Australopithecus Mrs. Ples, this South African cousin of Lucy

Part of a skeleton of Little Foot, an australopithecus more than three million years old

The famous australopithecus Lucy, discovered in Ethiopia, had a contemporary cousin living a few thousand kilometers in southern Africa, approximately 3.5 million years ago, according to a study that invites us to consider the “cradle of humanity” on the entire African continent.

New dating from a Sterkfontein cave in South Africa, northwest of Johannesburg, has given Australopithecus africanus fossils a million years old , one of the Australopithecus species, those predecessors of the human genus.

Among them, the fossil of Mrs. Ples, one of the first complete skulls of this genus of hominids, discovered in 1947 on this site full of calcite caves, which yielded several thousand fossils, including 500 of Australopithecus. It is listed by UNESCO as a World Heritage Site as the Cradle of Humankind.

The area housing Mrs. Ples had previously been dated between 2.1 and 2.6 million years ago, based on the age of sediments that fell into the cave after its training. But chronologically, it did not fit, remembers 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 (first representative of the genus Homo) had already appeared in the region. However, no trace of him or his tools at this level of the cave.

Another disturbing fact: the iconic skeleton of Little Foot, an even older Australopithecus found deep within the cave, and which recent research has just dated to 3.67 million years ago… x27;time gap with her little sister Mrs. Ples was too big 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. Since Australopithecine fossils are too old to be directly carbon-14 dated, only the sediments in which they are taken can be dated.

Dating by cosmogenic isotopes (cosmic rays that bombard the Earth) makes it possible to do in geological lace, by reconstructing as closely as possible the history of the cave, which is #x27;is filled over time like an hourglass.

As with Little Foot, analyzes have shown that rocks in the cave were buried with the fossils 3.4 to 3.6 million years ago. And that the intrusive sediments – the layer of calcite that gave rise to the initial dating – had been in place a million years later.

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.

Reconstruction of Lucy's appearance by John Gurche and exhibited at the Cleveland Museum of Natural History.

Two synchronous species living 4000 miles apart. different, and very much alike. Early australopithecines of the Little Foot species were quite massive, when Lucy and Mme Ples are more slender, says Laurent Bruxelles.

Are we dealing with the same species? 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 to the x27;scale of all of Africa, according to this cave expert.

With the dating of Little Foot (older than Lucy) had arisen quarrels over the location of the cradle of humanity, east or south. southern part 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 linear , comments the French geologist, quoting Yves Coppens, the famous paleontologist who died last week at the age of 87.

The co-discoverer of Lucy had long understood the pan-African side of evolution, concludes Laurent Bruxelles.