Final answer:
Denisovan alleles are present in modern human populations, particularly in Melanesia and parts of Asia, but not in Europe. Interbreeding between Denisovans, Neanderthals, and early modern humans has led to a genetic legacy visible in the DNA of certain contemporary populations. Ongoing research indicates the possibility of additional archaic hominin contributions to modern human genomes.
Step-by-step explanation:
Denisovans, an extinct group of archaic humans, have left a genetic legacy in several modern human populations. Accepted research indicates that alleles of Denisovans can be found in modern human populations in Melanesia, such as Indigenous Australians and Papua New Guineans, due to interbreeding between Denisovans, Neanderthals, and early modern Homo sapiens.
Denisovan DNA is notably absent in European populations but is present to a minor extent in Asia, as observed in populations like the Tibetans. In addition to Denisovan and Neanderthal ancestry, a potential "ghost population" may have also contributed to the genetic makeup of certain modern human groups.
Interbreeding events between different human species such as Denisovans and Neanderthals with early modern humans are supported by genomic studies showing shared DNA segments.
The Denisovan ancestry tends to be higher in populations residing in the Pacific Islands and parts of Asia, with statistical genetics indicating that previously estimated percentages of Denisovan DNA might even be challenged by the possible existence of additional archaic hominin contributors.
Various genetic analyses imply that the Denisovan ancestry in present-day human populations demonstrates complex interactions among different human species throughout history. Evidence of these ancestral genetic traces is particularly strong among populations in Melanesia and select Asian regions, offering insight into the evolutionary history of Homo sapiens.
It is clear that Denisovans, Neanderthals, and potentially other archaic hominins played a critical role in shaping the genetic diversity of modern human populations across the globe.