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  • 生命进化 - 高级

    What is a Dinosaur?
    ::什么是恐龙?

    A dinosaur is from a class of . They are diverse reptiles that first appeared during the Triassic period, approximately 230 million years ago, and were the dominant land vertebrates for 135 million years, from the beginning of the Jurassic period (about 200 million years ago) until they went extinct, at the end of the Cretaceous period, 65.5 million years ago. They are very strong evidence of evolution, the change in over time. Dinosaurs went extinct because they could not adapt to a catastrophic environmental change. The ability to adapt to a changing environment is a key feature of , the process of evolution.
    ::恐龙是来自某类恐龙。它们是在三亚西克时期(大约2.3亿年前)首次出现的多种爬行动物,从侏罗西克时期(大约2亿年前)开始(大约2亿年前)到6 550万年前的白鲸期结束时灭绝,是1.35亿年中占主导地位的脊椎动物。它们是演化和随时间变化的有力证据。恐龙之所以灭绝,是因为无法适应灾难性的环境变化。适应变化环境的能力是进化过程的一个关键特征。

    Evolution of Life
    ::生命的演变

    Evolution is the process by which of organisms change over time. It is a process that began on this planet well over 3.5 billion years ago and continues to this day, as populations of organisms continue to change.
    ::进化是生物随时间而变化的过程。 这是一个35亿多年前在这个星球上开始的过程,并且一直持续到今天,因为生物的数量在继续变化。

    Evolution occurs as organisms acquire and pass on new traits from one generation to the next generation. Its occurrence over large stretches of time explains the origin of new species and the great diversity of the biological world. Extant species are related to each other through common descent and products of evolution over billions of years. Analysis of the of different organisms indicates there is a similarity among very different organisms in the that helps make and other molecules. This genetic code is used by all known forms of life on Earth. The theory of evolution suggests that the genetic code was established very early in the , and some studies suggest it was established soon after the . The timeline of the evolution of life, shown in the Figure  , outlines the major events in the of life.
    ::随着生物从一代到下一代获得和传递新的特性,进化过程就发生在生物从一代到下一代的进化过程中,它发生的时间很长,解释了新物种的起源和生物世界的巨大多样性。外来物种通过共同的血统和数十亿年的进化产物相互联系。对不同生物体的分析表明,在帮助制造和其他分子的不同生物体之间存在相似之处。这个遗传代码被地球上所有已知生命形式所使用。进化理论表明,遗传代码是在...的早期建立的,有些研究表明,它是在...之后不久建立的。图中显示的生命进化时间表概述了生命中的主要事件。

    According to recent estimates, the Earth is about 4.5 billion years old. Most of the evidence for an ancient Earth is contained in the rocks that form the Earth's crust. The rock layers themselves, like pages in thick history book, record the surface-shaping events of the past. Buried within them are traces of life, including the plants and animals that evolved from organic structures that existed perhaps as many as 3 to 3.5 billion years ago.

    How do scientists know Earth is so old? The answer is in the rocks. Contained in rocks that were once molten, shown in the Figure  , are chemical elements that act like an atomic clock. The atoms of different forms of elements (called isotopes ) break down at different rates over time. Parent isotopes within these rocks decay at a predictable rate to form daughter isotopes. By determining the relative amounts of parent and daughter isotopes, the age of these rocks can be calculated—forming the so-called atomic clock.
    ::科学家如何知道地球如此老旧?答案在岩石中。在图中显示的曾经熔化的岩石中,含有化学元素,它们与原子钟一样。不同形式元素的原子(所谓的同位素)随着时间的推移以不同的速度破裂。这些岩石中的母同位素以可预测的速度衰减,形成女同位素。通过确定母同位素和女同位素的相对数量,这些岩石的年代可以计算为所谓的原子钟。

    Thus, the results of studies of rock layers ( stratigraphy ), and of ( paleontology ), along with the ages of certain rocks as measured by atomic clocks ( geochronology ), indicate that the Earth is over 4.5 billion years old, with the oldest known rocks being 3.96 billion years old. More about the history of life on Earth will be discussed in History of Life: Introduction (Advanced) concept.
    ::因此,对岩石层(地表学)和(地表学)的研究结果,以及以原子钟(地表学)测量的某些岩石的年代表明,地球已超过45亿年,已知最古老的岩石为39.6亿年。 关于地球上生命史的更多讨论将在《生命史:入门(先进)概念》中讨论。

    Molten rock, called lava, is expelled by a volcano during an eruption. The lava will eventually cool to become solid rock. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F). Not all types of rocks come from cooled lava, but many do.
    Evolution - Timeline
     This timeline shows the history of life on Earth. In the entire span of time, humans are a relatively new addition.

    History of Evolutionary Thought
    ::进进进思想史

    The theory of evolution by natural selection was proposed at about the same time by both Charles Darwin and Alfred Russel Wallace , shown in the Figure , and was set out in detail in Darwin's 1859 book On the . Natural selection is a process that causes heritable traits that are helpful for survival and to become more common, and harmful traits, or traits that are not helpful or advantageous for survival to become more rare in a population of organisms. This occurs because organisms with advantageous traits are more "fit" to survive in a particular environment and have "adapted" to the conditions of that environment. These individuals will have greater reproductive success than organisms less fit for survival in the environment. This will lead to an increase in the number of organisms with the advantageous trait(s) over time. Over many generations, adaptations occur through a combination of successive, small, random changes in traits, and natural selection of those variants best-suited for their environment. Natural selection is one of the cornerstones of modern biology .
    ::自然选择是一个过程,它带来有利于生存的遗传性特征,并变得更为常见,有害特性,或不利于生存的特征,或对于生物群中生存更为罕见的特征。 发生这种情况的原因是,具有有利特性的有机体更“适合”在特定环境中生存,并且“适应”了该环境的条件。 自然选择是现代生物学的基石之一。 自然选择是现代生物学的基石之一。

    Charles Darwin, left (1809-1882), and Alfred Russel Wallace, right (1823-1913). Both scientists proposed a process of evolution by natural selection at about the same time. However, Darwin is primarily associated with the theory of evolution by natural selection due to his abundance of data.

    The theory of evolution encountered initial resistance from religious authorities who believed humans were divinely set apart from the . There was considerable concern about Darwin’s proposal of an entirely scientific explanation for the origin of humans. Many people found such an explanation to be in direct conflict with their religious beliefs. A caricature of Darwin as a monkey, shown in the Figure  , reflects the controversy that arose over evolutionary theory. In the 1930s, Darwinian natural selection was combined with to form the basis of modern evolutionary theory.
    ::进化理论在最初受到宗教权威的抵制,他们认为人类被神性地分开了。 对于达尔文关于完全科学地解释人类起源的建议,人们相当关注。 许多人认为这种解释与其宗教信仰直接冲突。 图中显示达尔文的漫画反映了关于进化理论的争议。 在1930年代,达尔文自然选择与现代进化理论的基础相结合。

    An 1871 caricature portraying Darwin with an ape body and the bushy beard he grew in 1866. Such satire reflected the cultural backlash against evolution.

    The identification of DNA as the genetic material by Oswald Avery and colleagues in the 1940s, as well as the publication of the structure of DNA by James Watson and Francis Crick in 1953, demonstrated the physical basis for inheritance. Since then, genetics and molecular biology have become core aspects of evolutionary biology.
    ::1940年代Oswald Avery和同事将DNA确定为遗传材料,1953年James Watson和Francis Crick公布DNA结构,都表明了继承的物理基础。 从那时起,遗传学和分子生物学就成为进化生物学的核心方面。

    Currently, the study of evolutionary biology involves scientists from fields as diverse as biochemistry , ecology , genetics, and physiology , and evolutionary concepts are used in even more distant disciplines such as psychology, medicine, philosophy, and computer science .
    ::目前,进化生物学研究涉及来自生物化学、生态、遗传学和生理学等不同领域的科学家,进化概念被用于更遥远的学科,如心理学、医学、哲学和计算机科学。

    Misconceptions About Evolution
    ::对进化的误解

    The following list includes some common misconceptions about evolution.
    ::下表列出了对演变的一些常见误解。

    • The term evolution describes the changes that occur in populations of living organisms over time. Describing these changes does not address the origin of life. The two are commonly and mistakenly confused. Biological evolution likewise says nothing about cosmology, the Big Bang , or where the universe, galaxy, solar system, or Earth came from.
      ::进化一词描述了生物生物群体随时间的变化。描述这些变化并不涉及生命的起源。这两种变化通常被错误地混淆。 生物进化同样没有提及宇宙学、大爆炸或宇宙、星系、太阳系或地球的来源。
    • Humans did not evolve from chimpanzees or any other modern ape; instead, they share a common ancestor that existed around 7 million years ago.
      ::人类没有从黑猩猩或任何其他现代猿类进化而来;相反,它们拥有一个大约700万年前就存在的共同祖先。
    • The process of evolution is not necessarily slow. Millions of years are not required to see evolution in action. Indeed, it has been observed multiple times under both controlled conditions and in nature.
      ::进化过程不一定缓慢,数以百万计的年数并不需要看到行动的演变,事实上,在受控制的条件和性质下,都多次观察到了这种演变。
    • Evolution is not a progression from "lower" to "higher" forms of life, and it does not increase in complexity. For example, have simpler structures and a smaller amount of genetic material than humans do. This does not mean, however, that bacteria are “less evolved” than humans are. Bacteria have evolved over many millions of years and are well-adapted to their own environments.
      ::进化并不是从“低”到“高”生命的进化,也不增加复杂性。 比如,结构比人类简单,遗传物质数量也比人类少。 但这并不意味着细菌比人类“少进化 ” 。 细菌已经演化了数百万年,适应了自己的环境。

    After Darwin
    ::达尔文之后

    Since Darwin's time, scientists have gathered a more complete , including microorganisms and chemical fossils. These fossils have supported and added more information to Darwin's theories. However, the age of the Earth is now held to be much older than Darwin thought. Researchers have also uncovered some of the preliminary mysteries of the mechanism of heredity as carried out through genetics and DNA, which were areas unknown to Darwin. Another growing subject is the study of , which looks at how different organisms have similar body structures. Molecular biology studies of slowly changing genes reveal an evolutionary history that is consistent with fossil and anatomical records.
    ::自达尔文时代以来,科学家们收集了更完整的信息,包括微生物和化学化石。这些化石支持达尔文的理论并增加了更多的信息。然而,现在,地球的时代被认为比达尔文想象的要古老得多。研究人员还发现了遗传机制的一些初步奥秘,即通过遗传学和DNA进行遗传学和遗传学机制,达尔文不知道这些区域。另一个日益增长的主题是研究不同的生物体结构如何相似。关于缓慢变化的基因的分子生物学研究揭示了一种与化石和解剖学记录相一致的进化史。

    Summary
    ::摘要

    • Analysis of the DNA of different organisms indicates that there is a similarity in the genetic codes that help make proteins and other molecules in very different organisms.
      ::对不同生物体的DNA分析表明,遗传编码存在相似之处,有助于在非常不同的生物体中制造蛋白质和其他分子。
    • The theory of evolution by natural selection is based on the concept of the survival of the fittest, where individuals with beneficial traits are better able to survive and reproduce in the environment in which they live.
      ::自然选择的进化理论基于适者生存的概念,在这种概念中,具有有益特征的个人能够更好地在他们生活的环境中生存和繁殖。

    Review
    ::回顾

    1. What is evolution and natural selection?
      ::什么是进化和自然选择?
    2. Outline the formation of modern evolutionary theory.
      ::描述现代进化理论的形成
    3. How have more recent scientific findings fit with evolutionary theory since Darwin’s time?
      ::自达尔文时代以来,最近的科学发现如何与进化理论相适应?
    4. What are the misconceptions about evolution?
      ::进化的错误观念是什么?
    5. Large animals are more evolved than single-celled organisms such as bacteria. Do you agree with this statement? Explain your answer.
      ::大型动物的进化比细菌等单细胞生物的进化要多。 您同意这个说法吗 ? 请解释您的答复 。