Scientists have for the first time sequenced the genome of a 4,500-year-old human skull from Africa. Until now, Africa's warm climate had made DNA difficult to recover from ancient human remains.
The breakthrough was announced Thursday after researchers completed a study of the skull of a man buried face down in a cave in the southern Ethiopian highlands, the scientific journal Science reported.
"With an ancient genome, we have a direct window into the distant past. One genome from one individual can provide a picture of an entire population," said Andrea Manica, a senior author of the study from the University of Cambridge's Department of Zoology.
The discovery supports the theory that Eurasian farmers migrated into Africa some 3,000 years ago. Such a Stone Age resettlement had previously been theorized, but the rare find allowed scientists to see what DNA looked like well before the time the migration would have taken place.
"This is the first ancient human genome found in Africa to have been sequenced," said Marcos Gallego Llorente, a geneticist at the University of Cambridge and member of the international team of researchers who worked on the project.
A comparison with modern populations around the world allowed them to see that the migrants left their genetic mark in the furthest corners of Africa.
The cave was cool and dry enough to preserve his DNA for thousands of years, said the study, which noted that previous ancient genome analysis has been limited to samples from northern and arctic regions.
By comparing his ancient genome to DNA from modern Africans, researchers found that East African populations today have as much as 25 percent Eurasian ancestry from this event.
Clues surrounding 'Eurasian Backflow'
Researchers believe their findings show that the massive wave of backflow migration was far bigger than previously thought and may have amounted to a quarter of the population of the Horn of Africa at the time.
The so-called "Eurasian Backflow" is thought to have occurred some 3,000 years ago when people from the Near East and Anatolia streamed into the Horn of Africa, a reverse migration to that which led the first humans out of Africa about 100,000 years ago.
"The question is: what got them moving all of a sudden?" Manica said.
jar/msh (AFP, AP)