New datings of human fossils discovered at a famous South African site have revealed that these were much older than previously suggested.
Fossils 3.4 to 3.7 million years old
Located in the north ofSouth Africathem caves of Sterkfontein shelter largest concentration of Australopithecus remains in the worldwhich earned them the title of ” Cradle of Mankind “. Since the discovery of the first fossils in 1936, hundreds of bones of representatives of this family of primitive hominins, ancestors ofHomo sapienswere discovered there.
In the context of work published in the journal PNASan international team of researchers used an innovative technique, known as “ burial dating in order to determine their age more precisely. This consists of examining the concentrations of certain elements in the sedimentary layers containing the fossils, linked to the exposure of the rocks to cosmic radiation.
« When energetic particles from space hit rocks, they produce elements, like aluminum or beryllium, accumulating and decaying at a precise rate “, Explain Darryl Grangerprofessor of geology at thepurdue university and lead author of the study. ” This allows us to determine precisely when they were buried. »
Used in 2015 to date the remains of an Australopithecus specimen dubbed ” Little Foot the approach was recently applied to other Sterkfontein fossils, revealing that these were also between 3.4 and 3.7 million years old. That is 1.4 to 1.7 million more than previously thought.
Valuable light on human evolution
These new datings suggest that the hominins from the site were contemporaneous and not descendants of‘Australopithecus afarensiswhich surveyed what is now Ethiopia 3.2 million years ago and whose most famous representative is ” Lucy “. According Grangersuch results indicate that the two species had a common ancestor, yet to be discovered.
« Thanks to this dating method, we are able to make estimates that are much more precise than before. “, emphasizes the researcher. ” We hope that its application to more key sites in South Africa, and even beyond, will deepen our understanding of human evolution.. »
At the beginning of the year, the analysis of volcanic sediments in East Africa had for its part revealed that the oldest formal proof of the existence of our species was tens of thousands of years older than expected.