The team, which includes ASU doctoral graduate Benjamin Schoville, now at University of Queensland (Australia), and former Institute of Human Origins postdoctoral researcher Colin Wren, now at University of Colorado, Coloardo Springs, ran over 2,400 simulations using different population sizes, levels of tool reuse and rates of projectile hunting and compared the number of projectiles discarded at camps with those lost at hunting locations.

The model showed that the majority of projectile tools are consistently lost during hunting and that only a few tools are discarded at habitation camps, which are locations that would likely accumulate enough other artifacts to be archaeologically visible.

“Our conclusion is that even small numbers of projectile weapons in early archaeological sites may indicate that projectile weapons were used daily,” said Gravel-Miguel. “This has important ramifications for our understanding of the evolution of projectile weapons, as it suggests that its consistent adoption may have been earlier than previously thought based on the archaeological record.”

The earliest documented instance of a projectile weapon dates to around 500,000 years ago from the site of Kathu Pan in South Africa. While to date, it is the only instance of such technology we have for that time, the results of the model suggests that the rare Kathu Pan projectiles might indicate that projectile weapons were already used somewhat regularly at that time.

“As the use of projectile technology is associated with foresight, planning, improved hunting success and an expanded ecological niche, this suggests that, as early as a half million years ago, our ancestors may have evolved some important modern traits,” said Murray, a doctoral student in the School of Human Evolution and Social Change.

This research was published this week as “Exploring variability in lithic armature discard in the archaeological record,” Journal of Human Evolution, Claudine Gravel-Miguel, John K. Murray, Benjamin J. Schoville, Colin D. Wren, Curtis W. Marean.

Julie Russ

Assistant director, Institute of Human Origins