Stout (2007) The evolutionary neuroscience of tool making

The appearance of the first intentionally modified stone tools over 2.5 million years ago marked a watershed in human evolutionary history, xpanding the human adaptive niche and initiating a trend of technological elaboration that continues to the present day. However, the cognitive oundations of this behavioral revolution remain controversial, as do its implications for the nature and evolution of modern human technological bilities. Here we shed new light on the neural and evolutionary foundations of human tool making skill by presenting functional brain imaging ata from six inexperienced subjects learning to make stone tools of the kind found in the earliest archaeological record. Functional imaging of his complex, naturalistic task was accomplished through positron emission tomography with the slowly decaying radiological tracer 18flouro-deoxyglucose. Results show that simple stone tool making is supported by a mosaic of primitive and derived parietofrontal perceptual-motor ystems, including recently identified human specializations for representation of the central visual field and perception of three-dimensional form rom motion. In the naı̈ve tool makers reported here, no activation was observed in prefrontal executive cortices associated with strategic action lanning or in inferior parietal cortex thought to play a role in the representation of everyday tool use skills. We conclude that uniquely human apacities for sensorimotor adaptation and affordance perception, rather than abstract conceptualization and planning, were central factors in the nitial stages of human technological evolution. 2006 Elsevier Ltd. All rights reserved.