One of South Africa’s most famous fossil finds, the Taung Child, is still a candidate as a modern human ancestor, despite new evidence showing that it does not have modern human-like skull features, experts say.
Identified nearly 90 years ago by University of Witwatersrand Professor Raymond Dart, the fossil – which is part of an ape-like hominim called Australopithecus africanus – has been dated to roughly three million years old and is thought to have belonged to an adolescent, between the ages of three and nine.
Dart argued that this skull, found in a lime quarry in Taung in 1925, showed similarities to a modern human child, and was a bridge between our primate ancestors and Homo sapiens.
However, with the new Microfocus X-ray Computed Tomography facility – which uses x-rays to image cross-sections of an object without damaging it – has shown that this is not in fact the case, according to new research published on Monday in the journal Proceedings of the National Academy of Sciences.
The research, undertaken by Kristian Carlson from the Evolutionary Studies Institute at Wits and colleagues from Columbia University and Florida Atlantic University in the United States, has found that the similarities between modern human children and the Taung Child were overstated.
In the past, palaeoscientists were “trying to extend modern human-like cranial features – which allow for post-natal brain growth and which modern humans exhibit – to [the Taung Child and its species] the Australopithecines”, Carlson said. They had shown that “in the Taung Child, you don’t see evidence for these features”.
“This doesn’t change anything about Australopithecus’s importance in human evolutionary history. But some of these unique human adaptations [such as brain size and development] should be thought of as more recent,” he said.
Professor Francis Thackeray, the director of the Institution of Human Evolution, also at Wits, echoed these sentiments. “It doesn’t necessarily exclude A. africanus … as potential ancestors for H. sapiens. I would argue that this wonderful paper shows that there is a lot of variability in the hominim species,” he said.
“Paleosciences is going through a very exciting phase at the moment,” Thackeray said. Not only were there new hominim fossils being discovered in South Africa but there were also new techniques. With the CT scanner, funded by the department of science and technology through the National Research Foundation, “we are able to look internally, and nondestructively,” at fossils, he said.
He said that they expected many more new discoveries from old fossils, using the new micro-imaging techniques.