The researchers analyzed the fossils of Sahelanthropus tchadensis, discovered 21 years ago in the deserts of Chad, in central Africa. At the time, the discovery was said to have had “the impact of a small nuclear bomb” as it pushed the ancestral line of hominids – the line leading to Homo sapiens – by a million years, closer to the split with chimpanzees. The question of whether the species walked upright remained unanswered. Now, a team in France says they are “pretty sure” that Sahelanthropus was indeed bipedal. But other experts have expressed doubts about the study, published in the journal Nature, sparking debate about Sahelanthropus’ lifestyle and even whether it is in our evolutionary branch. The researchers examined a femur bone and two forearm bones discovered at the discovery site in the Toros-Menalla region of the Djurab Desert in Chad. They analyzed 23 features of the fossils that they say point to bipedalism and show a closer relationship to humanity than apes. “We can conclude from the evidence that we have ordinary bipedalism, plus quadrupedal arborealism, which is what is seen for early hominids and then gradually turns into obligate bipedalism in Homo,” said Jean-Renaud Boisserie, co-author of the study . from the University of Poitiers. More recent hominid fossils, including the 3-million-year-old Lucy skeleton, suggest that bipedalism is a defining feature of our ancestry. “We’re pretty confident,” said Franck Guy, also a co-author. “What we show is that the morphological pattern of the femur is more similar to what we know in humans, including fossils, than in apes.” Professor Bernard Wood, of George Washington University, who co-authored an earlier study that concluded Sahelanthropus was not typically bipedal, said: “These critically important fossils deserve better treatment than this wretched paper. The study cherry-picks evidence, ignores recent studies that lead to different conclusions than the authors are trying to defend, and fails to explore other equally, if not more likely, functional interpretations of these fossils. “All three bones resemble chimpanzees more than any other living great ape, including modern humans. This does not mean that Sahelanthropus was a chimpanzee, but it was probably closely related to chimpanzees and had a chimpanzee-like lifestyle. It was not an upright, terrestrial ape of the sort that our earliest ancestors are likely to have been.’ Archie Bland and Nimo Omer take you to the top stories and what they mean, free every weekday morning Privacy Notice: Newsletters may contain information about charities, online advertising and content sponsored by external parties. For more information, see our Privacy Policy. We use Google reCaptcha to protect our website and Google’s Privacy Policy and Terms of Service apply. Professor Fred Spoor, an expert on human origins at London’s Natural History Museum, who was not involved in the research, said the new study suggesting that Sahelanthropus did indeed walk on two legs appeared convincing. “I think what’s striking in this case is that 7 million years ago, so close to the possible split with chimpanzees, that even then there is a recognizable signal for bipedal behavior. It really looks like we’re bipedal, being bipedal is the defining nature of our evolutionary tree,” he said. Dr Sandra Martelli, associate professor at University College London, who was also not involved in the study, said: “The type of bipedal locomotion cannot be decided from the evidence presented, it could be arboreal or terrestrial or both, and mixed with mountaineering.”
