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Men are generally better than women on tests of spatial ability, such as mentally rotating an object through three dimensions or finding their way around in a new environment. But a new study suggests that under some circumstances a woman’s way of navigating is probably more efficient. Luis Pacheco-Cobos of the National Autonomous University of Mexico and his colleagues discovered this by following mushroom gatherers from a village in the state of Tlaxcala for two rainy seasons. Two researchers, each fitted with GPS navigation devices and heart-rate monitors, followed different gatherers on different days. They recorded the weight of the mushrooms each gatherer collected and where they visited. The GPS data allowed a map to be made of the routes taken and the heart-rate measurements provided an estimate of the amount of energy expended during their travels. The results, to be published in Evolution and Human Behavior, show that the men and women collected on average about the same weight of mushrooms. But the men travelled farther, climbed higher and used a lot more energy—70% more titan the women. The men did not move any faster, but they searched for spots with lots of mushrooms. The women made many more stops, apparently satisfied with, or perhaps belier at finding, patches of fewer mushrooms. Previous work has shown that men tend to navigate by creating mental maps of a territory and then imagining their position on the maps. Women are more likely to remember their mutes using landmarks. The study lends support to the idea that male and female navigational skills were honed differently by evolution for different tasks. Modern-day hunter-gatherers divide labor, so that men tend to do more hunting and women more gathering. It seems likely that early humans did much the same thing. The theory is that the male strategy is the most useful for hunting prey; chasing an antelope, say, would mean running a long way over a winding mute. But having killed his prey, the hunter would want to make a beeline for home rather than retrace his steps exactly. Women, by contrast, would be better off remembering landmarks and retracing the paths to the most productive patches of plants. The research suggests that in certain circumstances women are better at navigating than men, which might lend some comfort to a man desperately searching for an item in a supermarket while his exasperated wife methodically moves around the aisles filling the shopping trolley. He is simply not cut out for the job, evolutionarily speaking. What accounts for the difference between women and men in the navigational skill
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Many animals test their legs and totter forth only hours after they are born, but humans need a year before they take their first, hesitant steps. Is something fundamentally different going on in human babies Maybe not. (46) A new study shows that the time it takes for humans and all other mammals to start walking fits closely with the size of their brains.(47) In past studies to develop a new animal model for the brain events that support motor development, neurophysiologist Martin Garwicz discovered that the schedules by which ferrets and rats acquire various motor skills, such as crawling and walking, are strikingly similar to each other; the progress simply happens faster for rats. That made them wonder how similar the timing of motor development might be among mammals in general.(48) They compared the time between conception and walking in 24 species and looked at how well this duration correlated with a range of variables, including gestation time, adult body mass, and adult brain mass. As they report in this week’s issue of PNAS, brain mass accounts for the vast majority (94%) of the variance in walking time between species.Species with larger brains, such as humans, tend to take longer to learn to walk. (49) Strikingly, a model based on adult brain mass and walking time in the other 23 species almost perfectly predicts when humans begin to walk. "We’ve always considered humans the exception," Garwicz says, "But in fact, we start walking at exactly the time that would be expected from all other walking mammals. "Two other variables—gestation time and brain mass at birth—also correlate nicely with age of walking for most animals, but not for humans. That makes sense, the researchers say: Humans spend an unusually small portion of their development—and build an unusually small fraction of their brain mass—in the womb. (50) The model is able to accommodate this quirk of human development because it uses the time it takes babies to learn to walk from conception, not birth. (At the other extreme, animals such as horses, who have a long gestation and then walk almost immediately after they are born, also fit the model.)Barbara Finlay, a neuroscientist at Cornell University, says the findings support the existence of a kind of a development "clock" for mammals. In her own work, Finlay has found that various mammals have similar timetables for brain development before birth. But she had imagined that a postnatal milestone such as walking would be more idiosyncratic. "I was surprised," she says. "I thought the clock would start to fracture. " It will be interesting, she says, to see if the clock will keep time for later milestones, such as events related to reproduction. (47) In past studies to develop a new animal model for the brain events that support motor development, neurophysiologist Martin Garwicz discovered that the schedules by which ferrets and rats acquire various motor skills, such as crawling and walking, are strikingly similar to each other; the progress simply happens faster for rats.
As you crest a rise on Mississippi’s Highway 63, just north of Pascagoula and the Gulf coast, the vista unfolds. A calm brown waterway flows beneath the bridge, interlaced with palm-treed fingers of land; a chaos of water towers, cranes and derricks is revealed in the distance. The near view gives the region its charm; the distant one sustains it. The oil industry and shipbuilding both thrive along the coast. (41) Signal International, a marine-fabrication firm, brought around 500 welders and pipe fitters from India—most of them from the southern state of Kerala, many of whom had laboured in various Arab Gulf states—to work in its shipyards in Pascagoula and Orange, Texas. The workers allege that they paid exorbitant sums to recruiters in India (up to $20,000), who promised them green cards. But once they arrived, they were harassed, intimidated and kept in cramped and isolated conditions. (42) (43) They, like the Indians, were brought to America on H-2B visas, given for temporary employment in non-agricultural fields.Like much of America’s rickety immigration system, the H-2B programme draws scorn from all sides. Companies in such industries as forestry and fisheries depend heavily on guest workers. But since 1990 the H-2B has been capped at a paltry 66,000 a year. Even with exemptions for workers who extend their visas, that cap has been hit every year but one. In 2008 American companies requested nearly 294,000 H-2Bs. Unions, for their part, fret that guest workers take jobs from willing Americans, as well as driving down wages and benefits. And immigrant-rights advocates point to the potential for abuse inherent in the programme. (44) Their visas are tied to their jobs, which deters complaint.Mary Bauer, the legal director of the Southern Poverty Law Centre, a civil-rights programme that has represented numerous H-2B plaintiffs (including the Indian workers suing Signal), says that temporary workers appeal to employers because "they cannot work for anybody else. They have to accept any terms imposed on them. They have to borrow a substantial amount of money to get here, and almost anything asked of them they feel obligated to tolerate and do. "Things may be getting better. In February Superior Forestry Service, which provides the forest industry with immigrant workers, agreed to a $2.75m settlement in a suit brought by 2,200 workers who claimed they were short-changed on wages (the company denies malfeasance). (45) It won’t make everyone happy, but at least it should make some people a bit less unhappy.A. Although temporary agricultural workers are guaranteed housing, travel expenses, firm hours of work and access to lawyers, H-2B visa-holders are promised only prevailing local wages.B. They are now suing both Signal and the recruiters, who are also being sued by Signal—which claims that they misled the company as well as the workers.C. Furthermore, for American corporations, the more workers from overseas they possess, the more benefits they get.D. But the population has waned, displaced by hurricanes, so companies must look elsewhere for their workers. The results are not always happy ones.E. However, less workers are needed in some corporations, such as forestry and fisheries that have enough staff from immigrants.F. And in December 2009 Bernie Sanders, a senator from Vermont, introduced a bill that would provide guest workers with travel expenses and access to lawyers, regulate foreign recruiters and prevent companies that have massively laid off local staff from hiring immigrants.G. Just west of Pascagoula, in Gulfport, a group of Brazilian welders and pipe fitters have made similar allegations against another marine-fabrication firm. 42（）
As you crest a rise on Mississippi’s Highway 63, just north of Pascagoula and the Gulf coast, the vista unfolds. A calm brown waterway flows beneath the bridge, interlaced with palm-treed fingers of land; a chaos of water towers, cranes and derricks is revealed in the distance. The near view gives the region its charm; the distant one sustains it. The oil industry and shipbuilding both thrive along the coast. (41) Signal International, a marine-fabrication firm, brought around 500 welders and pipe fitters from India—most of them from the southern state of Kerala, many of whom had laboured in various Arab Gulf states—to work in its shipyards in Pascagoula and Orange, Texas. The workers allege that they paid exorbitant sums to recruiters in India (up to $20,000), who promised them green cards. But once they arrived, they were harassed, intimidated and kept in cramped and isolated conditions. (42) (43) They, like the Indians, were brought to America on H-2B visas, given for temporary employment in non-agricultural fields.Like much of America’s rickety immigration system, the H-2B programme draws scorn from all sides. Companies in such industries as forestry and fisheries depend heavily on guest workers. But since 1990 the H-2B has been capped at a paltry 66,000 a year. Even with exemptions for workers who extend their visas, that cap has been hit every year but one. In 2008 American companies requested nearly 294,000 H-2Bs. Unions, for their part, fret that guest workers take jobs from willing Americans, as well as driving down wages and benefits. And immigrant-rights advocates point to the potential for abuse inherent in the programme. (44) Their visas are tied to their jobs, which deters complaint.Mary Bauer, the legal director of the Southern Poverty Law Centre, a civil-rights programme that has represented numerous H-2B plaintiffs (including the Indian workers suing Signal), says that temporary workers appeal to employers because "they cannot work for anybody else. They have to accept any terms imposed on them. They have to borrow a substantial amount of money to get here, and almost anything asked of them they feel obligated to tolerate and do. "Things may be getting better. In February Superior Forestry Service, which provides the forest industry with immigrant workers, agreed to a $2.75m settlement in a suit brought by 2,200 workers who claimed they were short-changed on wages (the company denies malfeasance). (45) It won’t make everyone happy, but at least it should make some people a bit less unhappy.A. Although temporary agricultural workers are guaranteed housing, travel expenses, firm hours of work and access to lawyers, H-2B visa-holders are promised only prevailing local wages.B. They are now suing both Signal and the recruiters, who are also being sued by Signal—which claims that they misled the company as well as the workers.C. Furthermore, for American corporations, the more workers from overseas they possess, the more benefits they get.D. But the population has waned, displaced by hurricanes, so companies must look elsewhere for their workers. The results are not always happy ones.E. However, less workers are needed in some corporations, such as forestry and fisheries that have enough staff from immigrants.F. And in December 2009 Bernie Sanders, a senator from Vermont, introduced a bill that would provide guest workers with travel expenses and access to lawyers, regulate foreign recruiters and prevent companies that have massively laid off local staff from hiring immigrants.G. Just west of Pascagoula, in Gulfport, a group of Brazilian welders and pipe fitters have made similar allegations against another marine-fabrication firm. 41（）
We used to think that the left brain controlled your thinking and that the right brain controlled your heart. But neuroscientists have learned that it’s a lot more complicated.In 2007, an influential paper in the journal Behavioral and Brain Functions found that while most of us process emotions through the right hemisphere of the brain, about 35 % of people—especially victims of trauma—process their hurt and anger through their left brain, where logic and language sit. That may be because they had worked so hard to explain, logically, why they were suffering. But pushing emotions through the left brain taxed it: these people performed significantly worse on memory tests.Now a new paper—out in the September issue of The Journal of Nervous and Mental Disease—further complicates the picture with a surprising finding: whether you are right-handed, left-handed or ambidextrous (which the authors call, rather delightfully, " inconsistently handed") seems to be an important clue in understanding how you use your brain to process emotions.It’s been known for some time that lefties and the ambidextrous are more prone to negative emotions. The new study shows that they also have a greater imbalance in activity between the left and right brains when they process emotions. Of course, you can’t be sure which comes first: maybe angry people are more out of balance, or maybe the inability to find equilibrium makes you angry. As for the left-handed: maybe they’re more angry because the world is designed for the right-handed majority.The study also used an interesting method to find that angry people are, literally, hot-headed: the authors of the paper—led by Ruth Propper, a psychology professor at Merrimack College in Massachusetts- measured brain-hemisphere activation with a relatively old method called tympanic membrane temperature, which is essentially how hot it is in your inner ear. If you get angry a lot, your head tends to be warmer.One problem is that the study was small —just 55 undergraduates participated (they were paid $20 each for having to endure ear-temperature tests and psychological questioning). Also, The Journal of Nervous and Mental Disease, while peer-reviewed, is one of less-respected psychology journals. Still, I like the study just because it explains that when you get hot under the collar, you are actually hot under the collar. In order to understand how we use our brain to process emotions, we can get clue from （）.
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