By 50,000 years ago, the effects of a 'symbolic explosion' -an efflorescence of human art, song, dance and ritual -were rippling across the globe. Applied to archaeological evidence, standard neo-Darwinian theory offers new understandings of this improbable event. The present article defines 'symbolism', models quasi-ritual behaviour in late archaic Homo sapiens, extends the argument to the emergence of anatomically modern humans and concludes with preliminary tests against archaeological, ethnographic and rock art data.