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It is the ultimate battle of the sexes - and women usually win.
Now scientists have come up with a new theory for why woman live, on
average, longer than men: men are more biologically ‘disposable’.
The controversial theory, developed by Professor Tom Kirkwood of the
University of Newcastle, suggests that the female body is better at carrying out
routine maintenance and keeping the body’s cells alive.
Professor Kirkwood believes there is now growing evidence to suggest that
men are more disposable than women, because the cells of their bodies are not
genetically programmed to last as long as they are in females.
Many scientists believe that the aging process is caused by tiny faults
throughout our body. As the tiny faults build up the length of our lives is
determined by how quickly our body is able to carry out running repairs.
As the cells miss opportunities to repair themselves our body gradually
degrades until we eventually die.
Professor Kirkwood’s theory behind why our cells do not mend every tiny
problem in our body is that it is built into our DNA. The reason we do not live
forever is because it would have cost our hunter-gather ancestors too much
energy to constantly replenish cells when hunger was a more immediate danger, he
says.
‘Under the pressure of natural selection to make the best use of scarce
energy supplies, our species gave higher priority to growing and reproducing
than to living forever,’ he writes in the magazine American Scientist.
'In humans, as in most animal species, the state of the female body is very
important for the success of reproduction', he writes.
‘The foetus needs to grow inside the mother’s womb, and the infant needs to
suckle at her breast. So if the female animal’s body is too much weakened by
damage, there is a real threat to her chances of making healthy offspring. The
man’s reproductive role, on the other hand, is less directly dependent on his
continued good health.’
这是两性之间的终极较量——而且通常女性获胜。
如今，关于女性为何通常比男性长寿，科学家们提出了一种新的说法：从生理上来讲，男性的身体更“不耐用”。
这一颇具争议的理论是由纽卡斯尔大学的汤姆•柯克伍德教授提出来的。他认为，女性的身体更易于进行日常保养，使身体细胞存活。
柯克伍德教授认为，现在有越来越多的证据表明，同女性相比，男性的身体更不耐用，其原因是男性的身体细胞基因构造不像女性的一样能维持那么久。
许多科学家认为，人体衰老的过程是由全身的各种微小毛病引起的。因为这些微小毛病不断累积，人类生命的长短也将取决于身体进行自我修复的速度有多快。
由于各种细胞错过自我修复的机会，我们的身体状况也会逐步恶化，直到最终死亡。
至于我们的细胞为何不能修复身体中的各种微小毛病，柯克伍德教授认为，这是由我们DNA的先天构造决定的。他说，我们不能长生不老的原因在于，我们的祖先是以打猎和采集为生的，不断修复细胞会使他们耗费太多的能量，而饥饿对他们来说是更直接的威胁。
他在《美国科学家》杂志上发表的文章中写道，“面对自然选择的压力，要最大程度地使用稀缺能源，我们的物种更加注重成长和繁殖，而不是长生不老。”
他还写道，“正如大多数动物一样，对人类来说，女性的身体状况对繁衍的成功与否至关重要。”
“胎儿需要在母亲的子宫内成长，婴儿需要吮吸母亲的乳汁。因此，如果女性的身体过度受损，那么她生出健康后代的可能性就会受到严重威胁。相对而言，男性在繁衍中的作用，并不是那么直接地依赖于长期拥有健康的身体。”
Vocabulary:
disposable: made to be thrown away after use 用后即丢弃的 |
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发表于 2016-7-10 17:40:51