Recently, geneticists from Trinity College Dublin have shed new light on the influence of Denisovan DNA on modern human adaptation and mental health. In a review article published in Nature Genetics, Dr. Linda Ongaro, a postdoctoral researcher, and Professor Emilia Huerta-Sanchez outlined evidence suggesting that modern humans interbred with at least three distinct Denisovan populations. This reveals a complex history of interbreeding events that impacted human evolution, according to Science Daily and Phys.org.
“Our understanding of Denisovans is still limited, but recent discoveries are broadening our horizon,” Dr. Ongaro said, as reported by Scienze Notizie. She described these findings as "one of the most exciting discoveries in human evolution in the last decade," emphasizing their influence on our genetic heritage.
Denisovans were identified only recently, starting from the genetic analysis of a finger bone discovered in 2008 in a Siberian cave. Despite limited physical remains—including a finger fragment, a jawbone, teeth, and skull fragments—analysis of modern human genomes has revealed traces of Denisovan DNA, indicating multiple interbreeding events. According to Science Daily and Phys.org, these events involved genes from distinct Denisovan populations mixing with the genetic heritage of modern humans.
These interbreeding events transmitted genetic adaptations that Denisovans had developed to survive in harsh environments. For example, the EPAS1 gene helps regulate the body's response to low oxygen levels and gives Tibetans a physiological advantage in the high altitudes of the Tibetan plateau. “Among these is a genetic locus that confers a tolerance to hypoxia, or low oxygen conditions, which makes a lot of sense as it is seen in Tibetan populations,” Dr. Ongaro explained, according to IFLScience.
Similarly, Inuit populations carry Denisovan genes that help regulate body fat and maintain warmth, contributing to improved metabolism to cope with cold environments. Dr. Ongaro added, “This genetic adaptation impacts the way the body breaks down fats, ultimately providing heat when stimulated by cold, which confers an advantage to Inuit populations in the Arctic,” as reported by IFLScience.
Another significant gene inherited from Denisovans is a variant of the SLC30A9 gene, which affects zinc regulation and is implicated in mitochondrial metabolism. A research team led by Elena Bosch and Rubén Vicente identified this Denisovan genetic heritage. This gene helped Homo sapiens adapt to the cold climates of Asia and Europe. “This variant of the gene encodes the zinc transporter and modifies it,” Bosch stated, according to La Vanguardia. She added, “Zinc is an essential trace element involved in many key human processes.”
However, the Denisovan variant of the SLC30A9 gene is also associated with a higher predisposition to neuropsychiatric disorders such as depression and schizophrenia. Bosch noted, “Previous studies associate this variant with a higher predisposition to psychiatric diseases.” Vicente added, “In our laboratory, we have studied the Denisovan variant of this gene in cell cultures and compared its function with another human variant,” as reported by La Vanguardia.
The impact of Denisovans is evident in modern human DNA, with evidence of at least three past events where genes from distinct Denisovan populations mixed with human genetic heritage. According to Scienze Notizie, these crossings and interactions have left an indelible mark on our DNA and continue to influence us today.
Despite few physical remains, the influence of Denisovan DNA is visible in modern human populations. Papua New Guineans retain up to 5% Denisovan ancestry, a higher proportion than other groups.
The history of humanity is not linear; evolution is more like a vine that intertwines with other species. Researchers now believe that modern humans interbred with at least three distinct populations of Denisovans. “By interbreeding with Denisovans, Homo sapiens seem to have acquired a number of advantageous genes, although only a few beneficial traits derived from Denisovans have been identified so far,” Dr. Ongaro said, according to IFLScience.
The future of research includes more detailed genetic analyses in under-studied populations to identify hidden traces of Denisovan ancestry. Dr. Ongaro added, “Additionally, integrating more genetic data with archaeological information—if we can find more Denisovan fossils—would certainly fill in a few more gaps,” as reported by Science Daily.
The article was written with the assistance of a news analysis system.