Willis Eschenbach
Watts Up With That?
Sept 13, 2010

Buoyed by the equal parts of derision and support I received for writing in “I am So Tired Of Malthus” about how humans are better fed than at any time in history, I am foolishly but bravely venturing once again into the question of how we feed ourselves.

In a book excerpt in the February 2002 Scientific American entitled “The Bottleneck”, the noted ant entomologist Professor Edward O. Wilson put forward the familiar Malthusian argument that humans are about to run out of food. He said that we are currently getting wedged into a “bottleneck” of population versus resources. He warned of the dangers of “exponential growth” in population, and he averred that we will be squeezed mightily before the population levels off.

His solution? In part his solution was that everyone should become a vegivore.

Wilson: “If everyone agreed to become vegetarian, the present 1.4 billion hectares of arable land would support about 10 billion people.

Figure 1. Vegans are not aliens from the star Vega. They are humans who are strict vegivores, as the food chart above shows. They are known for their barbaric habit of boiling and eating the unborn fetuses of rice and wheat. And don’t get me started on what they do to the poor baby carrots, with their so-called … but I digress …


Is this correct? Would we have a net gain in carrying capacity if all the human carnetarians agreed to become vegivores?

Wilson gets his figure of 10 billion people by taking the total amount of the grain that is being fed to animals, and then figuring how many people that grain would feed. In 1999, about 655 billion tons of grain were fed to animals. That’s a lot of grain. At the world average of about 150 kg of grain per person per year, he’s right, that’s an increase of 4 billion more people who would have enough grain. There were 6 billion on the planet in the year 2000, si that makes a total of about 10 billion people.

So up to there, he is correct.*But wait. Although he stops the calculation at that point, there’s a few things he is leaving out of the calculation.

First, that’s just grain, which is not enough to keep a person alive. The extra 4 billion people would need additional nuts, seafood, fruits, vegetables, cotton, root crops, and all the other varieties of food and fiber. So the increase would have to be less than 4 billion people.

Second, people have a number of misunderstandings about where animals fit in on the farm. They believe that animals eat lots and lots of food that could be eaten by humans. Their claim is that if we just ate what the animals eat, we could eliminate the inefficiency, and feed many more people than we are feeding now. In other words, their claim is that having animals on the farms reduces the amount of food coming from the farm.

This is what Wilson is repeating here (although he has gone further than others by claiming that this would increase the carrying capacity of the earth by 2/3 again as much as the current population).

I grew up on a ranch where we had both animals (cattle, pigs, chickens) and field crops (hay, alfalfa). I can assure you that anyone who thinks animals reduce available food on the farm is what in my youth we would call a “city slicker”. Farmers around the planet keep animals for meat and milk. What, are farmers all stupid around the planet and only E. O. Wilson and his fellow vegetactivists are smart? Farmers would not keep animals if it were not a net gain.

While in some industrialized countries the cattle get up to 15% of their lifetime nutrition from grain, the vast majority of animals on farms worldwide live on a variety of things that will not or cannot be eaten by humans. Pigs eat garbage, hens eat bugs and grass and kitchen scraps, goats eat leaves, and cows have four stomachs, so they can turn cellulose, which humans cannot eat, into nutritious milk and meat.

If we got rid of all of our chickens worldwide, would we have more food available for humans? Not unless you like bugs and kitchen scraps better than you like eggs. Chickens are the poor woman’s Rumplestiltskin, spinning insects and weeds and melon rinds into golden eggs and tasty meat … I’ll let E. O. Wilson tell her she’s ruining the planet, not me.

If we call the goats down off the steep hillsides where they are grazing around the world, will we be able to put vegetable farms up there? Not unless you can farm sideways without water.

Cattle in the US eat thousands and thousands of tons of cottonseed meal annually, turning it into meat and milk. Would you prefer to eat the cottonseed meal yourself? Sorry, you can’t, it’s mostly cellulose.

The presence of livestock in a mixed farming economy does not decrease the amount of food that a farm can produce. That is a city slicker’s professorial fantasy. Animals increase the amount of food the farm can produce, otherwise farmers wouldn’t have them. Millions of tons of agricultural and processing leftovers, which would otherwise be wasted, are fed to animals. The animals in turn produce milk and eggs and meat, and then go on to enrich the soil through their urine and manure, just like they were perfected to do on the plains of Africa so long ago … what an amazing planet.

Which is why farmers everywhere around the world keep animals — farmers are not dumb, and they haven’t had the benefit of a college education, so they haven’t forgotten that goats eat leaves, pigs eat garbage, cows eat cellulose, and chickens eat bugs. They know the value of chicken manure and pig manure.

With that introduction, let’s see how we might best estimate the change if everyone became vegetarian. We can do it by looking at the land involved. Here’s the numbers: according to the FAO, out of all the land cultivated by humans, about a quarter of the land is used to grow food for animal consumption. This can be further broken down by the type of animal feed grown:

Figure 2. Area of arable land used for human crops, and for animal crops. Image is Van Gogh, “Ploughed Fields”.

Now if we all became vegivores tomorrow, and we converted all that quarter of the cultivated land to growing food and fiber for human use, what is the possible increase in the number of humans?

Looking at the chart, you would think that humans could increase by about a third of the current number. The land used for animals is about a third of the land used for humans. That would be about two billion more people, not the increase of four billion claimed by Wilson. However, the number cannot even be that large, because we have only looked at one side of the equation. We also have to consider the losses involved. By becoming vegivores, we have freed up the 23% of our cropland used to produce animal food, but we have lost the food coming from the animals. Now how much do we have to give back just to maintain the status quo, to make up for our dietary and other losses? These losses include:

• *We would have to replace the loss of the dietary protein provided by the 200 million tons of meat we eat each year, along with 275 million tons of milk, 7 million tons of butter and 47 million tons of eggs. Vegetarians say, “You don’t need animals, you can get enough protein from a vegetarian diet”, which is certainly true.

However, to do it, you need to eat more grains to get this protein, and in a twist of fate, to replace the total amount of meat protein in our diet with protein from grains would require about 50% more grain than we are currently feeding to animals. This is because animals eat many things other than grain, and we need to replace all that lost other-source protein with grain-source protein as well.

So immediately we have to devote about 18% of the total land to replacing lost protein for the existing world population. Subtracting this 18% from our original 23% of freed up land leaves us with only a 5% possible gain. Remember, this is all just to keep the world even, to maintain the world food status quo. We’re not talking at this point of feeding anyone extra. We’re just maintaining the current nutritional supplies of protein for the current population.

• We would also need to replace the amount of fat provided by the aforementioned animal products. While too much fat is a bad thing, dietary fat is an essential necessity of human nutrition.

The weight of dietary fat provided by animals is about a third of the weight of protein provided by animals. In addition, it takes much less land to produce vegetable replacements for the animal fat than for the animal protein. This is because there are vegetable products (oils) which are pure fat, while vegetable products are generally low in protein.

In the event, in order grow the oils to replace animal fat in our diet, we’d have to plant about 3% more* of our arable land to sunflowers or the equivalent. Deducting that from our 5% gain in available land, we are down to a 2% gain.

• Next, the land worldwide would be less productive because in many areas, animal manure and urine is the only fertilizer. We could easily lose more than a couple of percent that way, especially in developing nations. And once we do so, we are at zero gain, meaning we couldn’t add one single person to the world by voluntarily becoming vegivores. But there are several further losses yet.

• There is also a giant hidden loss of food in the change to vegevorianism, as tens of millions of tons of agricultural waste would have to be disposed of, instead of being converted by animals into millions of tons of human food. In many cases (e.g. oilseed residue meal) these wastes are not directly consumable by humans.

• In addition to losing the food animals make from waste, without animals to eat the waste we add the resulting problem of disposal of the agricultural waste, which is expensive in terms of time, energy, and money.

• We’d have to do without leather, hide, hair, horn, wool, and feathers. Especially in the developing world, these products are often extremely important to the health, warmth, clothing, and well-being of the local people, and there often are no local substitutes. This would be a huge cost of foregoing animals. In places where jackets are made of local sheepskins to keep out the frozen wind, explaining to some poor shepherd why he should go vegivore and trade his sheep for soybeans could be a tough sell …

• Finally, about half the land currently used for growing animal food is being used to grow grasses for animals. In practice, this land will mainly be the poorest and steepest of each country’s croplands (or else it would be planted to a field crop), and thus is not likely to be suitable for growing much more than grasses.

All up?

You’d lose by not having animals in the world’s farmyards. I don’t think you’d even come near breaking even — and neither do the farmers all around the world. They know what the numbers have just shown — we can support more people in a planet, a region, a country, or a farm if animals are part of our agricultural and dietary mix.