Variation and Correlations in Departures from Symmetry of Brain Torque, Humeral Morphology and Handedness in an Archaeological Sample of Homo sapiens

Antoine Balzeau,Lou Ball-Albessard,Anna Maria Kubicka

doi:10.3390/sym12030432

Abstract

The anatomical asymmetries of the human brain are the subject of a great deal of scientific interest because of their links with handedness and lateralized cognitive functions. Information about lateralization in humans is also available from the post-cranial skeleton, particularly the arm bones, in which differences in size and shape are related to hand/arm preference. Our objective here is to characterize the possible correlations between the endocranial and post-cranial asymmetries of an archaeological sample. This, in turn, will allow us to try to identify and interpret prospective functional traits in the archaeological and fossil records. We observe that directional asymmetry (DA) is present both for some endocranial and humeral traits because of brain lateralization and lateralized behaviors, while patterns of fluctuating asymmetry (FA) vary. The combined study of these anatomical elements and of their asymmetries can shed light on the ways in which the body responds to dependent asymmetrical stimuli across biologically independent anatomical areas. Variations in FA are, in this context, indicators of differences in answers to lateralized factors. Humeri tend to show a much larger range of variation than the endocast. We show that important but complex information may be extracted from the combined study of the endocast and the arms in an archaeological sample of Homo sapiens.

Highlights

In prehistoric sciences, the human archeopaleontological record is studied in order to better understand past human societies
All subsequent analyses are conducted on size-corrected data in relation with this first result, and, and more importantly, in order to allow for a direct comparison of endocranial and humeri data
The AP frontal petalia is significant on the archaeological sample studied here, while prevalence toward the right side was observed in our previous sample

Summary

Introduction

The human archeopaleontological record is studied in order to better understand past human societies. Our objective here is to propose an attempt to characterize departures from symmetry for the endocranial and humeral anatomy of an archaeological sample, in order to search for possible identifications and interpretations of prospective functional traits In this context, we deal with different aspects of asymmetry, looking at potential variations and correlations in directional asymmetries (DA) as indicators of brain/manual. We explore patterns of variations in fluctuating asymmetry (FA) for the different anatomical traits analyzed, in order to discuss variation in the respective biological responses of the brain and arms to asymmetrical stimuli linked to lateralized behaviors This approach is challenging because we study anatomical areas and traits that are morphologically different from each other, and which require the use of different methodologies. From a global anthropological point of view, this study is at the crossroad of various disciplinary fields and, as such, will open important perspectives for future research on the relationship between anatomy and behaviors in past human populations

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Conclusion