EUGENE M. MCCARTHY, PHD GENETICS
(Continued from the previous page)
Conclusion. Three main conclusions were reached in this section, each conflicting with neo-Darwinian theory's assumption that new forms treated as distinct species typically come into being as populations that gradually diverge in isolation:
Neo-Darwinism has claimed hybridization is unlikely to lead directly to the production of new stable forms of life, because hybrids, supposedly, are always too inviable and sterile to accomplish this. From the viewpoint of neo-Darwinism, hybrids are seen merely as entities selected against (because they are deemed less likely to survive and reproduce). This perception is peculiar, given that it is well known that many types of hybrids exhibit a vigor significantly in excess of their parents' (see Section 2). Moreover, as we have repeatedly seen, many hybrids are quite capable of producing offspring. It must be remembered, too, for any given category of organisms, the number of hybrid combinations can far exceed the number of different forms that the category contains. Therefore, even if most types of hybrids are inviable, there are so many different crosses and kinds of hybrids that a sufficient number of viable hybrids will be produced even if the hybrids produced by the great majority of crosses are inviable.
Among the conclusions reached in Section 5, a single fact is key: A broad survey of available evidence indicates forms of known origin are typically the products of stabilization processes. This fact is patently inconsistent with neo-Darwinism's claim that new types of organisms usually come into being gradually in isolation. Although it would be impossible to prove stable forms of life never come into existence via the gradual accumulation of favorable mutations in isolation, there certainly seems to be a dearth of evidence that they typically do. Scientific thought should be guided by observation. As Francis Bacon, the great proponent of induction, once said (The Advancement of Learning, 1605),
According to Bacon, then, our theories about how evolution typically occurs should be guided by what we have actually observed and know about the origins of new forms. Therefore, to the extent we can explain such origins without reference to reproductively isolated, gradual change, he would say that we should do so, since origins through such gradual changes are far more poorly documented than those occurring through stabilization processes.
Bacon's advice is consistent with the most basic philosophical rules used in judging theories. For example, Ockham's razor ("Vain to do with more what can be done with less") implies the best theory is the simplest one, that superfluous assumptions should be eliminated. Isaac Newton echoes this dictum in his First Rule of Reasoning in Philosophy, which says that
Stabilization processes are "true" in the sense that Newton intended because they are known to occur. We have already seen that many existing types of organisms are known beyond doubt to be the products of particular, well-characterized stabilization processes. On the other hand, the origin of new forms through the gradual accumulation of differences in reproductive isolation is a poorly documented phenomenon. Moreover, stabilization processes are a sufficient explanation for the origin of the typical form because, as we shall see in the next section, we know new forms typically do have an abrupt origin. Therefore, in accounting for the origins of the vast majority of living forms, the scenarios posited by neo-Darwinian theory are both insufficient and superfluous — stabilization theory provides a clearer, better-documented, and sufficient explanation. NEXT PAGE >>
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