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1 The Transformations of Darwinism No sphere of knowledge is free of controversy, and science is no exception. If anyone imagines that scientists are dispassionate and impartial people, discussing theories and ideas unemotionally in the cool clear light of reason , they have been seriously misled. Passion and fervor accompany all worthwhile scientific discussions. This is particularly evident when the discussion is about something like the theory of evolution, which bears directly on human history and our relationships with each other and the world around us. Because such discussions are tied up with ideas about “human nature,” and impinge on moral judgments and ethical issues, they can be very emotional, as well as intellectually exciting. We are not referring here to the arguments between people who accept evolutionary ideas and those who prefer to believe that the world was created by God in six real or metaphorical days. Such arguments have considerable sociological and political interest, but they are not really part of science, so we need say no more about them. What we are referring to are the heated discussions that have gone on and still go on among the evolutionary biologists themselves. When you read popular accounts of new discoveries in biology, you often come across phrases such as “according to Darwin’s theory of evolution . . . ” or “evolutionary biologists explain this as . . . ,” or “the evolutionary explanation is. . . . ” You get the impression that there is a tidy, well-established theory of evolution—Darwin’s theory of natural selection —which all biologists accept and use in the same way. The reality is very different, of course. Ever since Darwin’s book On the Origin of Species appeared in 1859, scientists have been arguing about whether and how his theory of evolution works. Can competition between individuals with heritable differences in their ability to survive and reproduce lead to new features? Is natural selection the explanation of all evolutionary change? Where does all the hereditary variation on which Darwin’s theory depends 10 Chapter 1 come from? Can new species really be produced by natural selection? Darwin ’s book was crammed with observations that supported his theory, but there were some glaring gaps in his evidence. The biggest was that he could say little about the nature and causes of hereditary variation. Right from the outset, even those who accepted Darwin’s evolutionary theory questioned its completeness and sufficiency, and struggled to try to find answers to the questions it raised about heredity and variation. In subsequent decades, as new discoveries were made and new theoretical approaches were developed, the debates continued. Existing ideas were constantly being challenged and revised, with the result that profound changes have occurred in the ways the concepts of evolution and heredity have been understood.1 Today, most biologists see heredity in terms of genes and DNA sequences, and see evolution largely in terms of changes in the frequencies of alternative genes. We doubt that this will be the situation in twenty years’ time. More and more biologists are insisting that the concept of heredity that is currently being used in evolutionary thinking is far too narrow, and must be broadened to incorporate the results and ideas that are coming from molecular biology and the behavioral sciences. We share this view, and in later chapters will explain why. But before doing so, we want to outline some of the history of evolutionary thinking over the last 150 years to see how the present gene-centered version of Darwinian theory came into being, and what it means for today’s evolutionary biologists. Since we cannot even attempt to look at all of the many twists and turns in the pathway of ideas that led to the present position, we will focus on some of the major turning points and the arguments that influenced the direction taken. Darwin’s Darwinism Darwin summarized his view of evolution in the last paragraph of The Origin . In what was for him an unusually poetic paragraph, he wrote: 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...

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Additional Information

ISBN
9780262322676
Related ISBN
9780262525848
MARC Record
OCLC
878130644
Pages
576
Launched on MUSE
2014-04-24
Language
English
Open Access
No
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