"But it's hard to argue with the clear and remarkable evidence that we can see in all of this material".
The remains were discovered in 1992 by construction workers expanding a freeway, but existing technology was not sufficient to radiometrically date the mastodon bones. Dating the tools proved to be challenging.
According to a paper published Wednesday in the journal Nature that includes two University of MI researchers, a stone tool and anvil unearthed during the discovery of the mastodon bones hint that relatives of humans may have been here much earlier than previously thought.
Rare archaeological sites in North and South America have been dated to possibly as old as 30,000 years - but 130,000 years is something altogether different. But California field paleontologist Richard Cerutti discovered the fossils that had been deposited much earlier. It's not believed that the humans killed the animal, however. Are those damage patterns on the bones caused by early migrants, or were they possibly made by something else in that landscape?
The bones also displayed spiral fractures, which suggests that they were broken while fresh and not some years later. "You can actually identify the particular hammer was hit on a particular anvil and trace it to the fragmented bones", Richard Fullagar, a research fellow at the Centre for Archaeological Science at University of Wollongong, said in the same press conference prior to the release of the paper.
The Nature analysis focuses on remains from a single mastodon, and five stones found nearby. "This, Holen [and his colleagues] have most certainly not done, making this a very easy claim to dismiss".
This new find, however, pushes back the record of human species far beyond scientists' expectations. This kind of tool use isn't specific to any one human species.
A new study sends waves across the academia revealing that there has already been human activity in North America since 131,000 years ago, and not 24,000 years ago as initially thought of.
In this April 28, 1993 photo provided by the San Diego Natural History Museum, a bulldozer refills the Cerutti Mastodon site in San Diego, Calif., after the excavation and salvage of fossils.
"If the results stand up to further scrutiny, this does indeed change everything we thought we knew", said Chris Stringer of the Natural History Museum in London. "This is up there with one of the discoveries of the century, I would say".
All other paleo-anthropological evidence available dates human arrival in the Americas to around 14,500 years ago, at the end of the Pleistocene period. Then the people vanished.
With a big find like this and a big controversial conclusion, it is necessary for your evidence to be as robust as possible. I'm not saying they're absolutely wrong and it can not be a human site, but I'd say the jury's still out. Mastodon molars are located in the lower right hand corner next to a large rock comprised of andesite which is in contact with a broken vertebra.
They also invite other scientists to examine and question their findings. According to a paper recently published in Nature, the San Diego Natural History Museum paleontologist-authors maintain that the bones show signs of percussion (breakage) associated with "humans with manual dexterity and the experiential knowledge to use hammerstones and anvils..."
"And people are welcome to come to the museum to examine these specimens for themselves".