美国国家公共电台 NPR How Do Eggs Get Their Shapes? Scientists Think They've Cracked It
时间：2019-01-17 作者：英语课 分类：2017年NPR美国国家公共电台6月
KELLY MCEVERS, HOST:
One of nature's most efficient life support systems is the egg. And over millions of years, eggs have taken on lots of different shapes, especially among birds. Biologists have been trying to figure out for a long time why that is. What is it that determines the shape of a bird egg? NPR's Christopher Joyce reports on a mystery solved.
CHRISTOPHER JOYCE, BYLINE 1: Chicken eggs are boring. Hummingbirds 2 have eggs like Tic Tacs. Birds called murres produce eggs shaped like big teardrops. Some eggs are more like ping-pong balls. In the 19th century, collectors almost wiped out many species; so enraptured 3 were they with bird eggs.
Biologist Mary Caswell Stoddard at Princeton University was in rapture 4, too. She'd heard the shape theories. Cone-Shaped eggs don't roll away. They roll in a tight circle. Maybe that's good for birds that nest on cliffs. Or elliptical eggs like slightly flattened 5 spheres - maybe they incubate better in nests. Stoddard looked at nearly 50,000 eggs and cross-checked them with 1,400 bird species. And she says, nope, eggs are shaped the way they are because...
MARY CASWELL STODDARD: Surprisingly, egg shape appears to be related to flight ability in birds.
JOYCE: Take chickens - lousy flyers and more oval eggs. But long-distance migrating birds...
STODDARD: We find that good flyers, birds that seem to be adapted for strong, powerful flight tend to lay more asymmetric 6 or more elliptical eggs. And this came as quite a shock to us.
JOYCE: But it made sense. Birds that evolved for powerful or long-distance flight needed a body to match - sleeker 7, more streamlined. That meant less internal cargo 8 space.
STODDARD: We think that the bird's abdominal 9 cavity becoming smaller, the internal organs becoming compressed - this has an effect on the egg-shaping process.
JOYCE: Think of a banana compared to a grapefruit - similar volume, sleeker shape. Even penguins 10, who are marathon flyers through the water, have elongated 11 eggs. Soddard describes how she cracked the egg mystery - her words, not mine - in the journal Science. Christopher Joyce, NPR News.
(SOUNDBITE OF DESMOND AND THE TUTUS SONG, "KISS YOU ON THE CHEEK")
- His byline was absent as well.他的署名也不见了。
- We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。
- Hummingbirds have discovered that nectar and pollen are very nutritious. 蜂鸟发现花蜜和花粉是很有营养的。
- Why do hummingbirds and gorillas both have backbones? 为什么蜂鸟和大猩猩都有脊骨？
- He was enraptured that she had smiled at him. 她对他的微笑使他心荡神驰。 来自《简明英汉词典》
- They were enraptured to meet the great singer. 他们和大名鼎鼎的歌手见面，欣喜若狂。 来自《简明英汉词典》
- His speech was received with rapture by his supporters.他的演说受到支持者们的热烈欢迎。
- In the midst of his rapture,he was interrupted by his father.他正欢天喜地，被他父亲打断了。
- She flattened her nose and lips against the window. 她把鼻子和嘴唇紧贴着窗户。
- I flattened myself against the wall to let them pass. 我身体紧靠着墙让他们通过。
- Most people's faces are asymmetric. 大多数人的脸不对称。
- We have made no reference to asymmetric carbon atoms. 我们未曾涉及不对称碳原子。
- As tight as a corset, the new speed suits make the wearer sleeker and more streamlined. 这种新型泳衣穿起来就像紧身胸衣，可使穿着者身形光滑，更具流线型。
- When he became leaner and faster, his digital doppelganger also became sleeker and more fleet-footed. 当真科比变得更瘦并且更快，他的虚拟兄弟也变得灵动飞快。
- The ship has a cargo of about 200 ton.这条船大约有200吨的货物。
- A lot of people discharged the cargo from a ship.许多人从船上卸下货物。
- The abdominal aorta is normally smaller than the thoracic aorta.腹主动脉一般比胸主动脉小。
- Abdominal tissues sometimes adhere after an operation.手术之后腹部有时会出现粘连。
- Why can penguins live in cold environment? 为什么企鹅能生活在寒冷的环境中？ 来自《简明英汉词典》
- Whales, seals, penguins, and turtles have flippers. 鲸、海豹，企鹅和海龟均有鳍形肢。 来自《现代英汉综合大词典》