Shock-absorbing spear points kept early North Americans on the hunt

Ancient North Americans hunted with spear points crafted to absorb shock.

Clovis people, who crossed a land bridge from Asia to North America around 13,500 years ago, fashioned stone weapons that slightly crumpled at the base rather than breaking at the tip when thrust into prey, say civil engineer Kaitlyn Thomas of Southern Methodist University in Dallas and colleagues. The Clovis crumple rested on a toolmaking technique called fluting, in which a thin groove was chipped off both sides of a stone point’s base, the researchers report in the May Journal of Archaeological Science.

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Computer models and pressure testing of replicas of fluted and unfluted Clovis points support the idea that fluted bases worked like shock absorbers, preventing tip breakage, the scientists conclude. Slight compression and folding of stone at the base of fluted points after an impact did not cause enough damage to prevent the points from being reused, they say.

“Fluted Clovis points have a shock-absorbing property that increases their durability, which fit a population that needed reliable weapons on a new, unknown continent,” says archaeologist and study coauthor Metin Eren of Kent State University in Ohio. While Clovis people weren’t the first New World settlers (SN: 6/11/16, p. 8), they roamed throughout much of North America. Individuals traveled great distances to find food and move among seasonal camps, Eren says.

Computer models run by Thomas, Eren and colleagues indicated that unlike unfluted points, fluted points increasingly divert pressure away from the tip and toward the base as physical stress on the weapon grows. Computerized, 3-D versions of fluted Clovis points exposed to high-impact pressure crumpled at the base, leaving the tip intact. Unfluted replicas, however, frequently broke at the tip.

Comparable results emerged when the researchers tested 60 fluted and unfluted stone replicas of Clovis points in a viselike machine that applied precise pressures. Each replica was the same size and represented the average outline shape of 241 previously excavated Clovis points. Standardized replicas enabled researchers to focus solely on whether fluting affected how Clovis points react to physical stress.

Fluted Clovis points may have been attached to handles or long shafts in ways that also enhanced the resilience of a weapon’s business end, Eren says. But no such handles, or even materials used to bind Clovis points to handles, have been discovered.

The fluted points would have taken patience and experience to produce, says Eren, himself a crafter of the stone tools. Previous finds suggest that as many as one out of five Clovis points broke as fluted sections were prepared. If all goes well for an experienced toolmaker, it takes 40 to 50 minutes to produce a fluted Clovis point, he estimates.

Fluting techniques became increasingly elaborate until the practice was abandoned around 9,500 years ago. At that time, familiarity with North America’s landscapes and stone sources triggered a shift to making unfluted spear points designed to kill more effectively, but not necessarily to last, Eren suspects. Some of those stone points may have been intended to shatter on impact, creating shrapnel-like wounds, he says.

Searching for signs of crumpling and crushing on the bottoms of early and later fluted Clovis points could help researchers see if the tools always worked as shock absorbers, says archaeologist Ashley Smallwood of the University of West Georgia in Carrollton.

Researchers have previously proposed that fluting represented a stylistic twist with no practical impact, or that it was a way for toolmakers to advertise their skills and suitability as mates, or was part of prehunt rituals. The new results provide an intriguing practical explanation for the technique’s popularity that deserves further study, says archaeologist Daniel Amick of Loyola University Chicago.  Aside from their durability, fluted points may have held symbolic meaning for Clovis people, he adds. For instance, if ancient Americans didn’t fully grasp how fluting strengthens stone points, they could have incorporated the technique into supernatural explanations for the success of hunts, Amick suggests.