Is Macroevolution Feasible?
I have postulated three requirements for macroevolution, in addition to those necessary for the microevolutionary mechanism: emergence of new functionalities, improvement by positive mutations, and a reasonable prevalence of such constructive mutations to form progressive chains of improvements. When a new function is to emerge, its minimal functionality must arise accidentally, before it can be selected. The possible emergence of a new functionality in a hidden state (in a temporary pseudogene or under cover of a different function) does not change this requirement, since the development of a function which is not expressed must proceed by means of a random walk. Once a minimal function is present, its further improvement by single-step mutations, under the influence of natural selection, is conceivable. But at least the original emergence of this new function must correspond to a macroevolutionary step, which is much more difficult, as has been shown. Every one of the many different
