Abstract

When and where did consciousness emerge in the course of evolution? Did it happen as recently as the past million years, for example concomitant with language or tool making in humans or primates? Or did consciousness arrive somewhat earlier, with the advent of mammalian neocortex 200 million years ago (Eccles, 1992)? At the other extreme, is primitive consciousness a property of even simple unicellular organisms of several billion years ago (e.g. as suggested by Margulis and Sagan, 1995)? Or did consciousness appear at some intermediate point, and if so, where and why? Whenever it first occurred, did consciousness alter the course of evolution?