And it is becoming clear just how much they have shaped the evolution of all organisms since the very beginnings of life. In this, they demonstrate the blind, pitiless power of natural selection at its most dramatic. And—for one group of brainy bipedal mammals that viruses helped create—they also present a heady mix of threat and opportunity. The world is teeming with them. One analysis of seawater found 200,000 different viral species, and it was not setting out to be comprehensive. Other research suggests that a single litre of seawater may contain more than 100bn virus particles, and a kilo of dried soil ten times that number. Altogether, according to calculations on the back of a very big envelope, the world might contain 1031 of the things—that is one followed by 31 zeros, far outnumbering all other forms of life on the planet. As far as anyone can tell, viruses—often of many different sorts—have adapted to attack every organism that exists. One reason they are powerhouses of evolution is that they oversee a relentless and prodigious slaughter, mutating as they do so.
此外，越發清楚的是，從生命誕生之初起，病毒就在很大程度上影響了所有生物的進化。在這個過程中，它們用最引人注目的方式，展示了自然選擇的隨機性和無情的力量。病毒幫助創造了一群頭腦發達的雙足哺乳動物；對他們而言，病毒既帶來了惱人的威脅也帶來了可喜的機遇。世界上充斥著病毒。在一項對海水的調查研究中，人們發現了200,000（20萬）種不同的病毒。並且還是不完全統計。其他研究則表明，一升海水中可能含有1000億以上的病毒顆粒，而一公斤乾燥土壤所含的病毒量是這個數量的十倍。總之，根據大量的數據估算，全世界可能有1031種（個）病毒——相當於1後面跟著31個0，遠超地球上所有其他生命形式的數目。據我們所知，種類繁多的病毒已經進化到能攻擊所有現存有機體的地步了。它們之所以有這麼強的進化能力，一部分是因為這些病毒目睹著無情而駭人的屠殺，並在這種過程中不斷變異。（董瑩譯）
反思：
1.在翻譯「And—for one group of brainy bipedal mammals that viruses helped create—they also present a heady mix of threat and opportunity. 」時，我的翻譯是「對他們而言，病毒既帶來了威脅也帶來了機遇。」其中「heady」沒有翻譯因為我覺得這裡不翻譯出來也不影響願意，而審校之後加上了「惱人的」和「可喜的」這兩個詞，我覺得還是加上比較好一些，更能表現出病毒對人類的意義。
2.在翻譯「In this, they demonstrate the blind, pitiless power of natural selection at its most dramatic. 」時，我沒有把「blind」直譯成「盲目的」而是意譯成了「隨機」。
This is particularly clear in the oceans, where a fifth of single-celled plankton are killed by viruses every day. Ecologically, this promotes diversity by scything down abundant species, thus making room for rarer ones. The more common an organism, the more likely it is that a local plague of viruses specialised to attack it will develop, and so keep it in check. This propensity to cause plagues is also a powerful evolutionary stimulus for prey to develop defences, and these defences sometimes have wider consequences. For example, one explanation for why a cell may deliberately destroy itself is if its sacrifice lowers the viral load on closely related cells nearby. That way, its genes, copied in neighbouring cells, are more likely to survive. It so happens that such altruistic suicide is a prerequisite for cells to come together and form complex organisms, such as pea plants, mushrooms and human beings. The other reason viruses are engines of evolution is that they are transport mechanisms for genetic information. Some viral genomes end up integrated into the cells of their hosts, where they can be passed down to those organisms』descendants.
這在海洋中尤為明顯，在那裡每天有五分之一的單細胞浮遊生物死於病毒。從生態學角度講，可通過消減（削減）物種的數量來促進多樣性，從而為更稀有的物種騰出空間。一個有機體越常見，就越有可能出現專門攻擊它的傳染病，進而控制這個有機體（該物種）。這種引發傳染病的傾向也是獵物發展出防禦機制的強大進化動力，而這些防禦機制有時會產生更廣泛的影響。例如，對於問題「為什麼一個體細胞會故意自我毀滅」來說，其中一個解釋是因為它的犧牲會降低附近密切相關細胞的病毒載量。這樣，它複製在鄰近細胞中的基因就更有可能存活。碰巧的是，這種利他的自殺是細胞聚集在一起並形成複雜有機體的先決條件，如豌豆植物、蘑菇和人類。病毒成為進化動力源的另一個原因是，它們能傳輸遺傳信息。一些病毒基因組最終整合到宿主的細胞中，然後遺傳給這些生物的後代。（夏馨怡譯）
反思：
1.如果計算機輔助翻譯的譯文可以保留，沒有重大錯誤，就不要輕易修改，避免出現一些不必要的錯誤。
2.在修改譯文的時候要注意根據原文的體裁進行合適的表達轉換，比如說明文就要用嚴謹的語言，散文就要用優美的語言，讓譯文更符合原文。