Section outline

  • General

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  • 比较解剖学

    What you will learn
    ::你会学到什么

    • How comparative anatomy provides evidence for evolution
      ::比较解剖如何为进化提供证据
    • How embryos , vestigial structures , and are used to determine evolutionary relationships
      ::如何利用胚胎、残余结构以及确定进化关系

    A gorilla sitting in a natural setting, showcasing its hand and arm anatomy.

    Is this evidence of evolution?
    ::这是进化的证据吗?

    Take a close look at this gorilla hand. The similarities to a human hand are remarkable. Comparing anatomy, and characterizing the similarities and differences, provides evidence of evolution.
    ::仔细看一看这只大猩猩的手。 与人类手的相似之处是惊人的。 比较解剖学和辨别异同的特征,提供了进化的证据。

    Evidence from Living Species
    ::活物种的证据

    Just as did many years ago, today’s scientists study living to learn about evolution. They compare the anatomy, embryos, and DNA of modern organisms to understand how they evolved.
    ::正如许多年前所做的那样,今天的科学家们研究生命来学习进化。 他们比较了现代生物的解剖学、胚胎和DNA,以了解它们是如何进化的。

    Comparative Anatomy
    ::比较解剖学

    Comparative anatomy is the study of the similarities and differences in the structures of different species. Similar body parts may be homologies or analogies. Both provide evidence for evolution.
    ::比较解剖学是研究不同物种结构的相似性和差异,类似身体部分可能是人类学或类比,两者都为进化提供了证据。

    Homologous structures are structures that are similar in related organisms because they were inherited from a common ancestor . These structures may or may not have the same function in the descendants. The Figure  shows the hands of several different mammals . They all have the same basic pattern of . They inherited this pattern from a common ancestor. However, their forelimbs now have different functions.
    ::同族结构是相关生物中相似的结构,因为它们是从共同的祖先继承下来的。这些结构在后代身上可能具有或可能没有同样的功能。图中显示了几个不同的哺乳动物的手。它们都有相同的基本模式。它们从共同的祖先那里继承了这种模式。然而,它们的前宫现在有不同的功能。

    Forelimb bone structures in various mammals, showing homologous similarities.
    The forelimbs of all mammals have the same basic bone structure.

    Analogous structures are structures that are similar in unrelated organisms. The structures are similar because they evolved to do the same job, not because they were inherited from a common ancestor. For example, the wings of bats and , shown in the Figure , look similar on the outside. They also have the same function. However, wings evolved independently in the two groups of . This is apparent when you compare the pattern of bones inside the wings.
    ::类比结构结构在非关联生物中是相似的结构。 结构相似, 因为它们进化为同一工作, 不是因为它们是从共同祖先继承下来的。 例如, 蝙蝠的翅膀和图所示的蝙蝠的翅膀在外表看起来相似。 它们也有相同的功能。 但是, 翅膀在两组中独立演变。 当比较翅膀内骨头的形态时, 这很明显 。

    Comparison of bat and bird wing skeletons to illustrate analogous structures.
    The wings of bats and birds serve the same function. Look closely at the bones inside the wings. The differences show they developed from different ancestors.

    Comparative Embryology
    ::比较内脏学

    Comparative embryology is the study of the similarities and differences in the embryos of different species. Similarities in embryos are evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails (see the Figure  ). Most vertebrates, except for , lose their gill slits by . Some of them also lose their tail. In humans, the tail is reduced to the tail bone. Thus, similarities organisms share as embryos may be gone by adulthood. This is why it is valuable to compare organisms in the embryonic stage. 
    ::比较胚胎学是对不同物种胚胎的相似性和差异的研究。胚胎的相似性是常见祖先的证明。例如,所有脊椎胚胎都有刺片和尾巴(见图 )。大多数脊椎动物,除......外,都失去了刺片。有些脊椎动物还失去了尾巴。在人类中,尾巴被减为尾骨。因此,相似性生物作为胚胎的共性,可能随着成年而消失。这就是为什么在胚胎阶段比较生物是有价值的。

    Comparison of vertebrate embryos at various stages showing similarities in structure.
    A comparison of the embryos of different vertebrates.

    Vestigial Structures
    ::立体结构

    Structures like the human tail bone and whale pelvis are called vestigial structures . Evolution has reduced their size because the structures are no longer used. The human appendix is another example of a vestigial structure. It is a tiny remnant of a once-larger organ . In a distant ancestor, it was needed to digest food . Why do you think structures that are no longer used shrink in size? Why might a full-sized, unused structure reduce an organism’s fitness ?
    ::人类尾骨和鲸骨骨盆等结构被称为前置结构。 进化已经缩小了体积,因为结构不再使用。 人类附录是前置结构的又一个例子。 它是一个一度大器官的微小残余物。 在一个遥远的祖先,它需要消化食物。 为什么你认为那些不再使用的结构会缩小体积? 为什么一个完整、未使用的结构会降低一个有机体的健康状况?

    Summary
    ::摘要

    • Scientists compare the anatomy, embryos, and DNA of living things to understand how they evolved.
      ::科学家比较了生物的解剖学、胚胎和DNA 来了解它们是如何进化的。
    • Evidence for evolution is provided by homologous structures. These are structures shared by related organisms that were inherited from a common ancestor.
      ::进化的证据由同族结构提供,它们是从共同祖先继承下来的相关生物共有的结构。
    • Other evidence for evolution is provided by analogous structures. These are structures that unrelated organisms share because they evolved to do the same job.
      ::类似结构为演变提供了其他证据,这些结构是互不关联的有机体共有的,因为它们进化成同一种工作。
    • Comparing DNA sequences provided some of the strongest evidence of evolutionary relationships.
      ::DNA序列的比较为进化关系提供了一些最有力的证据。

    Review
    ::回顾

    1. What are vestigial structures? Give an example.
      ::什么是遗迹结构?举个例子。
    2. Compare homologous and analogous structures.
      ::比较同族和类似结构。
    3. Why do vertebrate embryos show similarities between organisms that do not appear in the adults?
      ::为什么脊椎胚胎在成人没有出现的生物之间显示出相似之处?
    4. Humans and apes have five fingers they can use to grasp objects. Do you think these are analogous or homologous structures? Explain.
      ::人类和猿类有五根手指可以用来捕捉物体。 你认为它们是相似的或同质的结构吗? 请解释 。
    5. What is the strongest evidence of evolution from a common ancestor?
      ::一个共同的祖先有什么最有力的进化证据?