The petrified shoulder joint of an early hominin called “Little Foot” suggests that the upright walking species was also skilled in swing through trees, a skill that has long existed among modern humans.
About 3.7 million years ago, what is now South Africa, a human family member scattered two evolutionary moments: our tendency to spend time in trees and our emerging preference for walking on the ground. This specimen, named StW 573 or Little Foot, was a Australopithecus prometheus. The fossil was finally fully excavated in 2018, more than twenty years after its discovery, when paleontologists finished removing the fossil from the breccia in which it was wrapped. Immediately, Little Foot gave a remarkable look at human origins.
Research describing the morphology of the shoulder joint was published this week in the Journal of Human Evolution. The research team examined Little Foot’s chest belt: literally the shoulder blade and collarbone of the monster. By comparing the formation of the belt to that of other family members, including some of the great apes, the team expressed how Little Foot and others in its species got over it.
“By understanding how the shoulder joints of early hominins are structured, and broadly how their shoulder blades can move on their torso, we can understand how they used their upper limbs while dealing with the environment,” said Kristian Carlson, a biological person, said. anthropologist at the University of Southern California and lead author of the new paper, in an email. “This is an important question during this period of our evolutionary history.”
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In its subtle form, Little Foot’s chest belt indicated to researchers that the hominin does exploit trees for its survival, perhaps to obtain a meal or to prevent it from becoming one. This is in line with research last year on the vertebrae of the monster, which suggested that Little Foot was capable of head movements (useful for climbing) that go beyond modern human abilities. That said, Little Foot was still bipedal, with the upright gait accompanying people. The new finding brings an interesting comparison with Ardi (a copy of Ardipithecus ramidus), a lesser-known ancient family member from 4.4 million years ago. Paleoanthropologists recently suggested that Ardi’s hands were built to swing in trees, although some experts disagree, saying that Ardi was more human than ape-like. Although the fossil record is as hidden as it can be, the conclusions from the bones we draw from the ground remain fickle. It will take a while to see if the interpretations of Little Foot’s lifestyle that are pulled from these shoulder bones are stuck.
Little Foot’s chest belt is the earliest evidence of such a skeletal structure so close to when hominins were separated from monkeys and bonobo ancestors. The upper limb is an important piece of the puzzle, though Carlson said it can tell us just as much.
“As special as Little Foot is, it’s just one individual,” he explained. “While we are still intensively investigating other anatomical regions of the Little Foot skeleton, we should also appreciate the growing morphological variability that appears to be within the early fossil record of hominine, for example in Australopithecus.”
Based on their comparisons, the Carlson team determined that the shoulder structure of Little Foot could be a good indication of what the structure would look like in even older human relatives in the 7- to 8-million-year-old era. Such a discovery would make Little Foot look like a jumping chicken. But until that happens, we seem to be stuck with one of the most complete Australopithecine fossils ever found, and its continued analysis reveals new details and theories with each pass. Woe to us!
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