I don't think there was a thunderclap or a divine spark that suddenly made one species smart. You can see, in our ancestors, there was a gradual expansion of the brain; there was an expansion of the complexity of tools.

— Steven Pinker, Steven Pinker: Evolution of the Mind

Source: http://www.pbs.org/wgbh/evolution/library/07/2/text_pop/l_072_03.html

From the PBS Evolution library.

Topics: complexity