The diversity of North American projectile-point types, before and after the bow and arrow

Mimicking paleobiological studies of biodiversity, changes in the diversity of temporal types of North American projectile points are modeled to reveal evolutionary patterns of origination and extinction. Origination is modeled as rapid innovation of multiple point types (high diversity), and extinction is modeled as gradual winnowing of less-efficient types. Introduction of the bow and arrow as a new weapon-delivery system is modeled as an increase in point diversity. Six sequences of points (dart + arrow), six sequences of dart points, and six sequences of arrow points from western North America best match the model when the number of time periods >= 5 and the number of types is >3. (C) 2008 Elsevier Inc. All rights reserved.