This reassessment of the evidence goes against a saltationist
scenario where a single catastrophic mutation in a single individual would suddenly give rise to language, and suggests that a gradual accumulation of biological and cultural innovations is much more plausible.
Grafe shows how numerous poems focus on suddenness and sudden change in nature; even the poet's fondness for the sonnet form, because of its dependence on the volta, may derive from his saltationist
For him, essentially, it is a theory of differential rates of evolution; a modification of Darwin's gradualist model, not a saltationist
Unlike Darwin, Huxley was a saltationist
, one who believes evolutionary change occurs not over the course of thousands of generations but in catastrophic leaps of mutation in single generations.