Ancient tooth DNA reveals past species of human

An obscure branch of the human tree of evolution survived for thousands of years in a remote mountain range in Siberia – and even though it eventually died out, left genetic traces within living Homo sapiens, according to a new study.

Scientists said they know the Denisovans interbred with both Neanderthals as well as modern humans, noting the tiny amount of DNA from Denisovans in the modern day Melanesians who live on a number of islands in the Pacific Ocean.

Denisovans were only discovered in 2008, and had originally been thought to have existed about 50,000 years ago, based on fossils found in a southwestern Siberian cave.

The most recent study notes that while Denisovans’ remains have only been found in one location, Denisovan DNA has been linked to “the ancestors of present-day populations across Asia and Oceania” which suggests “they may have lived in other parts of Asia”.

An worldwide team of researchers used DNA sequencing on the two molars and confirmed that the teeth belonged to two males that lived 60,000 years apart from each other. Here we present nuclear DNA sequences from Denisova 4 and a morphological description, as well as mitochondrial and nuclear DNA sequence data, from another molar (Denisova 8) found in Denisova Cave in 2010.

The anthropologists described the Denisovans as long lost cousins to today’s humans, who lived during the same time as both Neanderthals and humans. Their DNA shows more diversity and variation over time than Neanderthals. The Denisovans were more closely related to Neanderthals, having diverged from Homo sapiens about 500,000 years ago. “Denisovans may therefore have been present in southern Siberia over an extended period”. Still, these two species are considered the closest extinct relatives of modern humans. This also indicates that Denisovans were alive on Earth at the same as humans and Neanderthals for thousands of years.