(本文選自《經(jīng)濟學(xué)人》20190202期)
背景介紹：
? ? ? ?大熊貓是中國的國寶尾抑，也是一種稀有動物歇父，目前全球僅有不到3000只。眾所周知再愈，大熊貓通常只吃竹子榜苫，那么它是從古至今一直以竹子為食呢，還是因為某種原因在進化的過程中才形成這種獨特的飲食習(xí)慣践磅，本文將探討大熊貓以竹子為食的原因单刁。
Panda evolution
熊貓的演化
The giant panda’s unusual diet may be the result of human pressure
人類的壓迫可能導(dǎo)致了大熊貓不同尋常的飲食習(xí)慣
Civilisation’s rise drove it into China’s bamboo forests
文明的崛起把大熊貓趕進了中國的竹林
The giant panda?is beloved of conservationists. It is the?mascot?of the WWF (World Wide Fund for Nature, formerly the World Wildlife Fund) and, with its striking black-and-white pelage, is one of the most?recognisable?large animals in the world.?
大熊貓深受自然資源保護者的喜愛灸异。它是世界自然基金會（前身為世界野生動物基金會）的吉祥物府适，有著引人注目的黑白毛發(fā)，是世界上最具辨識度的大型動物之一肺樟。
It is also evolutionarily weird. It is a type of bear, and therefore a member of the order of mammals known, after their usual dietary habits, as the Carnivora. But it is anobligate?herbivore.
從物種的演化來看檐春，大熊貓也是一種奇怪的動物。它是熊科動物的一種么伯，因而根據(jù)它們通常的飲食習(xí)慣疟暖，大熊貓應(yīng)該是屬食肉目的一種哺乳動物。但它卻是一種專性食草動物田柔。
And it is rare. Optimistic estimates put the global panda population at between 2,000 and 3,000 individuals—with all those not living in zoos occupying a few?fragments?of bamboo forest in central China. Pessimists reckon those numbers are on the high side.?
大熊貓是稀有動物俐巴。據(jù)樂觀估計，全球大熊貓的數(shù)量大約為2000-3000只硬爆，這還包括那些生活在中國中部地區(qū)幾片殘存的竹林中的野生大熊貓欣舵。悲觀主義者認為這個數(shù)據(jù)有所偏高。
It is ironic, then, that this icon of the natural world might actually be an accidental consequence of human activity.?
具有諷刺意味的是缀磕，大熊貓這個自然界的明星很有可能是人類活動所導(dǎo)致的一個意外產(chǎn)物缘圈。
Yet this is a plausible interpretation of results just published in a paper in Current Biology, by Wei Fuwen of the Institute of Zoology, in Beijing.
不過劣光，這只是北京動物研究所的魏輔文最近在《當(dāng)代生物》雜志上發(fā)表的一篇文章對這一結(jié)果所做的一種合理的解釋。
Pandas are not merely herbivores, they are monovores—eating bamboo to the exclusion of almost anything else. Dr Wei wondered when this transition to?monovory happened. The answer was, far more recently than anyone had expected.
大熊貓不僅僅是食草動物糟把，還是單食主義者绢涡，它們除了吃竹子外，幾乎不吃其他任何東西遣疯。魏輔文想知道這種向單一飲食轉(zhuǎn)變的過程是何時發(fā)生的雄可。答案是，比所有人預(yù)想的時間都要早得多缠犀。
Past estimates of changes in pandas’ diets have depended on studies of their skulls and genes. The jaws of 4m-year-old fossils suggest that the ancestors of modern pandas were already by then eating a lot of tough vegetable matter.?
過去對大熊貓飲食變化的估計依賴于對它們頭骨和基因的研究滞项。400萬年前的顎骨化石顯示，現(xiàn)代大熊貓的祖先已經(jīng)開始食用很多難嚼的蔬菜了夭坪。
Analysis of a gene called Tas1r1, responsible for the taste sensation called “umami”, which detects glutamic acid, a common component of meat, tells a similar story.?
對Tas1r1基因的分析也得出了相同的結(jié)論文判，這是一種負責(zé)“鮮味”味覺感受的基因，可以讓大熊貓察覺到谷氨酸（肉類食物中常見的成分）的存在室梅。
It indicates that selective pressures in favour of this gene started to relax about 4.2m years ago.?By around 2m years ago, conventional theory has it, pandas had completed the transition to an all-bamboo diet.?
研究發(fā)現(xiàn)戏仓，大約420萬年前，對這一基因有利的選擇壓力開始逐漸降低亡鼠。傳統(tǒng)理論認為赏殃，大約200萬年前，大熊貓就已經(jīng)完成了全竹飲食的轉(zhuǎn)變间涵。
Dr Wei has, however, brought a third line of evidence to bear. This is the isotopic composition of the animals’ bones and teeth.
而魏輔文又提出了第三條證據(jù)仁热，依據(jù)的是大熊貓骨骼和牙齒的同位素組成。
Dr Wei studied carbon and nitrogen isotopes in the bones of a dozen ancestral pandas, dating from between 11,000 and 5,000 years ago, and compared them with those of modern pandas.?
魏輔文對12只古代大熊貓（可以追溯到1.1萬至5000年前）骨骼中的碳同位素和氮同位素進行了研究勾哩，并將它們與現(xiàn)代大熊貓骨骼中兩種元素的同位素進行了對比抗蠢。
The ancient animals had a wider range of 15N/14N and 13C/12C ratios in their bones than did the modern ones. That suggests they had broader diets.?
與現(xiàn)代大熊貓相比，古代大熊貓的骨骼中15N/14N值和13C/12C值的變化范圍更大思劳。這表明它們的飲食范圍更廣迅矛。
Oxygen isotopes collected from fossil teeth told a similar story. The ancient pandas had more variable 18O/16O values, suggesting that they lived in more varied environments than do their modern kin.
從牙齒化石中收集的氧同位素也證明了這一點。古代大熊貓的18O/16O值變化較大潜叛，這表明它們生活在比現(xiàn)代大熊貓更多樣化的環(huán)境中秽褒。
The question is, what made them change?
問題是，是什么讓他們改變了（飲食和居住環(huán)境）威兜？
Dr Wei does not speculate. But there is one obvious possible?culprit: the spread of Homo sapiens.?
雖然魏輔文沒有做出任何推測销斟，但有一個顯而易見的罪魁禍?zhǔn)?人類的擴張。
Growing human populations could easily have displaced the ancestors of modern pandas to fringe areas where there was little to eat but bamboo. And if bamboo is all there is to eat, then those that prefer to eat it will be at an evolutionary advantage.?
不斷增長的人口迫使大熊貓的祖先們轉(zhuǎn)移到了邊緣地區(qū)椒舵，在那里除了竹子幾乎沒什么可以吃的蚂踊。如果竹子是唯一可吃的食物，那么那些喜歡吃竹子的大熊貓將在進化上處于優(yōu)勢逮栅。
The modern, bamboo-eating panda—symbol of animals under pressure from man—may thus have been made the way it is by precisely such human pressures.
以竹子為食的現(xiàn)代大熊貓是受到了人類壓迫的動物的代表悴势，可能正是由于人類的壓迫窗宇，它們才變成了現(xiàn)在的樣子。
(紅色標(biāo)注詞為重難點詞匯)?
本文翻譯：Vinnie
校核：Vinnie
編輯：Vinnie
小編說
通過對大熊貓頭骨和基因的研究特纤，動物學(xué)家發(fā)現(xiàn)原來大熊貓以前并不是一個“素食主義者”军俊，而是在進化的過程中形成了這種特殊的飲食習(xí)慣。北京動物研究所的魏輔文最近通過對大熊貓骨骼和牙齒同位素組成的分析也證實了這一點捧存》喙《經(jīng)濟學(xué)人》認為是人類的壓迫導(dǎo)致大熊貓不得不遷往竹林，最終演化為以竹子為食的飲食習(xí)慣昔穴。對此镰官，你有什么看法，歡迎在留言區(qū)寫下你的觀點吗货。
重難點詞匯：
mascot ['m?skɑt] n. 吉祥物泳唠；福神
recognisable ['rek?gna?z?bl] adj. 可辨認的；可認識的宙搬；可承認的
obligate ['ɑbl?,ɡe?t] vt. 使負義務(wù)笨腥；強使，強迫勇垛；對…施以恩惠 adj. 有責(zé)任的脖母，有義務(wù)的；必需的
fragment ['fr?ɡm(xù)?nt] n. 碎片闲孤；片段或不完整部分 vt. 使成碎片 vi. 破碎或裂開
culprit ['k?lpr?t] n. 犯人谆级，罪犯；被控犯罪的人
