英文书摘精选 为什么人类身上没有斑点或条纹?
时间：2018-12-28 作者：英语课 分类：初学者听力文摘精选
Why Don’t Humans Have Spots Or Stripes?
为什么人类身上没有斑点或条纹？
Have you ever wondered why we humans don’t have spots or stripes? Well, maybe you haven’t, but it is interesting that so many creatures are multicolored but we are not.
你是否曾经好奇过为什么我们人类身上没有斑点或条纹？也许你没想过，可那么多生物五彩斑斓，我们却不是，这很有意思。
Melanin Pigments 1
黑色素
Humans and animals get their skin color from melanin pigments, which can be either black or yellow. Together, these two pigments account for just about every color you might see on the skin of mammals: white, red, yellow, brown, and black and every shade in between.
人类和动物的皮肤颜色来自黑色素，它不是黑色就是黄色。二者混合可呈现你能见到的各种哺乳动物的皮肤颜色：白色、黄色、棕色、黑色和他们之间的过渡色。产生黑色素的皮
The skin cells that produce melanin are known as melanocytes. In the embryos 2 of mammals, the melanocytes originate from the same group of cells that produces the spinal 3 cord and the brain. From there, these cells migrate through the developing skin towards the belly 4 of the animal.
肤细胞是黑素细胞，在哺乳动物的胚胎中，黑素细胞源自制造出脊髓和大脑的同组细胞。这些细胞从那里出来通过皮肤的生长迁往动物的肚子。
Streaks 5 and Stripes
条纹和条痕
If the melanocytes that produce dark pigments and light pigments migrate in streaks, you end up with stripes. The same goes for spots, but in this case, only random 6 patches of certain pigments survive. In either case, the migration 7 pattern is genetically 8 determined 9.
如果产生深浅色素的黑素细胞以条纹状迁移，那么你身上就有条纹。斑点也是这么来的。但在这种情况下， 只有随机的某些色素斑点能够存活。不论哪种情况，其迁移方式由基因决定。
For certain species, like zebras, stripes provided an evolutionary 10 advantage because they worked as camouflage 11. Those animals with stripes were more likely to survive, and to pass along the genes 12 that produce stripes to their offspring. For humans, this apparently 13 wasn’t the case. However, it’s likely that our overall skin color probably is a result of adaptation as well.
对于特定物种 ，比如斑马， 条纹因可作为伪装对进化有利。身上有条纹的动物更有可能生存下来，并把能产生条纹的基因传给后代。对于人类来说，情况显然不同。但是我们全身皮肤的颜色也可能是适应环境的结果。
- The Romans used natural pigments on their fabrics and walls. 古罗马人在织物和墙壁上使用天然颜料。 来自辞典例句
- The original white lead pigments have oxidized and turned black. 最初的白色铅质颜料氧化后变成了黑色。 来自辞典例句
- Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
- Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句
- After three days in Japan,the spinal column becomes extraordinarily flexible.在日本三天，就已经使脊椎骨变得富有弹性了。
- Your spinal column is made up of 24 movable vertebrae.你的脊柱由24个活动的脊椎骨构成。
- The boss has a large belly.老板大腹便便。
- His eyes are bigger than his belly.他眼馋肚饱。
- streaks of grey in her hair 她头上的绺绺白发
- Bacon has streaks of fat and streaks of lean. 咸肉中有几层肥的和几层瘦的。 来自《现代英汉综合大词典》
- The list is arranged in a random order.名单排列不分先后。
- On random inspection the meat was found to be bad.经抽查，发现肉变质了。
- Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
- He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。
- All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
- Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物
- I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
- He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
- Life has its own evolutionary process.生命有其自身的进化过程。
- These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
- The white fur of the polar bear is a natural camouflage.北极熊身上的白色的浓密软毛是一种天然的伪装。
- The animal's markings provide effective camouflage.这种动物身上的斑纹是很有效的伪装。
- You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
- Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
- An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。
- He was apparently much surprised at the news.他对那个消息显然感到十分惊异。