American scientists analyzed the genome of an ancient man from the Chinese cave Maludong ("Deer Cave"), who lived about 14 thousand years ago, published in 2022. They came to the conclusion that the findings of the original work, which received wide coverage, were incorrect, and the studied sample itself was apparently heavily contaminated with modern human DNA. Critical comments on the article were published in the journal Current Biology, and the scientists posted additions to them in the form of a preprint on the website bioRxiv.org.
In 1989, researchers discovered ancient human remains in the Maludong (Deer Cave) cave in southern China: a braincase, several other skull and jaw fragments, a pair of teeth, and fragments of a femur and tibia. Although the remains belonged to people who lived at the end of the Pleistocene era, about 14,000 years ago, they combined features that are characteristic of both sapiens and more archaic representatives of our genus. Analysis of these bones and finds from another Chinese cave, Longlin, led some scientists to hypothesize that such a mosaic morphology may be the result of hybridization between representatives of different species.
In 2022, Chinese scientists presented the results of a genetic study of the remains from the Maludong site. According to them, they isolated ancient DNA from a fragment of the cranial section of the MLDG-1704 skull. The analyzed sequence, given the code name MZR, represented the first genome of a late Pleistocene human from southern East Asia. At that time, the scientists determined that the remains belonged to a sapiens woman with no signs of recent admixture with representatives of archaic populations. In addition, one of the important conclusions of this work concerned the fact that the population to which the Maludong man belonged was genetically very similar to a significant portion of the ancestors of Native Americans.
However, American paleogeneticists and bioinformaticians, led by renowned researcher David Reich from Harvard University, submitted critical comments to this article to the journal Current Biology, where the genome of the ancient man from Maludun was published almost three years ago. In fact, the arguments of the American scientists negate all previously obtained conclusions of genomic analysis. According to the authors, the read DNA sequence does not meet the criteria that would allow it to be used in population studies.
Thus, critics drew attention to the very large number of errors in the published sequence, and their level was extremely high even for mitochondrial DNA, the quality of coverage of which is usually orders of magnitude higher than for nuclear DNA. For example, American scientists noted that the frequency of errors in the mitochondrial DNA sequence was so high that they were not even able to determine which mitochondrial haplogroup this person was a carrier of, not to mention more distant conclusions about the individual's maternal line, which are contained in the original work.
The American researchers also posted some of their critical comments and thoughts about this genome as a preprint on the bioRxiv.org website. Their gist is that the sample selected for analysis was apparently heavily contaminated with modern genetic material. Moreover, the published DNA sequence can be modeled by approximately 90 percent from the DNA of a modern resident of China, that is, the place where the original research was conducted. At the same time, the Americans were unable to isolate exclusively fragments of the ancient DNA sequence from this genome.
Anthropological finds from China often become the subject of discussions. We told about one such story, connected with the problem of when the first sapiens settled in the territory of modern China, in the article “Teeth of Discord”.
