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The Dawn of Human Culture by Richard G. Klein with Blake Edgar, John Wiley & Sons, £20.95, ISBN 0471252522

WHAT price a few bits of eggshell? If it’s the handful perused by renowned evolutionary anthropologist Richard Klein, you can’t buy them at any price. In The Dawn of Human Culture, co-written with Blake Edgar, he identifies a critical threshold for human evolution between 50,000 and 40,000 years ago in East Africa, by which time fully modern humans had appeared.

The eggshells in question were found by palaeontologists at Enkapune Ya Muto or “Twilight Cave” in Kenya, fashioned into tiny, painstakingly made beads some 40,000 years ago. They represent the earliest surviving examples of human symbolic thinking in material form, and indicate cognitive skills linking language and culture. Arguably, they also testify to their makers’ capacity for mental modelling and communication in social networks.

Up to this point, humans’ mental and physical evolution had gone in tandem, and rather slowly. By 200,000 years ago, human brains had reached their current size. What occurred 50,000 years ago was an organisational change in the brain’s “software”—a development difficult to identify from skeletal remains. Nevertheless, from this point on our bodies changed little while our behavioural abilities accelerated rapidly. European cave paintings and ivory figurines from the Aurignacian period, 32,000 years ago, reinforce Klein’s arguments and suggest it was our African ancestors who finally did for the indigenous Neanderthals.