Variable cognition in the evolution of Homo: biology and behaviour in the African Middle Stone Age
The emergence of the human mind is a core problem in human evolutionary studies, and many attempts have been made to describe the pattern of emergence, to characterise how it is distinctive from other forms of cognition, and to determine how and why it evolved. It is now evident that the African Middle Stone Age (MSA) is the context in which many key elements developed or came together, for this is the period in which both anatomical and behavioural modernity can first be identified. And yet, there are many unsolved problems. While the MSA is the setting for the first modern human behaviours, many of those behaviours are shared with Eurasian and African archaic hominins, suggesting either convergence or a deep shared ancestry. The MSA is also a period of at least 300 Ky, with both long periods of continuity and the recurrent appearance of novel traits, and the pattern does not match particularly closely with the evidence for the origin of anatomical modernity. In this paper we review the evidence for cognitive and behavioural evolution in the context of the African MSA, and draw the conclusion that a more sophisticated way of measuring human cognition across this period is required. We introduce the variable cognitive state model as a means of achieving this, and consider how it might be applied to the archaeological evidence.