2015职称英语考试理工类B级模拟阅读(5)

　　Longer Lives for Wild Elephants

　　Most people think of zoos as safe places for animals，where struggles such as difficulty finding food and avoiding predators dont exist. Without such problems, animals in zoos should live to a ripe old agel.

　　To learn more about how captivity affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands.Zoos keep detailed records of all the animals in their care，documenting factors such as birth dates，illnesses，weight and death.These records made it possible for the researchers to analyze 40

　　The team found that female African elephants born in zoos lived an average of l 6.9 years.Their wild counterparts who died of natural causes lived an average of 56 yearsmore than three times as long.Female Asian elephants followed a similar pattern.In zoos, they lived l 8.9 s years, while those in the logging camps lived 41.7 years.

　　Another finding from the study showed that Asian elephants born in zoos were more likely to die early than Asian elephants captured in the wild and brought to zoos.Mason suggests stress in the mothers in zoos might cause them to have babies that are less likely to survive.

　　词汇：

　　Ripe adj.成熟的

　　Captivity n.监禁;束缚

　　Obesity adj.过度肥胖;肥胖症