有一种理论认为，两足动物的进化与核心家庭有关：一夫一妻制的父母合作照顾他们的后代。
One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring.
马是分阶段进化的，每一阶段都几乎保持了数百万年的不变，而最终被一种独特的新型马所取代。
Horses evolved in discrete steps, each of which persisted almost unchanged for millions of years and was eventually replaced by a distinctive newer model.
它们进化出了一种特殊的“加热器”，由经过改造的肌肉组织构成，可以温暖眼睛和大脑，使这些关键器官保持最佳状态。
They have evolved special "heaters" of modified muscle tissue that warm the eyes and brain, maintaining peak performance of these critical organs.
今天，让我们来看看一种爬行动物，一种在过去七千万年里没有进化很多的食肉动物。
For today, let's look at a reptile, a predator that hasn't evolved much in the last seventy million years.
例如，彼得·谢尔登对于三叶虫的研究，那是一种已灭绝的身体分节的海洋生物，他的研究让我们得以一窥三百万年以来一个海洋环境的进化过程。
For example, Peter Sheldon' s studies of trilobites, a now extinct marine animal with a segmented body, offer a detailed glimpse into three million years of evolution in one marine environment.
那么，为什么动物会进化出一种似乎会危及它们自身的特性呢？
So why would animals evolve a characteristic that seems to endanger them?
也许这是打哈欠进化为社交线索的一种暗示——“到我们大家睡觉的时间了”。
That may be a hint that yawn evolved as a social cue—"time for us all to go to bed".
一旦人类被看作是在进化过程中发展起来的，那么“人类是包含在他的本质中的一种物质”的观点似乎就站不住脚了。
Once man came to be seen as developing in the process of evolution, the idea of a substance which is contained in his essence seemed untenable.
它可能是一种树，今天在澳大利亚生长的其他树就是从它进化而来的。
It's probably a kind of tree from which other trees that grow in Australia today evolved.
陨石的撞击代表了一种可能导致全球性灾难并严重影响地球上所有生命进化的机制。
Impacts by meteorites represent one mechanism that could cause global catastrophes and seriously influence the evolution of life all over the planet.
一种完全无毒的蛇家族，王蛇，也进化出了能中和响尾蛇毒液的血清。
One family of completely harmless snakes, the kingsnake, has also evolved serum that neutralizes rattlesnake venom.
这种结合不对称、解剖学和偶然性的进化论机制并未提供一种充分的解释，以说明蜗牛的右旋何以会成为主要的旋向。
This evolutionary mechanism combining dissymmetry, anatomy, and chance does not provide an adequate explanation of why right-handedness should have become predominant.
研究结果为一种长期存在的假设提供了最好的证据，即单半球睡眠是在生物寻找敌人的过程中进化而来的。
The results provide the best evidence for a long standing supposition that single hemisphere sleep evolved as creatures scanned for enemies.
在这里，进化理论必须遵从一种基于明确的发展机制的理论，这种机制可以支持右撇子或左撇子。
Here, the evolutionary theory must defer to a theory based on an explicit developmental mechanism that can favor either right-or left-handedness.
在这里，进化理论必须遵从一种基于明确的发展机制的理论，这种机制可以支持右撇子或左撇子的现象。
Here, the evolutionary theory must defer to a theory based on an explicit developmental mechanism that can favor either right or left-handedness.
在这里，进化理论必须遵从一种基于明确的发展机制的理论，这种机制既可以支持右撇子，也可以支持左撇子。
Here, the evolutionary theory must defer to a theory based on an explicit developmental mechanism that can favor either right-handedness or left-handedness.
哭泣作为一种情感的表达是人类独有的，这在人类进化和人类文化的发展中发挥了重要的作用。
Crying as an expression of feeling is unique to humans and has played an essential role in human evolution and the development of human cultures.
但哭泣作为一种情感的表达是人类独有的，这在人类进化和人类文化的发展中发挥了重要的作用。
But crying as an expression of feeling is unique to humans and has played an essential role in human evolution and the development of human cultures.
除了相互交错相扣的地下走茎外，它们还有另一种进化……嗯，我们又回到了反渗透。
In addition to the interlocking underground rhizomes, they have yet another adaptation, and it is ... well, we are back to reverse osmosis again.
大多数研究人员希望发现从一个物种到另一个物种的两种转变模式都在进化中起作用。
Most researchers expect to find that both modes of transition from one species to another are at work in evolution.
在去年发表的一篇论文中，耶鲁大学的生物学家冈特·瓦格纳报告了一种名为“Bachia”的南美蜥蜴的进化史。
In a paper published last year, biologist Gunter Wagner of Yale University reported some work on the evolutionary history of a group of South American lizards called Bachia.
他们都像从一种温和的，可爱的祖先进化来的，这种动物眼睛大大的，嘴唇很薄，几乎没有鼻子，带着毛茸茸的绒毛。
They seem all to be descended from the same bland and adorable ancestor, a wide-eyed, thin-lipped soul with barely any nose and a mane of bouclé hair.
这是在追踪如何进化出一种可以帮助我们应对压力的蛋白质后，得出的研究结论。
That's the conclusion of a study tracing how we evolved a protein that helps us respond to stress.
使用“达尔文选择”或“达尔文进化论”这样的短语意味着工作中必须有另一种进化形式，一种可以用另一个形容词来描述的过程。
Using phrases like "Darwinian selection" or "Darwinian evolution" implies there must be another kind of evolution at work, a process that can be described with another adjective.
这种默认模式可能通过我们狩猎和聚会时警告危险的出现来带给我们一种进化的优势。
This default mode probably gave us an evolutionary advantage by making us alert to dangers while we were hunting and gathering.
有一种进化理论认为，流泪可能被演化为一个有价值的信号，因为它只能让实际上最靠近我们的人可以看到我们在流泪。
One theory is that crying may have evolved as a kind of signal — a signal that was valuable because it could only be picked up by those closest to us who could actually see our tears.
其完全不同的形状反映出这两种进程的进化参数。
The shapes are very dissimilar, reflecting the evolutionary parameters of each process.
因为所有三个关键阶段——复制、改变和选择——都由大脑完成，所以这是一种新型进化过程。
This is a new evolutionary process because all of the three critical stages - copying, varying and selection - are done by those brains.
学者说，新奇是另一种进化策略：各式各样的基因组合是生存的最优选择。
Some scholars say novelty is yet another evolutionary strategy: varied genetic combinations are optimal for survival.
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