In October 2015, scientists reconstructed the genome of a 4,500-year-old man who lived in Ethiopia. It was the first time that anyone had created a complete genetic snapshot of an African from an ancient skeleton.

Since then, other researchers have recovered DNA from skeletons unearthed in other regions of the continent. Now researchers have found the first genetic material from West Africa. On Wednesday a team reported that they had recovered DNA from four individuals in Cameroon, dating back as far as 8,000 years.

These ancient genomes contain vital clues to the history of the continent that have largely disappeared in the past few thousand years. Taken together, they are giving scientists a new vision of our species since it arose in Africa.

In the new study, published in Nature, the researchers reported that modern humans diverged into four major populations between 200,000 and 250,000 years ago. One of those populations is new to scientists; few traces of it remain in the DNA of living Africans.