Debate heats up over whether 130,000-year-old bones were broken by humans
Last year, archaeologists in California made a startling announcement: they had discovered a 130,000 year-old prehistoric human campsite in the Golden State. According to currently accepted evidence, the first modern humans were just venturing out of Africa at that time, and no one would set foot in the Americas for about 115,000 years. Not surprisingly, the claim met with skepticism from other archaeologists, who said that the evidence at the site wasn’t enough to support rewriting the entire story of human migration.
That evidence is a collection of broken mastodon bones, rounded cobbles, and flat stones. These bits and pieces were unearthed during a 1992 highway construction project in San Diego and are now known as the Cerutti Mastodon Site. Archaeologist Steven R. Holen of the San Diego Natural History Museum and his colleagues say that early humans used the cobbles as hammers and the flat stones as anvils to crack open mastodon bones to get the marrow inside. They say the Cerutti site represents a very early wave of human migration into the Americas, perhaps one that didn’t last long enough to get a foothold. That explains why no other human campsites this old have turned up in the Americas.
There’s no question about the age of the site. Radiometric testing relying on uranium decay and several other methods put the bones at over 100,000 years old, and even critics agree that the dating is reliable. The debate centers on whether the items at Cerutti are really proof of human activity, and competing arguments have been published in today's issue of Nature.