A collection of delicate stone tools discovered on California's Channel Islands indicates that early humans in the Americas were hunting local waterfowl some 11,200 to 12,200 years ago.

"The points we are finding are extraordinary," Jon Erlandson, director of the University of Oregon's Museum of Natural and Cultural History, who has been working on the islands for decades, said in a prepared statement. Made primarily from local chert using a bifacial technique, the tools "are ultra thin, serrated and have incredible barbs on them. It's a very sophisticated chipped-stone technology," he said. 

Traces of the Clovis culture from some 13,500 years ago have been found in inland sites, and there is evidence for human occupation of the coasts of Chile from about 14,000 years ago. Human remains from some 13,000 years ago had been uncovered on Santa Rosa Island, one of the Channel Islands, but "this is among the earliest evidence of seafaring and maritime adaptations in the Americas," Erlandson said. Previous evidence had suggested only prolific local hunting around the islands from some 8,000 to 10,200 years ago.

Fifteen stone crescents, 52 small stemmed barbed points and a sampling of other tools from Santa Rosa Island, along with 31 crescents, 32 stemmed points and 23 Amol points found on San Miguel Island, are described in a paper published online March 3 in Science.

The find on the islands was a rare one, researchers suggest. During the Pleistocene, when these tools were made, more of the world's water was tied up in glaciers, making sea levels some 50 to 60 meters lower than they are today. The subsequent rise in sea levels may have flooded many costal Paleolithic sites.

The lower sea levels of the time would have exposed the land connecting the contemporary islands to the mainland of California, and the researchers suggest that the areas might have been seasonal hunting grounds.

What was on the menu in these ancient settlements? "We think the crescents were used as transverse projectile points, probably for hunting birds," Erlandson said. "Their broad stone tips, when attached to a dart shaft, provided a stone age shotgun-approach to hunting birds in flight."

On Santa Rosa Island, much of the animal bones dating to that era are from local waterfowl, including cormorants (Phalacrocorax), short-tailed albatross (Phoebastria albatrus), Canada geese (Branta canadensis) and snow geese (Chen caerulescens). The researchers also found traces of small marine mammals, along with rockfish, sculpin, surfperch as well as herring and/or sardine. Slightly downhill from the site, the team uncovered a burned bone from the now-extinct flightless bird Chendytes lawi. On San Miguel Island, by contrast, the excavation turned up mostly shellfish: mussel (Mytilus californianus), black turban snail (Chlorostoma funebralis), giant chiton (Cryptochiton stelleri), crabs and red abalone (Haliotis rufescens).

Torben Rick, curator of North American Archaeology at the Smithsonian Institution and co-author of the new paper, added that the tools "show that very early on, New World coastal peoples were hunting such animals and birds with sophisticated technologies that appear to have been refined for life in costal and aquatic habitats."

The early inhabitants might have also been engaged in trading networks. One Santa Rosa Island tool was made of obsidian from a volcanic area some 300 kilometers away, "which suggests that Channel Island peoples participated in long-distance trade nearly 12,000 years ago," the authors noted in their study.

Taken together, the tools reveal "another extension of the diversity of Paleoindian economies," Erlandson said.

The researchers also note that the shape of the tools echoes the shapes of those found on the Pacific coast of South America and as far away as Japan, suggesting that the early Californians were not a western branch of the Clovis culture, but rather from a more coastal diaspora that rimmed the Pacific.

Image of stone crescent tool courtesy of Jon Erlandson.