A new dating of a cave of sterkfontein in South Africa gave a million year old egg to the fossils of Australopithecus Africanus.
Le Monde
The famous Australopitheque Lucy, discovered in Ethiopia, had a contemporary cousin living a few thousand kilometers in southern Africa, about 3.5 million years ago, according to a study that invites you to consider the “cradle of the ‘Humanity “on the whole African continent.
A new dating of a cave of Sterkfontein in South Africa, northwest of Johannesburg, gave an old, one million years, to the fossils of Australopithecus Africanus, one of the Australopithecal species, these predecessors of the human race.
Among them, the fossil of “Madame Ples”, one of the first complete skulls of this kind of hominine, discovered in 1947 on this site full of calcite caves, which delivered several thousand fossils, including 500 of Australopithecus, listed by UNESCO as World Heritage under the name of “Cradle of humanity”.
The area housing “Madame Ples” had previously been dated between 2.1 and 2.6 million years, according to the age of the sediments fallen into the cave after its training. But “chronologically, it did not stick,” recalls Laurent Brussels, CNRS researcher, one of the authors of the study published this week in the journal Pnas.
little sister of “Little Foot”
“It was weird to see Australopithecus lasting for so long”, explains this geologist to AFP: at 2.2 million years, Homo Habilis (first representative of the genus Homo) had already appeared in the region. Now no trace of him, nor his tools, at this level of the cave.
Another disturbing fact: the emblematic skeleton of “Little Foot”, an even older Australopithecus found in the depths of the cave, and that recent research had just dated 3.67 million years … the gap temporal with her “little sister”, “Madame Ples”, was too big in view of the thickness of the sedimentary layers separating them.
With the South African paleontologist Ronald Clarke, principal author of the study, Laurent Brussels decides to use the same dating method as that of “Little Foot”. The Australopithecus fossils being too old to be able to be dated directly at carbon 14, we can only date the sediments in which they are taken.
Dating by “cosmogenic isotopes” (the cosmic rays that bombard the earth) allows you to work in geological lace, by reconstituting the history of the cave as close as possible, which has been filled over time as a Sablier.
As for “Little Foot”, the analyzes showed that the rocks of the cave had been buried with the fossils 3.4 to 3.6 million years ago. And that the “intrusive” sediments – the calcite layer which had given rise to the initial dating – had set up a million years later.
quarrels of chapel
This revelation made of Australopithecus Africanus a contemporary of Australopithecus Afarensis of East Africa, the species of the famous Lucy Discovery in 1974 in the Ethiopian Rift.
Two “synchronous” species living 4,000 kilometers from each other, and very similar. “The first Australopithecus of the species of Little Foot were quite massive, when Lucy and Madame Ples are more gracile”, describes Laurent Brussels.
Are we dealing with the same species? “We can never prove that they have been interfered. But at the level of millions of years, just 4,000 kilometers away, these species have had time to move, to cross … so we can Largely imagine a common evolution on the scale of all of Africa “, according to this expert in caves.
With the dating of “Little Foot” (older than Lucy), had appeared from chapel quarrels on the location of the cradle of humanity, east or south of the African continent. By revealing these new parallel destinies, this last study invites us to consider, once again, this notion on the scale of the continent.
The excavations of the Sterkfontein site – far from having delivered all its secrets – confirm that the tree of human evolution is more “bushy than linear”, comments the French geologist, citing Yves Coppens, the famous Paleontologist who died last week at 87 years old. Lucy’s Codecotor had long understood the Pan -African side of evolution “, welcomes Laurent Brussels.