Joe Cocke, found the bone of an extinct species of bison on the Peninsula. The fossil has was marks on it which would indicate human butchering and was dated at 13,500 years old.Chuck Bennett/Daily Breeze/SCNG
Five faint butchering cuts in an ancient bison bone found in Lunada Canyon show that humans existed in California at least 500 years earlier than previously believed.
The bone is part of a pelvis from a now-extinct species, Bison Antiquus. Cal State Long Beach’s anthropology department tested the specimen, determining the bone was 13,500 years old and the cuts were made by ancient human tools.
“It’s one of the oldest signs of humans in California,” said Joe Cocke, who found the bone in 2012. He is also the docent at the Point Vicente Interpretive Center, where the bone is on display.
Cocke was on his usual weekly fossil hunting hike in Lunada Canyon in Rancho Palos Verdes when he saw part of a bone sticking out of the bottom of a cliff face. As a former preparator for the Los Angeles County Natural History Museum, Cocke can recognize a bone from a mile away.
“It just looks different, it was in kind of a sandy layer and all of a sudden I just saw this odd thing sticking out and I knew it was a bone,” Cocke said. “I’ve done this all my life.”
Because the canyon walls were steep and looked unstable, Cocke used a 6-foot pole with a nail on the end to dig the bone out. He washed off the bone at home and noticed the faint cuts. He knew they were the same age as the bone because a thin layer of calcium carbonate, which accumulates as a bone fossilizes, was on the bone and the inside of the cuts.
He took the specimen to the Page Museum at the La Brea Tar Pits to confirm the species, then sent it to the anthropology department at CSULB. There, experts tried Carbon-14 dating, which measures the amount of radioactive carbon still in an organic object after it has died.
The lab found there was not enough collagen in the bone to carbon date it, but analysts offered to do a more accurate test involving digging into the cliff base at night: optically stimulated luminescence dating.
OSL dating tests the common quartz crystals in the soil around the fossil for the last time the rock was exposed to light. Cocke and his team had to go back to the site, where he found the bone on a moonless night. The team then dug about 1 foot into the cliff to collect untouched dirt, wrapped it in black tarp and delivered it in a sealed package to the lab at CSULB.
“We had to collect it in total darkness, because if we collected the samples and they saw sunlight, it would reset the clock,” Cocke said.
The lab ran 13 separate tests and confirmed the fossil’s age. The cuts on the bone also were analyzed under an electron microscope, which revealed the cuts most likely were made with an obsidian blade.
Cocke said obsidian flakes at different angles when it is sharpened, so the different angles of the blade cuts can be seen under an electron microscope.
Cocke speculates that the cuts were made from people scraping the meat from the bones. The people — probably in small nomadic family groups of six to 10 people — were always on the hunt for food. The Bison Antiquus once stood about 7 1/2 feet tall at its shoulders.
“They were huge,” Cocke said. “You know these (people) were probably small little guys, too. I’m sure a lot of them were injured. I can’t even imagine trying to kill something like that with primitive spears, but they did.”
Part of a bison neck vertebra also was found at the scene, but because there were no cuts or things of note on the bone, the center did not want to test it. Bison bones are one of the most common fossils found in North America, but this one is unique because of the butchering cuts, Cocke said. There’s likely more fossils in the cliff face, possibly even parts of the same bison, but he feels that it would be too dangerous to dig further into the cliff.
Before this specimen, the earliest sign of human life in California was a fragment of a human femur discovered in 1959 on the Channel Islands. The “Arlington Man,” as it was called, was carbon dated in 1999 and found to have lived at least 13,000 years ago.