Australian scientists said today they had analyzed the oldest DNA ever taken from human remains, and that the results challenge the theory that modern humans evolved from African ancestors alone.
Researchers at Australian National University said they had analyzed DNA taken from remains unearthed in 1974 at Lake Mungo in the state of New South Wales. Dating in May 1999 put the age of the skeletal remains at between 56,000 and 68,000 years old.
ANU anthropologist Alan Thorne said that neither “Mungo Man’s” completely modern skeleton nor its DNA had any links with human ancestors from Africa found in other parts of the world.
“Neither of them [the skeleton or DNA] show any evidence that they ever were in Africa,” Thorne told Reuters. “There’s modern humans in Australia that have nothing to do with Africa at all.”
The findings, revealed in The Australian newspaper today, challenge the prevailing “out of Africa” theory of evolution because “Mungo Man” has a genetic line which has vanished yet his skeleton is completely modern.
The “out of Africa” theory holds that modern humans evolved from a common homo erectus ancestor in Africa.
Homo sapiens then left Africa and spread across the world between 150,000 and 100,000 years ago.
The ANU researchers say that because Mungo Man is modern anatomically, yet has a vanished DNA line, it means at least one group of homo erectus’ descendants evolved outside of Africa.
Under the counter “regional continuity” theory which Thorne supports, modern man evolved from homo erectus in several different places — what is now Africa, Europe, east Asia and west Asia — followed by interbreeding between the regions.
“Everywhere was becoming modern at roughly the same rate,” Thorne said. “As they are today, genes were flowing from Shanghai to Paris, from Singapore to Cape Town.”
DNA is a kind of genetic fingerprint unique to every individual and which transmits hereditary characteristics.
The ANU research says that Mungo Man’s mitochondrial DNA contained different sequences of the four chemicals which form DNA to that which has been found in other remains. Mitochondria are the energy packs within cells.
The previously oldest human DNA tested came from Neanderthal remains — a 45,000-year-old specimen in western Germany and 28,000-year-old remains from Croatia.
While the genetic footprint was different, ANU evolutionary genetecist Simon Easteal said Mungo Man would have looked very much like modern humans.
“This individual has facial features, has morphology that is essentially modern, that wouldn’t stand out in a crowd today,” Easteal told Reuters.
“If he was part of a wave of modern people that had come out of Africa and spread, eventually reaching Australia, then his mitochondrial DNA would reflect that,” he said.
Thorne said the dating of Mungo Man meant there was no doubt that ancestors of Australia’s Aborigines came to the continent from Asia about 70,000 years ago — some 30,000 years earlier than was thought.
“There’s no question that somewhere in southeast Asia is where watercraft got invented,” Thorne said. “The first oceanic crossings were to Australia.”