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Spear Led to Era of Early-Human Peace, Expert Says

Hillary Mayell
for National Geographic News
September 6, 2005
 
The invention of the spear about a million years ago sparked 985,000 years of relative peace between tribes of early humans, according to a recent report.

This advent of weaponry also marked a split in the behavioral paths of chimps and humans, says the report's author, Raymond C. Kelly, an anthropologist at the University of Michigan in Ann Arbor.

Studies by Jane Goodall and others show that if a group of chimps from one community spots an individual from a neighboring group, they stalk and kill the trespasser.

This type of violence occurs almost exclusively among adult males in border areas where two or more groups hunt for food. The killing is opportunistic and is done to establish territorial dominance.

Strength in numbers benefits the group attacking and outweighs the attackers' risk of injuries or fatalities.

Early human behavior followed this pattern until about a million years ago, when humans invented throwing weapons to hunt large mammals, Kelly says. The ability to kill from a distance and the use of ambush tactics significantly affected border interactions.

The size of a group was no longer a guarantee of success, and the potential of being seriously wounded or killed increased.

Kelly believes the change in circumstances forced early humans to come up with new ways to resolve conflicts and to maintain friendly relations.

The anthropologist cites the Andaman Islanders of India, which he studied for decades, as an example. On the part of the islands where neighboring groups had friendly relations, a territory of 16 square miles (41 square kilometers) supports 45 people.

But in the part of the island where there was conflict between neighbors, a territory of the same size supported only 33 people. The larger population size would mean the cooperative groups contributed more genes to subsequent generations—meaning that there was an evolutionary advantage to peaceful relations.

Others are skeptical that more weaponry would reduce violence.

"Maybe it did, but it seems to me unlikely to have done so," said Richard Wrangham, an anthropologist at Harvard University in Cambridge, Massachusetts. "It is easier to make surprise attacks with weapons than without, and hard to defend against them."

Kelly's report was published in the August 30 issue of Proceedings of the National Academy of Sciences.

Era of Warfare

Cooperation among groups allowed for the expansion of early human populations and helped spur migration out of Africa, Kelly says. It also led to new patterns of social organization that eventually led to war—preplanned military attacks on settlements.

The earliest archaeological evidence for organized warfare dates from between 12,000 and 14,000 years ago and is found in Sudan, Africa. In other parts of the world, wars weren't conducted until as recently as 4,000 years ago.

Kelly ties the advent of military warfare to the development of agriculture, which increased the value of territory exponentially. Until then, he argues, most human conflict was like that of chimps—sporadic, unplanned fights over turf.

Warfare changed the cost-benefit equation of attacking another group's territory. Tactics such as targeting an enemy's unarmed women, children, and elderly people returned the advantage to the attackers.

Harvard's Wrangham agrees, saying that today's guerrilla wars and terrorism—as opposed to "traditional" wars such as World War II—are "a return to 'normal human behavior.'

"Instead of having mutually agreed lethal battles in the style that dominates recent European history, which was not an evolutionarily typical style, we are now exposed to surprise attacks," he said. "Surprise attacks are the human norm, and unfortunately they are effective, costly for the victim group, and hard to defend against."

Kelly believes the recent long period of warlessness among Canada, Mexico, and the United States provides a ray of hope.

"The U.S. was at war with Canada in 1812 and with Mexico in 1848 but has managed to live in peace with its neighbors for the past 150 years," he said. "So we clearly have the capacity to maintain peaceful relations with neighbors over extended periods."

"These capacities are as much a product of [human] evolution as the capacity to engage in lethal intergroup violence."

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