科學家揭祕女性爲何比男性活得久

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.’

這是兩性之間的終極較量——而且通常女性獲勝。

如今，關於女性爲何通常比男性長壽，科學家們提出了一種新的說法：從生理上來講，男性的身體更“不耐用”。

這一頗具爭議的理論是由紐卡斯爾大學的湯姆•柯克伍德教授提出來的。他認爲，女性的身體更易於進行日常保養，使身體細胞存活。

柯克伍德教授認爲，現在有越來越多的證據表明，同女性相比，男性的身體更不耐用，其原因是男性的身體細胞基因構造不像女性的一樣能維持那麼久。

許多科學家認爲，人體衰老的過程是由全身的各種微小毛病引起的。因爲這些微小毛病不斷累積，人類生命的長短也將取決於身體進行自我修復的速度有多快。

由於各種細胞錯過自我修復的機會，我們的身體狀況也會逐步惡化，直到最終死亡。

至於我們的細胞爲何不能修復身體中的各種微小毛病，柯克伍德教授認爲，這是由我們DNA的先天構造決定的。他說，我們不能長生不老的原因在於，我們的祖先是以打獵和採集爲生的，不斷修復細胞會使他們耗費太多的能量，而飢餓對他們來說是更直接的威脅。

他在《美國科學家》雜誌上發表的文章中寫道，“面對自然選擇的壓力，要最大程度地使用稀缺能源，我們的物種更加註重成長和繁殖，而不是長生不老。”

他還寫道，“正如大多數動物一樣，對人類來說，女性的身體狀況對繁衍的成功與否至關重要。”

“胎兒需要在母親的子宮內成長，嬰兒需要吮吸母親的乳汁。因此，如果女性的身體過度受損，那麼她生出健康後代的可能性就會受到嚴重威脅。相對而言，男性在繁衍中的作用，並不是那麼直接地依賴於長期擁有健康的身體。”

Vocabulary:

disposable: made to be thrown away after use 用後即丟棄的