An ancient skull discovery in China offers some intriguing possibilities, including the chance that researchers have found a yet-undiscovered early human species.
Before the arrival of Homo sapiens, the western regions of Asia and most of Europe was ruled by the Neanderthals, and scientists had long come to such a conclusion. But studies covering the eastern and central parts of Asia and the prehistoric humans who lived there thousands of years ago have been quite limited due to a lack of remains found in those areas.
In an interview with BBC News, Washington University of St. Louis researcher Erik Trinkaus stressed that there’s still no way to find out whether the ancient skulls his team discovered in Xuchang, China, may be skulls belonging to Denisovans. This is a much-talked-about, yet “mysterious” population of early humans whose only proof of existence was DNA analysis performed on fossils from Siberia, including a tooth and a finger bone.
“The issue here is the patterns of variation and the population dynamics of ‘archaic’ populations during the later part of the Pleistocene.”
— Corey S. Powell (@coreyspowell) March 3, 2017
Adding some perspective to the new study, Homo sapiens had first come about in Africa approximately 200,000 years ago, and they would eventually spread out to other continents some 60,000 years ago and later. The arrival of this modern human species had displaced their ancestors’ populations, including the Neanderthals and Denisovans. However, what has piqued scientists the most about this phenomenon was the interbreeding that took place as Homo sapiens took over the rest of the world — this is a theory that had long been posited by researchers and documented in studies.
BBC News noted that the ancient skulls, which were discovered in partial form between 2007 and 2014 without any faces, may be about 105,000- to 125,000-years-old. But they share features with Neanderthal skulls discovered in the west years ago, yet also have their fair share of differences from those fossils. These similarities include braincases comparable to the largest ones found in Neanderthals and those of modern humans, while the differences include a noticeably smaller bone mass in some areas, including the back of the skull and over the eyes, in the Xuchang finds.
Trinkaus explained to BBC News that the discovery proves some form of interconnection between multiple populations of early humans through their similarities and differences.
“There’s a certain amount of regional diversity at this time, but also there are trends in basic biology that are shared by everybody. And the supposed Neanderthal characteristics show that all these populations were interconnected.”
— John Hawks (@johnhawks) March 2, 2017
Speaking to Science, study co-author Xiu-Jie Wu of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing said that the ancient skulls may point to an “unknown or new archaic human that survived on in East Asia 100,000 years ago.” She believes that the skulls’ shared similarities with Neanderthal and modern human fossils hint that the archaic population may have interbred “at least at low levels” with other early humans of their time. This, however, makes them highly akin to Denisovans, who have been shown to have interbred with Neanderthals and early modern humans alike.
Chris Stringer, a researcher from London’s Natural History Museum who did not take part in the new study, told BBC News that one of the ancient skulls, which was codenamed Xuchang 1, has a “remarkable brain size” – as mentioned above, the size is comparable to that of early modern human brains and the largest known Neanderthal brains. He stopped short, however, of declaring the finds a representation of a yet-undiscovered early human species, instead focusing on how the skulls’ lack of teeth makes it impossible to determine whether they are Denisovan skulls or not.
“From genetic data, the Denisovans are believed to have split from the Neanderthal lineage about 400,000 years ago – about the time of the Sima de los Huesos early Neanderthals known from Atapuerca in Spain. So one might expect some level of Neanderthal features in their morphology, added to by evidence of some later interbreeding with the Neanderthals.
“We must hope that ancient DNA can be recovered from these fossils in order to test whether they are Denisovans, or a distinct lineage.”
Meanwhile, Trinkaus was quoted by Science as saying that he “has no idea what a Denisovan is,” referring to this early human population as nothing more than a DNA sequence.
[Featured Image by Vladislav Gajic/Shutterstock]