男人為什麼存在？這是個哲學問題還是個科學問題？英語讀頭條

Why Do Men Exist?

男人為什麼存在？

The existence of men has long puzzled scientists. Sexual reproduction is inefficient and costly, yet the majority of multicellular species opt for this method to keep their genes going. So why do men exist? Researchers from the University of East Anglia (UAE) believe they may have finally cracked it, suggesting that the evolutionary force known as 『sexual selection』 plays a key role in improving population health and protecting us against extinction.

「男人為什麼會存在」長期以來一直困擾著科學家們。性繁殖效率低、成本高，但大多數多細胞物種選擇這種方法來保持基因的持續。那麼男人為什麼存在呢？東英吉利大學 (阿聯酋) 的研究人員認為，他們可能最終找到了答案，他們的發現表明被稱為 "性選擇" 的進化驅動力，在改善人類群體的健康和保護我們免遭滅絕起著關鍵作用。

The study, published in the journal Nature, looked at Tribolium flour beetles to understand why most multicellular organisms rely on sex to reproduce. Under controlled laboratory conditions, researchers studied 50 generations of beetles over a ten year period and tested the impact of sexual selection. Famously theorized by Charles Darwin, sexual selection is a process whereby males compete for a chance to reproduce and females choose which male to reproduce with.

這項研究發表在《自然》雜誌上，通過觀察三棱粉甲蟲來了解為什麼大多數多細胞有機體依賴性繁殖。在受控實驗室條件下，研究人員在十年時間內研究了50代甲蟲，並測試了性選擇的影響。被達爾文非常著名的推論說，性選擇是，雄性為繁殖的機會而競爭、雌性為選擇和哪一個雄性繁殖的一個過程。

Tribolium flour beetles：三棱粉甲蟲

"Almost all multicellular species on earth reproduce using sex, but its existence isn"t easy to explain because sex carries big burdens, the most obvious of which is that only half of your offspring—daughters—will actually produce offspring. Why should any species waste all that effort on sons?」 lead researcher Professor Matt Gage, from UEA"s School of Biological Sciences, said in a statement.

「地球上幾乎所有多細胞物種都使用性繁殖，但因為性承擔著巨大的負擔，所以它的存在並不容易解釋， 最明顯的是，只有一半的後代 — 女兒 — 實際上會生產後代。那為什麼任何物種要在兒子身上花費那麼多的經歷呢？ 「來自東英吉利大學生物科學學院的首席研究員，Matt Gage博士，在一份聲明中說。

"We wanted to understand how Darwinian selection can allow this widespread and seemingly wasteful reproductive system to persist, when a system where all individuals produce offspring without sex—as in all-female asexual populations—would be a far more effective route to reproduce greater numbers of offspring," he added.

「我們想弄明白達爾文的物競天擇的規律怎麼會允許這種廣泛的且貌似浪費的生殖系統持續存在。 相比之下，所有個體都能不通過性即能繁衍後代的系統 - 就像母性無性繁殖人口那樣 - 會是一個更有效的繁衍更多後代的方式。」他補充說。

The researchers found that when sexual selection was removed and beetles were paired up into monogamous couples, the population"s health declined rapidly and the bugs were wiped out by the 10th generation. Conversely, beetles that had a strong influence on sexual selection, where intense competition saw 90 males trying to compete to reproduce with only 10 females, were more resilient to extinction.

研究人員發現，當性選擇被排除的情況下，甲蟲被配對成一夫一妻制的夫婦時，人口的健康迅速下降，到了第十代，這批蟲子就滅絕了。相反，在強烈性選擇影響的甲蟲 ，90隻雄性試圖與僅有的10隻雌性繁衍的激烈的競爭中，它們更有頑強的生命力。

"To be good at out-competing rivals and attracting partners in the struggle to reproduce, an individual has to be good at most things, so sexual selection provides an important and effective filter to maintain and improve population genetic health,」 said Gage. "Our findings provide direct support for the idea that sex persists as a dominant mode of reproduction because it allows sexual selection to provide these important genetic benefits.」

「要善於在競爭中勝過對手，並吸引伴侶在爭鬥中進行繁殖，個人必須擅長絕大多數的技能，因此性選擇為此提供了一個重要而有效的篩選機制，來維持和改良人口遺傳基因，」 Gage說。「由於它允許性選擇，所以才能作為繁殖的主導模式，我們的研究結果對於這一理論直接提供了支持。」

The study suggests that sexual selection plays a crucial role in sifting out harmful genetic mutations, as competition means females are less likely to mate with genetically inferior individuals. Even after 20 generations of inbreeding, the study found that the populations that were strongly influenced by sexual selection had a higher fitness and were able to maintain population health and avoid extinction.

研究表明，性選擇在篩選有害基因突變方面起著至關重要的作用，因為競爭意味著雌性不太可能與基因低下的個體交配。該研究發現，即使在20代近親繁殖後，受性選擇強烈影響的群體仍具有較強的體質，能夠維持群體健康，避免滅絕。

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