January 10, 2001
SYDNEY, Australia (Reuters)
-- Modern humankind's evolutionary plot thickened on Wednesday when the man who discovered an Australian fossil whose DNA promises to rewrite human history said the skeleton was not as old as it has been claimed.
But geologist Jim Bowler, who discovered the "Mungo Man" fossil in a dry lake bed in New South Wales state in 1974, did not challenge the theory that his fossil's DNA proved modern man did not evolve from African ancestors alone.
Australian National University (ANU) scientists said on Tuesday that tests on mitochondrial DNA taken from bone chips from Mungo Man suggested he was around 62,000 years old and whose DNA is the oldest genetic material ever tested.
Bowler said their estimate was out by about 20,000 years.
But he did not dispute the ANU team's claim that Mungo Man challenged the prevailing "out of Africa" theory of evolution because its completely modern skeleton and DNA had no links with human ancestors from Africa found in other parts of the world.
"The genetics and the mitochondrial data stand alone," Bowler told Reuters.
"It wouldn't matter if it was 20,000 or 60,000 years -- to be extracting mitochondrial DNA from that bone is extraordinary and the implications don't change," he said.
ANU anthropologist Alan Thorne said Mungo Man supported the counter "regional continuity" theory of evolution because its DNA has a genetic line which has vanished yet its skeleton is completely modern.
The "out of Africa" theory holds that modern humans can be traced to homo sapiens who evolved from homo erectus ancestors in Africa. Homo sapiens then left Africa and moved around the world.
Thorne says that, because Mungo Man has a vanished DNA line, it means homo erectus left Africa and then evolved into homo sapiens in other parts of the world at the same time.
Bowler however disputes the ANU's claim that they have analyzed the oldest DNA ever taken from human remains. The ANU team says three different, sophisticated types of testing in May 1999 fixed Mungo Man's age at between 56,000 and 68,000 years.
Bowler said the ANU team missed important geological fieldwork providing the skeleton's relationship with its surroundings and the layers above and below the skeleton which fixed Mungo Man's age at between 40,000 and 45,000 years old. DNA has been tested from Neanderthal remains of about the same age in western Germany.
"They failed to check the field relationships, which is a mortal sin for earth scientists -- understandable for anthropologists but not for earth scientists," Bowler said.
"On that basis their dates I believe are seriously in error."
Thorne rejected Bowler's argument, saying the ANU tests were the most sophisticated available.
"But it doesn't matter for this debate whether the genetic material is 40,000 or 60,000," Thorne told Reuters on Wednesday.
Mungo Man's age based on surroundings
Bowler said he had fixed Mungo Man's age because geological tests had identified when the lake began to dry out and because clay from the drying lake floor had been found with the remains.
He unearthed Mungo Man after finding the tip of its cranium near the surface of a sand dune in windswept Lake Mungo, a dry creek bed about 800 km (500 miles) west of Sydney.
It was found with its arms crossed over its pelvis and it was sprinkled with a fine powder of red ochre, indicating it had been buried ceremonially.
The skeleton is now kept under the ANU's protection in Canberra with the permission of the area's Aboriginal elders.
The controversy over Mungo Man's age throws into dispute when the ancestors of Aborigines first arrived in Australia from Asia, with prevailing opinion at between 40,00 and 50,000 years ago.
Back to Science