Neanderthals in California? Maybe so, provocative study says

The fossil remains were discovered by museum paleontologists during routine paleontological mitigation work at a freeway expansion project site managed by the California Department of Transportation (Caltrans). Dating the tools proved to be challenging.

Using stone hammers and anvils similar to those found, they broke open large elephant bones much in the way pre-historic humans might have done. "The evidence we found at this site indicates that some hominin species was living in North America 115,000 years earlier than previously thought".

"This discovery is rewriting our understanding of when humans reached the New World", said Judy Gradwohl, president and chief executive officer of the San Diego Natural History Museum. It's not believed that the humans killed the animal, however.

"We anticipate people will be curious to see if they can't replicate those results", Paces said. They also may have extracted marrow from the bones for nutrition. Vance Holliday of the University of Arizona in Tucson said the paper shows the bones could have been broken the way the authors assert, but they haven't demonstrated that's the only way.

However, the position of other stones and bones in the area created what was described as a "paleo crime scene". Out of the ancient stream deposits came the remains of a camel, horse and other mammals - including the bones, tusks and teeth of a mastodon. "A claim like this can never rest easily on a single site, but the team [has] presented evidence which can't be ignored".

"This is a whole new ball game", Steve Holen, co-director of the Center for American Paleolithic Research and the paper's lead author, told CNN. To give some perspective, it's believed humans migrated out of Africa 125,000 years ago at the earliest.

"The evidence from the Cerutti Mastodon site has been rigorously researched and presented, and might be more hard to refute, even though the proposed hominin narrative derived from these data has some gaping holes that need filling", Erella Hovers, an archaeologist at the Hebrew University of Jerusalem, writes in a commentary on the study.

"I know people will be skeptical of this because this is so surprising", Holen said.

Whomever they were, "there is a mass of evidence that, put together, should overcome any skepticism", says study co-author Richard Fullagar of Australia's University of Wollongong. His experiments about stone tools were used to determine some of the bone fragments were broken apart in that way.

"Normally at an archeological site you find chipped stone tools, irrespective of what they're doing at the site". Then the people vanished. Or is there a long, but as of yet, scarcely recognized presence of humans in this hemisphere? The users evidently found them and brought them to the site. "There's still some information missing". And Gary Haynes, an archaeologist at the University of Nevada in Reno, notes that "the features of the broken bones ... are also produced when heavy construction equipment crushes buried bones".

The researchers are confident that under careful examination, other scientists will come to the same conclusions.

"Since the original discovery, dating technology has advanced to enable us to confirm with further certainty that early humans were here signficantly earlier than commonly accepted", said co-author Thomas Demere, a paleontologist at the San Diego Natural History Museum.