A report published March 15 in the journal Cell about archaic DNA in modern human genomes expands our understanding of human origins.
“This discovery provides a more nuanced understanding of the mixing of modern and archaic humans as humans migrated out of Africa,” said lead author and professor of biostatistics at the University of Washington School of Public Health. Sharon Browning said. “Through DNA analysis, we found that there were at least two instances of inbreeding between Neanderthals and Denisovans. We now know that there were at least three instances of inbreeding, including at least one occasion between Neanderthals and Denisovans. , at least twice with the Denisovans.
Prior to this study, it was known that the genomes of certain populations, such as Papuans, contain about 5% Denisovan ancestry, and to a lesser extent Denisovan ancestry is present throughout Asia. . However, when DNA sequences are compared, the Denisovan sequences show a much closer match between those of the Han Chinese, the Chinese Dai people, and the Japanese.
Two populations, Neanderthals and Denisovans, contributed to the ancestry of modern humans (Sharon Browning and Serena Tucci, 2018). From: Analysis of human sequence data reveals two pulses of archaic Denisovan admixture.
Denisovans are a distinct lineage of the hominid family tree whose existence was revealed in 2010. Analysis of bone fragments and molars found in Siberia’s Denisova Cave has revealed a previously unknown complete human genome. But beyond their DNA, little is known about the Denisovans. No evidence exists to tell us what they looked like, what they ate, or what tools or techniques they had.
Browning, along with other researchers involved in the project, applied a new reference-free statistical method called Sprime (pronounced es-prime) to existing genetic data from the 1000 Genomes Project and the Simons Genome Diversity Project. . Using the new Sprime method, researchers were able to search 5,639 whole genome sequences from modern humans in Eurasia and Oceania and identify segments of DNA that were likely inherited from ancient human populations. These genetic variations were compared to Neanderthal and Denisovan sequences.
In the future, Browning and her colleagues plan to study additional Asians, as well as other peoples such as Native Americans and Africans. “We hope to use Prime to find evidence of introgression from other archaic humans,” Browning said. “We can partially reconstruct the genomes of ancient human populations that have left no viable DNA for direct sequencing, such as populations that lived in warm, humid regions of the world where DNA decays rapidly. Maybe.”
Other co-authors on the paper include Brian Browning, professor of medical genetics and adjunct professor of biostatistics at Wisconsin; Ying Zhou, Postdoctoral Fellow, University of California. Serena Tucci, Postdoctoral Fellow, Princeton University. Joshua Akey, Professor of Ecology and Evolutionary Biology and Lewis Sigler Institute for Integrative Genomics, Princeton University;
Research reported in this publication was supported by the National Institute of General Medical Sciences of the National Institutes of Health under award number R01GM110068.
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