Question

Denisovans are an early hominin species that was first identified in 2010.  They were named after the Denisova cave in Siberia where the first evidence of their existence (a tooth and a bone) were discovered in 2008.  There is disagreement whether they constitute a species or subspecies, so they are respectively referred to as either Homo denisova or Homo sapiens denisova.   Current research suggests that H. sapiens and Denisovans may have overlapped in different geographical regions, and more importantly, interbred. Provide TWO pieces of evidence, with explanation, that support the hypothesis that H. sapiens and Denisovanindividuals interbred.  

Answer 1

Homo sapiens:-

Humans (Homo sapiens) are the only extant members of the subtribe Hominina. Together with chimpanzees, gorillas, and orangutans, they are part of the family Hominidae (the great apes, or hominids). Terrestrial animals, humans are characterized by their erect posture and bipedal locomotion; high manual dexterity and heavy tool use compared to other animals; open-ended and complex language use compared to other animal communications; larger, more complex brains than other animals; and highly advanced and organized societies.

Denisovan individuals:-

The Denisovans or Denisova hominins ( /dɪˈniːsəvə/ di-NEE-sə-və) are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic (potentially surviving as late as 30–14,500 years ago in New Guinea). Denisovans are known from few remains, and, consequently, most of what is known about them comes from DNA evidence. Pending consensus on their taxonomic status, they have been referred to as Homo denisova, H. altaiensis, or H. sapiens denisova.

evidence that support the hypothesis that H. sapiens and Denisovan individuals interbred:-

The availability of edible insects in East Asia aided the spread of the unaggressive, highly cooperative Neanderthals, who interbred with H. sapiens in Asia, resulting in a higher admixture of Neanderthal DNA in East Asian populations. Geographical variation in degree of interbreeding between H. sapiens and Neanderthals likely contributed to neurological and behavioral differences in modern humans. Similarly, people with Denisovan genetic admixture were better able to dwell in mountainous regions, allowing their genetic legacy to cross the Himalayas and persist in Southeast Asian and Oceanian H. sapiens. In the Sub-Saharan region, unaffected by Denisovan or Neanderthal interbreeding, H. sapiens interbred with H. heidelbergensis, because high humidity militated against fire-making and allowed the survival of these non-fire-making hominins.

Neanderthals are an extinct species of human (in the genus Homo), related to modern humans . Traces left by Neanderthals include bone and stone tools, which have been found all over Eurasia, from Western Europe to central and northern Asia. Neanderthals are generally classified by biologists as H. neanderthalensis, and sometimes as Homo sapiens neanderthalensis.

Denisovans are another extinct species of humans, similar to Neanderthals. The Denisova Cave is located in southwestern Siberia, in the Altai Mountains near the Russian border with China and Mongolia . Research shows that Denisovans shared a common origin with Neanderthals but were genetically distinct.

Recent genetic studies have shown a higher Neanderthal admixture in East Asians compared with Europeans , most likely indicating that at least two independent gene-flow events must have taken place in early modern humans and that the early ancestors of East Asians experienced more admixture than those of Europeans after the divergence of these two groups ; to put it in another way, studies seeking to explain why East Asians inherited 15–30 % more Neanderthal DNA than Europeans have concluded that East Asians interbred with Neanderthals in two waves .

The first interbreeding with Neanderthals occurred in the Middle East before the ancestors of modern non-Africans spread out across Eurasia. The ancestors of modern Europeans and Asians then split out of this migrant group , and the ancestors of East Asians interbred again with Neanderthals after the split. The first humans with proto-Neanderthal traits are believed to have existed in Eurasia as early as 350,000–600,000 years ago, with the first “true Neanderthals” appearing between 200,000 and 250,000 years ago.

As this implies, Neanderthals and Denisovans were likely more closely related to one another than either was to modern humans . Although the range covered by Denisovans is argued, studies have confirmed the impact of Denisovan ancestry in the islands of Oceania, particularly Papua New Guinea, and some parts of mainland Asia, such as Tibet.