Ancient African skeletons hint at a “ghost lineage” of humans

Enlarge / A 1994 photograph of the excavations that yielded the skeletons at Shum Laka. (credit: Pierre de Maret)

Understanding humanity's shared history means understanding what happened in Africa. But figuring out what happened in Africa has been a difficult task. Not every area is well represented in the fossil history, and most African environments aren't conducive to the preservation of ancient DNA. DNA sequencing of modern African populations lags behind other regions, in part because DNA sequencing hardware is more common elsewhere. Finally, as in many other areas, massive migrations within the continent have helped scramble the genetic legacy of the past.

Now, researchers are describing a new window into our collective past: DNA from ancient skeletons found in a rock shelter in West Africa. The skeletons come from a location and time that are both near the origin of the Bantu expansion that spread West African peoples across the entirety of Africa but have little in common with Bantu-speaking populations. Yet, at the same time, they provide hints of what might have happened very early in humanity's history, including the existence of a lineage of archaic humans we've not yet identified.

Right time, right place

The skeletons come from a site called Shum Laka, which is located in a grassland area of Cameroon. For those not up on their African geography, Cameroon is located at the angle where West Africa meets Southern Africa. This is also the region where the Bantu people put together a collection of agricultural and metallurgical technologies that allowed them to sweep across the rest of the continent, leaving their linguistic and genetic mark on many other populations.