SSS 2008-01-30
时间：2018-12-24 作者：英语课 分类：Scientific American(一)月
This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.
Every expecting mother gets asked the question: boy or girl? For mammals like us, it’s an easy call. Two X chromosomes 1 you get pink booties. X and a Y you get blue. But for some reptiles 2, the answer depends on the weather. Well, on the temperature to be precise. For many lizards 4 and turtles and gators, the sex of the hatchlings depends on the temperature in the nest where the eggs incubate. But why would animals bother with such a seemingly slapdash system for assigning sex? And the only logical answer is, there must be some benefit. Each sex must fare better at the temperature that tends to produce that sex. A fine theory, but no one has been able to test it until now. In the January 20 online issue of Nature, scientists at Iowa State University describe how they used hormones 5 to produce lizards with the wrong sex:animals that came out male even though they were incubated at the female temperature, and vice 6 versa. They found that females born and raised at the female temperature made more babies than females hatched at the wrong, male temperature, Ditto for the males. Call it the Goldilocks principle: you are born at a temperature that’s just right, at least if you are a lizard 3.
Thanks for the minute for a Scientific Americans' 60-Second Science. I’m Karen Hopkin.
- Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
- Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》
- Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
- Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》
- A chameleon is a kind of lizard.变色龙是一种蜥蜴。
- The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。