The human who really wasn’t

The debate over the date on which Homo sapiens left Africa is still hot. In recent years, increasing evidence has been published of deposits with H. sapiens older than 50,000 years that the “Out of Africa” ​​model establishes for the first migrations of our species outside the African continent.

Among these evidences is the deposit of Fuyan Cave, in Daoxian, southern China, published in 2015 by researchers from the National Research Center on Human Evolution (CENIEH), Maria Martinón-Torres Y José María Bermúdez de Castro, in the journal Nature, in the framework of a collaboration with researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing.

Earlier this year, a study published in the journal Proceedings of the National Academy of Science of USA (PNAS) by the researcher Xue-feng Sun from Nanjing University and his team questioned the age of up to five Chinese sites, including Fuyan. In this work they reviewed the dating of these deposits, and in the case of Fuyan, they presented two new “human” teeth, which they attributed to the same sample published by Martinón-Torres and Bermúdez de Castro.

Through genetic analysis and Carbon 14 dating of these new teeth, Sun and his colleagues concluded that Fuyan’s teeth originally dated between 80,000 and 120,000 years According to the IVPP team, they were barely 10,000 years old.

Now, the CENIEH researchers, in collaboration again with scientists from the IVPP in Beijing, are publishing a replica in PNAS where they question the quality of the study by Sun and his colleagues. In addition to problems with the dating and context of the fossil remains, the main criticism is that one of the “human” teeth analyzed by Sun’s team and from which they have extracted human DNA, is actually a tooth from a herbivore. probably a deer.

In addition to problems with the dating and context of the fossil remains, the main criticism is that one of the “human” teeth analyzed is actually a tooth from a herbivore, probably a deer.

“Science advances with data and to be able to refute a hypothesis it is necessary that the data be reliable”, affirms the director of CENIEH, María Martinón-Torres and first author of this article. “Extract Human DNA of a tooth that is not human, questions the credibility and scientific standard of all the work, ”he continues.

Surprisingly, in its reply to PNAS, led in this case by Darren curnoe from the Australian Museum in Sydney, the researchers insist on their taxonomic identification despite not providing any data. “We are still waiting for a minimal description, a morphological and metric comparison, a microtomography, an image analysis that supports such a claim. Something. Science is based on data, ”says Martinón-Torres.

Researchers from CENIEH and IVPP have compiled assessments from dozens of specialists from around the world who confirm that the tooth is not human. “Furthermore, the context in which these two new teeth were found is unknown,” says José María Bermúdez de Castro, coordinator of the CENIEH Paleobiology Program. “Sun, Curnoe and their team allege that they have found them at the same level as the sample that we published in 2015, but at no time have they contacted or coordinated with Liu Wu Y Xiujie Wu of the IVPP, those responsible for the excavation and therefore those who know the site and the stratigraphy ”.

In addition to being unprofessional and rigorous, this way of proceeding departs from the code of good conduct that is expected in the scientific field

As the CENIEH researchers explain, as a whole, Sun’s study is fraught with problems. “In addition to unprofessional and rigorous, this way of proceeding is far from the code of good conduct that is expected in the scientific field ”, they add.

Dating, also questioned

On the other hand, a team of researchers from the University of Oxford criticizes the dating methods used by Sun and his colleagues in their article. In a separate letter sent to PNAS magazine, Tom Higham and Katerina Douka, dating experts by Carbon-14, point out that the methods used by the Nanjing University group are not as robust as recommended in the dating of samples of that age.

In particular, the chemical pre-treatment methods that are recommended for dating bones and Pleistocene coals. According to Higham and Douka, this means that the dates proposed in Sun’s study are not reliable and should, in any case, be considered minimum estimates.

Rights: Creative Commons.

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