The researchers found fossils that helped them resolve years of controversy about how early hominins moved: they used their upper limbs to climb like monkeys, and their lower limbs to walk like humans. Hominids are the family of the most progressive primates, including humans.
The authors reconstructed the lumbar vertebrae from the lower back. They belonged to one Australopithecus sediba and also to a woman from Malapa, South Africa. Sediba is an extinct Australopithecus species found in Malapa Cave in South Africa.
Along with previously unearthed fragments, archaeologists have recovered one of the most complete specimens of the lower back. This helped researchers understand how an ancient human relative walked and climbed.
The fossils have been dated to about 2 million years BC. The vertebrae were removed from the cement rock. It turned out that the sediba, like humans, had only five lumbar vertebrae.
The lumbar region is critical to understanding how our ancestors began to walk on two legs, as well as how well they were adapted to it.
Scott Williams, professor at New York University and Wits University and lead author of the article.
In early studies, scientists suggested that sediba had a relatively straight spine, without the curvature commonly seen in modern humans. They also believed it looked more like the backbone of extinct Neanderthals and other more primitive ancient hominins older than 2 million years old.
But the authors of the new work conclude that sediba is a transitional form of an ancient relative of man, and his spine clearly occupies an intermediate position between the spine of modern humans (and Neanderthals) and apes.