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  • General

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  • 演变证据

    A diagram of a human skeleton highlighting the tailbone at the end of the spine.

    Why do you have a tail bone ?
    ::为什么你有尾骨?

    If you look closely at a skeleton, you might notice a triangular bone at the end of the spinal column. This is your tailbone. Why would you have a tailbone when you don't have a tail? You have a tailbone because your ancient ancestors did have a tail. These sorts of "left-over" structures support the theory of evolution.
    ::如果你仔细看一具骨骼, 你可能会注意到脊柱末端的三角骨。 这是你的尾骨。 为什么你没有尾巴时会有一个尾骨? 你有一个尾骨是因为你的祖先确实有尾巴。 这些“ 左侧” 结构支持进化理论。

    Structural Evidence
    ::结构性证据

    Even though two different species may not look similar, they may have similar internal structures that suggest they have a common ancestor . That means both evolved from the same ancestor organism a long time ago. Common ancestry can also be determined by looking at the structure of the organism as it first develops.
    ::尽管两种不同的物种看起来可能并不相似,但它们可能有着类似的内部结构,表明它们有一个共同的祖先。 这意味着两者都从很久以前的同一祖先生物体中演变而来。 共同的祖先也可以通过观察生物体最初形成的结构来确定。

    Vestigial Structures
    ::立体结构

    Some of the most interesting kinds of evidence for evolution are body parts that have lost their use through evolution ( Figure ). For example, most need their wings to fly. But the wings of an ostrich have lost their original use. Structures that have lost their use through evolution are called vestigial structures . They provide evidence for evolution because they suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose.
    ::一些最有趣的进化证据是那些在进化过程中失去用途的人体部分(图 ) 。 例如, 多数人需要翅膀飞翔。 但是, 食鸟的翅膀已经失去了最初的用途。 在进化过程中失去其用途的结构被称为隐形结构。 它们为进化提供了证据,因为它们表明有机体已经从使用结构转变为不使用结构,或将其用于不同的目的。

    Penguins do not use their wings, known as flippers, to fly in the air. However, they do use them to move in the water. The theory of evolution suggests that penguins evolved to use their wings for a different purpose. A whale’s pelvic bones, which were once attached to legs, are also vestigial structures. Whales are descended from land-dwelling ancestors that had legs.
    ::企鹅不会用翅膀 — — 即脚拨鼠 — — 在空中飞翔。 但是,它们确实利用翅膀在水中移动。 进化理论表明企鹅会进化为不同的目的使用翅膀。 鲸鱼的骨骼曾经与腿相连,但骨骼也是残余结构。 鲸鱼来自有腿的陆地祖先。

    Homologous structures are structures that have a common function and suggest common ancestry. For example, homologous structures include the limbs of mammals , such as bats , lions, whales, and humans, which all have a common ancestor. Different mammals may use their limbs for walking, running, swimming or flying. The method the mammal uses to move is considered a common function.
    ::例如,同族结构包括哺乳动物的四肢,如蝙蝠、狮子、鲸鱼和人类,它们都有共同的祖先。不同的哺乳动物可以用他们的四肢来行走、跑步、游泳或飞行。哺乳动物使用的移动方法被认为是一种常见的功能。

    A mole emerging from the soil, showing its claws and covered eyes.
    Moles live underground where they do not need eyes to find their way around. This mole’s eyes are covered by skin. Body parts that do not serve their original function are vestigial structures.

    Similar Embryos
    ::相似的胸膜

    Some of the oldest evidence of evolution comes from embryology , the study of how organisms develop. An embryo is an animal or plant in its earliest stages of development. This means looking at a plant or animal before it is born or hatched. Centuries ago, people recognized that the embryos of many different species have similar appearances. The embryos of some species are even difficult to tell apart. Many of these animals do not differ much in appearance until they develop further.
    ::一些最古老的进化证据来自胚胎学,即研究生物体是如何发育的。胚胎是处于早期发育阶段的动物或植物。这意味着在植物或动物出生或孵化之前先看植物或动物。在几个世纪前,人们认识到许多不同物种的胚胎有着相似的外观。有些物种的胚胎甚至难以分辨。许多这些动物在发育更深之前,外观没有多大差别。

    Some unexpected traits can appear in animal embryos. For example,  all vertebrate embryos have " gill slits" which are not actually gills. They connect the throat to the outside early in development but eventually close in many species; only in and larval do they contribute to the development of gills. In mammals, the tissue between the first gill slits forms part of the lower jaw and the bones of the inner ear.
    ::动物胚胎中可能会出现一些出乎意料的特征。 比如, 所有脊椎胚胎都有“ 断裂” , 这些“断裂”其实不是子。 它们将喉咙与发育早期的外部连接起来,但最终会在许多物种中接近; 只有在幼虫体内和幼虫中, 它们才有助于刺菌的发育。 在哺乳动物中, 最初的刺裂之间的组织构成下巴和内耳骨的一部分。

    The similarities between embryos suggests that these animals are related and have common ancestors. For example, humans did not evolve from chimpanzees. But the similarities between the embryos of both species suggest that we have an ancestor in common with chimpanzees. As our common ancestor evolved, humans and chimpanzees went down different evolutionary paths and developed different traits.
    ::胚胎之间的相似点表明这些动物是相互联系的,并且有着共同的祖先。例如,人类并不是从黑猩猩演变而来的。但这两种物种的胚胎之间的相似点表明,我们与黑猩猩有着共同的祖先。 随着我们共同的祖先的进化,人类和黑猩猩沿着不同的进化道路走下去,形成了不同的特征。

     

     

    Summary
    ::摘要

    • Vestigial structures, or structures that have lost their use through evolution, are important evidence of evolution.
      ::历史结构,或因演变而失去使用力的结构,是演变的重要证据。
    • Studying the embryos of organisms also provides evidence that two very different animals could have descended from a common ancestor.
      ::研究生物胚胎也提供了证据,证明两种截然不同的动物本可以从共同的祖先中降生。

    Review
    ::回顾

    1. What is a vestigial structure? Give an example.
      ::什么是遗迹结构?举个例子。
    2. How does embryology provide evidence for evolution?
      ::胚胎学如何为进化提供证据?
    3. Give an example of a structure that is present in human embryos, but has disappeared by birth.
      ::举一个例子,说明人类胚胎中存在的结构,但因出生而消失。