A study determined that the oldest human fossils are a million years older than previously believed

The skeleton of “Little Foot” in Sterkfontein, South Africa. Undated photo provided by Reuters on March 1, 2021. RJ Clarke/Handout via REUTERS (RJ CLARKE/)

Since the first fossils appeared in 1936, the South African caves of Sterkfontein have become famous for their hundreds of Australopithecus fossils and because they contain a Registration quite full of nearly four million years of human evolution and its surroundings.

At this site, located southwest of Pretoria, in South Africa, some of the most emblematic fossils of Australopithecus have been foundas the “Mrs. Ples”, the most complete australopithecus skull ever foundthis was discovered in April 1947 by the Scottish doctor Robert Broom, who called it an australopithecus or plesianthropist, (hence the “Mrs. Ples”). Also there was discovered “Little Foot” (“little foot”), the almost complete skeleton of an australopithecus child from 3.7 million years ago, this genus did not exceed a meter and a half in height and its body and head were similar to that of the current chimpanzee, but it already had the main feature that distinguishes hominids from primates: it walked upright. However, the age of other hominins unearthed at the same site has been the subject of much debate.

Now, after reviewing the sediments of one of the Sterkfontein cave levels, called ‘Member 4′, Researchers at the University of the Witwatersrand (Johannesburg, South Africa) have determined that they are between 3.4 and 3.6 million years old and that they are much older than previously thought.. The details of the study have been published this Monday in the journal Proceedings of the National Academy of Sciences (PNAS). the find ends a decades-long debate and shows that the South African Australopithecus was three million years old (some paleontologists argued that this genus was two million years old) and was contemporary with Australopithecus afarensis from East Africa.

“Little foot”, one of the fossils that mark a milestone in the investigation of the origin of humanity (DIAMOND LIGHT SOURCE LTD / Handout via REUTERS) (DIAMOND LIGHT SOURCE LTD /)

To do the new dating, the authors reviewed the sediments and fossils of the australopithecus from Member 4 and from the Jacovec Cavern, which contains hominin fossils in a deeper chamber of the cave. “The new ages place Member 4 between 3.4 and 3.6 million years old, indicating that the Sterkfontein hominins were contemporaries of other early Australopithecus species, such as Australopithecus afarensis, in East Africa.” , defends Dominic Stratford, director of research for the caves and one of the authors of the article.

The new ages have been based on the radioactive decay of the rare isotopes aluminium-26 and beryllium-10 in the mineral quartz, “whose radioactive decay dates from the moment when the rocks were buried in the cave along with the fossils,” explains the lead author of the study, Darryl Granger, of Purdue University (USA). The finding has important implications for South Africa’s role in hominin evolution. ”The youngest hominids, including Paranthropus and our genus Homo, appear between about 2.8 and 2 million years ago. Based on the dates suggested above, the South African species of Australopithecus were too young to be their ancestors, so it has been considered more likely that Homo and Paranthropus evolved in East Africa,” says Stratford.

Scientists reconstruct the face of 'Lucy', our australopithecus ancestor, and explain what the museums failed
Digital model of the composite male skull of Australopithecus afarensi reconstructed in Kimbel et al. (1984) and Kimbel and White (1988) (A). Mandible belonging to partial skeleton AL 288-1 (Lucy) (B). Reconstruction of Lucy’s skull that was produced by scaling the male skull to fit the AL 288-1 mandible (C). Image credit: R. Campbell, G. Vinas, M. Henneberg, R. Diogo

The new dates show that Australopithecus existed in Sterkfontein almost a million years before the appearance of Paranthropus and Homo.which provides more time for them to evolve here, in the Cradle of Humanity, and places hominids here at the forefront of the story of early human evolution. For CSIC paleoanthropologist Antonio Rosas “the new dating provides very important data in the study of human evolution”; ”Apart from reconsidering the possible ancestor-descendant relationships between the genera Australopithecus, Paranthropus and Homo, already very relevant, it indicates that the diversification of primitive hominids (including Australopithecus) is very old and that should lead us to clarify the causes of this diversification”, he comments in declarations to EFE.

It also suggests that “not only East Africa is involved in these early evolutionary phases. It is an exciting subject”, emphasizes Rosas. And it is that, as Stratford concludes, “This important new dating work pushes back the age of some of the most exciting fossils in human evolution research, and one of the most iconic fossils from South Africa. “Mrs. Ples”, a million years to a time when, in East Africa, there were other emblematic primitive hominids like Lucy”. Not in vain, the Sterkfontein area, where the first specimens of australopithecines in the world were found, including the famous “Lucy”, discovered in the 1980s in Ethiopia, which was declared a World Heritage Site by the United Nations.



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