Farming’s rise cultivated fair deals

Market economies may owe more to cultural evolution than to Stone Age instincts

Blanche DuBois, Tennessee Williams’ wide-eyed protagonist who relied on “the kindness of strangers,” had nothing on ancient farmers.

LET’S MAKE A DEAL A Samburu woman in Kenya, from a population of livestock herders, plays an experimental economics game while a research assistant watches. Carolyn Lesorogol

GIVE IT UP An Au man, from a group of foragers and plant growers in Papua New Guinea, ponders how to divide money between himself and an anonymous partner. David Tracer

In rapidly expanding settlements, early cultivators had no choice but to bargain for daily goods with lots of folks they didn’t know. A fundamental redefinition of a fair deal soon followed, according to a new cross-cultural study.

Around 10,000 years ago, residents of large farming communities had to learn to make fair exchanges with strangers and to retaliate against selfish exploiters, researchers propose in the March 19 Science.

Before the rise of modern agriculture and resulting trade, the researchers contend, people rarely had to behave this way with strangers. During Stone Age days, members of small hunter-gatherer groups exchanged favors only with those they knew.

“Cultural and institutional evolution harnessed and extended our evolved psychology so that we could cooperate and exchange goods in vast communities,” says anthropologist and study director Joseph Henrich of the University of British Columbia in Vancouver.

To arrive at this conclusion, the team set up money-swapping games played by people from small societies around the world — farmers, hunter-gatherers, seaside foragers, livestock herders, and wage laborers — and looked at how each group divvied up resources.

Participants who regularly have to deal with outsiders treated strangers more fairly, sharing a pool of money or valuables more equally, the team found.

Game players’ willingness to split up resources fairly with an unknown partner rose sharply with their “market integration,” or the extent that they lived in communities with market economies. The researchers measured market integration by calculating the degree to which families purchased food, rather than hunting or growing it.

Fair play also rose substantially among volunteers who subscribed to Christianity or Islam, as opposed to local religions. Large-scale religions with strict moral codes galvanize a “golden rule” approach to social exchanges, the researchers propose. Supernatural threats, such as the prospect of spending eternity in hell, and community-building rituals jointly promote fairness toward strangers, in their view.

In addition, participants from the largest communities were most likely to punish players whom they regarded as offering unfair deals. That meant canceling the deal and getting nothing or paying part of one’s own pool of money to cause an even bigger loss for the unfair player.

That’s not good news for traditional economic theories that regard self-interest as the engine of commerce. If those theories are right, players should take whatever someone else gives them, because that’s better than nothing.

Neither do the new results bode well for evolutionary psychologists who argue that people in small Stone Age groups evolved brain circuits for kin favoritism, tit-for-tat exchanges and protecting one’s own reputation. In their view, these biologically ingrained social tactics now often lead people astray, Blanche Dubois–style, by inducing excessive trust in strangers.

“This new study powerfully challenges the view in evolutionary psychology that cultural inventions during the last 10,000 years are irrelevant to human cooperation,” remarks economist Ernst Fehr of the University of Zurich.

Market economies didn’t exist during the Stone Age, Fehr notes. But Henrich’s study indicates that the relatively recent expansion of market economies inspired a growing concern for dealing fairly with strangers, he says. People living in communities most like those of Stone Age hunter-gatherers — small in numbers and lacking a “moralizing god” — made the most unfair offers to strangers and were least likely to punish stingy partners. Reputation concerns and a focus on give-and-take exchanges can’t explain such behaviors, Fehr asserts.

Henrich’s data suggest that modern economic development has prompted people to find new ways to be selfish within vast markets, comments economist Karla Hoff of the World Bank in Washington, D.C.

Henrich’s new data build on a previous study of fair play in 15 small-scale societies (SN: 2/16/02, p. 104). In each group, a person given a chunk of money or other valuable stuff tended to offer a substantial, but highly variable, share to an anonymous partner. Partners often rejected offers deemed to be too low, resulting in both parties getting nothing.

In the new study, three economic games were played by 2,148 volunteers from 15 small-scale populations, including five communities from the earlier project. Community sizes ranged from 20 to 4,600 people.

One game allotted an amount of money, set at one day’s local wage, to a pair of players who could not see each other. One player decided how much to keep and how much to give to the other player. This provided a basic measure of fair play toward strangers.

A second game worked in much the same way. But the receiving player first decided the amount that he or she considered a minimum acceptable offer. If that minimum was met, the deal went through. If not, both players got nothing.

A third game was similarly framed, but also provided one-half day’s local wage to a third person who observed the action. The observer first determined the amount of a minimum acceptable offer between the other players. If the offer fell short, the observer forked over 20 percent of his or her pot and the offending player lost triple that amount.

Going from a fully subsistence-based society with a local religion to a fully market-based society grounded in Christianity or Islam led to increases in amounts offered by players of about 23 percent in the first game, 20 percent in the second game and 11 percent in the third game.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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