本文节选自《经济学人》2019.02.02期，Science & technology版块中的一篇关于熊猫饮食生活习惯改变的报道。
建议大家先自主阅读原文，再学习精读笔记。本文共六段，读完笔记后，回头再读原文段落，测试自己是否能够流畅阅读，把握文章脉络。
文末会总结此次学习写作可以使用的词句，读者也可自己总结。会定期将内容进行总结，做成word分享，希望大家也能坚持学习
1
Pandas are not merely herbivores, they are monovores—eating bamboo to the exclusion ofalmost anything else. Dr Wei wondered when this transition to monovory happened. The answer was, far more recently than anyone had expected.
merely：仅仅。Not merely 不仅仅，后面可如原文一样直接加句子，也可以和not only 一样，后面接but also，表示不仅……，而且
herbivores：食草动物。Carnivore 食肉动物。Omnivore 杂食动物
monovores：monovore，mono-是表示“单、一”的前缀，故该词应当为专食动物，即只吃一种食物的动物
to the exclusion of：把……除外。exclusion是排除，排斥的意思【写作推荐】词组积累
transition：过渡，转变
far more recently than anyone had expected：（对于这句话的理解，很多人可能会认为翻译为：比任何人预期的都更近。是近期发生的事）不过事实是:Something is expected or predicted to happen within a time frame, but it occurs at the beginning of the time frame not towards the middle or the end.
Example:
"Global temperatures are predicted to rise by at least one percent in the next fifty years. However this level was attained last year which was far more recently than anyone had expected"（说明，在时间线上，far more recently than anyone had expected表示的是时间更早，而不是离现在更近）【疑难句】
熊猫不仅仅是食草动物，他们也是“专食动物”—— 只吃竹子，其他几乎什么都不吃，魏博士想知道是何时出现的这样的变化。答案是，比任何人预期的时间都早得多。
2
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. 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. 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. Dr Wei has, however, brought a third line of evidence to bear. This is the isotopic composition of the animals’ bones and teeth.
depended on：依靠，同义的还有rely on，或者count on
tough：除了困难的意思外，还有坚硬的意思，这里应该是后者。tough vegetable matter 坚硬的植物性物质
were already：已经是 + by then 那时，意为那时就已经
responsible for：为……负责，是造成……的原因。文中指的是基因对人体某种表现的掌控【地道表达】responsible for the taste sensation
glutamic acid：谷氨酸
a component of：是……的一个组成部分
tells a similar story：讲述了一个类似的故事，意指说明了同样的问题，情况也与此相似【地道表达】
in favour of：赞成，有利于
has it (that)：称……属实，说……是真的。比如 rumor has it that we’ll have a new manager. 据传，我们即将有一位新经理
brought a third line of evidence to bear：bring sth to bear (on sb/sth)：to use energy or pressure to achieve sth or make sb to do sth. 即把精力用于完成某事或使某人全力以赴做某事。We must bring all our energies to bear upon the task，我们必须全力以赴不辱使命。
过去对熊猫饮食的评估依靠研究它们的颅骨和基因。一个距今400万年的下颌骨化石表明，现代熊猫的祖先在那时就已经以坚硬的植物性物质为食了。Tas1r1基因调控着人味觉中的“鲜味”，这种味觉可感知谷氨酸这种在肉中常见的组成物质，对此基因的分析也说明了相似的问题，研究表明，对此基因有利的食物的选择压力于大约420万年前开始减轻。传统理论认为，在大约200万年年前，熊猫完成了向只以竹子为食的转变。不过，魏博士致力于用第三条线索来支撑这个理论，这条线索即是动物骨头和牙齿中的同位素成分。
3
You are what you eat
Hydrogen apart, the most common elements in food are carbon, oxygen and nitrogen. Each of these has several isotopes (atoms of the same element whose nuclei have different numbers of neutrons with-in, and therefore different atomic weights). The two principal isotopes of carbon,12C and 13C, and of nitrogen, 14N and 15N, have different ratios in different plant species—and these ratios tend to be preserved in the tissues of animals that eat those plants. The isotopes of oxygen, 16O and 18O, vary in ratio according to the local climate.
nuclei：原子核nucleus的复数形式
ratios：比率，比例
tend to：往往，趋于【写作推荐】词组积累
be preserved in：被保存在【写作推荐】词组积累
vary in：在某方面不同，vary in color 颜色不一。可以替代is different in【写作推荐】词组积累
人如其食
除了氢以外，食物中最常见的元素为碳、氧和氮。这些元素每个都有数种同位素（原子相同而原子核中的中子数不同，并使原子质量不同）。碳元素的两种主要的同位素为12C和13C，而氮主要为14N和15N。他们在不同的植物中占比例不同，并且这些比例往往会被保存在食用这些植物的动物组织中。氧的同位素16O和18O的比例会根据气候环境而发生变化。
4
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. 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. 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.
a dozen：一打，十二个
dating from：追溯到，date back to/date from the 17th century，可以追溯到17世纪【写作推荐】词组积累
a wider range of：更广泛的【写作推荐】词组积累
魏博士研究了十二只1.1万至5000年前的熊猫祖先骨骼中的碳、氮同位素，并把他们和现代熊猫骨骼中的碳、氮同为素进行比较，与现代熊猫相比，熊猫祖先的骨骼中15N/14N和13C/12C的比例变化范围更大。这表明它们的饮食更广泛。从它们的牙齿化石中收集的氧同位素也说明了相同的问题。古代熊猫18O/16O值比现代熊猫更多变，说明它们生存在更多变的环境中
5
Whether the fossil pandas in Dr Wei’s study were still eating any meat remains unclear. What is clear, however, is that they were not yet the obligate bamboo feeders which they are today, and that they were making forest fringes, subtropical zones and open land their home, rather thandwelling solely in bamboo forests. The question is, what made them change?
obligate：【生】专性的
feeders：进食某种食物者，plankton feeders 以浮游生物为食者
making some place their home：把某个地方当作自己的家园
swelling：dwell 居住，栖身
solely：仅仅，单单
魏博士所研究的熊猫化石在活着时是否仍然会吃肉我们并不清楚，但我们知道的是，它们还不像今天一样专以竹子为食，而且它们把森林边缘，亚热带和开阔地带当作自己的家园，而不是只居住在竹林中。问题是，是什么使它们的饮食和生活发生了变化。
6
Dr Wei does not speculate. But there is one obvious possible culprit: the spread of Homo sapiens. Early Chinese history is shrouded in myth, but organised states clearly existed by about 5,000 years ago. 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. 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.
speculate：推测、推断
culprit：罪犯，引起问题的事物
homo sapiens：智人
is shrouded in：笼罩在，处于某种环境下的意思。Shroud 裹尸布，覆盖物【写作推荐】词组积累
displace：~ sb迫使（某人）离开家园to force people to move away from their home to another place
fringe：fringe sth，形成……的边缘，the coconut palms fringe the beach 沿海岸边长着椰子树
been made the way it is by：be made the way it is by，受……影响变成了现在的样子【写作推荐】词组积累
魏博士并没有做任何推测，但有一个明显的罪魁祸首：智人的扩张。中国的早期历史笼罩在神话之中，但有组织的国家在大约5000年前就已经存在了。人口数量的增长，很容易使古代熊猫被迫转移到除了竹子外，没有其他食物可食用的地区。如果竹子是这些地方唯一能吃的东西，那么那些喜欢吃竹子的熊猫就占据了进化的优势地位。现代，吃竹子的熊猫就是那些受到人类影响的动物代表，可能就是因为人类的压力才变成现在这副样子
总结
to the exclusion of：把……除外。exclusion是排除，排斥的意思【写作推荐】词组积累
far more recently than anyone had expected：（对于这句话的理解，很多人可能会认为翻译为：比任何人预期的都更近。是近期发生的事）不过事实是:Something is expected or predicted to happen within a time frame, but it occurs at the beginning of the time frame not towards the middle or the end.
Example:
"Global temperatures are predicted to rise by at least one percent in the next fifty years. However this level was attained last year which was far more recently than anyone had expected"（说明，在时间线上，far more recently than anyone had expected表示的是时间更早，而不是离现在更近）【疑难句】
responsible for：为……负责，是造成……的原因。文中指的是基因对人体某种表现的掌控【地道表达】responsible for the taste sensation
tells a similar story：讲述了一个类似的故事，意指说明了同样的问题，情况也与此相似【地道表达】
tend to：往往，趋于【写作推荐】词组积累
be preserved in：被保存在【写作推荐】词组积累
vary in：在某方面不同，vary in color 颜色不一。可以替代is different in【写作推荐】词组积累
dating from：追溯到，date back to/date from the 17th century，可以追溯到17世纪【写作推荐】词组积累
a wider range of：更广泛的【写作推荐】词组积累
is shrouded in：笼罩在，处于某种环境下的意思。Shroud 裹尸布，覆盖物【写作推荐】词组积累
been made the way it is by：be made the way it is by，受……影响变成了现在的样子【写作推荐】词组积累