研究生英语精读教程第三版下第三单元

Unit Three Evolution and Natural Selection

［1］The idea of evolution* was known to some of the Greek philosophers. By the time of Aristotle①, speculation* had suggested that more perfect types had not only followed less perfect ones but actually had developed from them. But all this was guessing; no real evidence was forthcoming*. When, in modern times, the idea of evolution was revived*, it appeared in the writings of the philosophers – Bacon①, Descartes②, Leibniz③ and Kant④. Herbert Spencer① was preaching* a full evolutionary doctrine* in the years just before Darwin's② book was published, while most naturalists would have none of it. Nevertheless a few biologists ran counter to the prevailing* view, and pointed to such facts as the essential unity of structure in all warm-blooded animals.

［2］The first complete theory was that of Lamarck①(1744～1829), who thought that modifications* due to environment, if constant and lasting, would be inherited and produce a new type. Though no evidence for such inheritance was available, the theory gave a working hypothesis* for naturalists to use, and many of the social and philanthropic* efforts of the nineteenth century were framed on the tacit* assumption that acquired improvements would be inherited.

［3］But the man whose book gave both Darwin and Wallace the clue was the Reverend* Robert Malthus① (1766～1834),sometime curate* of Albury in Surrey. The English people were increasing rapidly, and Malthus argued that the human race tends to outrun its means of subsistence* unless the redundant* individuals are eliminated. This may not always be true, but Darwin writes:

［4］In October 1838,I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on, from long continued observation of the habits of animals and plants, it at once struck* me that, under these circumstances, favorable variations* would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of new species. Here then I had a theory by which to work.

［5］Darwin spent twenty years collecting countless facts and making experiments on breeding* and variation in plants and animals. By 1844 he had convinced himself that species are not immutable*, but worked on to get further evidence. On 18 June 1858 he received from Alfred Russell Wallace a paper written in Ternate, in the space of three days after reading Malthus's book. Darwin saw at once that Wallace had hit upon the essence of his own theory. Lyell① and Hooker②