"Goldschmidt suggested that major evolutionary changes could occur by sudden macromutations, sudden shifts, so great that a child could be classified as a member of a different species from its parents. I think it is very unlikely that any such process has been important in evolution, mainly because most mutations are bad, and the bigger the mutation the more bad they are. There is no need to postulate any such mechanism because the slow incremental step-by-step cumulative evolution of micromutations is fully adequate to explain all evolution."

Richard Dawkins