Paper short abstract:

Brain imaging used recently to view activated brain parts of the 'expert' and 'naïve' stone knappers for understanding brain development in Oldowan and Acheulean contexts remains inconclusive without recourse to raw materials, ecology, diet, gender, body form, manual dexterity, etc. of the hominins.

Paper long abstract:

In recent years some scholars like Stout et al., 2011 and Faisal et al., 2010 have used fMRI, PET, MRI scanning techniques in experiments on 'naïve' and 'expert' knappers and equated the observed differences in activation of the brain parts with brain developments in Oldowan and Acheulean hominins. Their conclusions emerged at three level: (1) The Oldowan technology impacted primary motor and somatosensory cortices, superior parietal lobule, cerebellum and fusiform gyrus of right inferior temporal lobe of brain. (2) the mode I resulted bilateral activation in primary somatosensory and motor cortex and visual processing area as well as inferior parietal lobule. (3) the 'naïve' knappers revealed activation on ventral, lateral and dorsal visual areas, whereas the 'experts' knappers showed on the broadmann area 19.

However, laboratory experiments on modern humans may not be n exact proxy for the Oldowan or Acheulean hominins over million years ago. They were constrained by a multitude of selective pressures of predation, ecological setting, the availability of diet owing to seasonality, availability of the stone tool raw material- its quality, hardness and softness, and besides hominin's own morphological idiosyncrasy- the body form, sexual dimorphism, manual dexterity, i.e., the size of the thumb and its opposability for holding the objects, the stone hammer, etc. Other than H.habilis and H. erectus, we need to evaluate such results from bio-cultural aspects of the tiny Homo floresiensis hobbit with exceptional complexity of stone tool making, the large robust Paranthropus robustus and the small Australopithecus afarensis having body, diet and culture contrasts. In fact, brain activation and evolution is very complex phenomenon.

Faisal, A., Stout, D., Appel, J. and Bradley, B. (2010). The Manipulative Complexity of Lower Paleolithic Stone Toolmaking. PLoS ONE 5(11): e13718. doi:10.1371/journal.pone.0013718

Stout, D. (2011) Stone tool making and the evolution of human culture and cognition. Philos. Trans. R Soc. London, B, 366, 1050-1059.

Stout, D., Richard Passingham, R., Christopher Frith, C. Jan Apel, J. and Thierry Chaminade, T. (2011). Technology, expertise and social cognition in human evolution. European Journal of Neuroscience, pp. 1-11, doi:10.1111/j.1460-9568.2011.07619.x

Ms.Tanusree Pandit (tanusree2@gmail.com) & Dr. Anek R. Sankhyan (arsankhyan@gmail.com) ex-Anthropologist, Anthropological Survey of India, 27, J. L. Nehru Road, Kolkata-700016, India & President Palaeo Research Society, Ghumarwin (H.P.)-174021, India.