WEST LAFAYETTE, INDIANA—According to a statement released by Purdue University, Australopithecus fossils discovered deep in South Africa’s Sterkfontein Caves are more than a million years older than previously thought. An international team of scientists from Purdue University, the University of the Witwatersrand, and the University of Toulouse Jean Jaurès dated the breccia where the fossils were found to be between 3.4 and 3.7 million years ago. The process included using accelerator mass spectrometry to measure radioactive nuclides in the rocks that were produced by exposure to cosmic rays, in addition to careful mapping of earlier excavations and a study of how the cave’s sediments accumulated. Previous attempts to date the cave’s Australopithecus fossils involved examinations of animal fossils found near them and the age of the cave’s flowstones, said Darryl Granger of Purdue University. But, he explained, the animal bones had been disturbed during earlier investigations, and young flowstone can be deposited in old sediment, creating the potential for inaccurate dates. Read the original scholarly article about this research in Proceedings of the National Academy of Sciences of the United States of America. To read about an Australopithecus anamensis cranium unearthed in Ethiopia, go to "Artifact."
