There, archaeologists discovered a collection of a mastodon – an extinct species of elephant – bones along with stones which appeared to have been scraped and hammered.
However, no other traces of human activity in the region, so researchers were left scratching their heads over the anomaly.
But a new survey from researchers has discovered ancient mastodon bones in the region which were embedded into the upward facing sides of two cobblestones collected from the site.
According to the new research, the data suggests that the bones were indeed hammered in using rocks – a technique which is presumably unique to humans.
The team said if the bones were merely passively moved next to the rocks, there would be no trace of the bones in the pebbles.
Critics of the discovery claim the stones may have embedded fragments of mastodon bones in them due to either work carried out by modern humans – such as road works which flattened the two together – or by a natural force.
However, the new study, published in the Journal of Archaeological Science, said the hammer technique was very much deliberate.
The researchers wrote: “Cobbles from the Cerutti Mastodon (CM) site have impact marks and usewear suggesting that mastodon bones were placed on stone anvils and struck with stone hammers to produce two concentrations of broken bones and stones.
“Fossil bone residues documented with the Raman microscope were only found in residue extractions sampled from the potentially used surfaces and are therefore considered to be more likely use-related.
“As our investigations have indicated that the bone residues are less likely to originate from sediments or contact with bones in the bone bed as discussed above, the most parsimonious explanation is that the residues (and wear) derive from deliberate contact with bone.
“We consider this scenario to be the most likely.”
The claim was actually first made in 2017 by a team led by Stephen Holen of the San Diego Natural History Museum, but this was quickly put down by other scientists who believed the bones were accidentally embedded in the rocks during road works.
The rebuttal in 2017 read: “The extraordinary claim by Holen et al. of prehistoric hominin involvement at the CM site should not be contingent on evidence that is open to multiple, contrasting interpretations.
“Until unambiguous evidence of hominin activities can be presented, such as formal stone tools or an abundance of percussion pits, caution requires us to set aside the claims of Holen et al. of prehistoric hominin activities at the CM site.”
Further research will now be conducted to determine human’s, or an unknown human relative’s, involvement in the ancient rocks, which could re-write the path of humanity’s history.
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