“What We Have Is A Very Good Candidate”: Has The Ancestor Of Homo Sapiens Finally Been Found In Africa?

From genetic data, we know that Homo sapiens, Neanderthals, and Denisovans all split from a common ancestor some time between about 765,000 and 550,000 years ago. However, because we’ve never found that particular progenitor, we don’t know where it lived.

Previously, the best candidate came from the Gran Dolina cave in Spain, which was occupied some 800,000 years ago by a species that possessed an intriguing mix of features reminiscent of modern humans, Neanderthals, and more archaic humans like Homo erectus. Known as Homo antecessor, this ancient hominin has been credited by some scholars with being the common ancestor of Homo sapiens, Neanderthals, and Denisovans, implying that the split occurred somewhere in Eurasia, rather than in Africa.

The problem with this theory, however, is that all Homo sapiens fossils from before about 90,000 years ago come from Africa, beginning with the earliest-known modern humans from Jebel Irhoud in Morocco about 315,000 years ago. Unfortunately, though, until now we’d never seen anything like Homo antecessor in Africa, meaning we had no proof that our lineage actually began on the continent.

Whatever happened to the descendants of these guys, they give us a picture of what could be the ancestral form of our own species

Jean-Jacques Hublin

“Africa is quite rich in terms of fossil hominins before one million years ago, but between one million and 600,000 years ago there is almost nothing,” says Professor Jean-Jacques Hublin from the Max Planck Institute for Evolutionary Anthropology. “It was more an absence of evidence than evidence of absence, as we just hadn’t found any fossils in Africa – but there is no absence anymore,” he told IFLScience.

At a site called Grotte à Hominidés in Morocco, Hublin and his colleagues discovered a pair of partial jawbones, as well as numerous teeth and vertebrae, that combine ancient features seen in Homo erectus with more derived traits reminiscent of modern humans and Neanderthals. Importantly, however, this hominin differs morphologically from Homo antecessor, suggesting that it sat at the apex of a separate-yet-related human lineage.  

“What we have is a very good candidate for the ancestor of what’s going to be our own species in Africa,” says Hublin. In other words, it’s looking increasingly like Homo antecessor might have given rise to Neanderthals in Europe while Homo sapiens descended from these newly discovered African hominins. 

“Whatever happened to the descendants of these guys, they give us a picture of what could be the ancestral form of our own species more than 400,000 years later,” says Hublin.

The age of the fossils is also highly significant, as it places this ancient group of hominins in the same chronological ballpark as Homo antecessor, while also indicating that they lived around the time our lineage split from our common ancestor with Neanderthals and Denisovans. In general, fossils of this age are notoriously difficult to date, but these particular individuals happened to be found in a layer of sediment that aligns with the Brunhes–Matuyama reversal, when the Earth’s magnetic poles flipped some 780,000 years ago, leaving a distinct magnetic signal in rocks across the globe.

However, while the new Moroccan hominin reinforces the argument for an African origin for Homo sapiens, Hublin is reluctant to tag the fossil as a new species. Instead, he suggests it probably represents a late iteration of Homo erectus, which was on its way to evolving into something that we now call a human being.

The study is published in the journal Nature.