An ancient hominid jaw found at Grote a Hominides in Morocco.
Hamza Mehimdate, Casablanca Prehistory Program
Fossils nearly three-quarters of a million years old discovered in North Africa may belong to a common ancestor Neanderthals, Denisovan and modern humans who lived shortly before the split of the three hominin lineages.
The last common ancestor of modern humans, Neanderthals and Denisovans, is believed to have lived somewhere between 765,000 and 550,000 years ago. But exactly when and where he lived, two remain The Great Questions of Human Evolution.
New fossils may not represent the last common ancestor of three human species, says Jean-Jacques Hublen at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, but they are definitely close to the point at which ancient human lineages diverged.
Hublin and his colleagues analyzed several fossils found in a cave called Grotte à Hominidés on the outskirts of Casablanca, Morocco, including two adult jawbones, a child's jawbone and several vertebrae. One adult jaw was reported in a previous study in 1969, but the others are described for the first time.
Fossilized molars resemble those of early wise man and Neanderthals, but the jaw shape is reminiscent of ancient African humans such as The man stood up.
Fortunately for scientists, the Moroccan hominids lived around the same time as a shift in the Earth's magnetic field, recorded in the geological layer in which the fossils were found, which allows them to be dated to approximately 773,000 years ago.
Hublin says the discoveries fill a “major gap” in the history of African hominids that existed between 1 million and 600,000 years ago. Paleogenetic studies show that this is when the ancestors of Neanderthals and Denisovans separated from the lineage that led to the emergence of X. sapiens. Neanderthals dominated Europe for hundreds of thousands of years. The Denisovans reached East Asia.And HOUR. sapiens It is believed that they continued to evolve in Africa.
The newly described fossils were nearly contemporary with a Spanish population of hominins called predecessor of homo, which was previously considered a possible common ancestor between X. sapiens and Neanderthals.
Jean-Paul Raynal and Fatima Zora Sihi-Alaoui work on the excavations that led to the discovery of fossils in Morocco.
R. Gallotti, Program on the Prehistory of Casablanca
Both X. predecessor and Moroccan hominids show a “comparable mosaic of primitive and derived traits,” Hublin says, meaning there may have been connections and genetic exchange between populations across the Strait of Gibraltar. However, there are also clear differences between the fossils from the two regions: the Spanish fossils are more similar to Neanderthals.
“The last common ancestor of these lineages was likely present at that time on both sides of the Mediterranean and was already diverging,” Hublin says. “This confirms the deep African origin wise man and opposes the Eurasian origin scenarios proposed by some authors.”
Julien Louis from Griffith University in Brisbane, Australia, says he was struck by the differences in physical characteristics among early Pleistocene hominins that are closely related to or ancestral to our own species.
“The important point is that these differences appear to have arisen even before homo predecessor made its way to Spain, implying that the species was one of several that potentially originated in North Africa, but then somehow crossed the strait,” says Luis.
Chris Stringer at the Natural History Museum in London says study of Chinese hominin fossils published last yearto which he contributed, proposed that the last common ancestor X. sapiensNeanderthals and Denisovans may have lived more than 1 million years ago.
“It was unclear what continent this common ancestor lived on,” says Stringer. “However, even if the last common ancestor lived outside of Africa, our analysis showed that later evolution wise man was still taking place in Africa, so in this case there would have been an early migration to Africa to continue this evolution.”
New Moroccan fossils may even represent early sapiens the ancestor lives in Africa, he says, but there aren't enough skeletal fragments to assign it to the species.
He aims to compare new fossils with those he has already studied to determine where they might end up.
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