(Reuters) – Sophisticated scanning technology reveals interesting secrets about Little Foot, the remarkable fossil of an early human forerunner who inhabited South Africa 3.67 million years ago at a critical time in our evolutionary history.
Scientists said on Tuesday they had examined key parts of the nearly complete and well-preserved fossil at Britain’s national synchrotron installation, Diamond Light Source. The scan focused on the cranial vault of the Little Foot – the upper part of the brain – and the lower jaw or mandible.
Researchers have gained insight not only into the biology of Little Foot species, but also into the hardships this individual, an adult woman, faced during her lifetime.
Little Foot’s species have mixed monkey-like and human features and is considered a possible direct ancestor of humans. Paleoanthropologist Ron Clarke of the University of the Witwatersrand, who unearthed the fossil in the 1990s in the Sterkfontein Caves northwest of Johannesburg and co-authored the new study, identified the species as Australopithecus prometheus.
“In the cranial vault, we could identify spongy bone vascular channels that are likely involved in brain thermoregulation – how the brain cools,” said Cambridge University paleoanthropologist Amélie Beaudet, who led the study published in the journal e-Life.
“This is very interesting because we didn’t have much information about this system,” Beaudet added, noting that it probably played a key role in tripling the size of Australopithecus’ brain in modern humans.
Little Tooth’s teeth were also revealing.
“Dental tissue is very well preserved. She was relatively old because her teeth are quite worn, “said Beaudet, although Little Foot’s exact age has not yet been determined.
Researchers have noticed tooth enamel defects that indicate two bouts of childhood physiological stress, such as illness or malnutrition.
“There is still much to learn about the biology of early hominin,” said study co-author Thomas Connolley, a leading Diamond Beam scientist, using a term that includes modern humans and some extinct members of the human evolutionary line. Synchrotron X-ray imaging allows the examination of fossil specimens in a manner similar to a patient’s X-ray CT scan, but in much greater detail. ”
The small leg, whose pseudonym reflects the small bones of the leg that were among the first elements of the skeleton found, was about 130 cm high. The small foot has been compared in importance to the fossil named Lucy, which is about 3.2 million years old and less complete.
Both are species of the genus Australopithecus, but possess different biological features, just as modern humans and Neanderthals are species of the same genus – Homo – but have different characteristics. Lucy’s species is called Australopithecus afarensis.
“Australopithecus could be the direct ancestor of man – humans – and we really need to learn more about the different species of Australopithecus in order to decide which of them would be the best candidate to be our direct ancestor,” said Beaudet.
Our own species, Homo sapiens, first appeared about 300,000 years ago.
Synchrotron findings are based on previous research on Little Foot.
The species was able to walk completely upright, but had features that suggested it also climbed trees, perhaps sleeping there to avoid large predators. He had gorilla-like facial features and strong climbing hands. His legs were longer than his arms, as in modern humans, making him the oldest hominin known to have that trait.
“All previous remains of the Australopithecus skeleton were partial and fragmentary,” Clarke said.
Report by Will Dunham in Washington, edited by Rosalba O’Brien