Introducing platform surface interior angle (PSIA) and its role in flake formation, size and shape

PLoS ONE, vol. 15, pp. e0241714

Abstract

Four ways archaeologists have tried to gain insights into how flintknapping creates lithic variability are fracture mechanics, controlled experimentation, replication and attribute studies of lithic assemblages. Fracture mechanics has the advantage of drawing more directly on first principles derived from physics and material sciences, but its relevance to controlled experimentation, replication and lithic studies more generally has been limited. Controlled experiments have the advantage of being able to isolate and quantify the contribution of individual variables to knapping outcomes, and the results of these experiments have provided models of flake formation that when applied to the archaeological record of flintknapping have provided insights into past behavior. Here we develop a linkage between fracture mechanics and the results of previous controlled experiments to increase their combined explanatory and predictive power. We do this by documenting the influence of Herztian cone formation, a constant in fracture mechanics, on flake platforms. We find that the platform width is a function of the Hertzian cone constant angle and the geometry of the platform edge. This finding strengthens the foundation of one of the more influential models emerging from the controlled experiments. With additional work, this should make it possible to merge more of the experimental results into a more comprehensive model of flake formation.

Authors 13

1. Shannon Patrick McPherron corresponding

   Max Planck Institute for Evolutionary Anthropology

   Affiliation as printed

   Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

2. Aylar Abdolahzadeh

   University of Pennsylvania

   Affiliation as printed

   Department of Anthropology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America

3. William Archer

   National Museum · Max Planck Institute for Evolutionary Anthropology

   Affiliation as printed

   Department of Archaeology and Anthropology, National Museum, Bloemfontein, South Africa

   Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

4. Annie Chan

   Centre de recherche sur les civilisations de l'Asie orientale · Ludwig-Maximilians-Universität München

   Affiliation as printed

   Centre de Recherche sur les Civilisations de l'Asie Orientale, Paris, France

   Department of Asian Studies, Ludwig-Maximilians-Universität München, Munich, Germany

5. Igor Djakovic Aachen Department of Archaeology, University of Leiden, Leiden

   Leiden University

   Affiliation as printed

   Department of Archaeology, University of Leiden, Leiden, The Netherlands

6. Tamara Dogandžić

   Max Planck Institute for Evolutionary Anthropology

   Affiliation as printed

   Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

7. George M. Leader

   The College of New Jersey · University of Pennsylvania

   Affiliation as printed

   Department of Anthropology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America

   Department of Sociology and Anthropology, The College of New Jersey, Ewing, New Jersey, United States of America

8. Li Li

   University of Tübingen

   Affiliation as printed

   Department of Early Prehistory and Quaternary Ecology, Eberhard Karls University of Tübingen, Tübingen, Germany

9. Sam C.H. Lin

   University of Wollongong

   Affiliation as printed

   Centre for Archaeological Science, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, Australia

10. Matthew Magnani

    Harvard University

    Affiliation as printed

    Department of Anthropology, Harvard University, Cambridge, Massachusetts, United States of America

11. Jonathan S. Reeves

    University of Tübingen

    Affiliation as printed

    Department of Early Prehistory and Quaternary Ecology, Eberhard Karls University of Tübingen, Tübingen, Germany

12. Željko Režek

    Max Planck Institute for Evolutionary Anthropology

    Affiliation as printed

    Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

13. Marcel Weiß

    Max Planck Institute for Evolutionary Anthropology

    Affiliation as printed

    Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany