William H. Calvin is an American theoretical neurophysiologist and professor at the University of Washington in Seattle. He is known for popularizing neuroscience and evolutionary biology, including the hybrid of those two fields, neural Darwinism. He relates abrupt climate change to human evolution and more recently has been working on global climate change issues.

Neural Darwinism is a biological, and more specifically Darwinian and selectionist, approach to understanding global brain function, originally proposed by American biologist, researcher and Nobel-Prize recipient Gerald Maurice Edelman. Edelman's 1987 book Neural Darwinism introduced the public to the theory of neuronal group selection (TNGS) – which is the core theory underlying Edelman's explanation of global brain function.