英文短文欣赏(带翻译).doc

Puzzles of Evolution A SINGLE mutation may have cleared the way for rapid brain evolution. Other primates have strong jaw muscles that exert a force across the whole skull, constraining its growth. But around 2 million years ago a mutation weakened this grip in the human line. A brain growth spurt began soon after (Nature, vol 428, p 415). What drove this spurt is another matter. The environment probably presented mental challenges. Social developments would have played a part, too. To test the relative importance of these pressures, David Geary at the University of Missouri in Columbia compared the skull size of various hominins against environmental conditions each lived in, such as the estimated variation in annual temperatures, and against proxies for social pressure, such as group size. Both were associated with bigger brains, but the difficulties of navigating a larger social network had the greatest impact (Human Nature, vol 20, p 67). A big brain is incredibly hungry, so early humans needed to change their diet to support it. The transition to eating meat would have helped. So would the addition of seafood about 2 million years ago, providing omega-3 fatty acids for brain building (Proceedings of the National Academy of Sciences, vol 107, p 10002). Cooking might have helped too, by easing digestion. This would have allowed ancestral humans to evolve smaller guts and devote the spare resources to brain building. Big brains come at a price, however, including the dangers of giving birth. By the time the benefits no longer outweighed the costs, we had a 1.3 kilogram lump of jelly smart enough to question its own existence. OUR ancestors have achieved some epic migrations. Homo erectus made the first great trek out of Africa and into east Asia 1.8 million years ago. Around a million years later, the predecessors of Neanderthals turned up in Europe. And 125, 000 years ago, Homo sapiens made an early foray into the Middle East. None of these populations lasted. But some 65, 000 years ago, one group of modern humans left Africa and conquered the world - an extraordinary achievement for any species, let alone a puny, furless ape. What possessed them to spread so far and wide? It may have begun with a big squeeze. All humans belong to one of four mitochondrial lineages (L0, L1, L2 and L3) corresponding to four ancestral mothers, but only L3 is found outside Africa. Quentin Atkinson at the University of Auckland, New Zealand, and colleagues have found that this lineage experienced a population explosion in the 10, 000 years leading up to the exodus (Proceedings of the Royal Society B, vol 276, p 367). So overcrowding in the Horn of Africa may have pushed the group to cross the Red Sea and move along the southern coast of Asia. That still leaves the question of why numbers increased. Atkinson notes that for 100, 000 years the African climate had oscillated between drought and floods before becoming stable around 70, 000 years ago. Perhaps the environmental instability had forced early humans to become more inventive, with adaptations that helped population expansion once conditions improved. Paul Mellars at the University of Cambridge has argued that the explosion in numbers was driven by a major increase in the complexity of technological, economic, social and cognitive behaviour (Proceedings of the National Academy of Sciences, vol 103, p 9381). The ability to control fire came much earlier, as, probably, did language. But the period does see a blossoming of innovation such as the manufacture of complex tools, efficient exploitation of food sources, artistic expression and symbolic ornamentation. These cultural advances would have been crucial, says Mark Pagel at the University of Reading, UK. Not only can we walk, we can change the world when we get there. This flexibility would have propelled migrants ever onward, he notes, as populations quickly reached carrying capacity and individuals moved into new territory to avoid competition. Some of it would have been accidental, adds Chris Stringer of Londons Natural History Museum: the peopling of Australia may have come about when seafarers travelling between islands were blown further afield. Genetic mutations could also have made us more adventurous. For example, the so-called novelty-seeking gene, DRD4-7R, is more common in populations that migrated fastest and furthest from Africa (American Journal of Physical Anthropology, vol 145, p 382). Of course there is the human spirit - to climb the unclimbed mountain, says Stringer. 人类进化十大谜（六-七）也许是某次基因变异为大脑的快速进化铺平了道路。其他灵长类的颚肌发达，所施加的力量覆盖整个头骨，从而限制了头骨的生长 。但在200万年前，人类这一分支的某个基因突变削弱了这股力量。不久，大脑陡然开始快速增长（自然第428卷第415页） 。 促使大脑快速生长的动力却是另一件事。环境很可能形成了对智力的挑战 。社会发展也起了一部分作用。为了测试这些压力的相对重要性，来自哥伦比亚密苏里大学的大卫吉利（David Geary）对众多古人类的头骨大小与其居住的环境条件，诸 如年度温差的估值，和社会压力的代数值， 如族群规模，进行了对比 。尽管这两个因素都与大脑生长有关，但影响最大的是在较大的社会关系网中生存的难度。 大脑袋需要大量的营养，因此早期人类需要改变他们的饮食结构来供养大脑。转而食 肉有所帮助。同样，约200万年前开始摄入海鲜食品也为脑部发育提供了欧米伽-3脂肪酸（国家科学院院志第207卷第10002页）。烹饪 也有一份贡献，它减轻了消化压力， 使古人类进化出更小的内脏，把省出来的资源用于大脑成长。 A Bright Light Shining Upon UsThe incident was so extreme, it almost defies description. In the wee hours of the morning of 19 March, astronomers detected from more than halfway across the universe a burst of gamma rays brighter than a hundred-billion suns-and aimed squarely at Earth. Now, after 6 months of analysis, an international team of astronomers has discovered why the event was so extraordinary. From brief glimpses throughout the past decade, astronomers have pieced together a standard theory of gamma ray bursts. When massive stars exhaust their nuclear fuel and can no longer resist the relentless, crushing force of gravity, they collapse violently. As a star much more massive than the sun contracts to the size of an asteroid-or even smaller if it becomes a black hole-it creates unimaginable densities, temperatures, and energy. A great deal of that energy rebounds outward in a jet of particles traveling at nearly the speed of light. When that jet meets surrounding gas or dust, it generates gamma rays. New details are revising that picture. A team of 93 scientists report tomorrow in Nature that the naked eye burst from March-originating in a galaxy about 7.5 billion light-years away in the direction of the constellation Bootes-shows a feature that has never been seen before. After analyzing data from NASAs Swift spacecraft, which was designed to move very quickly in the direction of gamma radiation, and other data from both satellite and ground-based telescopes and detectors, the team says the super bright beam was surrounded by a less energetic, slower jet about 20 times wider. This could mean, the team suggests, that a bright, narrow beam accompanies all gamma ray bursts but cant be spotted unless it is aimed directly at Earth. Events such as the naked-eye burst are cracking away at the simple picture theorists have assembled over the past decade, says astrophysicist Joshua Bloom of the University of California, Berkeley. Moreover, this incident could constitute the first of a remarkable series of glimpses into the most distant parts of the universe, he says. The burst was so bright, Bloom explains, that it could be observed with relatively small telescopes-and even with the naked eye. If astronomers get lucky again, they might spy similar bursts from even farther away, perhaps among the very earliest stars. /cgi/content/full/2008/910/2 射向地球的一束强光这是一个如此极端的事件，简直无法形容。3月19日凌晨时分，天文学家们发现了伽马射线的爆发现象，射线来自宇宙半空之外，比一千亿个太阳还要明亮，径直地射向地球。目前，一个由天文学家构成的跨国研究小组经过6个月的分析之后，发现了这次伽马射线爆发事件为何如此异乎寻常。 在过去的整整十年中，天文学家们综合了所瞥见的爆发现象，创建了有关伽马射线爆发的标准理论。当耗尽核燃料的时候，大型恒星再也抵挡不住核心引力造成的残酷的粉碎性重压，它们发生剧烈塌缩。一颗比太阳大许多的恒星塌缩成一颗小行星大小的星体，如果成为黑洞的话，塌缩后会比小行星更小，因而产生了无法想象的高密度、高温和高能，其中大量的能量以粒子喷流的形式向外弹回，以接近光速的速度穿行于宇宙空间。当这种喷流遇到周围的气体或尘埃的时候，伽马射线就产生了。 然而，新发现的详情正在使上述画面有所改动。由93名科学家组成的研究小组在明天出版的自然（Nature）杂志上报道：3月份，“肉眼可见”的伽马射线爆发起源于75亿光年以外的一个星系中，该星系处于牧夫座的方向上；这次伽马射线爆发呈现出以前从未见过的特点。美国国家航空航天管理局“雨燕”号太空船的设计目的就是为了神速地对准伽马射线射来的方向。对“雨燕”号太空船的数据资料，以及对其他太空和地面望远镜与探测器的数据资料进行分析之后，研究小组称：这个超级明亮的光束周围是能量较低的、速度较慢的喷流，其宽度是约光束的20倍。研究小组提出：这有可能意味着，明亮的细光束伴随着所有的伽马射线，但是其方向若不是直指地球，是不会被发现的。 加州大学伯克利分校的天体物理学家乔舒亚布卢姆指出，在理论学家们利用过去十年的资料所拼凑起来的那幅简单画面中，肉眼可见的爆发事件是不存在的。他说：况且，在对最遥远的宇宙天区进行的一系列引人注目的观测中，该事件可以算得上是首屈一指的。布卢姆解释说，这次爆发极为明亮，利用相对小型的望远镜就可以观察到，甚至用肉眼都可以观察到。如果再次拥有好运气的话，天文学家们会发现来自更远处的类似爆发，这种爆发可能会来自一颗最早的恒星。 True Romance: Love At Long Last PETER: I was at a skating rink one night when I was 16, in 1958, and I saw this young lady. I waited for you to take a break and get a Coke before I made my move. I grabbed you by the hand and said, “My names Thomas Peter Headen.” And you said, “My names Jacqueline LeFever.” I looked in those big green eyes, and it was a done deal. So we dated. Then, in 1959, your father got transferred to Japan. I decided, Well, Ill go get her. I joined the Marine Corps, and I said, “I want to go to Japan.” The Marine Corps said, “Youll go to Japan when we tell you you can go to Japan.” So I went to a base in California.JACQUE: I dated a Marine while I was in Japan, and I ended up getting married I guess just because I thought thats what I was supposed to do. We came back to the States in 1962, but I didnt know what happened to you.PETER: Well, I finally got orders to Okinawa. And I said, Oh, boy. Ill go see Jacque when I get to Japan! I was home on leave you always get leave before you go overseas and stopped by to say hi to your mother. And she said right away, “Jacque got married. But here, you can have this picture of her.” I made some excuse that I had an appointment or something the walls were kind of crawling in on me and I left. I went overseas for 14 months, and then I came back to Camp Lejeune, North Carolina, not knowing you were right outside the gate of that base. I got discharged, and I went home to Maryland. One night the phone rang it was you.JACQUE: I came to visit my mom. And I was calling your mother to see where you were, and you answered the phone I was shocked, needless to say.PETER: You said, “I want to show you something.” We went to your mothers house, and here was this little baby. Your daughter was about three months old, and she had those same big green eyes. You went back to North Carolina, and I re-enlisted. That was 1964, and I said, “Send me overseas.” I didnt want to be in North Carolina where youre sitting outside the gate. So I left on August 12 for Vietnam. I came back to the States after 26 months and was stationed at Camp Pendleton, California. One day I was sitting in the barracks, and I decided, Im going to write her a letter and tell her how I feel, because we were going back to Vietnam.JACQUE: You wrote, “I just have to get this off my chest I love you. Ive always loved you. I have to say it and get it over with, and Im done.” In the meantime Id had another child a little boy. So there I was in an apartment with two little babies and just miserable, actually. I got married for all the wrong reasons. But I came from a divorced family, and I didnt want my kids to have a broken home.PETER: When I came back from Vietnam, I spent 24 hours at home, and then I went to my mother at about 4 a.m. and said, “Ive got to go to North Carolina.” And she kind of looked at me: “I think you better leave that one alone shes married. But I guess you got to do what you got to do.” I said, “Yeah, I got to do what I got to do.”JACQUE: I sent you away.PETER: That was September 25, 1968.JACQUE: Thirty years after that, I left my husband. It wasnt easy. My kids were grown, they had their college education, they had their families, but I was lonesome and miserable.PETER: I was sitting there one night, and the phone rang matter of fact, it was September 25, 1998.JACQUE: That night, I had made up my mind: I am out of here. Im so unhappy. And I sat there and I said, Nobody ever loved me but Peter. And thats when I thought, Im going to go find him. I asked the operator, “Do you have a T. P. Headen in Waldorf?” And she said, “No.” And I said, “Well, Im really desperate to find this person. I know hes in Charles County, Maryland, somewhere.” And she said, “I have a T. P. Headen in White Plains.” So I said, “Oh, my God, thats it! Thats him!” I started crying, and I said, “I have been trying to find this person for 30 years. Hes the love of my life.” And she said, “You want me to dial the number for you?” I said, “Yeah, you can dial the number.” She said, “Can I stay on the line?” I said, “I dont care what you do!”PETER: And you said, “You know who this is?” I said, “Yeah, I know exactly who this is.” You said, “I bet youre mad at me.” I said, “No. Matter of fact, Im still in love with you.”JACQUE: I felt like I was 15 all over again. We decided we would meet in Memphis, and I picked you up at the airport. You jumped in the car and gave me a big old kiss.PETER: We got married in May, the 15th. I took you down to Key West and out on a three-masted schooner, and we married at sunset. Theres no address on our marriage certificate, just a longitude and a latitude. Its worked out well. Its just sad, the time we lost you cant get that back. We could have been together when we were 18, 19, you know? But I got you back. And youre just as beautiful as you were when you were 15.JACQUE: Thats because you make me feel beautiful.RECORDED IN CHARLOTTE HALL, MARYLAND, ON JUNE 4, 2009.The Headens now live in Peters family home. The picture Jacques mother gave Peter in 1962, which he carried to war, is on their nightstand.真实罗曼史：永恒的爱彼得：1958年的一个晚上，我在滑冰场碰到了这个年轻的小姐，我在等待你休息之前喝了一罐可乐，随后走向你并抓住你的手说：“我的名字是托马斯彼得海登。”你说：“我的名字叫杰奎琳利菲尔。”我望向你碧绿而明亮的杏眼，便确定我们彼此都有好感。之后我们开始约会了。然而，在1959年，你的父亲被调到了日本，我便决定追随着你一起去。所以我加入了海军陆战队，对上级请示：“我希望调去日本。”然而海军陆战队却拒绝了我的请求：“当我们需要派遣你去日本时你才能去，这不是由你决定的。”所以我去了位于加利福尼亚的海军基地。杰奎琳：当我身处日本时我与一位海军士兵约会了，最后我们结了婚我猜当时我只是觉得这么做才是正确的选择吧。直到1962年我们才回到美国，当时你毫无音讯。彼得：好吧，最后我终于接到了一个命令是去日本冲绳的。然后我说，噢，我的天啊！我正要去看望杰奎琳的时候又要动身去日本了！我在