Most popular arguments for vegetarianism revolve around cruelty to animals. While there’s nothing wrong with these arguments, I think a more compelling case can be made for vegetarianism by appealing to the energy dynamics of trophic levels.
This sort of argument is relatively simple, but does presuppose some basic knowledge of ecology and thermodynamics. What follows is an extremely basic overview of these principles:
The Science
In any given ecosystem, species can be divided into trophic levels, or what is more commonly known as the “food chain”.* At the bottom of the food chain you have the producers, i.e. plants and other autotrophs. Next come the primary consumers, i.e. herbivores of all kinds, from insects to elephants. Above them are the secondary consumers; carnivores who eat the primary consumers. And above the secondary consumers may be a level of teritiary or even quaternary consumers (There’s also a class of decomposers, which consume the waste products of every other trophic level, but they are irrelevent for the purpose of this analysis).
That’s all simple and straightforward. Equally simple, but perhaps not so straightforward, are the basic dynamics of what these organisms are producing and consuming: energy. The process of consumption is the flow of energy through an ecosystem. Energy enters the ecosystem as sunlight, which is converted into food by producers via photosynthesis, and is then transferred throughout the rest of the food chain by consumption.
The second law of thermodynamics stipulates that a 100% efficient transfer of energy is impossible; some energy is always lost through transference. Which means that the higher up you go on the food chain, the greater the cumulative loss of energy.
For example, herbivores usually eat only a fraction of the plants produced in a given habitat. Of the plant matter they do ingest, much of it is used as fuel for cellular respiration. Only a small amount of the original energy is available for the herbivore’s growth and development. The rest of the energy is lost (released in the form of heat) in the process of energy transference. And the amount lost by a secondary consumer is even higher. On average, only 10% of the energy at each trophic level is actually available to be stored at the next level. This means that 90% of the energy is lost at each transfer. The further removed an organism from photosynthetic production, the more energy required to support it. After a certain point, there are no more levels to a food chain simply because there isn’t enough energy to sustain another trophic level.
More concretely: let’s say you have 1000 kg. of corn. If you converted this corn to beef (i.e. by feeding it to cows), you could feed ten people. If, however, this 1000 kg of corn was consumed directly it could feed one-hundred people. You don’t need an advanced degree to see which allocation of resources is more efficient.**
The Ethics
When we speak of energy efficiency, we normally think of things like electricity and gas, not food. But we should. In terms of energy, it is much more efficient to be a primary consumer than it is to be a secondary or tertiary consumer. It costs much more in terms of resources to produce a pound of meat than it does to produce a pound of vegetation. This usually also means more pollutants and pesticides are released into the environment as part of the meat production process as well.
Simply put, eating meat is a comparatively inefficient way of tapping into the energy created by producers. Given the scale of this comparative inefficiency, meat consumption comes with a heavy environmental price tag.
In my opinion this is a stronger argument than quibbling over whether or not cows or chickens suffer as part of the process of the slaughter.** While we can’t get inside an animal’s head and quantify their experience, we can show scientifically the devastating impact of meat-eating on the environment and the associated costs and wastes built into it. To me this elicits a stronger ethical imperative to refrain from or lower our meat consumption. Even if you don’t believe animals suffer, human suffering—and the likelihood of extinction as we lurch toward (or even past) our carrying capacity–is ultimately increased by the current scale of meat consumption. As the human population increases, the strain this places on the environment increases—and we should understand this as increases the ethical cost of eating meat as well.
Disclaimer: I’m not a vegetarian, although I am an aspiring vegetarian. I have cut land animals entirely out of my diet, but I do still occasionally eat seafood. I’m working toward cutting this out as well.
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* – Food chains are more accurately described as a “food networks”, since they are rarely as simple, linear, and unbranched as the term “chain” implies. But for the purposes of this entry we can simplify.
** – This calculation is oversimplified to illustrate the basic principle.
*** – For the record, I think it’s pretty obvious that animals do suffer and that we should try to prevent them from suffering as much as possible. But you will always find people who are willing to argue this point.
