ABSTRACT
In order for a mutation-or a heresy-to survive, to have impact, it must emerge into a supportive environment. A mutation or heresy has to live long enough in the environment it would re-make in order for the re-making to take place. A land mammal that created an offspring with gills would be giving birth to a dead end-unless the mammal happened to already live near the water, or unless the mammal happened to be human in the later part of the twentieth century, when we might conceivably have the technological wherewithal to produce a suitable environment for such a child. For most mutations and heresies, such favorable circumstances are not at hand.
