2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
The landscape of the area in South Africa, where the Cradle of Humanity is located
Scientists have suggested that the fossils of ancient hominins from the Cradle of Humanity caves in South Africa date back to dry periods, according to Nature. Probably at this time the vegetation that covered the holes in the caves disappeared and the remains of people and animals accumulated there. The researchers came to this conclusion after dating the stalactites and stalagmites formed in the caves.
Several cave complexes located on an area of 474 square kilometers, where numerous remains of hominins were found, are called the cradle of humanity. In particular, bones of two species of Australopithecus were found here, the sediba (Australopithecus sediba) and the most complete skeleton of the African Australopithecus (Australopithecus africanus), the so-called Mrs. Pleuse; fossils of massive paranthropus (Paranthropus robustus) and Homo naledi. The remains found in the Cradle of Humankind support hypotheses about the diversity of hominins and their evolutionary history. Some of these hypotheses link the evolution of humans and their ancestors to climatic conditions. But it is difficult to verify them, since the dating of the layers in which the fossils were found are not accurate, or scientists disagree on the dates.
South African and Australian geologists and anthropologists led by Robyn Pickering of the University of Cape Town decided to date the carbonate dripstone formations in the caves surrounding the layers in which hominin fossils were found. Dating was carried out using the uranium-lead method, which makes it possible to determine the age of rocks from about one to 4.5 million years with an error of 1 to 15 percent. Researchers dated 25 samples from different caves, and found data on the age of four more sediments in the literature.
A drip formation (white layer), and underneath the sediments in which the fossils were found.
It turned out that the streaks were formed during six intervals in the period from 3.2 to 1.3 million years ago. According to the authors of the study, these intervals indicate rainy periods, during which drips formed, and the holes in the caves were most likely obstructed by vegetation. At this time, neither rock deposits, nor animals, people or their ancestors entered the caves. In dry periods, on the contrary, the vegetation from the surface of the caves disappeared, the soil eroded, and, probably, new entrances were formed.
“In our study, we have shown that dripstone formations can behave like volcanic layers in East Africa, forming simultaneously in several caves. This allows us to directly link the ages of the sediments and the fossils …”, says one of the study authors Andy Herries of the Australian University of La Trobe.
It is generally quite difficult to understand the intricacies of different types of people and ancestors of the genus Homo, but a family tree can help with this. And you can check the knowledge gained with the help of a test.
