A Kiwi scientist has helped rewrite the early history of mankind with DNA detective work revealing a mysterious wave of journeying ancient humans, simply known as "population X".
New research, published today in major journal Nature, has changed what we know about the timing and route that humans took out of the African continent to other parts of the globe tens of thousands of years ago.
It also finally explains intriguing clues scattered around the planet that hinted the human migrations to Europe, Asia and Oceania took place much further back in time than researchers thought.
While it's long been theorised that our ancestors moved out of Africa in a single event around 50,000 years ago, the new study points to a large wave of humans that made the shift between 100,000 and 120,000 years ago.
Not only did they uncover population X, but found that modern Papuans carry its legacy in tiny amounts of their DNA.This group had remained anonymous to researchers, until an international team of investigators used modern techniques to analyse hundreds of pieces of genetic material from 148 populations worldwide.
Massey University computational biologist Professor Murray Cox, who contributed to the findings with his earlier studies of human groups across Indonesia, said there had long been fascinating traces of such earlier groups, including skull remains in Israel, strange collections of tools in India and claims of early human remains in China.
"None of them were really that convincing, but now, for the first time, we've got whole-genome data from a wide group of people around the world, and suddenly there's this signal of something much earlier than that 50,000-year-ago exodus.
"Now, it looks like there was an earlier group that made it out 100,000 to 120,000 years ago; they're not in all of us, but they are in some living people today - mostly Australian aboriginal people and those from New Guinea."
While there were no bone remains to give a precise indication of what the humans of population X looked like, Cox expected that, even by that stage, they already looked like us.
With the stunning insights that DNA could offer, the picture of early humans had changed radically over recent years, revealing diverse groups mixing with each other.
Further studies would throw up more details around this early expansion, and the data could also be used to analyse modern human immunity to certain diseases or tolerance to certain substances.
"The unravelling of our evolutionary history will require more archaeological investigations and further genetic studies into more remote groups in order to give us the full picture.
"This data is just one small piece of a much larger modern biology puzzle - in our field we must rely on our fellow researchers to solve these mysteries as the data sets and manpower needed exceeds the capabilities of any one team studying any one location."
Was the story likely to change yet again?
"There are two answers to that - a lot of the discoveries recently have been made because we are getting more and more genetic data, and this paper kind of almost puts an end to it, because now that we've got the whole genome, there's really nothing more to go for."
The only exception, Cox said, was that we still had relatively poor tools and methods to interrogate the data.
"Give it five years, and I think this story might be fairly set in stone."
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