(Reuters) – Advanced scanning technology reveals intriguing secrets about Little Foot, the remarkable fossil of an early human precursor that inhabited South Africa 3.67 million years ago at a critical time in our evolutionary history.
Scientists said Tuesday that they have examined important parts of the nearly complete and well-preserved fossil in the UK national synchrotron facility, Diamond Light Source. The scan focused on Little Foot’s cranial vault – the top part of her braincase – and her lower jaw, or mandible.
The researchers gained insight not only into the biology of the Little Foot species, but also into the hardships that this individual, an adult female, faced during her lifetime.
The Little Foot species mixed apelike and humanoid traits and is considered a possible direct ancestor of humans. Paleoanthropologist Ron Clarke of the University of the Witwatersrand, who excavated the fossil in the Sterkfontein Caves northwest of Johannesburg in the 1990s and co-authored the new study, identified the species as Australopithecus prometheus.
“In the cranial vault, we were able to identify the vascular channels in the spongy bone that are likely involved in brain thermoregulation – how the brain cools,” said paleoanthropologist Amélie Beaudet of the University of Cambridge, who led the study published in the journal e-Life. .
“This is very interesting because we didn’t have much information about that system,” added Beaudet, noting that it probably played a key role in the threefold increase in Australopithecus’ brain size to modern humans.
Little Foot’s teeth were also revealing.
“The dental tissues are really well preserved. She was relatively old because her teeth are pretty worn, ”Beaudet said, although Little Foot’s exact age has not yet been determined.
The researchers found defects in the tooth enamel that indicate two periods of physiological stress in childhood, such as illness or malnutrition.
“There is still much to learn about early hominin biology,” said study co-author Thomas Connolley, principal bundle scientist at Diamond, using a term that encompasses modern humans and certain extinct members of the human evolutionary lineage. “Synchrotron X-ray imaging enables examination of fossil specimens in the same way as an X-ray CT scan of a patient in a hospital, but with much more detail.”
Little Foot, whose nickname reflects the small foot bones that were among the earliest elements of the skeleton found, was about 4 feet 3 inches (130 cm) long. Little Foot has been compared in importance to the fossil called Lucy which is about 3.2 million years old and less complete.
Both are species of the genus Australopithecus, but possessed different biological characteristics, just as modern humans and Neanderthals are species of the same genus – Homo – but had different characteristics. Lucy’s species is called Australopithecus afarensis.
“Australopithecus could be the direct ancestor of Homo – humans – and we really need to learn more about the different Australopithecus species to decide which is the best candidate to be our direct ancestor,” Beaudet said.
Our own species, Homo sapiens, first appeared about 300,000 years ago.
The synchrotron findings build on previous research on Little Foot.
The species could walk completely upright, but had characteristics that suggested that it also climbed trees and perhaps slept there to avoid large predators. It had gorilla-like facial features and powerful hands for climbing. Its legs were longer than its arms, as in modern humans, making this the oldest hominin known to have that trait.
“All previous Australopithecus skeletal remains were partial and fragmentary,” said Clarke.
Reporting by Will Dunham, Washington, published by Rosalba O’Brien