A new dating from a Sterkfontein cave in South Africa, northwest of Johannesburg, has given fossils of Australopithecus africanus, one of the species of Australopithecines, those predecessors of the human race.
Among them, the fossil of Madame Ples, one of the first complete skulls of this genus of hominins, discovered in 1947 on this site full of calcite caves, which yielded several thousand fossils, including 500 of Australopithecines, inscribed by the ‘UNESCO World Heritage Site under the name of
Cradle of Mankind.
The area housing Ms Ples had previously been dated to between 2.1 and 2.6 million years old, based on the age of sediments that fell into the cave after it was formed. But
chronologically, it did not matchremembers Laurent Bruxelles, researcher at the National Center for Scientific Research (CNRS) in France, one of the authors of the study published this week in the journal PNAS.
It was weird to see Australopithecines persisting for so long., explains this geologist to AFP: at 2.2 million years ago, Homo habilis (the first representative of the homo genus) had already appeared in the region. However, no trace of him or his tools at this level of the cave.
Another disturbing fact: the emblematic skeleton of Little Foot, an even older Australopithecus found deep in the cave, and which recent research had just dated to 3.67 million years ago… The time difference with its
little sister Mrs. Ples was too tall considering the thickness of the sedimentary layers separating them.
Together with the South African paleontologist Ronald Clarke, lead author of the study, Laurent Bruxelles decided to use the same dating method as that of Little Foot. Australopithecus fossils being too old to be dated directly with carbon 14, we can only date the sediments in which they are taken.
Dating by cosmogenic isotopes (the cosmic rays which bombard the Earth) makes it possible to do in the geological lace, by reconstructing as closely as possible the history of the cave, which has filled over time like an hourglass.
As with Little Foot, analyzes showed that the rocks in the cave had been buried with the fossils 3.4 to 3.6 million years ago. And that the sediments
intrusive – the layer of calcite which had given rise to the initial dating – had been put in place a million years later.
A contemporary cousin
This revelation makes Australopithecus africanus a contemporary of Australopithecus afarensis from East Africa, the species of the famous Lucy discovered in 1974 in the Ethiopian Rift.
synchronous living 4000 kilometers apart, and looking a lot alike.Ples are more slender”,”text”:”The first Australopithecines of the species of Little Foot were quite massive, when Lucy and Mrs. Ples are more slender”}}”>The first Australopithecines of the species of Little Foot were quite massive, when Lucy and Mrs. Ples are more slenderdescribes Laurent Brussels.
Are we dealing with the same species?km away, these species have had plenty of time to move, to interbreed… so we can easily imagine a common evolution on the scale of all of Africa”,”text”:”We can never prove that they were interfertile. But on the scale of millions of years, at only 4000km away, these species have had plenty of time to move, to interbreed… so we can largely imagine a common evolution on the scale of the whole of Africa”}}”>We can never prove that they were interfertile. But on the scale of millions of years, at only 4000 km away, these species have had plenty of time to move, to interbreed… so we can largely imagine a common evolution on the scale of the whole world. ‘Africaaccording to this cave expert.
With the dating of Little Foot (older than Lucy) there were quarrels about the location of the cradle of humanity, in the East or in the South of the African continent. By revealing these new parallel destinies, this latest study invites us to consider, once again, this notion on a continental scale.
The excavations of the Sterkfontein site – far from having revealed all its secrets – confirm that the tree of human evolution is more
bushy than linearcomments the French geologist, quoting Yves Coppens, the famous paleontologist who died last week at the age of 87.
Lucy’s co-discoverer had
understood for a long time the pan-African side of the evolutiongreets Laurent Brussels.