Ruck, Lana

Many acknowledge that stone tool manufacture, handedness, and brain evolution are intricately linked in Homo sapiens and other hominids, and there is extensive literature on the value of lithic analysis in understanding hominid biological, cognitive, and cultural evolution. Analyses of handedness as preserved in the paleoarchaeological record, however, are rare, despite their relevance and importance to understanding structural and functional asymmetries in the human body and brain. I will attempt to address the inherent issues in analyzing certain aspects of hominid evolution—particularly evidence of handedness as a proxy for hemispheric specialization of the brain—via experimental archaeology. Three people, including myself, assessed Acheulean handaxes and associated debitage created by two right- and two left- handed expert flintknappers using previously established methods, including: Toth’s 1985, Rugg & Mullane’s 2001, and Bargalló & Mosquera’s 2013 methods. While these publications form the basis of handedness-related lithic analysis, they have methodological inconsistencies that have lead to poor reliability and replicability. The goals of this project are to address issues within this scope of analysis, particularly the combination of expert and novice subjects and a lack of objectivity. Improving the existing methodologies will encourage analysis of fossil evidence from Paleolithic assemblages in the future. The ultimate goal of this approach is to be able to track population-level hominid handedness rates through time via preserved stone tools, and use them as a proxy for the development of human lateralities, cognitive evolution, and the acquisition of language.

Human handedness is likely related to brain lateralization and major cognitive innovations in human evolution. Identifying handedness in the archaeological record is,
therefore, an important step in understanding our cognitive evolution. This thesis reports
on experiments in identifying knapper handedness in lithic debitage. I conducted a blind
study on flakes (n=631) from Acheulean handaxes replicated by right- and left-handed
flintknappers. Several flake characteristics significantly indicated handedness, with a
binary logistic regression correctly predicting handedness for 71.7% of the flakes.
However, other characteristics were not associated with handedness. This is a result of
personal knapping styles, as additional analyses show that individual knappers associate
with some attributes better than handedness does. Continued work on these methodologies will enable analysis of Paleolithic assemblages in the future, with the ultimate goal of tracking population-level hominid handedness rates through time and using them as a proxy for cognitive evolution and language acquisition.