Stone tips
Clovis-style stone tips recreated by Kent State University archaeologists.Kent State University

The Clovis people first crossed the icy land bridge between Asia and North America about 13,500 years ago, bringing stone-tipped hunting weapons with them. But it wasn't until they arrived in North America that they discovered a way to make more durable, reliable arrow and spear tips, marking the first human innovation on American soil.

The innovation was a small change to the stone tips of arrows and spears, thinning out the base with a narrow groove, called 'fluting'. The discovery could well have been made by accident, say the authors of a study on Clovis fluting technology published in the Journal of Archaeological Science.

"It was risky and couldn't have been easy to learn how to do this effectively," study author Metin Eren of Kent State University said in a statement.

Narrowing the base of the stone tip can make the tip more brittle rather than more robust if done incorrectly. Even the process of chipping the narrow groove is difficult to do without accidentally destroying the stone tip entirely.

"Archaeological evidence suggests that up to one out of five points break when you try to chip this fluted base, and it takes at least 30 minutes to produce a finished specimen," said Eren.

Eren and his colleagues used computer models to test the effects of fluting on the stone tips, and then attempted to recreate the tips themselves using materials that would have been available to Clovis people.

But the effort pays off if the fluting is done just right. Carefully fluted stone tips are more likely to stay in one piece after colliding with their target. For the Clovis people, this would have been prehistoric beasts that roamed North America, such as mastodons and mammoths.

A stone point that could be reused had the potential to revolutionise Clovis hunting. They could allow hunters to travel for much greater distances in the knowledge that their weapons would last for several kills.

Making Clovis tools
A researcher making a stone tip with fluting.Kent State University

"Though it was a time-consuming process and risky technique, successfully fluted Clovis points would have been extremely reliable, especially while travelling great distances into unknown regions on a new continent. They needed points that would hold up and be used over and over again," said Eren.

"It's amazing to think that people 12,000 years ago were flaking shock absorbers and engineering stone weapons in a way that it took 21st century modern engineering to figure out."