Scientists from the UC San Francisco found specific shoulder fossils which may lead to an evolutionary pattern in between humans and an ape-like ancestor. Moreover, the fossils may shed light on the human race’s evolution, in accordance to the African ancestor.
The shoulder shape of modern humans has been changing across time. The newly developed study could predict which people are at the highest risk of getting rotator cuff injuries.
The lead author of the study, Nathan Young, assistant professor at UC San Francisco School of Medicine, explained that
“our study suggests that the simplest explanation, that the [common] ancestor looked a lot like a chimp or gorilla, is the right one, at least in the shoulder.”
According to Young and his team member’s discovery, wonders how it was possible that our common ancestor evolved a shoulder like that of modern humans. He suggested that the explanation would be related to the invention of tools, therefore a reduction in tree climbing.
The fossil shoulder blades pertaining to early hominins were compared with those of modern humans and those of tree-dwelling monkeys, the orangutan, the gibbon and African apes. This was fulfilled via 3-D measurements.
According to the findings, modern humans’ shoulder shape is similar to that of the orangutan, whereas the scapular blade shape is correlated to that of African apes.
Moreover, Young’s team was aimed at analyzing the Australopithecus species – A. afarensis and A. sediba. They also looked at H. ergaster and Neandertals. All this was done to determine how much their shoulders resemble ours.
The senior curator of Anthropology at the California Academy of Sciences, Zeray Alemseged, explained that
“the results showed that australopiths were intermediate between African apes and humans.”
He suggested that the shoulder positioning was in correlation with the sophisticated use of tools in Australopithecus.
A fellow of human evolutionary biology at Harvard University, Neil Roach, reported that the unique ability of us being able to throw objects with accuracy and speed was due to shoulder shifts.
Roach explained that
“our unique throwing ability likely helped our ancestors hunt and protect themselves, turning our species into the most dominant predators on earth.”
The information provided by the study could first and foremost explain why some people are inclined to develop shoulder injuries.
The scientists published their information in the journal Proceedings of the National Academy of Sciences.
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