Why the World Used to Have More Wars

Human prehistory was dominated by wars—usually over critical resources such as hunting grounds, water, and good cropland. Too many people in one region meant that all might starve, so each tribe tried to drive others farther away. Archeologists say the frequent prehistoric wars often killed up to 25 percent of the males—along with large numbers of noncombatant females.

World War II, the most dreadful combat in recent history, killed about 2 percent of the humans alive in 1939. The world’s recent conflicts in Iraq and Kosovo killed less than one thousandth of a percent of the human population.

Why do today’s wars impose such a low percentage of deaths? We’re living in the first era when humans haven’t had to kill each other to protect food supplies for their families.

Stephen LeBlanc, of Harvard’s Peabody Museum, writes in the May/June issue of Archaelogy that resource-scarcity warfare left ample evidence of violent deaths, including mass graves, crushed skulls, and spear points between skeletal ribs. Researchers also find bows, arrows, spears, piles of slingshots and plaster sling missiles, lots of doughnut-shaped stones perfect for war club heads, and even prehistoric bone armor in the Arctic.

“The prehistoric people who lived in southern California had the highest incident of warfare deaths known anywhere in the world,” says LeBlanc. “Thirty percent of a large sample of males dating to the first centuries A.D. had wounds or died violent deaths. About half that number of women had similar histories. When we remember that not all warfare deaths leave skeletal evidence, this is a staggering number.”

There are other obvious clues: Homes in prehistoric villages were usually crowded together, almost certainly for defense. Archeologists can usually find evidence of the walls.

We used to hear that the famous cliff dwellings of Mesa Verde and Chaco Canyon in the U.S. Southwest were built twenty feet up the steep cliffs “because that made them cooler in summer.” No one wanted to believe the “peaceful” farming Indians engaged in warfare. But some of the fortress-like villages were suddenly abandoned and burned to the ground. Ultimately, the pueblo peoples abandoned their cliff dwellings.

What if a major shift in the climate made food scarce? The pueblo peoples flourished from 900 to 1150 AD (the period of the medieval warming and perhaps high rainfall as a result of increased transpiration). They spread over the countryside in thousands of small stone houses. After 1100, however, they began to build their fortress-like cliff dwellings. After 1250, they abandoned the cliff dwellings too, and by 1400, their remnants were concentrated in the region’s few river valleys. Did the Little Ice Age bring droughts?

Would the pueblo dwellers have fought over the scarce corn in their granaries? There was even evidence of cannibalism!

Canadian social scientists Christina Mesquida and Neil Wiener say the greater the proportion of a prehistoric society composed of unmarried young men, the greater the likelihood of war. Why? The young men were not unmarried for lack of interest in females. They must have lacked the resources to support wives and children. A successful war would provide more access to game animals and cropland; and, perhaps, more women.

The other important idea about war, says LeBlanc, is that it stops when there are enough resources to go around. The longest period of peace among the pueblo peoples of the American southwest occurred from 900 to 1100 AD—during the medieval warming’s favorable climate.

As recently as the 1930s, Japan invaded Manchuria for oil and soybeans fields, ultimately igniting World War II. They turned out to be horribly expensive soybeans.

Fortunately, since 1960, virtually no country has felt pressure to invade its neighbors for food or farmland. Why? The scientific Green Revolution tripled yields on most of the world’s good farmland. Countries short of food today are much more likely to build a fertilizer plant or a plant-breeding research facility than to invade a neighbor.

Despite the widespread warfare, says LeBlanc, prehistoric tribes’ communal decision-making ensured that warring was not done lightly. Going to war was based on pressures deciding life or death for the tribe. A thuggish, hotheaded Saddam Hussein wouldn’t be put in charge, any more than he would be elected and re-elected by a modern democracy.

Food for Peace is not just the slogan for a U.S. famine-assistance program. Food security, made possible by high-yield farming, literally is the peace-maker of the world.