Most people think of zoos as safe heavens for animals, where problems such as difficulty finding food and avoiding predators (食肉动物) don’t exist. Therefore, animals in zoos should live to a ripe old age. But that may not be true for the largest land animals on earth. Scientists have known that elephants in zoos often suffer from poor health. They develop diseases and they are even unable to have babies. To learn more about how captivity (圈养) affects elephants, a team of international scientists compared the lifespans (寿命) of the zoo-born elephants with the lifespans of thousands of wild elephants. They also compared some Asian elephants living in zoos with some Asian elephants which work in logging camp (伐木场), over almost the same time period. The team found that elephants born in zoos lived an average of 16.9 years, but elephants that died of natural causes lived an average of 56 years. Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camp lived 41.7 years. Scientists don’t yet know why wild elephants seem to live so much better than their zoo-raised counterparts (同类). Georgia Mason, a biologist at the University of Guelph in Canada, who led the study, thinks stress and obesity (肥胖) may be to blame. Zoo elephants don’t get the same kind of exercise they would in the wild. Elephants’ social lives are also much different in zoos than in the wild, where they live in large family groups. 小题1:Most people believe that________.
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