Humans

War spawns cooperation, plus microloan payoffs, preschool’s benefits and more in this week’s news

Fighting to get along
War, what is it good for? Absolutely nothing except cooperation. Violent conflict makes it more likely that people on the same side will sacrifice to punish uncooperative comrades and reward accommodating ones, say marketing professor Ayelet Gneezy of the University of California, San Diego and anthropologist Daniel Fessler of the University of California, Los Angeles. Israeli volunteers played two-person cooperation games for potential cash payoffs before, during and after Israel’s 2006 war with Hezbollah. Wartime players frequently surrendered money in order to deny payments to noncooperators and gave money to cooperators, the researchers report online June 8 in the Proceedings of the Royal Society B. —Bruce Bower

Babies see, hear quantities
Infants have eyes and ears for numbers, even when all their mouths do is babble. Psychologist Lisa Feigenson of Johns Hopkins University finds that 6-month-olds can recognize whether numbers of faces and tones are matched or mismatched, as long as the mismatches are large enough. Babies looked longer at faces that numerically mismatched a previously heard series of tones, signaling surprise at quantitative disparities, Feigenson reports in an upcoming Journal of Experimental Child Psychology. Babies failed to notice when one quantity was not at least twice as much as the other, she says. —Bruce Bower

Surprising payoffs for small loans
Giving small loans to tiny businesses in developing countries may fight poverty in surprising ways. These loans, known as microcredit, don’t generate bigger businesses, greater income or improved well-being among borrowers, say economists Dean Karlan of Yale University and Jonathan Zinman of Dartmouth College. Instead, microcredit boosts borrowers’ access to informal credit networks in their communities , and is typically used to pay family debts rather than business expenses, Karlan and Zinman report in the June 10 Science. Marginally credit-worthy small business operators in the Philippines were surveyed for one to two years after random approval or rejection for microloans of no more than several hundred dollars. —Bruce Bower

Preschool’s enduring benefits
Preschool attendance, even for a year or two, gives poor kids a boost that lasts into adulthood. Compared with inner-city peers who didn’t go to preschool, children who attended federally funded preschool classes went farther in school, made more money, more often had health insurance and had lower arrest and drug abuse rates by age 28, say psychologist Arthur Reynolds of the University of Minnesota in Minneapolis and his colleagues. Preschool particularly aided boys and children of high school dropouts, two groups especially likely to encounter school and social problems, the researchers report online June 9 in Science. —Bruce Bower

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