Document Detail


Upper limb kinematics and the role of the wrist during stone tool production.
MedLine Citation:
PMID:  20734439     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Past studies have hypothesized that aspects of hominin upper limb morphology are linked to the ability to produce stone tools. However, we lack the data on upper limb motions needed to evaluate the biomechanical context of stone tool production. This study seeks to better understand the biomechanics of stone tool-making by investigating upper limb joint kinematics, focusing on the role of the wrist joint, during simple flake production. We test the hypotheses, based on studies of other upper limb activities (e.g., throwing), that upper limb movements will occur in a proximal-to-distal sequence, culminating in rapid wrist flexion just prior to strike. Data were captured from four amateur knappers during simple flake production using a VICON motion analysis system (50 Hz). Results show that subjects utilized a proximal-to-distal joint sequence and disassociated the shoulder joint from the elbow and wrist joints, suggesting a shared strategy employed in other contexts (e.g., throwing) to increase target accuracy. The knapping strategy included moving the wrist into peak extension (subject peak grand mean = 47.3 degrees) at the beginning of the downswing phase, which facilitated rapid wrist flexion and accelerated the hammerstone toward the nodule. This sequence resulted in the production of significantly more mechanical work, and therefore greater strike forces, than would otherwise be produced. Together these results represent a strategy for increasing knapping efficiency in Homo sapiens and point to aspects of skeletal anatomy that might be examined to assess potential knapping ability and efficiency in fossil hominin taxa.
Authors:
E M Williams; A D Gordon; B G Richmond
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  American journal of physical anthropology     Volume:  143     ISSN:  1096-8644     ISO Abbreviation:  Am. J. Phys. Anthropol.     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-08-24     Completed Date:  2010-12-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0400654     Medline TA:  Am J Phys Anthropol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  134-45     Citation Subset:  IM    
Affiliation:
Hominid Paleobiology Doctoral Program, Department of Anthropology, The George Washington University, Washington, DC 20052, USA. emswill@gwmail.gwu.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Biomechanics
Female
Hominidae / physiology*
Humans
Male
Muscle Contraction
Rotation
Upper Extremity / physiology*
Video Recording
Wrist / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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