Left and right hands, brain and cognitive evolution – Exploring prehistoric handedness rates through hominins’ lithic production

Lay summary authored by Stefanos Ligkovanlis. Read the full paper here: http://doi.org/10.5334/oq.111

What do we know about the prehistory of handedness? Did our distant ancestors share similar rates of hand preference with us? And what does this ratio might reveal about prehistoric societies and their cognitive capabilities? Such questions are not new, but until know days they have not received a decisive answer.  Utilising, thus, preexisting knowledge and investigations, my research aimed to explore further the issue of prehistoric handedness with main emphasis given to Neanderthal populations.

Fig. 1: Digital measurements on experimentally produced lithic artifacts and snapshots of modern left and right-handed knappers’ flaking procedures (figure provided by S. Ligkovanlis).

For doing so, the current survey focused on lithic technology with the idea that chiropractic procedures of the stone artifacts’ construction can leave characteristic traces on them, reflecting the hand preference of their manufactures. The methodological protocol of the research included the conduction of an experiment series with the participation of modern right- and left-handed flintknappers and the multifactor evaluation of their results, using computerized techniques. These procedures showed, that the geometrics of a specific element created during lithic production flakes, the ‘cone of percussion’ of the flakes, are strongly and correspondingly related with the knappers’ hand-preference.

After these positive results, the research methodology for distinguishing handedness through lithic artifacts has been applied on the actual archaeological record: flint flakes, from Kalamakia cave-southern Greece. These artifacts have been constructed during the Middle Palaeolithic period by Neanderthals. The analyses conducted indicate that right-handed flintknappers on the site predominated over left-handed ones.

Fig. 2: Possible rates of left- and right-handed Neanderthal flintknappers among the occupational levels of Kalamakia cave-southern Greece. PLH: Possible left-hander. PLR: Possible right-hander (figure provided by S. Ligkovanlis).

Although more effort is needed in order the methods and results of the current study to be verified, I suggest that my research opens a new hopeful perspective for the exploration of the handedness phenomenon during human evolution. The proposed method could easily be applied to lithic artifacts constructed during different periods of the prehistory, by different types of hominins such as Homo erectus, Homo heildebelgensis etc., in order the evolutional trends of hand-preference to be investigated.

Although this is a next logical step to this research discipline the cognitive extensions and interpretations of handedness evolution through millennia (e.g. how exactly the formulation of hand-preference could be connected with the cerebral development and the neurophysiological prerequisites for speech pronunciation and comprehension) should also occupy future efforts. This ‘requests’ could only be fulfilled within an interdisciplinary framework, where collaborative research will be invited to interpret the behavioural and neuroscientific dimensions of what the evolution of handedness means even today, beyond a convenient arrangement at the dining table!

Full paper: Ligkovanlis, S., 2022. Hand-Preference and Lithic Production-Exploring Neanderthal Handedness Rates through the Study of Hertzian Fracture Features on Lithic Blanks. Open Quaternary, 8(1), p.4. DOI: http://doi.org/10.5334/oq.111