Denisovans were ancient humans who lived more than 50,000 years ago in Asia. They are known only from a few skeletal remains. Most of these remains were found at Denisova Cave, on the Anuy River in the Altai Mountains of southern Siberia. Scientists identified this population by analyzing ancient DNA (deoxyribonucleic acid, a genetic material) recovered from bones found at the cave. It was the first time scientists had identified a prehistoric human population through DNA analysis alone. The cave also preserves stone tools and other archaeological evidence that other ancient people lived there over the last 120,000 years.
Russian archaeologists first explored Denisova Cave in the 1970’s. Since then, archaeologists have conducted periodic excavations at the site. They have found stone tools and other remains that show modern humans occupied the cave over the past 35,000 years. Before that, they found, other ancient humans had left tools and skeletal remains in the cave. The skeletal remains included two molar teeth and a single finger bone discovered in the early 2000’s. Scientists identified the bone as being from the little finger of a female. They were able to extract and sequence the entire genome of the individual from this bone. The term genome refers to all the genes on a cell’s threadlike structures called chromosomes.
Scientists examining the genome found that it was from a previously unknown population of humans. They referred to this group as Denisovans. Another bone in the cave was from a Neandertal. The Neandertals were prehistoric humans who lived in Europe and Asia. They are mainly known from fossils that date from about 150,000 to 39,000 years ago. The Denisovan genome differed markedly from that of Neandertals. This evidence suggests that the two populations had lived apart for thousands of years.
In 2016, scientists analyzed genetic material recovered from fossils at a site called Sima De Los Huesos in Spain (see Atapuerca fossil site). An analysis of this material showed that the fossils found there were from an early population of Neandertals. The evidence suggests that Neandertal and Denisovan populations separated some time before 430,000 years ago.
In 2017, scientists extracted genetic material from another fossil tooth originally discovered at Denisova cave in 1984. They determined the deciduous tooth (baby tooth) was substantially older than the other remains, at about 150,000 years old. The fossil tooth shows that the Denisovan population inhabited the region in Siberia over a long period.
Scientists have also compared the Denisovan genome to that of living people around the world. They found similarities between the Denisovan genome and that of native peoples in Australia, New Guinea, the southern Philippines, and Melanesia. Denisovans contributed up to 5 percent of the genomes of some people living in these regions today. Anthropologists believe that the ancestors of these people must have encountered and bred with some members of the ancient Denisovan population.
In 2019, scientists analyzed proteins extracted from a fossil jawbone that had been excavated in Tibet in 1980. The analysis identified the jawbone as Denisovan. Scientists also determined the fossil was about 160,000 years old. The fossil represents the earliest evidence of human populations inhabiting the high Tibetan Plateau. Today, the Indigenous (native) people of that region in Nepal and Tibet possess a genetic adaptation that enables them to better withstand the physical effects of hypoxia (insufficient levels of oxygen in the blood) caused by their high-altitude environment. The analysis of Denisovan genetic material shows they also possessed this genetic trait. Scientists believe that the modern inhabitants of the Tibetan Plateau inherited this adaptation from Denisovan ancestors in the distant past.
The identity and appearance of the Denisovans remains a mystery. Several other fossil bones and fragmentary skeletons of ancient people from China and Southeast Asia have been discovered. Some show anatomical similarity to the fossils from Denisova Cave and Tibet. However, none of the recently discovered remains preserve DNA. Anthropologists continue trying to gather DNA and other evidence from fossils to learn more about the Denisovans and their relationship to modern humans.
See also Pääbo, Svante; Prehistoric people
