问答题 Such non adaptive change evolution may be quite rare. But geologic time is so vast, as Darwin himself pointed out, that species pass through countless generations over millions of years. Therefore even the rare event may become probable, given enough time. This reasoning has led some evolutionary biologists to think that many of the evolutionary changes we see resulted from nonadaptive changes controlled by genetic drift rather than by natural selection. Many species, for example, originate the small populations. Sometimes just a few individuals that migrate to an island, thus becoming isolated from the parent species, develop into a new species.无