SHELLFISH AND THE RISE OF MODERN HUMAN BEHAVIOUR

Artefacts from the African Middle Stone Age (MSA; ∼200 to ∼50 ka), provide us with the first glimpses of modern human art and culture. Approximately 50 ka, one or more subgroups of modern humans expanded from Africa to populate the rest of the world.

Significant behavioural change accompanied this expansion, and archaeologists commonly seek its roots during this period. Recognizable art objects and “jewellery” become common only in sites that postdate the MSA in Africa and Eurasia, but some MSA sites contain possible precursors, including abstractly incised fragments of ochre and perforated mollusc shells interpreted as beads.

Was population growth the driver of change?

Researchers had previously theorised that it was an increase in population that drove behavioural innovations which in turn led to the creation of these artefacts and eventually, the expansion out of Africa. However, by examining mollusc shells from Stone Age sites, Richard Klein of Stanford University and Teresa Steele of University of California, Davis, have determined that a significant population increase did not occur until the Later Stone Age (LSA), after the out of Africa migration had already begun. Their research appears in the June 2013 edition of the Proceedings of the National Academy of Sciences.

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