A recently released study brought to light new data about the human spine, which seems to have evolved even earlier than initially believed. The source of these new discoveries is a 3.3 million years old infant fossil, called Selam.
Research results became available in the Proceedings of the National Academy of Sciences on May 22.
Selam, an Old Infant Revealed New Spinal Data
The human spinal column is quite different from that of apes, one of the closest species to us in the animal kingdom, most likely due to our bipedalism. Human spines have 12 rib-bearing vertebrae while most apes have one less such structure.
Now, this early human ancestor, Selam, shows that this distinction may have evolved farther back than initially believed. Previously, this feature was first noted in early humans aged to be some 60,000 years old or even closer.
Selam is the fossil of a 2 to and half years old child who was part of the Australopithecus afarensis, an early human species. Its fossil was discovered back in 2000, in Dikika, Ethiopia, and has since been cleaned and carefully studied.
These remains present the as yet most complete spinal column found in any human relative as they still have a neck, rib cage, and vertebrae.
“This type of preservation is unprecedented, particularly in a young individual whose vertebrae are not yet fully fused,” stated Zeresenay Alemseged.
He is a study co-author and an organismal biology and anatomy professor at the University of Chicago, as well as Selam’s discoverer.
The new study used high-resolution imaging technology to study the fossil bones. Which showed that this specimen has 12-rib bearing vertebrae and a corresponding 12 pairs of ribs.
As the paper points out, this is a first in such old remains and the as yet most complete example of a modern human spinal structure.
Alemseged considers that Selam and its structure mark an important, if not key event in the human evolution. This development of the back structure eventually led to the appearance of bipedalism and all its ensuing progress.
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