People living in Red Deer Cave in southern China were not, as some have previously thought, representatives of an extinct species of humans. Instead, DNA analysis shows, they were very much part of the modern human family, but the population has turned out to be scientifically important for a different reason.
Human remains were first found at Red Deer Cave in Yunnan, southern China, in 1989. Excitement surged in 2012 when new discoveries suggested they might represent some of the last surviving representatives of human species other than Homo sapiens. Alternatively, it was thought the cave's inhabitants could have been hybrid populations between Neanderthals or Denisovans and modern humans.
All this was based on the shape of bones and teeth left in Malu dong (Red Deer) Cave. Neither the newly discovered bones, nor a reexamination of specimens that had been held in museums, yielded sequencable DNA at the time, unsurprisingly given the area's warm climate. A paper in Current Biology has changed that, and with it our thinking about who the Red Deer Cave people were.
"Ancient DNA technique is a really powerful tool," said senior author Dr Bing Su of the Kumming Institute of Zoology in a statement. "It tells us quite definitively that the Red Deer Cave people were modern humans instead of an archaic species, such as Neanderthals or Denisovans, despite their unusual morphological features."
The DNA was extracted from a skull found in the cave and dated as around 14,000 years old. Ironically, the Neanderthal-like shape of the skull and the relatively small brain space were key features that had led researchers to think the caves inhabitants at the time were not modern humans.
Having established the Red Deer Cave People's status as members of our species, Su and co-authors then sought their closest surviving relatives by comparing the skull's DNA to that of existing populations.
The analysis demonstrates a strong connection to Native American peoples, as well modern East Asians. Comparing with other ancient DNA, the closest affinity is found with a 13,900-year-old specimen from Siberia, and the oldest human DNA found in the Americas.
It's not news that Native Americans have a strong historical connection to East Asia, but the Reed Deer Cave findings have caused the authors to propose a different migration path from that previously favored. Instead of the first people to cross the Pacific being long-time residents of Siberia, they suggest a population had lived in southern China for a period, before some journeyed north, probably along a coastal route by way of Japan.
The findings also add to growing evidence for considerable genetic diversity of hominins in southern East Asia during the last Ice Age, some of which was reflected in the shape of their bones. The paper notes Yunnan is still the most ethnically and linguistically diverse region in China today, as well as being a center of plant and animal biodiversity.