The first portrait of the anatomy of an extinct group of ancient humans known as Denisovans has been created based on epigenetic changes.
Researchers used a type of epigenetic change, known as methylation, to map differences in DNA over time. By comparing these maps across the genomes of extinct and modern humans, they were able to produce a rough sketch of what a Denisovan might have looked like.
Professor Liran Carmel at the Hebrew University of Jerusalem in Israel, and co-leader of the research, said: 'This might shed light on many of the questions that people have about the Denisovans, including how they adapted to their environment, and how the genetic traces they've left in modern humans might have helped them adapt to theirs.'
'This is a highly original and exciting study, which is extraordinary not just with respect to the specific findings but also with respect to the entire approach,' Dr David Reich, a geneticist at Harvard University in Boston, Massachusetts, who was not involved in the study told the Guardian.
The research, published in Cell, is the first study to use gene methylation to predict the anatomy of a Denisovan. Methylation acts as a switch to turn the expression of a gene up or down. The researchers compared the methylation patterns of DNA from the bones of a girl found in a Denisova Cave in Siberia to those from Neanderthals, chimpanzees and modern humans. They discovered 56 traits that differed between them, 32 of which they used to reconstruct the Denisovan skeleton.
'In many ways, Denisovans resembled Neanderthals but in some traits they resembled us and in others they were unique,' said Professor Carmel. 'They were humans very similar to us so pointing out the differences between us is critical to understand what makes us human and what might have led to the way we adapted to the world.'
Since the study was only based on an individual and the method could not provide exact body measurements, the researchers caution that it is not an exact representation of what the Denisovan looked like. 'We can say [Denisovans had] longer fingers [than modern humans for example], but we cannot say two millimetres longer,' said Professor Carmel. 'It's an interesting approach, but we can't verify the predictions until several Denisovan skeletons are found.'
The Denisovans are thought to have lived across much of Asia tens of thousands of years ago, but until now very little was known about their appearance. About five percent of the ancestry of people from Oceania can be traced to Denisovans.