University of Massachusetts Amherst ScholarWorks@UMass Amherst Masters Theses Dissertations and Theses November 2014 Were Neandertal Humeri Adapted for Spear Thrusting or Throwing? A Finite Element Study Michael Anthony Berthaume University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/masters_theses_2 Part of the Biological and Physical Anthropology Commons, Biomechanical Engineering Commons, Biomechanics and Biotransport Commons, Evolution Commons, and the Other Ecology and Evolutionary Biology Commons Recommended Citation Berthaume, Michael Anthony, "Were Neandertal Humeri Adapted for Spear Thrusting or Throwing? A Finite Element Study" (2014). Masters Theses. 72. https://doi.org/10.7275/5952474 https://scholarworks.umass.edu/masters_theses_2/72 This Open Access Thesis is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. WERE NEANDERTAL HUMERI ADAPTED FOR SPEAR THRUSTING OR THROWING? A FINITE ELEMENT STUDY A Thesis presented by MICHAEL A. BERTHAUME Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of MASTER OF ARTS September 2014 Department of Anthropology © Copyright by Michael A. Berthaume 2014 All Rights Reserved WERE NEANDERTAL HUMERI ADAPTED FOR SPEAR THRUSTING OR THROWING? A FINITE ELEMENT STUDY A Thesis Presented by MICHAEL A. BERTHAUME Approved as to style and content by: ________________________________________ Brigitte M. Holt, Chair ________________________________________ Laurie R. Godfrey, Member ________________________________________ Michael O. Sugerman, Member _________________________________ Thomas Leatherman, Department Head Department of Anthropology DEDICATION To my amazing family, Mom, Dad, Andy, Maria, Angie, there is no way I could be where I am today without your amazing love and support, whether it be taking me in, helping me move, listening to me drone on about teeth and FEA of biological systems, or making me crack up at one of our three hour long family dinners. Together, we make the craziest, happiest, and most powerful and loving group of people I know. Thank you. Insanity runs in my family. It practically gallops. -Cary Grant ACKNOWLEDGEMENTS When I started in the anthropology program at the University of Massachusetts, Amherst, I had three goals. First, to learn about the paleoanthropological record. Second, to learn how to teach. And third, to learn how to ask a relevant question. While I will never be able to fully achieve these goals in my lifetime, I am considerably closer to achieving them than I was three years ago. This thesis would not have been possible without the incredible support and guidance granted to me by my advisor, Dr. Brigitte Holt, and my committee members, Drs. Laurie Godfrey and Michael Sugerman, or finite element training I received from Drs. Ian Grosse, Elizabeth Dumont, and the Biomesh Workshop. For that I am forever in their debt. I would like to extend my thanks to NESPOS for access to Regourdou 1’s scans, Drs. Colin Shaw and Tim Ryan for access to the Norris Farms scans, and Dr. Brigitte Holt for access to Grotte des Enfants 4’s scans. In addition, I would like to thank Dr. Elizabeth R. Dumont and Dan Pulaski in the Mammology Department at UMass, Amherst for access to the computer programs necessary to construct the finite element models, and Carl Jewell and Dr. Joe Hamill for help in collecting the EMG data in the Biomechanics Lab at UMass, Amherst. Finally, I would like to thank the University of Massachusetts, Amherst for granting the Faculty Research Grant/Healey Endowment grant to Dr. Brigitte Holt in order to obtain the scans of Grotte de Enfants 4, Prof. Patrick Simon (Musée d'Anthropologie Préhistorique de Monaco) for access to GDE 4, Centre d'Imagerie Médicale de Monaco for taking the CT scans. v ABSTRACT WERE NEANDERTAL HUMERI ADAPTED FOR SPEAR THRUSTING OR THROWING? A FINITE ELEMENT STUDY SEPTEMBER 2014 MICHAEL A. BERTHAUME B.S., UNIVERSITY OF MASSACHUSETTS AMHERST M.A., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Brigitte M. Holt An ongoing debate concerning Neandertal ecology is whether or not they utilized long range weaponry. The anteroposteriorly expanded cross-section of Neandertal humeri have led some to argue that their humeri were adapted to thrust hunting weapons, while the rounder cross-section of Late Upper Paleolithic humeri suggests modern humans threw their weapons. We test the hypothesis that Neandertal humeri were built to resist strains engendered by thrusting rather than throwing, using finite element (FE) models of one Neandertal, one Early Upper Paleolithic (EUP) human and three recent human humeri, representing a range of cross-sectional shapes and sizes. Electromyography and kinematic data and articulated skeletons were used to determine muscle force magnitudes and directions during three positions of spear throwing and three positions of spear thrusting. Maximum von Mises strains, an indicator of bone remodeling, were determined at the 35% and 50% cross-sections of all models. During throwing and thrusting, von Mises strains produced by the Neandertal humerus fell roughly within or below those produced by the modern human humeri, although the Neandertal experienced significantly higher strains during one stage of thrusting. The EUP humerus performed similarly to the vi Neandertal, but slightly poorer during spear thrusting. This indicates the Neandertal and EUP human humeri were just as well adapted at resisting strains during throwing as recent humans and just as well or worse adapted at resisting strains during thrusting as recent humans. We also did not find any correlation between strains and biomechanical metrics used to measure humeral adaptation in throwing and thrusting (retroversion angle, Imax/Imin, J). These results failed to support the hypothesis that the shape of Neandertal humeri reflects thrusting loads, and suggest they were capable of using long distance weaponry. vii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ........................................................................................ v ABSTRACT ................................................................................................................ vi LIST OF TABLES ....................................................................................................... x LIST OF FIGURES .................................................................................................... xi CHAPTER 1. INTRODUCTION ................................................................................................. 1 1.1 Overview .................................................................................................. 1 1.2 Background: Evidence of long range weapons by Neandertals ............... 1 1.2.1 Lithic Evidence .......................................................................... 1 1.2.2 Faunal Evidence ........................................................................ 4 1.2.3 Skeletal Evidence ...................................................................... 5 1.3 Hypotheses ............................................................................................... 7 2. MATERIALS AND METHODS .......................................................................... 9 2.1 Materials and Sample ............................................................................... 9 2.2 Finite Element Model Construction ....................................................... 12 2.3 EMG: Spear Thrusting ............................................................................ 19 2.4 Interpreting the Finite Element Models .................................................. 22 3. RESULTS ............................................................................................................. 25 3.1 Muscle Activation Patterns During Spear Thrusting.............................. 25 3.2 FEA Simulations .................................................................................... 25 4. DISCUSSION ....................................................................................................... 31 5. CONCLUSION .................................................................................................... 35 APPENDIX: NUMERICAL STRAIN RESULTS DURING SPEAR THRUSTING AND THROWING................................................................36 BIBLIOGRAPHY...................................................................................................... 39 viii LIST OF TABLES Table Page 2.1 Morphological characteristics of the five humeri used to create FE models ..........10 3.1 R2 values for the Imax/Imin ratio, J, J normalized, and the retroversion angle vs. maximum von Mises strain at the 3 positions of spear throwing and spear thrusting at 35% and 50% of the length of the humerus. *=p<0.0126 .............................................................................................29 3.2 Number of times one of the cross-sections was primarily in torsion, bending, or neither .................................................................................................30 ix LIST OF FIGURES Figure Page 1.1 Increasing robustness and ellipticity in humeral cross-sections. ....................6