Among many anti-Paleo arguments the veganazis pass around is that the paleo diet is somehow bad for the environment. They argue that paleo foods use up a disproportional amount of our limited resources - either land or energy - and so eating this way is somehow unfair to others or not sustainable. This line of thinking is wrong, and muddled, in a variety of ways, and since I haven't attacked a veganazi in a while I figured I'd take the time to do it here.
The first gross mistake made by your typical veganazi is to assume that the beef we are eating is itself grain fed. This is consistent, at least - after all, the veganazis don't want you to eat your natural diet, they certainly don't care if a cow eats its natural diet. The problem is that this assumption grossly distorts the energy and land calculations in the veganazi's favor. Let me explain.
Suppose Abe needs 2000 Calories/day to sustain his life. Suppose he gets that from corn and soy products primarily. It wouldn't be too hard to calculate how much land was used, for how long, to grow that food, and how much energy it took to harvest, process, and ship that food to him (I don't have those numbers, and I won't look them up, but I think we can agree that we could get some kind of average number on these counts). Now suppose Abe's identical twin brother Ben also needs 2000 Calories/day to sustain his life, but he gets his in the form of grain fed beef. How much land and energy would be used/consumed getting him his daily allotment? I don't know, but it would have to be much more than Abe's. Why? Because you know that to get 2000 Calories of beef, that cow had to consume much more than 2000 Calories worth of grains (that's simple thermodynamics, really). How much more? I'm not worried about a number right now. Plus the cow needed land of its own to live (in addition to the land used to provide it with the grains it ate) and energy to ship the grain to the cow, to process the cow, and to ship the meat to Ben. However much land and energy are used, it has to be more than was used feeding Abe.
The hitch is that if Ben eats grass fed beef then the energy and land cost of producing the corn and soy his cow ate would be exactly zero. Instead, the cow would be eating grass that grows just outside his barn. That drastically changes the energy and land cost of the beef, while making the beef itself a much more nutritious product. And tastier, but that's another story.
Is it possible that Ben's energy and land costs would be higher than Abe's even if he's fed exclusively on grass fed beef? I have no idea. But if large swaths of the population switched from corn and soy to beef we wouldn't just be adding to the burden on the earth - we'd need more grassland from the cows but we'd also need a lot less land to grow soy and corn. And land on which cattle graze is a heck of a lot friendlier to the environment than fields factory farmed to produce soy and corn.
Next the veganazi tells you that we couldn't support the current population on beef, because there isn't enough room to feed all the cows we'd need to raise. Is he right? Again, I have no idea, nor do I care. Let's assume for a moment that it is true - that there isn't enough land that can grow grass to support all the cows we'd need to feed the human race a beef based diet. Even then, the fact that we don't have the resources to feed a diet to every last person on earth has nothing to do with the healthfulness or personal benefits of that diet. I mean, suppose some rare truffle only found on the upper plains of the Ukraine could cure cancer. Would the fact that there isn't enough of the truffle to give to every cancer inflicted person have anything to do with its benefits? If a researcher discovered this truffle and shouted "eureka!" would we keep his discovery out of the scientific journals because he couldn't cure everyone?
The veganazi also assumes that we should be worried that, suddenly, the great majority of people in this world will start thinking for themselves and making rational choices about diet to maximize their own health. Do you really think that's a likely scenario? And if it did, by some miracle, happen, would the problems that ensue really outweigh the benefits?
The veganazi's argument (that we couldn't feed everyone on a paleo diet) really means this: we should accept a less than optimal diet, less than optimal health, for ourselves and our children, and lie to them and to one another about it, so that nobody winds up better off than anybody else. It's the same weird socialist impulse that would say Ferrari shouldn't build sports cars because there are poor people who can't afford them. And, presumably, nobody should have iPads (at least not until Apple can provide one to every person on earth) or drive cars or wear designer clothes.
A meat based diet is healthier, by far, than a plant based one. I'm willing to put my money where my mouth is on this one - I pay a lot of money for my high quality food. If the paleo diet grows in popularity, good food might get more expensive. That doesn't change the fact that it's healthier, it just means I'm going to have to make sure to earn enough money to afford it. And, as the demand for grass fed beef grows, you can bet lots of entrepreneurial people are going to work out ways to raise grass fed beef in more economical ways. And if it is true that many people are too poor to afford a meat-based diet, I will feel bad for them, but there are lots of wonderful things that poor people can't afford - that's what the word "poor" means. They also can't drive nice cars or live in big houses or visit the best doctors. That's how the system works. The alternative to rationing high quality goods is to deny them to everyone - and how does that make us better of?
If you care about the environment, buy grass fed, locally raised beef and organic produce. You'll have a much, much smaller carbon footprint and energy footprint than any veganazi chowing down on factory farmed soy products, grains, and other plants that are harvested by gas guzzling machines and shipped in gas guzzling trucks to your supermarket.
And if the time comes when everyone wants to eat beef, and the soy is rotting in the fields as ranchers rush to plant grass for their hungry herds, and the price of meat starts to go up, at least we'll save a ton of money on our health care bills, old age homes, joint replacements, oxygen tanks, and escalators. Maybe it would all even out in the end.