Researchers at the University of Southern California (USC) have published the results of a cutting-edge study analyzing a three-million-year-old fossil nicknamed Little Foot. The exceptionally well-preserved specimen belongs to the Australopithecus family of hominins – one of the earliest evolutionary branches of the human family tree. While this particular fossil may at first glance resemble a modern human, there are many key differences that clash with Homo sapiens (wise man).
California researchers were particularly interested in Little Foot’s shoulders or, more specifically, his collarbones, shoulder blades and joints.
Many other members of the fossil exhibit human-like characteristics that enabled it to walk upright.
But the shoulders are distinctly ape-like, which sheds new light on how these human ancestors behaved.
Analysis of bones from Little Foot shows that Australopithecus was well adapted to life in the canopy – climbing, hanging, and climbing trees.
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This is in stark contrast to the type of shoulders that made the task of throwing speers easier.
According to Kristian J Carlson, lead author of the study and associate professor of clinical integrative anatomical sciences at the Keck School of Medicine, this is some of the best evidence to date of how our ancestors used their arms. over three million years ago.
He said: âLittle Foot is the Rosetta Stone for the first human ancestors.
“When we compare the shoulder with living humans and monkeys, it shows that Little Foot’s shoulder was probably a good model of the shoulder of the common ancestor of humans and other African apes like chimpanzees and gorillas. “
The discovery sheds new light on our separation from the apes, as it shows that humans and apes have shared skeletal similarities for much longer than previously thought.
Professor Carlson said: âWe see compelling evidence in Little Foot that the arm of our ancestors 3.67 million years ago was still used to support substantial weight during arboreal movements in trees to climb or hang. under the branches.
“In fact, based on comparisons with living humans and apes, we propose that Little Foot’s shoulder morphology and function is a good model for that of the common ancestor of humans and chimpanzees. seven to eight million years ago. “
For example, Little Foot’s collarbone has an S-shaped curve, which is commonly found in monkeys.
The shoulder joint is also at an inclined angle which would make it easier to hang from the branches.
Various species of Australopithecus are believed to have existed in Africa during the late Pliocene and early Pleistocene, until their extinction around 1.4 million years ago.
According to the Smithsonian National Museum of Natural History, scientists have discovered more than 300 Australopithecus fossils, making it one of the best known and most studied human ancestors.
The most famous of the Australopithecines discovered was Lucy, found in Ethiopia in 1974.
The USC-led study was conducted with researchers from the University of Wisconsin, the University of Liverpool, and the University of the Witwatersrand in South Africa.