Not a radical. Process is natural selection, distributed by migration. Contrast Darwin and J.B. Lamarck. Darwin did not know about genetics. Long necks more advantageous for survival.
Species get better and better adapted.
Human beings included in evolution, too. Responses to Darwin's theory a. favorable reviews. Huxley's enthusiasm, another opportunity to attack religion. Industrialism, physics and biology, ethics. Nature is a little cruel, that she may be very kind.