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  • As this whole volume is one long argument, it may be convenient to the reader to have

  • the leading facts and inferences briefly recapitulated.

  • That many and grave objections may be advanced against the theory of descent with modification

  • through natural selection, I do not deny. I have endeavoured to give to them their full

  • force. Nothing at first can appear more difficult to believe than that the more complex organs

  • and instincts should have been perfected not by means superior to, though analogous with,

  • human reason, but by the accumulation of innumerable slight variations, each good for the individual

  • possessor. Nevertheless, this difficulty, though appearing to our imagination insuperably

  • great, cannot be considered real if we admit the following propositions, namely, -- that

  • gradations in the perfection of any organ or instinct, which we may consider, either

  • do now exist or could have existed, each good of its kind, -- that all organs and instincts

  • are, in ever so slight a degree, variable, -- and, lastly, that there is a struggle for

  • existence leading to the preservation of each profitable deviation of structure or instinct.

  • The truth of these propositions cannot, I think, be disputed.

  • Turning to geographical distribution, the difficulties encountered on the theory of

  • descent with modification are grave enough. All the individuals of the same species, and

  • all the species of the same genus, or even higher group, must have descended from common

  • parents; and therefore, in however distant and isolated parts of the world they are now

  • found, they must in the course of successive generations have passed from some one part

  • to the others. We are often wholly unable even to conjecture how this could have been

  • effected. Yet, as we have reason to believe that some species have retained the same specific

  • form for very long periods, enormously long as measured by years, too much stress ought

  • not to be laid on the occasional wide diffusion of the same species; for during very long

  • periods of time there will always be a good chance for wide migration by many means. A

  • broken or interrupted range may often be accounted for by the extinction of the species in the

  • intermediate regions. It cannot be denied that we are as yet very ignorant of the full

  • extent of the various climatal and geographical changes which have affected the earth during

  • modern periods; and such changes will obviously have greatly facilitated migration.

  • On this doctrine of the extermination of an infinitude of connecting links, between the

  • living and extinct inhabitants of the world, and at each successive period between the

  • extinct and still older species, why is not every geological formation charged with such

  • links? Why does not every collection of fossil remains afford plain evidence of the gradation

  • and mutation of the forms of life? We meet with no such evidence, and this is the most

  • obvious and forcible of the many objections which may be urged against my theory. Why,

  • again, do whole groups of allied species appear, though certainly they often falsely appear,

  • to have come in suddenly on the several geological stages? Why do we not find great piles of

  • strata beneath the Silurian system, stored with the remains of the progenitors of the

  • Silurian groups of fossils? For certainly on my theory such strata must somewhere have

  • been deposited at these ancient and utterly unknown epochs in the world's history.

  • I can answer these questions and grave objections only on the supposition that the geological

  • record is far more imperfect than most geologists believe. It cannot be objected that there

  • has not been time sufficient for any amount of organic change; for the lapse of time has

  • been so great as to be utterly inappreciable by the human intellect. The number of specimens

  • in all our museums is absolutely as nothing compared with the countless generations of

  • countless species which certainly have existed. We should not be able to recognise a species

  • as the parent of any one or more species if we were to examine them ever so closely, unless

  • we likewise possessed many of the intermediate links between their past or parent and present

  • states; and these many links we could hardly ever expect to discover, owing to the imperfection

  • of the geological record. Numerous existing doubtful forms could be named which are probably

  • varieties; but who will pretend that in future ages so many fossil links will be discovered,

  • that naturalists will be able to decide, on the common view, whether or not these doubtful

  • forms are varieties? As long as most of the links between any two species are unknown,

  • if any one link or intermediate variety be discovered, it will simply be classed as another

  • and distinct species. Only a small portion of the world has been geologically explored.

  • Only organic beings of certain classes can be preserved in a fossil condition, at least

  • in any great number. Widely ranging species vary most, and varieties are often at first

  • local, -- both causes rendering the discovery of intermediate links less likely.

  • It is interesting to contemplate an entangled bank, clothed with many plants of many kinds,

  • with birds singing on the bushes, with various insects flitting about, and with worms crawling

  • through the damp earth, and to reflect that these elaborately constructed forms, so different

  • from each other, and dependent on each other in so complex a manner, have all been produced

  • by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction;

  • inheritance which is almost implied by reproduction; Variability from the indirect and direct action

  • of the external conditions of life, and from use and disuse; a Ratio of Increase so high

  • as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing

  • Divergence of Character and the Extinction of less-improved forms. Thus, from the war

  • of nature, from famine and death, the most exalted object which we are capable of conceiving,

  • namely, the production of the higher animals, directly follows. There is grandeur in this

  • view of life, with its several powers, having been originally breathed into a few forms

  • or into one; and that, whilst this planet has gone cycling on according to the fixed

  • law of gravity, from so simple a beginning endless forms most beautiful and most wonderful

  • have been, and are being, evolved.

As this whole volume is one long argument, it may be convenient to the reader to have


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B1 中級

物種的起源 (Charles Darwin's "The Origin of Species")

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    潘宇將 發佈於 2021 年 01 月 14 日