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  3. Conventional wisdom has it that male birds are loyal and faithful because th

Conventional wisdom has it that male birds are loyal and faithful because th

游客2023-09-13  49
问题     Conventional wisdom has it that male birds are loyal and faithful because the business of feeding nestling is so demanding that it takes two to rear the clutch successfully. Cooperation is therefore the best way of ensuring reproductive success.
    By contrast, most mammals have a lengthy gestation (怀孕) follower by lactation (哺乳期), which leaves males on the sidelines. With little to contribute to the rearing process, they tend to opt for polygamy (一夫多妻) in one form or another.
    Male mammals are only monogamous (一夫一妻的) under a limited number of condition. One is when females are so widely dispersed that a male would find it difficult to defend more than one at a. time. In this case, he may do well to stick with one female to make sure that no other males mate with her when she does come into estrus (发情期). The dik-dik, a diminutive African antelope, is one species that seems to live by this role.
    However, many species are monogamous even when males could in principle defend several females. In these cases, it turns out that the male provides a service for the female. By investing in her and his young, the male gains more offspring in a lifetime than he does by pursuing the alternative strategy of polygamy.
    In South American marmoset and tamarin monkeys, this service amounts to full responsibility for everything to do with childcare, except lactation. As a result, females manage to produce twins twice a year—if they had to do all the work alone, it is unlikely that they could do better than a single infant once a year. So, males who become monogamous and share the workload can expect to obtain around four times as many offspring as males who abandon their mates in favor of serial polygamy. A polygamous male would have to locate and mate with at least four times as many females as a monogamous one, so it pays to be monogamous.
    As for humans, monogamy may have developed hand in hand with the evolution of large brains. Pair bonding could have ensured that women got enough food to raise-their big-brained, slow-growing and highly vulnerable offspring to adulthood. Our ancestors probably opted for some form of monogamy when they began eating meat and hunting. [br] We can conclude from the first two paragraphs that whether a male practices monogamy of polygamy depends on ______.
选项 A、the amount of nurturing the young
B、the sex of offspring
C、the attractiveness of his female partner
D、the time of conception
答案 A
解析 推理判断题。从头两段中the business of feeding nestlings is so demanding和with little to contribute to the rearing process这两句话中，我们可知，选项A“养育后代的工作量”是对这两句的概括，故答案为A。B“后代的性别”、C“雌性伴侣的吸引力”和D“受精时间”都没有提到。
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