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  3. Darwin discovered two major forces in evolution—natural selection and sexual selection and wrote three radical scientific master

Darwin discovered two major forces in evolution—natural selection and sexual selection and wrote three radical scientific master

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问题     Darwin discovered two major forces in evolution—natural selection and sexual selection and wrote three radical scientific masterpieces, "On the Origin of Species"(1859), "The Descent of Man and Selection in Relation to Sex"(1871)and " The Expression of the Emotions in Man and Animals"(1872).
    The "Origin", of course, is what he is hest known for. This volume, colossal in scope yet minutely detailed, laid the foundations of modern biology. 【F1】Here, Darwin presented extensive and compelling evidence that all living beings—including humans have evolved from a common ancestor, and that natural selection is the chief force driving evolutionary change.【F2】Sexual selection, he argued, was an additional force, responsible for spectacular features like the tail feathers of peacocks that are useless for(or even detrimental to)survival but essential for seduction.
    【F3】Before the "Origin", similarities and differences between species were mere curiosities; questions as to why a certain plant is succulent like a cactus or deciduous like a maple could be answered only, "Because". Biology itself was nothing more than a vast exercise in catalog and description. After the "Origin", all organisms became connected, part of the same, profoundly ancient, family tree. Similarities and differences became comprehensible and explicable. In short, Darwin gave us a framework for asking questions about the natural world, and about ourselves.
    He was not right about everything. How could he have been? Famously, he didn’t know how genetics works; as for DNA—well, the structure of the molecule wasn’t discovered until 1953. So today’s view of evolution is much more nuanced than his.【F4】We have incorporated genetics, and expanded and refined our understanding of natural selection, and of the other forces in evolution.
    But what is astonishing is how much Darwin did know, and how far he saw. His imagination told him, for example, that many female animals have a sense of beauty that they like to mate with the most beautiful males. For this he was ridiculed. But we know that he was right. Still more impressive: he was not afraid to apply his ideas to humans. He thought that natural selection had operated on us, just as it had on fruit flies and centipedes.
    As we delve into DNA sequences, we can see natural selection acting at the level of genes. Our genes hold evidence of our intimate associations with other beings, from cows to malaria parasites and grains.【F5】The latest research allows us to trace the genetic changes thai differentiate us from our primate cousins, and shows that large parts of the human genome bear the stamp of evolution by means of natural selection.
【F3】
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答案在《物种起源》发表之前，物种之间的相似性与差异性至多只能激发人们的好奇。诸如为什么某种植物，比如仙人掌。是多汁植物，或者为什么枫树每年落叶这样的问题，答案只能是“没有为什么”。生物学本身只不过是对浩瀚资料的编目和描述。
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