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In many cases, the newcomers may actually benefit the natives. In a 2010 review article in the Annual Review of Ecology, Evolution, and Systematics, the Rutgers ecologist Joan Ehrenfeld reported that rapidly accumulating evidence from many introduced species of plants and animals shows that they improve ecosystem functioning by increasing local biomass and speeding up the recycling of nutrients and energy. For example, zebra mussels are very effective filter feeders that have helped clear up the polluted waters of the Great Lakes enough to permit native lake grasses and other plants to flourish.
“Imagine that an alien scientist from outer space were to visit both New Zealand and Great Britain,” write Sax and Gaines. “Would this individual be able to distinguish which species are native and exotic, and would it be able to demonstrate that invaders have caused more damage or disruption to ecological processes than natives?” The answer to both questions is no.
Markets Make People Nicer
In The Communist Manifesto, Karl Marx thundered that the bourgeoisie and the markets that allow them to prosper “left remaining no other nexus between man and man than naked self-interest, than callous ‘cash payment.’ ” In other words, markets destroy fellow-feeling, turning human beings into cold, cruel calculators. But recent research on how 15 small-scale societies play certain canonical economic games suggests that simply isn’t so.
The societies investigated by the economists and anthropologists organized as the MacArthur Foundation’s Norms and Preferences Network ranged from hunter-gatherers to slash-and-burn horticulturalists on five continents. To probe these societies’ attitudes toward sharing and fairness, the researchers had their members play several games. One of these is called the Ultimatum Game. In it, researchers provisionally allot a divisible pie ($10, say) to one player. This player, the “proposer,” offers a portion of the pie to the second subject, the “responder.” The responder, who knows both the offer and the total amount of the pie, chooses to either accept or reject the offer. If the responder accepts, he or she gets the amount offered and the proposer gets the remainder. If the responder rejects the offer, neither player receives anything.
Rationally speaking, one might expect that the proposer would offer as little as possible ($1, say) and that the responder would never reject an offer because, after all, one dollar is better than nothing. Yet in hundreds of experiments in nearly two dozen countries, subjects rarely act in that purely self-interested way. In modern societies, the most frequent amount offered by proposers is 50 percent, and responders commonly reject offers under a third. After examining a number of different explanations, most researchers have concluded that those choices are based on the players’ sense of what is fair. Since these experiments are usually conducted using western undergraduates, the Preference Network researchers wondered if the results would hold true across societies.
The experimenters offered participants the equivalent of a day or two’s wages in their societies. The researchers found that the average offers from proposers ranged from a low of 26 percent to a high of 58 percent and that the most frequent offers ranged from 15 percent to 50 percent. Some groups, such as the Machiguenga and Quichua in South America and the Hadza in Africa, offered around 25 percent of the pie. The most frequent offer from the Machiguenga proposers was 15 percent. Only one Machiguenga responder rejected such a low offer.
Societies like the Machiguenga and Hadza, which deal with few outsiders and are not economically dependent on people other than close kin, turn out to be the stingiest players. The Orma in Africa and the Achuar in South America, who are more integrated into markets, tend to play more like the western undergraduates. “The higher the degree of market integration and the higher the payoffs of cooperation, the greater the level of prosociality found in experimental games,” the researchers found.
Herbert Gintis, co-director of the Preference Network team, speculates that markets bring strangers into contact on a regular basis, encouraging people to develop more concern for others beyond their family and immediate neighbors. Instead of parochialism, being integrated into markets encourages a spirit of ecumenism. “Extensive market interactions may accustom individuals to the idea that interactions with strangers may be mutually beneficial,” the researchers theorize. “By contrast, those who do not customarily deal with strangers in mutually advantageous ways may be more likely to treat anonymous interactions as hostile, threatening, or occasions for opportunistic pursuit of self-interest.”
Markets teach participants the habits of cooperation, trust, and fairness. Based on his research, Gintis argues that history traces humanity’s ascent from tribal selfishness to more cosmopolitan liberality. “Market societies give rise to more egalitarianism and movements toward democracy, civil liberties, and civil rights,” Gintis argues. “Market societies and democratic societies are practically co-extensive.” And they are more generous too.