Thorough study of ‘Little Foot’ fossil sheds light on human origins


(Reuters) – Sophisticated scanning technology is revealing intriguing secrets about Little Foot, the remarkable fossil of an early human precursor that inhabited South Africa 3.67 million years ago during a critical juncture in our evolutionary history.

Little Foot’s skeleton is seen in Sterkfontein, South Africa, in this undated brochure photo, obtained by Reuters on March 1, 2021. RJ Clarke / Handout via REUTERS

Scientists said Tuesday they examined key parts of the nearly complete and well-preserved fossil at Britain’s national synchrotron facility, Diamond Light Source. The scan focused on Little Foot’s cranial vault, the top of her skull, and her lower jaw or mandible.

The researchers obtained information not only on the biology of Little Foot’s species, but also on the difficulties that this individual, an adult female, faced during its lifetime.

Little Foot’s species combined ape-like and human-like traits and is considered a possible direct ancestor of humans. University of the Witwatersrand paleoanthropologist Ron Clarke, who unearthed the fossil in the 1990s in the Sterkfontein Caves northwest of Johannesburg and is a co-author of the new study, has identified the species as Australopithecus prometheus.

“In the cranial vault, we were able to identify the vascular channels in the cancellous bone that are likely involved in thermoregulation of the brain, how the brain cools,” said Cambridge University paleoanthropologist Amélie Beaudet, who led the study published in the e-Life magazine. .

“This is very interesting, as we didn’t have a lot of information about that system,” added Beaudet, noting that it likely played a key role in the triple increase in brain size from Australopithecus to modern humans.

Little Foot’s teeth were also revealing.

“The dental tissues are very well preserved. He was relatively old as his teeth are quite worn, ”Beaudet said, although Little Foot’s exact age has yet to be determined.

The researchers detected defects in tooth enamel indicative of two episodes of physiological stress in childhood, such as disease or malnutrition.

“There is still a lot to learn about the biology of early hominids,” said study co-author Thomas Connolley, principal scientist of lines of light at Diamond, using a term that encompasses modern humans and certain extinct members of the human evolutionary lineage. “Synchrotron X-ray images allow the examination of fossil samples in a similar way to an X-ray CT scan of a patient in a hospital, but with much greater detail.”

Little Foot, whose nickname reflects the small foot bones that were among the earliest skeletal elements found, was about 4 feet 3 inches (130 cm) tall. Little Foot has been compared in importance to the fossil named Lucy, which is approximately 3.2 million years old and less complete.

Both are species of the genus Australopithecus but they had different biological traits, just like modern humans and Neanderthals are species of the same genus, Homo, but they 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 in order to decide which would be 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 fully upright, but had features that suggested it climbed trees as well, perhaps sleeping there to avoid large predators. He had gorilla facial features and powerful hands for climbing. His legs were longer than his arms, just like in modern humans, making him the oldest hominin definitely known to have that trait.

“All previous Australopithecus skeletal remains have been partial and fragmentary,” Clarke said.

Will Dunham’s Washington report, edited by Rosalba O’Brien

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