Category Archives: News

News, Scientific American MIND

Some Are More Equal

Life may not be fair, but humans have a strong bias for fairness. In experiments humans will generally reject or punish a partner who offers noticeably less than half a shared reward, even if they wind up empty-handed. Chimps, it turns out, are not so picky and will (rationally, an economist might point out) take whatever they can get, according to an October 2007Science paper. So what could explain this difference between our closest living relatives and us?

The answer may lie in the social relationships that influence so many of our actions. Recent studies of primate fairness seem to contradict each other–unless you consider exactly who is cheating whom.

In 2003 a provocative study led by Sarah F. Brosnan, now at Georgia State University, concluded that capuchin monkeys were exhibiting humanlike social indignation when they turned down unfair deals. The monkeys refused to perform tasks if they saw companions getting better rewards for the same work. They threw tantrums, and their food rewards, to protest the unequal treatment.

In 2006, however, a group at American University reported the opposite result–their capuchins’ behavior was not affected by the food their partners got. In response, Brosnan’s group released an updated study, again showing the capuchins’ penchant for fairness. But some experts are still not convinced–Clive Wynne of the University of Florida warns that the different study designs make comparisons “messy.”

Brosnan argues that social relationships are more important than the other groups are accounting for. Her group found that chimpanzees were more likely to accept unfair deals from members of their social group than from outsiders. In another study, humans accepted unfair deals from a computer but not from people. These results imply that relationships matter when primates judge fairness, Brosnan says, and “may explain the failure to find a response in the [Science] study.” The chimps, in other words, may have been willing to accept unfair offers because they came from old pals.

Studying animal fairness could ultimately help us understand human cooperation and justice–but the jury is still out.

First published by Scientific American MIND: [html] [pdf].

News, Science Magazine

Man With A One Wheel Mind

unicycleA retired unicycling dermatologist has gotten press, and a few laughs, by claiming a link between testosterone and humor.

Sam Shuster of Newcastle upon Tyne, U.K., rode around town on his unicycle for a year, recording the reactions of 400 passersby. Reporting in the 22 December 2007 issue of the British Medical Journal, Shuster relates that about 75% of male reactions were “attempts at comedy,” whereas 95% of the females “praised, encouraged, or expressed concern.” The most aggressive reactions came from youthful males, who shouted things such as “Fall off, granddad” and kicked soccer balls at him. Responses mellowed with time, Shuster observed, with older men joking about his having lost a wheel or his handlebars. Elderly men tended to comment on the difficulty, saying things such as “It’s quicker to walk.” Shuster’s interpretation is that as men age, “aggression is concealed by wit.” He speculates that humor eventually takes on a life of its own, persisting beyond high testosterone levels.

Sociologist Alan Booth of Pennsylvania State University in State College is skeptical of a testosterone-humor connection–except “to the extent humor means demeaning someone.” Aggression is “probably just one aspect” of humor, suggests psychologist Roy Baumeister of Florida State University in Tallahassee. He says that in his experience, men are often more likely than women to use self-deprecating humor, hardly an expression of aggression.

Originally appeared in Science Magazine as a Random Sample: [html] [pdf]

News, Science Magazine

When Worlds Collide

collideOur solar system may have plenty of cosmic cousins. Scientists studying archived data have spotted an adolescent sunlike star with a dusty belt that shows evidence of the creation and violent destruction of baby planets. “There is no doubt that they are detecting the dusty debris of rocky [Earth-like] planet formation,” says Scott Kenyon of the Harvard-Smithsonian Center for Astrophysics. A report of the find, by a team headed by Joseph Rhee of the University of California, Los Angeles, is in press at The Astrophysical Journal.

Until 2005, astronomers had observed only very young possible planet-forming systems. Then data from the retired Infrared Astronomy Satellite revealed a more mature system, bolstering predictions that collisions continue well after planets form. The latest observation, from a star called HD 23514 in the Pleiades cluster, should “help generalize the model of planetary formation,” says David Trilling of the University of Arizona in Tucson. Combined, the two discoveries allowed the team to estimate that about 1 in 1000 stellar systems share our system’s turbulent past–and could share its present architecture.

First published in Science Magazine as a Random Sample: [html] [pdf].

News, Science Magazine

Sex, Worms, and Videotape

The brain reigns as the most important sex organ–even for microscopic worms. By “masculinizing” the tiny brains of genetically female nematodes, researchers have given these ladies sexual behavior typical of male worms and begun to unravel the neuronal circuits behind worm attraction.

Sex isn’t to Caenorhabditis elegans–a 1-millimeter worm that feeds on soil bacteria–what it is to humans. The vast majority of individuals are genetically female, but they are really hermaphrodites, producing enough sperm to self-fertilize as many as 300 eggs. When food is abundant, females can release pheromones to attract the rare males, whose more robust sperm can fertilize as many as 1200 eggs. Whereas males actively seek out the pheromones, hermaphrodites don’t.

To understand what makes the two sexes behave differently, Jamie White of the University of Utah, Salt Lake City, and his colleagues looked to the worms’ brains, which number fewer than 400 neurons and are very different in males and hermaphrodites. In one experiment, White’s group enlisted the help of a gene called fem-3, which, when it is overexpressed throughout the developing hermaphrodites’ bodies, makes them males. The researchers overexpressed it in just the nervous systems, producing worms that had the bodies of hermaphrodites–they lacked the tail males use to copulate–but with intact male nervous systems.

The researchers filmed these mixed-up worms on a petri dish dabbed with the female pheromone. The modified worms moved toward the pheromone; in fact, their behavior was indistinguishable from a male’s. Apparently, a masculinized brain is all it takes for the worms to develop male-typical behavior, says White. That finding matches studies on mice and fruit flies that show that, depending on which genetic cues are activated in the nervous system, “core anatomy is capable of generating either male or female behavior,” says neuroscientist Cori Bargmann of Rockefeller University in New York City.

The researchers also discovered that three small groups of cells in males’ nervous systems–called AWA, AWC, and CEM–play a key role in the sexual attraction of males to females. When both the AWA and AWC groups, or just the CEM group, were zapped with a tiny laser beam, males lost interest in pheromones, the videotape revealed. When the same was done to the cell groups of immature males, however, the worms still displayed sexual attraction when they became adults. Apparently, the remaining neural groups take over the job of the lost cells. That makes sense, White says: “Sexual behavior needs to be very robust.” This way, if something goes wrong in one type of neuron during development, “the male can still reproduce.”

First published by ScienceNOW: [htmll] [pdf].