The spines of our early ancestors have been mysterious. They are not well preserved in the fossil record, Alemseged explains, because they are much more fragile than other parts of the animal, like teeth.

This specimen is particularly unique, because it belongs to a child whose individual vertebrae are “still in the process of fusing and forming.” He says that’s why “the data is so unique, shedding light on one of the key milestone events in human evolution and that is the transition from the more ape-like arrangement of the backbone to the more humanlike arrangement of the backbone.”