3.3-Million-Year-Old Human Spine Fossil Sheds Light On How Efficiently Our Ancestors Walked

Paleontologists discovered the fossil of an early human relative believed to be 3.3 million years old, which revealed a spinal column that bears an uncanny resemblance to the spinal structure of present-day human beings. The discovery points to the fact that the vertebrae development, which allows humans to walk, may have evolved much earlier than previously believed.

The human spine fossil belongs to a two and a half year-old child and was discovered in 2000 in Dikika, Ethiopia. Scientists at the University of Chicago conducted the excavation and subsequent study of the human spine fossil.

How The 3.3-Million-Year-Old Fossil Was Discovered

The human spine fossil is named “Selam” and means “peace” in Ethiopia’s Amharic language. University of Chicago’s Zeresenay Alemseged discovered the Selam fossil. The study’s senior author revealed that the Selam fossil belonged to the Australopithecus afarensis species, which is the same one as the famed Lucy skeleton.

Since its discovery, the researchers moved the delicate Selam fossil to the National Museum of Ethiopia. Once the specimen was safely transferred to the museum, researchers began to slowly carve out the sandstone, which engulfed the skeleton. They also deployed imaging tools to examine its structure in detail.

After years of continued research and analysis, Alemseged concluded that the Selam fossil was more than 3-million-years-old and that the spinal column of the subject was similar to modern-day humans, shedding further light regarding the exact period when humans began walking upright.

Importance Of The Fossil Discovery

Human beings and their distant relatives, the primates, share many features regarding the overall spinal structure. However, some major difference also lie among the two spinal columns. In humans, the spine consists of lesser rib-bearing backbones vis-à-vis primates. Similarly, the human spine also possesses greater number of lower back vertebrae, which essentially enables people to walk upright unlike the primates.

“For many years we have known of fragmentary remains of early fossil species that suggest that the shift from rib-bearing, or thoracic, vertebrae to lumbar, or lower back, vertebrae was positioned higher in the spinal column than in living humans. But we have not been able to determine how many vertebrae our early ancestors had,” Carol Ward, University of Missouri School of Medicine’s professor of Pathology and Anatomical Sciences, explained.

Alemseged and his team later transferred the Selam fossil to France. Here the human spine fossil underwent further tests and high-resolution imaging. This allowed scientists to essentially virtually recreate the fossil’s full spinal column and rib structure. The tests revealed that the Australopithecus afarensis possessed 12 pairs of ribs and 12 thoracic vertebrae, similar to modern-day humans.

The study’s results were published in the journal PNAS.

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