DNA Genomic Research Shows Archaic Humans Bred with Mystery Species

Newly discovered ancient genomic profiles, one from a Neanderthal and one from a different archaic human group called the Denisovans, suggest that interbreeding occurred between the members of several ancient hominid groups living in Europe and Asia more than 30,000 years ago, including an as-yet unknown human ancestor from Asia.

The new findings were presented on November 18, 2013, at a meeting at the Royal Society (London, UK). “What it begins to suggest is that we’re looking at a ‘Lord of the Rings’-type world—that there were many hominid populations,” said Dr. Mark Thomas, an evolutionary geneticist at University College London (UK), who was at the meeting but was not involved in the work.

The first Neanderthal and the Denisovan genome sequences transformed the analysis of ancient human history, not least because they revealed that these groups interbred with anatomically modern humans, contributing to the genetic diversity of many people currently alive.

All humans whose ancestry originates outside of Africa owe about 2% of their genome to Neanderthals and specific populations living in Oceania, such as Australian Aboriginals and Papua New Guineans, received approximately 4% of their DNA from interbreeding between their ancestors and Denisovans, who are named after the cave in Siberia’s Altai Mountains where they were discovered. The cave contains remains deposited there between 30,000 and 50,000 years ago.

Those conclusions, however, were based on low-quality genome sequences, riddled with errors and full of gaps, Dr. David Reich, an evolutionary geneticist at Harvard Medical School (Boston, MA, USA) reported at the meeting. His team in collaboration with Dr. Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany) has now produced much more complete versions of the Denisovan and Neanderthal genomes, similar to the quality of contemporary human genomes. The high-quality Denisovan genome data and new Neanderthal genome were derived from bones found at Denisova Cave.

The new Denisovan genome indicates that this mysterious population traveled around. Dr. Reich reported at the meeting that they interbred with Neanderthals and with the ancestors of human populations that now live in China and other areas of East Asia, in addition to Oceanic populations, as his team earlier reported. Most remarkably, according to Dr. Reich, the new genomic data indicate that Denisovans interbred with another extinct population of ancient humans that lived in Asia more than 30,000 years ago, which is neither Neanderthal nor human.

The meeting was pulsating with theories about the identity of this potentially new population of humans. “We don’t have the faintest idea,” said Dr. Chris Stringer, a paleoanthropologist at the London Natural History Museum (UK), who was not involved in the work. He hypothesized that the population could be related to Homo heidelbergensis, a species that left Africa about half a million years ago and later gave rise to Neanderthals in Europe. “Perhaps it lived on in Asia as well,” Dr. Stringer remarked.

The findings were published November 2013 in Nature News.

Related Links:
Harvard Medical School
Max Planck Institute for Evolutionary Anthropology