Scientists say they are revising their claim that Eurasian farmers who migrated to Africa some 3,000 years ago have left their genetic mark in the furthest corners of the continent.

Cambridge University researchers say an error in the way specialized software was used wrongly suggested that the ancient migrants' DNA spread as far as Central and West Africa.

Authors Marcos Gallego Llorente and Andrea Manica say their main finding, that present-day East African populations have as much as a quarter Eurasian ancestry, remains true.

The finding was made by comparing ancient DNA from the skull of a man buried in the highlands of Ethiopia 4,500 years ago to that of current African populations.

The original paper was published in the journal Science in October. Science issued a corrected version Thursday.