Scaling Laws of Paleoindian Projectile Point Design

Abstract

Across late Pleistocene North America, Paleoindians designed a variety of projectile point styles that vary in form over time and space, but also share similar performance requirements and a common technological history. In order for projectile points to be effective components of hunting weaponry, at a minimum they must be engineered to be both effective at penetrating prey and robust to failure. These universal performance criteria suggest the design space underlying the diversity of projectile point styles we observe in the archeological record must be highly constrained by engineering principles. Here, using a large sample of complete points (n = 2360) from 16 Paleoindian projectile point types we examine the diversity of Paleoindian projectile point designs using a combination of engineering principles, allometric scaling theory, and statistical models. First, we define the design space of Paleoindian projectile points by examining the dimensions of length, width, and thickness that define the basic three-dimensional volumes of the points and their size allometries. Second, we derive three hypotheses for the optimal allometric design of points from first principles of engineering that quantify design trade-offs between robustness and penetration capability. We then test the predictions of the hypotheses with data and show that the empirical observations match the theoretical predictions in almost every case. Our analysis shows that Paleoindian projectile points are engineered to resist breaking while maximizing penetrating capabilities, and we show the engineering principles behind this optimization. We also show that within these design criteria, some types are designed to emphasize penetration, whereas others emphasize robustness. These results demonstrate that once bifacial point traditions emerge in Paleoindian North America there is a high retention of design, engineering, and performance criteria throughout the Paleoindian record, and probably beyond.