THE PAST — JULY 7, 2022
New dating method shatters our understanding of human evolution
Fossils of Australopithecus in a South African cave are one million years older than previously thought. This challenges the consensus that humans first evolved in East Africa.
KEY TAKEAWAYS
- The Sterkfontein caves in South Africa are home to hundreds of fossils of early hominins in the genus Australopithecus. Original age estimates of these fossils suggested that they were no more than 2.4 million years old — younger than our genus, Homo.
- Researchers used a new, more accurate technique to redate the fossils and made an important discovery: The fossils were much older than previously thought. They were deposited between 3.4 million and 3.7 million years ago.
- The finding challenges our understanding of human evolution, including the consensus that we evolved in East Africa.
Hominins link the great apes with modern humans on the evolutionary tree. Ancestral hominins mark a crucial transition in the story of human evolution, and they have fascinated paleoanthropologists for decades.
In 1936, South African doctor and paleontologist Robert Broom made a historic discovery in the Sterkfontein caves in South Africa. Broom discovered the first adult specimen of the genus Australopithecus, a group of early hominins from which our own genus, Homo, emerged.
Since 1936, the Sterkfontein caves have become ground zero for Australopithecus research and fossil finds. The complex cave system runs 60 meters deep, and it has revealed hundreds of Australopithecus fossils within its sediment. From these rocks emerged notable discoveries, such as the nearly complete skeletons of specimens dubbed “Little Foot” and “Mrs. Ples.”
Age is just a method
The cave features six areas, or members: Members 1 to 3 lie underground, while Members 4 to 6 are exposed to the air because of erosion in the cave roof. Most Australopithecus fossils are in Member 4. The Sterkfontein caves are one part of a World Heritage Site with a telling name — the Cradle of Humankind.
The complex cave system still houses many secrets, but the discoveries already made retain mysteries of their own. Among the most debated issues is the age of the fossils found in Member 4. Researchers have estimated the age of Australopithecus in the lower Member 2 section at 3.7 million years, which jars with the estimated age of the fossils found higher in the cave. Researchers originally estimated the fossils in Member 4 to be between 2 million and 2.4 million years old. The geological peculiarities of the cave challenge traditional methods of aging fossils, casting further doubt on the accuracy of these estimations.
Purdue University’s Darryl Granger is among the researchers who questioned the age of the Member 4 Australopithecus. Recently, Granger and a team of scientists from France and South Africa endeavored to redate the famous fossils using a new method. They published their results in the Proceedings of the National Academy of Sciences.
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Read more here/Leia mais aqui: The Big Think.
