omnivorism. There’s a good chance that someone who eats nothing but chicken nuggets and french fries will develop a more varied diet if she becomes vegan, since she would have no choice but to dabble in the fruit and vegetable aisles, if only to survive. But dream up the most diverse plant-only diet conceivable and it’s not going to have more variety than the most diverse omnivorous diet conceivable. It’s a physical impossibility. All you need to do is take that vegan diet and add a dash of smoked salmon to it and suddenly you have even more variety.
In “Universal Veganism?,” Jean Kazez makes a similarly obvious point that is lost on many who see veganism as the solution to world hunger: if humans reduce the number of foods they allow themselves to eat, there will be less food for humans.
71% of earth is covered with ocean, and seafood provides 20% of animal protein, world wide — 50% in some countries. In a vegan world, the ocean simply stops being used as source of nutrition. Land gets wasted too. Only 10% of the earth’s land surface is arable—used to grow for crops. 26% of the land surface is used as grazing land. Most of that grazing land is not convertible to cropland, so if animals weren’t being raised on it, it would simply be lost to food production. The total lost to food production: about 79% of the planet’s surface.
Some vegans might say that Kazez has unfairly overlooked seaweed, and a few vegans might even say that vegans can eat bivalves and jellyfish; nevertheless, it would be difficult to credibly argue that a vegan humanity has more food available to it than an otherwise vegan humanity that eats just about every kind of animal from the sea.
It’s probably impossible to figure out the exact percentage of grazing land that cannot be used as cropland, but there’s certainly some, and if you raise animals on it instead of using that land for nothing, that’s more food for humans. On top of that, eating insects and wild land animals increases the human food supply, as would repealing the taboos against eating dead pets and family members. The latter is unlikely to happen outside of mass starving scenarios, but still, the point is that this particular argument for veganism makes no logical sense.
A lot of vegans see it differently because they only consider animals that are fed on foods that humans can eat. Yes, there’s plenty of that going on, but you could abolish that without abolishing all animal product consumption. And if you did, you’d have a world with more food for humans than a vegan world would.
Or maybe not.
Devin, a commenter, made this point:
If it truly is most calorie-efficient to eat plants directly than it is to eat other animals that eat plants, if humans were to convert the entire biosphere to food production for humans and make every other animal (non-autotroph, anyway) go extinct, then it could in theory provide the most possible food for humans. After all, if every other animal is extinct, they’re not consuming any part of our potential food supply.
Ethics-centric veganism does not oppose humans taking over land for homes, agriculture, entertainment facilities, general civilization business or anything else we want to use it for, as long as our purpose is anything other than intentionally killing animals in order to use their products for ourselves. It doesn’t go against veganism to knock over a forest filled with animals and turn it into cropland for humans. Vegans know that would kill a lot of animals for our own selfish ends, but that’s okay as long it’s a side consequence of our territorial expansion rather than the primary objective. Similarly, it wouldn’t go against veganism to transform the oceans into algae factories, even though that would kill off the sentient sea creatures, since the foreseen fish deaths would be a side-effect rather than the primary goal.
Theoretically, then, a vegan world might provide the most food—but only if humans were to achieve this world by exterminating all other animals and planting highly efficient crops on their graves. So long as other animals exist, humans who eat animals will always have a greater potential food supply than humans who don’t. But maybe a world without other animals (and is thus vegan by default) is one that could be maximally exploited for human sustenance.
Even here, however, veganism doesn’t necessarily rule. Any animals who eat food that humans cannot — such as grass or waste — could still add to the human food supply if they only ate grass on land that could not be used for crops and were successfully kept away from human food. And of course the cannibalism taboo also reduces the potential food supply for humans in a vegan world.
It’s likely that the world with the largest possible food supply for humans would be one where the oceans were turned to edible algae, the forests were knocked down for soybeans, only the grass- and waste-eating animals were spared extinction and human funerals were barbecues instead of burials.