About 8500 years ago, hunter-gatherers living beside Eagle Lake in Wisconsin hammered out a conical, 10-centimeter-long projectile point made of pure copper. The finely crafted point, used to hunt big game, highlights a New World technological triumph—and a puzzle. A new study of that artifact and other traces of prehistoric mining concludes that what is known as the Old Copper Culture emerged, then mysteriously faded, far earlier than once thought.
The dates show that early Native Americans were among the first people in the world to mine metal and fashion it into tools. They also suggest a regional climate shift might help explain why, after thousands of years, the pioneering metallurgists abruptly stopped making most copper tools and largely returned to stone and bone implements.
Earth’s largest and purest copper deposits are found around North America’s Great Lakes. At some point, Native Americans learned to harvest the ore and heat, hammer, and grind it into tools. They left behind thousands of mines and countless copper artifacts, including lethal projectile points, hefty knives and axes, and petite fish hooks and awls. Today, it’s not uncommon to meet residents of the region “who have buckets of copper artifacts [that they’ve found] tucked away in their basements,” says David Pompeani, a geologist at Kansas State University, Manhattan, who studies ancient mining.