为何人类爱吃肉

 　　为何人类爱吃肉

对多数人类来说，肉的味道非常美妙。众多的美食中，为何我们对它情有独钟呢？

　　It is no less remarkable¹ for people today, even those of us whose tastes run more to sirloin. Because if you look at where our species came from, none of our primate² cousins could ever survive such a meat-intensive diet. Like so much else that makes us unique, we owe our ability to eat all of that meat to changes in our DNA³.

　　Monkeys and apes have molars and stomachs adapted to pulping⁴ plant matter, and in the wild they eat mostly vegan diets. A few primates⁵, like chimpanzees, do eat a few ounces of termites⁶ or other animals each day. But for most monkeys and apes, a high-fat, high-cholesterol⁷ diet trashes their insides. Captive primates with regular access to meat and dairy products often end up wheezing⁸ around inside their cages, their cholesterol pushing 300 and their arteries⁹ paved with lard.

　　Our protohuman ancestors certainly ate meat; they left too many stone cleavers¹⁰ lying next to piles of bones for it all to be coincidence. And it isn't hard to figure out why they indulged. To most people, meat tastes really good. It provides precious protein, and it's packed with fatty calories, an important consideration when food sources were precarious¹¹. But for eons early humans probably suffered no less than other primates for their love of flesh─Paleolithic Elvises wandering the savanna¹².

　　Twice, however, since human beings diverged¹³ from chimpanzees a few million years ago, the human gene¹⁴ called apoE has mutated, giving us distinct versions. Overall it is the strongest candidate around for a human 'meat-eating gene' (though it isn't the only candidate).

　　The first mutation¹⁵─well before humans learned to control fire some 500,000 years ago─seemed to have boosted the performance of killer¹⁶ blood cells that attack microbes, like the deadly microbes lingering in mouthfuls of raw flesh. This mutation also protected against chronic¹⁷ inflammation, the collateral¹⁸ tissue damage that occurs when microbial infections never quite clear up.

　　Unfortunately, this version of apoE may have mortgaged our long-term health for short-term gain: We could eat more meat, but it left our arteries looking like the insides of Crisco cans. Luckily, a second mutation appeared around 226,000 years ago, which helped us break fats down and whisk cholesterol from our blood. What's more, it kept cells fitter and made bones denser¹⁹ and tougher to break in middle age, further insurance against early death.

　　ApoE probably also boosted our brains. To function properly, brain cells need to sheathe²⁰ their axons in myelin, which acts like rubber insulation²¹ on wires and helps brain signals travel much faster. Cholesterol is a major component²² of myelin, and while the cholesterol in our bellies²³ doesn't end up in our brains (the brain manufactures its own cholesterol), the version of apoE that helps whisk cholesterol from our blood also helps to distribute brain cholesterol where it's needed and therefore helps prevent myelin deterioration²⁴. The ability to eat more meat was perhaps just a side benefit of boosting our brain power.

　　Before we congratulate ourselves on our spiffy apoEs, however, consider this: Bones with hack²⁵ marks and other archaeological evidence indicate that we started dining on meat at least 2.5 million years ago, eons before the more recent fat- and cholesterol-fighting apoE emerged. So for millions of years we were either too dim to link eating meat and early demise²⁶, too pathetic to get enough calories without meat or too brutishly indulgent to stop ingesting food we knew would kill us. Even less flattering is what the germicidal properties of the earlier apoE mutation imply: that protohumans scavenged carcasses and ate putrid²⁷ leftovers²⁸.

　　Still, eating meat did help our ancestors survive, and live long enough to pass down their traditions to future generations. Now we celebrate most every holiday by eating (or avoiding) meat.

1 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

2 primate   

n.灵长类（目）动物，首席主教；adj.首要的

参考例句：

• 14 percent of primate species are highly endangered.14%的灵长类物种处于高度濒危状态。
• The woolly spider monkey is the largest primate in the Americas.绒毛蛛猴是美洲最大的灵长类动物。

3 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

4 pulping   

水果的肉质部分( pulp的现在分词 )； 果肉； 纸浆； 低级书刊

参考例句：

• The other main type of chemical pulping is called the sulfite process. 另外一种重要的化学制浆称亚硫酸盐工艺。
• The auto catalytic reaction of amur silver grass ethanol pulping was studied. 对荻采用自催化乙醇法制浆的反应历程进行了研究。

5 primates   

primate的复数

参考例句：

• Primates are alert, inquisitive animals. 灵长目动物是机灵、好奇的动物。
• Consciousness or cerebration has been said to have emerged in the evolution of higher primates. 据说意识或思考在较高级灵长类的进化中已出现。

6 termites   

n.白蚁( termite的名词复数 )

参考例句：

• Termites are principally tropical in distribution. 白蚁主要分布在热带地区。 来自辞典例句
• This spray will exterminate the termites. 这种喷剂能消灭白蚁。 来自辞典例句

7 cholesterol   

n.（U）胆固醇

参考例句：

• There is cholesterol in the cell of body.人体细胞里有胆固醇。
• They are determining the serum-protein and cholesterol levels.他们正在测定血清蛋白和胆固醇的浓度。

8 wheezing   

v.喘息，发出呼哧呼哧的喘息声( wheeze的现在分词 )；哮鸣

参考例句：

• He was coughing and wheezing all night. 他整夜又咳嗽又喘。
• A barrel-organ was wheezing out an old tune. 一架手摇风琴正在呼哧呼哧地奏着一首古老的曲子。 来自《现代汉英综合大词典》

9 arteries   

n.动脉( artery的名词复数 )；干线，要道

参考例句：

• Even grafting new blood vessels in place of the diseased coronary arteries has been tried. 甚至移植新血管代替不健康的冠状动脉的方法都已经试过。 来自《简明英汉词典》
• This is the place where the three main arteries of West London traffic met. 这就是伦敦西部三条主要交通干线的交汇处。 来自《简明英汉词典》

10 cleavers   

n.猪殃殃（其茎、实均有钩刺）；砍肉刀，剁肉刀( cleaver的名词复数 )

参考例句：

• These monsters would not lay down their cleavers even when on the brink of their own destruction. 这些魔鬼临死也不会放下屠刀。 来自《简明英汉词典》

11 precarious   

adj.不安定的，靠不住的；根据不足的

参考例句：

• Our financial situation had become precarious.我们的财务状况已变得不稳定了。
• He earned a precarious living as an artist.作为一个艺术家，他过得是朝不保夕的生活。

12 savanna   

n.大草原

参考例句：

• The savanna is also the home of meat-eaters--the lion,leopard,and hyena who feed on the grasseaters.大草原也是食肉动物的家乡--狮子、豹、鬣狗--它们都是以草食动物维持生命的。
• They sped upon velvet wheels across an exhilarant savanna.他们的马车轻捷地穿过一片令人赏心悦目的大草原。

13 diverged   

分开( diverge的过去式和过去分词 )； 偏离； 分歧； 分道扬镳

参考例句：

• Who knows when we'll meet again? 不知几时咱们能再见面！
• At what time do you get up? 你几时起床？

14 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

15 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

16 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

17 chronic   

adj.(疾病)长期未愈的，慢性的；极坏的

参考例句：

• Famine differs from chronic malnutrition.饥荒不同于慢性营养不良。
• Chronic poisoning may lead to death from inanition.慢性中毒也可能由虚弱导致死亡。

18 collateral   

adj.平行的；旁系的；n.担保品

参考例句：

• Many people use personal assets as collateral for small business loans.很多人把个人财产用作小额商业贷款的抵押品。
• Most people here cannot borrow from banks because they lack collateral.由于拿不出东西作为抵押，这里大部分人无法从银行贷款。

19 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

20 sheathe   

v.（将刀剑）插入鞘；包，覆盖

参考例句：

• Sheathe your swords!把你们的剑插到鞘里！
• The two opponents decided at last to sheathe the sword and met at a dinner given.这两个对手终于决定讲和，在朋友举行的晚宴上会面了。

21 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

22 component   

n.组成部分，成分，元件；adj.组成的，合成的

参考例句：

• Each component is carefully checked before assembly.每个零件在装配前都经过仔细检查。
• Blade and handle are the component parts of a knife.刀身和刀柄是一把刀的组成部分。

23 bellies   

n.肚子( belly的名词复数 )；腹部；（物体的）圆形或凸起部份；腹部…形的

参考例句：

• They crawled along on their bellies. 他们匍匐前进。
• starving children with huge distended bellies 鼓着浮肿肚子的挨饿儿童

24 deterioration   

n.退化；恶化；变坏

参考例句：

• Mental and physical deterioration both occur naturally with age. 随着年龄的增长，心智和体力自然衰退。
• The car's bodywork was already showing signs of deterioration. 这辆车的车身已经显示出了劣化迹象。

25 hack   

n.劈，砍，出租马车；v.劈，砍，干咳

参考例句：

• He made a hack at the log.他朝圆木上砍了一下。
• Early settlers had to hack out a clearing in the forest where they could grow crops.早期移民不得不在森林里劈出空地种庄稼。

26 demise   

n.死亡；v.让渡，遗赠，转让

参考例句：

• He praised the union's aims but predicted its early demise.他赞扬协会的目标，但预期这一协会很快会消亡。
• The war brought about the industry's sudden demise.战争道致这个行业就这么突然垮了。

27 putrid   

adj.腐臭的；有毒的；已腐烂的；卑劣的

参考例句：

• To eat putrid food is liable to get sick.吃了腐败的食物容易生病。
• A putrid smell drove us from the room.一股腐臭的气味迫使我们离开这房间。

28 leftovers   

n.剩余物，残留物，剩菜

参考例句：

• He can do miracles with a few kitchen leftovers.他能用厨房里几样剩饭做出一顿美餐。
• She made supper from leftovers she had thrown together.她用吃剩的食物拼凑成一顿晚饭。