A Dynamical Analysis of the Suitability of Prehistoric Spheroids from the Cave of Hearths as Thrown Projectiles.

Andrew D Wilson,Lawrence Barham,Qin Zhu,Geoffrey P Bingham,Ian Stanistreet

doi:10.1038/srep30614

Abstract

Spheroids are ball-shaped stone objects found in African archaeological sites dating from 1.8 million years ago (Early Stone Age) to at least 70,000 years ago (Middle Stone Age). Spheroids are either fabricated or naturally shaped stones selected and transported to places of use making them one of the longest-used technologies on record. Most hypotheses about their use suggest they were percussive tools for shaping or grinding other materials. However, their size and spherical shape make them potentially useful as projectile weapons, a property that, uniquely, humans have been specialised to exploit for millions of years. Here we show (using simulations of projectile motions resulting from human throwing) that 81% of a sample of spheroids from the late Acheulean (Bed 3) at the Cave of Hearths, South Africa afford being thrown so as to inflict worthwhile damage to a medium-sized animal over distances up to 25 m. Most of the objects have weights that produce optimal levels of damage from throwing, rather than simply being as heavy as possible (as would suit other functions). Our results show that these objects were eminently suitable for throwing, and demonstrate how empirical research on behavioural tasks can inform and constrain our theories about prehistoric artefacts.

Highlights

While other animals have been known to throw objects on occasion[1,2], none can match the speed, accuracy and distances that a trained human can achieve
This article applies research on how modern humans perceive the throwing affordances of objects to inform a mathematical analysis of spheroids found at the Middle Pleistocene site of Cave of Hearths, South Africa, in order to evaluate the potential of these objects as projectiles for throwing
They are the product of human action through percussion, or they can be naturally shaped stones that have been selected and transported by humans for use[7,8]. They are found at African archaeological sites in levels dating from 1.8 million years ago (Early Stone Age) to at least 70,000 years ago (Middle Stone Age) making them one of the longest-used technologies[9]

Summary

Introduction

While other animals have been known to throw objects on occasion[1,2], none can match the speed, accuracy and distances that a trained human can achieve. Imagine a human, searching for an object to throw so as to cause the most damage possible to a prey animal or a competitor Their job is to find an object of an optimum size and weight; large and heavy enough to fly far and cause damage, but not too large or heavy as to interfere with producing the high speed throw required for distance and damage. This article applies research on how modern humans perceive the throwing affordances of objects to inform a mathematical analysis of spheroids found at the Middle Pleistocene site of Cave of Hearths, South Africa, in order to evaluate the potential of these objects as projectiles for throwing We describe these spheroids, and outline the task dynamical approach to affordance perception that informs current research into how perception-action systems select and control skilled behaviours. They are found at African archaeological sites in levels dating from 1.8 million years ago (Early Stone Age) to at least 70,000 years ago (Middle Stone Age) making them one of the longest-used technologies[9]

Methods

Results

Conclusion