Most males in the animal kingdom do little parenting. Sometimes, though, parental investment by a male pays off. Songbird chicks

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问题     Most males in the animal kingdom do little parenting. Sometimes, though, parental investment by a male pays off. Songbird chicks are usually tended by both mother and father. Wolf packs see alpha males and females collaborate to raise the cubs. And in human beings, too, the children’s father hangs around to lend a hand in bringing up the kids. Sometimes.
    Understanding why some men settle down to form families with the mothers of their children, and others don’t, is normally seen as the prerogative of social science. But biology has a role, too. And the latest work by Lee Gettler of the University of Notre Dame, in Indiana, clarifies how part of that biological mechanism operates.
    Previous studies suggest that high levels of testosterone, the principal male hormone, are bad for family life. Fathers with lower testosterone levels provide more child care and are better partners to the children’s mothers. Conversely, high-testosterone males are less likely to stick around.
    Dr Gettler has shown something further. This is that a man’s adult testosterone level seems correlated with whether his father was present during his teenage years. His data come from a survey begun in Cebu City, in the Philippines, in 1983. This monitored the health and nutrition of 966 men enrolled as babies. It also collected extensive information on whether the fathers of these men were around and providing parental care in the households in which they were brought up. It further documented whether participants got married, had children and, if they did, whether they participated in child care. Crucially, it also measured their testosterone levels at the ages of 21, 26 and 30.
    Overall, Dr Gettler and his colleagues found that on becoming fathers, men had lower testosterone levels if their own fathers had lived with them and been involved in their care during their teenage years. Specifically, if that had happened, testosterone levels in their saliva were 16% below those of men whose fathers had not stuck around to help raise them.
    This difference has two possible explanations. One is that it is directly genetic, with high-testosterone fathers (those least likely to stick around) begetting high-testosterone sons. In this case the correlation with paternal absence would be a coincidence. The other is that teenage experience actually modulates testosterone levels. This explanation, which Dr Gettler favours, could lead to a vicious circle of high-testosterone men abandoning their sons, who thus become high-testosterone in their turn.
    Testosterone levels are not completely deterministic in the matter of parental care. Some of those in the survey whose fathers were absent during their adolescence, and who ended up with high levels of the hormone, did nevertheless became nurturing parents.
In his study work, Gettler showed that________.

选项 A、a man’s testosterone level is determined by nutrition
B、father’s parenting in children’s life is positively influential
C、the adopted babies had a high level of testosterone
D、marriage reduces a man’s adult testosterone level

答案B

解析 观点题。根据题干中的Gettler可定位至第四段。第四段介绍了Gettler博士的研究过程。第二句指出,a man’s adult testosterone level seems correlated with whether his father was present during his teenage years (一个男人成年后的睾酮水平似乎与他的父亲是否陪伴他度过青春期有关),这说明父亲对子女的照顾有着很重要的影响,故B项正确。A项属于主观臆断,第四句指出,该研究监控了参与者婴儿期的健康和营养水平,上下文并没有进一步明确营养与睾酮水平的关系,更别提是“决定性作用”了,故排除该选项。C项属于偷换概念,966 men enrolled as babies意思是研究招募的参与者都是男宝宝,并不是说这些宝宝是被领养的,故排除。D项属于无中生有,第六句提到了婚姻,但没有进一步提供婚姻与睾酮水平的关系,故排除。故本题答案为B项。
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