According to the American Dietetic Association, "most of mankind for most of human history has lived on vegetarian or near vegetarian diets."

How did agriculture arise? One particularly interesting theory is put forth by Mark Nathan Cohen in his book The Food Crisis in Prehistory. This view is startlingly simple: agriculture developed because the world was overpopulated. Relative to the existing hunter-gatherer technology, the environment was incapable of supporting the existing population.

'"It seems odd at first to think of the world as being overpopulated...when the population was only a fraction of what it is today or to think of the world as environmentally exhausted, when it was more fertile then than it is now,'" observes author Keith Akers in A Vegetarian Sourcebook.

"But we must remember that the hunter-gatherer technology is extremely inefficient with respect to land resources. It is estimated that each of the Kung bushmen (a modern hunter-gatherer society) requires over 10 square kilometers of land -- more than 2500 acres. At this rate of land use, the world could hardly have supported more than a few million hunter-gatherers."

According to one theory, primitive men were anatomically ill equipped to be full-time predators. Plant food was thus the basis of their diet, and meat was eaten infrequently. Hunting with primitive weapons--bones, sticks, and spears--is far more difficult than most people realize. Even throwing a rock with accuracy demands great practice and skill. If this theory is correct, primitive man's time was spent mostly gathering and foraging for plant foods.

A study of the Bush People of the Kalahari in Africa found that, even during a serious drought, the most important source of food came from vegetables. Four out of eleven males never went hunting. The others killed 18 animals in eight days. Their chances of obtaining meat on any day was about 25 percent.

On the other hand, the women always returned from their gathering expeditions with food; a 100 percent success rate. The entire tribe was able to comfortably feed itself if each member contributed 15 hours of work per week--even better than our own society's achievement.

"It seems...the real heroes of our Stone Age period were the women, not the men," observes British author Peter Cox in his 1986 book, Why You Don't Need Meat: "...our ancestors ate much more plant food than is popularly believed."

Nathan Pritikin, author of The Pritikin Plan, recommended not more than 3 ounces of animal protein per day; three ounces per week for his patients who had already suffered a heart attack.

Half the water consumed in the U.S. goes to irrigate land growing feed and fodder for livestock. Huge amounts of water are also used to wash away their excrement. U.S. livestock produce 20 times as much excrement as does the entire human population, creating sewage which is 10 to several hundred times as concentrated as raw domestic sewage. Animal wastes cause 10 times as much water pollution than does the U.S. human population; the meat industry causes 3 times as much harmful organic water pollution than the rest of the nation's industries combined.

Meat producers, the number one industrial polluters in our nation, contribute to half the water pollution in the United States. The water that goes into a 1,000 lb. steer could float a destroyer. It takes 25 gallons of water to produce a pound of wheat, but 2,500 gallons to produce a pound of meat. If these costs weren't subsidized by the American taxpayers, hamburger meat would be $35 per pound!

The burden of subsidizing the California meat industry costs taxpayers $24 billion annually. Livestock producers are California's biggest consumers of water. Every tax dollar the state doles out to livestock producers costs taxpayers over 7 dollars in lost wages, higher living costs and reduced business income. 17 western states have enough water supplies to support economies and populations twice as large as the present.

Overgrazing of cattle leads to topsoil erosion, turning once-arable land into desert. We lose 4 million acres of topsoil each year and 85 percent of this loss is directly caused by raising livestock. To replace the soil we've lost, we're destroying our forests. Since 1967, the rate of deforestation in the U. S. has been 1 acre every 5 seconds. For each acre cleared in urbanization, 7 are cleared for grazing or growing livestock feed.

One-third of all raw materials in the U. S. are consumed by the livestock industry and it takes 3 times as much fossil fuel energy to produce meat than it does to produce plant foods. A report on the energy crisis in Scientific American warned: "The trends in meat consumption and energy consumption are on a collision course."

Nor can fish provide any help here. There are signs that the fishing industry (which is quite energy-intensive) has already overfished the oceans in several areas. And fish could never play a major role in the worlds diet anyway: the entire global fish catch of the world, if divided among all the world's inhabitants would amount to only a few ounces of fish per person per week.

Obviously, then, the idea of providing the entire world with a Western-style diet is absurd. But what about satisfying today's demand for meat--which provides only a fraction of the population with a Western-style diet? If the world population triples in the next 100 years, and meat consumption continues, then meat production would have to triple as well. Instead of 3.7 billion acres of cropland and 7.5 billion acres of grazing land, we would require 11.1 billion acres of cropland and 22.5 billion acres of grazing land.

But this is slightly larger than the total land area of the six inhabited continents! We are desperately short of forests, water and energy already. Even if we resort to extreme methods of population control: abortion, infanticide, genocide, etc...modest increases in the world population would make it impossible to maintain current levels of meat consumption. On a vegetarian diet, however, the world could easily support a population several times its present size. The world's cattle alone consume enough to feed over 8.7 billion humans.