Scientists theorize that members of the recently identified ‘hominin’ group known as the Denisovans interbred with modern humans, passing on various genes through multiple distinct mating events that influenced early human development. They provide evidence suggesting that different Denisovan populations, which likely occupied vast regions stretching from Siberia to Southeast Asia and from Oceania to South America, were well-suited to diverse environments. Additionally, they highlight several Denisovan-derived genes that offered modern humans advantages in these various settings.
Scientists theorize that members of the recently identified “hominin” group known as the Denisovans interbred with modern humans, passing on various genes through multiple distinct mating events that influenced early human development.
The first draft of the Neanderthal genome was published in 2010, and subsequent comparisons with modern human genomes indicated that Neanderthals and contemporary humans had mated in the past. Shortly thereafter, researchers analyzing a genome extracted from a finger bone found in the Denisova cave in Siberia uncovered that this bone belonged to a new hominin group now referred to as Denisovans, who also engaged in interbreeding with modern humans.
“This discovery ranks among the most thrilling in the study of human evolution over the last decade,” stated Dr. Linda Ongaro, a Postdoctoral Researcher at Trinity College Dublin’s School of Genetics and Microbiology, and the lead author of an intriguing new review article published in the prestigious journal Nature Genetics.
“It’s a widespread myth that humans evolved abruptly and neatly from a single common ancestor. However, with each new finding, we increasingly understand that interbreeding with various hominins played a critical role in shaping who we are today.”
“In contrast to Neanderthal fossils, the Denisovan record is sparse, consisting only of a finger bone, a jawbone, teeth, and some skull pieces. Nevertheless, by examining the surviving Denisovan fragments within modern human genomes, researchers have identified evidence of at least three separate instances when genes from distinct Denisovan groups were incorporated into the genetic makeup of modern humans.”
Each of these instances shows varying degrees of connection to the sequenced Altai Denisovan, highlighting the intricate relationship between these sister lineages.
In their review, Dr. Ongaro and Prof. Emilia Huerta-Sanchez present evidence that several Denisovan populations likely ranged widely from Siberia through Southeast Asia and into Oceania and South America, with adaptations to their unique environments.
They also discuss numerous Denisovan-origin genes that provided modern humans with beneficial traits suited to these various environments.
Dr. Ongaro noted: “Among these is a genetic region that promotes tolerance to hypoxia, or low oxygen levels, which is notably found in Tibetan communities; several genes that enhance immune response; and another that affects lipid metabolism, generating heat when exposed to cold conditions—offering a survival advantage to Inuit populations in the Arctic.”
“There are many potential research avenues ahead that will allow us to better understand how the Denisovans influenced contemporary humans, including conducting more comprehensive genetic studies in lesser-researched populations, which may uncover previously unrecognized Denisovan ancestry. Moreover, combining more genetic findings with archaeological data—especially if more Denisovan fossils can be discovered—would certainly help bridge knowledge gaps.”
