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  3. Being a man has always been dangerous.There are about 105 males born for every 100 females, but this ratio drops to near balance

Being a man has always been dangerous.There are about 105 males born for every 100 females, but this ratio drops to near balance

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问题     Being a man has always been dangerous.There are about 105 males born for every 100 females, but this ratio drops to near balance at the age of maturity, and among 70-year-olds there are twice as many women as men.But the great universal of male mortality is being changed now, by babies survive almost as well as girls do.This means that, for the first time, there will be an excess of boys in those crucial years when they are searching for a mate.More important, another chance for natural selection has been removed.Fifty years ago, the chance of a baby (particularly a boy baby) surviving depended on its weight.A kilogram too light or too heavy meant almost certain death.Today it makes almost no difference.Since much of the variation is due to genes one more agent of evolution has gone.
    There is another way to commit evolutionary suicide: stay alive, but have fewer children.Few people are as fertile as in the past.Except in some religious communities, very few women has 15 children.Nowadays, the number of births, like the age of death, has become average.Most of us have roughly the same number of offspring.Again, differences between people and the opportunity for natural selection to take advantage of it have diminished India shows what is happening.The country offers wealth for a few in the great cities and poverty for the remaining tribal peoples.The grand mediocrity of today everyone being the same in survival and number of offspring means that natural selection has lost 80% of its power in upper-middle-class India compared to the tribes.
    For us, this means that evolution is over; the biological Utopia has arrived.Strangely, it has involved little physical change.No other species fills so many places in nature.But in the pass 100,000 years-even the pass 100 year our lives have been transformed but our bodies have not.We did not evolve, because machines and society did it for us.Darwin had a phrase to describe those ignorant of evolution: they "look at an organic being as average looks at a ship, as at something wholly beyond his comprehension." No doubt we will remember a 20th century way of life beyond comprehension for its ugliness.But however amazed our descendants may be at how far from Utopia we were, they will look just like us.
What used to be the danger in being a man according to the first paragraph?
选项 A、A lack of mates.
B、A fierce competition.
C、A lower survival rate.
D、A defective gene.
答案C
解析 本题可参照文章的第1段。身为男人，总是有危险。男女出生比率大约为105：100，但到成年时，这种比率下降，几乎达到平衡，在70岁的老年人中，女性比男性多一倍。可是男性死亡率普遍高的现象正在改变。如今的男婴同女婴和存活率一样。这意味着，男孩到了寻找伴侣的关键年龄，将第一时间出现男孩过剩现象。更重要的是，自然选择的另一个偶然性失去了作用。50年前，婴儿(尤其是男婴)存活下来的几率取决于其体重。轻一公斤或重一公斤都几乎代表着必死无疑。体重在今天几乎不起作用。由于很多差别是由基因引起的，因而又一个进化因素消失了。
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