First edition.

Inscribed by the author on the front endpaper: "For .... My very best fan. With best wishes & thanks for your interest / Steve Gould".

Stephen J. Gould (1941-2002) was an American paleontologist, evolutionary biologist and historian of science. He was also a leading writer of popular science. His most noted contribution to his field was the theory of punctuated equilibrium [which posits that evolution does not proceed at a steady rate but by periods of equilibrium punctuated by sudden leaps ahead].

First editions of this, Gould's second book, are scarce; inscribed copies are rare. 
Price: 750.00 USD