London, July 16 : New analysis of 28,000-year-old Cro-Magnon DNA has revealed similarities to modern Europeans, thus debunking theories about their interbreeding with Neanderthals.
According to a report in New Scientist, the Cro-Magnons were the first modern Homo sapiens in Europe, living there between 45,000 and 10,000 years ago.
Their DNA sequences match those of today's Europeans, according to Guido Barbujani, an evolutionary anthropologist at the University of Ferrera, Italy, suggesting that "Neanderthal hybridization" did not occur.
A group of geneticists, coordinated by Barbujani and David Caramelli of the Universities of Florence, shows that a Cro-Magnoid individual who lived in Southern Italy 28,000 years ago was a modern European, genetically as well as anatomically.
Barbujani's team published similar findings in 2003, but that study left open the possibility that the Cro-Magnon DNA had been contaminated by the researchers' own genes.
Now, Barbujani's team has sequenced a section of DNA from everyone who handled the sample and found no trace of contamination.
"We knew we had a full and complete list of people who had potentially contaminated the specimen," he said. "In this case we are really sure that that sequence does not represent contamination," he added.
"The risk in the study of ancient individuals is to attribute to the fossil specimen the DNA left there by archaeologists or biologists who manipulated it," said Barbujani. "To avoid that, we followed all phases of the retrieval of the fossil bones and typed the DNA sequences of all people who had any contacts with them," he added.
The results demonstrate for the first time that the anatomical differences between Neandertals and Cro-Magnoids were associated with clear genetic differences.
Tom Gilbert, an expert on ancient DNA at the University of Copenhagen, Denmark, says the new tests convinced him of the Cro-Magnon DNA authenticity.
"The reanalysed Cro-Magnon DNA, which comes from maternally-inherited mitochondria, casts further doubt on the kinship between Neanderthals and humans," he said.
Nearly every ancient human skeleton recovered in Europe belongs to either Cro-Magnons or Neanderthals, not the hybrids that would be expected from interbreeding.