What defines a person as a person? Although this is a difficult question, paleontologists and archaeologists tend to do so cite several specific characteristics in an attempt to answer. homo sapiens, they typically speak, create complex tools, make complex social and symbolic meanings, and communicate with each other using words and sentences—all features that are difficult to find in the fossil record.
Slightly more apparent in this record is the species’ ability to walk upright, which some experts consider one of the most defining traits of Homo sapiensas well as numerous other hominins including Homo habilis and Homo erectus. That said, despite its importance, scientists still struggle to determine when hominin bipedalism evolved and with which specific species.
According to new analysis of fossils in Naturea team of researchers found that the oldest hominin species, Sahelanthropus tchadensis, he walked on two legs. This supports the theory that hominins evolved their bipedalism early, when they were still spending their time swinging through trees.
Old types, new skills
It is believed to represent first human ancestor after the separation from the apes, S. tchadensis is considered the oldest known hominin. Discovered in the Jurab desert in Chad in 2001, the first fossils of this species include a nearly complete skull and a fragmented set of teeth that date back seven million years. Finds from the same site also include a femur or femur and two ulna or forearm bones, all attributed to the same species.
Immediately after these discoveries, scientists turned to the skull, which they named “Tumai”. They found that the internal structure of the skull (and in particular the orientation and position of the occipital foramen, an oval-shaped opening that contains the spinal cord) indicated that the species walked upright. Now analysis of femur and ulna bones confirms this theory, suggesting that even the earliest hominins evolved bipedalism, although they retained the ability to climb trees.
Studying S. tchadensis Movement
In their analysis, the researchers applied microtomography imaging techniques to measure more than 20 features of the femur and ulna fossils. They then compared these measurements to those of a wide variety of extinct and extant apes, including orangutans, gorillas, chimpanzees and a number of hominins, including our own species.
Femur comparisons suggest this, according to scientists S. tchadensis it moved on two legs not only on the ground but also on the treetops of West Africa. Moreover, comparisons of the ulnae show that the species’ multi-limbed bipedalism coincides with other forms of locomotion, including quadrupedal tree-climbing aided by a strong grip.
“Taken together,” the scientists concluded in their analysis, “these findings suggest that hominins were already bipedal at about seven years of age[million years ago]but also suggest that tree climbing was probably a significant part of their locomotor repertoire.