I've been a proud omnivore for nearly my entire life. Well, there was a period after we visited Cabela's, but I got over that partly because it was getting too hard to feed me. And 1 Corinthians 10:26-26 makes God's position on vegetarianism clear. (Just kidding) But while browsing a random Facebook thread (I can't even remember what it was), I stumbled across the most convincing argument for avoiding meat I've heard. Let me paraphase.
If you've taken a biology class (or especially a biogeography class), you may know what a trophic level is. It's basically an organism's level in the food chain, with primary producers (plants) at the lowest level and apex predators at the highest. Most of the animals we eat (i.e. cows, pigs, etc.) eat plants and are therefore second-level primary consumers. Obviously the energy in living matter originates in the sun; plants take in the sun's energy by photosynthesis to grow, and are then eaten by animals and their energy passed on. So far so good, right?
Well, if you scroll down to the section titled biomass transfer efficiency, you'll see an explanation of the problem I saw pointed out. The transfer of energy from one trophic level to the next is inefficient; most of the energy organisms take in goes towards basic metabolism, with only 10% actually stored by growing. This means that the energy we get by eating (for example) a steak is one tenth the energy from plants that went into producing that steak (by being eaten by the cow).
The timing of this thought was more or less perfect, as today I drove out to celebrate Easter prematurely with my family. To get there, we drove for about three hours, mostly through endless fields of feed corn. Feed corn that, of course, goes to feed cattle that we will likely eat later. Imagine how many more people we could feed if instead of growing feed corn in that space, we grew something humans could actually eat? The world's arable land is limited, and if feeding people is our ultimate objective, it's more efficient to do it directly.
This is a purely pragmatic, not a moral, argument for avoiding meat (which is different than how it was originally presented). It doesn't indicate that we should give up meat altogether, merely that we should question how we use our arable land. There are probably lots of holes in the argument as I presented it, but the basics of it were new to me and quite interesting. Please post comments or corrections.