[Update, Feb. 4, 2016: Some of the conclusions reached in this study have subsequently been called into question, and the researchers asked the journal Science to publish an erratum. Read more about the new developments.]

A team of scientists reported on Thursday that it had recovered the genome from a 4,500-year-old human skeleton in Ethiopia — the first time a complete assemblage of DNA has been retrieved from an ancient human in Africa.

The DNA of the Ethiopian fossil is strikingly different from that of living Africans. Writing in the journal Science, the researchers conclude that people from the Near East spread into Africa 3,000 years ago. In later generations, their DNA ended up scattered across the continent.

“It’s a major milestone for the field,” said Joseph Pickrell, an expert on ancient DNA at the New York Genome Center who was not involved in the study. For decades, scientists had doubted that ancient DNA could survive in the tropics. The study raises hopes that scientists can recover far older human genomes from Africa — perhaps dating back a million years or more.