Criticisms Mount Against Claim of Hominins in the Americas Over 100,000 Years Ago
A startling claim was made almost a year ago: researchers said that they had evidence of hominins in the Americas at least 100,000 years before most people believed. They called for open-minded consideration of their evidence and have been met with debate. Skeptics say that there is no way the story is as it has been presented. But apart from a disbelief in the extremely old date, what else do they say does not fit?
One group of archaeologists has had their criticism published recently in Nature. They claim that the mastodon bone damage came about through disturbances at the site by modern construction equipment. Their evidence comes from “similar-looking damage, which was caused by natural wear and tear and heavy equipment” on mammoth bones that were found in Waco, Texas, USA. That collection of bones dates to approximately 60,000 years ago and came from 26 mammoths.
A Wooly mammoth (left) and an American mastodon (right) facing each other, showing the physical differences between the two animals. (Dantheman9758/ CC BY SA 3.0 )
As Ancient Origins reported in April 2017 , construction workers came across a collection of ancient bones in San Diego, California, USA in 1992. It took years of testing before an interdisciplinary team of researchers could ascertain that the mastodon bones date to 130,000 years ago. But with this information in hand an even more shocking claim was waiting to be made – there are marks the researchers assert were left on the bones by hominins.
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A concentration of fossil bone and rock. The unusual positions of the femur heads, one up and one down, broken in the same manner next to each other is unusual. 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. Upper left is a rib angled upwards resting on a granitic pegmatite rock fragment. ( San Diego Natural History Museum )
The researchers knew from the beginning that their date would be controversial. Thus, they waited 24 years to ascertain their facts before publishing their findings in the journal Nature. As they wrote in their paper:
“The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent results; and (4) unquestionable artefacts are found in primary context.”
The Cerutti Mastodon site had spiral-fractured mastodon bone and molar fragments, many of which the team claim preserves evidence of percussion. The site also had flat rocks that could have been anvils and a collection of small stones that may have been used as hammers. These artifacts were found in the same layer as the mastodon bones and apparently show evidence of use wear and impact marks . The site is said to have looked “like a perfectly preserved tableau of an ancient tool-making workshop.”
Marks on mastodon bones – natural, construction damage, or evidence of hominins in the Americas over 100,000 years ago? ( Kate Johnson/ SDNHM )
Regarding the spiral fracture, Joseph Ferraro at Baylor University’s Institute of Archaeology in Waco, Texas, says “A dinosaur would break a leg. It happens. There are natural processes that could reasonably explain spiral fractures.” In general, Ferraro believes natural wear and construction work (some of the bones at Waco were found during a building project) explain the marks seen on the mastodon bones.
Thomas Deméré, principal paleontologist at the San Diego Museum of Natural History and one of the authors of the study under fire are standing by their claims . The team calls for critics to examine the bones in-person before putting forward their disagreements. Furthermore, they suggest the current criticism is based on superficial claims and an inappropriate comparison between the Cerutti Mastodon site and what has been found in Waco. Deméré also asserted “We’re really quite familiar with what kind of damage is caused by heavy equipment.”
A map of the Cerutti Mastodon site that shows fractured mastodon leg bones, bone fragments, broken molars, and tusks that lay clustered around two large stones—other stones lay nearby. ( San Diego Natural History Museum )
According to Ars Technica, there are two main arguments that have been provided against the paper: the site was too disturbed by construction to be reliable – such as Ferraro and his team state – or, simply, the evidence provided just isn’t enough to convince other researchers.