Sunday , January 23 2022

Evolution: South Africa's hominin record is a fair weather friend



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New research by an international scientist team led by isotope geochemistry Cape Town University Dr Robyn Pickering is the first to provide a timeline for cavern fossils within Cradle of Humanity. It also brings light on climate conditions of our earliest earliest in the area.

Published online in the magazine Nature on 21 November 2018, the work corrects assumptions that the region's rich threatens could never be associated with each other. In fact, the research suggests fossils from Cradle caves up to six fixed periods.

"Unlike previous dating, which often focused on one cave, sometimes only one chamber of the cave, we provide a direct age for eight caves and a model to explain the age of all fossils of & # 39; the whole region, "said Dr Robyn Pickering.

"Now we can link the findings of separate caves and create an enhanced picture of evolutionary history in southern Africa."

Cradle of Humanity is a World Heritage Site that includes complex fossil caves. This is the site of the world's richest early women and houses almost 40% of all the ancient human fossils, including the famous skull Australopithecus africanus, known as Mrs. Ples.

Using uranium lead dating, he analyzed 28 flow layers that were discovered between a rich fossil sediment in eight caves across the Cradle. The results showed that these fossils and caves came to six narrow time windows between 3.2 and 1.3 million years ago.

"The keystone is the keystone," Pickering said. "We know they're only growing in caves during wet times, when there is more rain outside the cave. By dating the stones, we choose these times o no longer. So we know that the caves during the times between them are open, the climate was drier and more like what we are currently experiencing. "

This means that the early homininians living in the Cradle experience major changes in the local climate, from wetter to drier conditions, at least six times between 3 and 1 million years ago. However, only the drier times stored in the caves, swelling and the record of early human evolution.

To date, the lack of dating methods for Cradle fossils make it difficult for scientists to understand the relationship between the hominin species of East and South Africa. In addition, the South African record has often been considered inherently compared to East Africa where volcanic ash layers allow a high resolution solution.

Professor Andy Herries, co-author of the study at the University of La Trobe in Australia, states that "although South Africa's record was the first to show Africa as the source of origin for people, the complexity of caves and & # 39 ; or being hard to date has meant that the South Africa record has been hard to interpret. "

"In this study, we show that the flowing stones in the caves can act almost like the volcanic layers of East Africa, forming at different caves at the same time, allowing us to connect directly to them. sequences and fossils to regional progression, "he said.

Dr Pickering started dating Cradle caves back in 2005 as part of PhD research. This new publication is a result of 13 years of work and brings together a team of 10 scientists from South Africa, Australia and the United States. The results return the Cradle to the next and open new opportunities for scientists to answer complex questions about human history in the region.

"Robyn and his team have contributed to our understanding of human evolution," said Professor Bernard Wood, the Principal Study of Human Paleobiology at the George Washington University in the USA, which is not author of the study.

"This is the most important priority I've done since their own fossils have been discovered. Fossil dates are very much. The value of African-based evidence has increased frequently by the example study This is from seasonal context and deposition. "

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