The controversy, sparked by a paper in Nature, last week led scientists to denounce their opponents, with others accusing opponents of building theories in “less than five minutes of observation”. The core of the controversy is clear. Could Toumaï – which means “hope of life” in Chad’s local Daza language – walk on two legs, an ability that suggests it could indeed be the oldest member of the human family? The scientists who discovered the fossils believe this is the case. Others disagree, vehemently. They say Toumaï – a member of an extinct species known as Sahelanthropus tchadensis – was not bipedal but moved on all fours like a chimpanzee. Claims of ancient human ancestry are false, they argue, accusing opponents of cherry-picking data. The controversy is vicious even for paleontology, a field noted for the bitterness of controversy over the interpretation of ancient skulls and bones. In this case, the controversy began with the discovery in 2001 in the Djurab desert of a deformed skull and other bones by paleontologists from France and Chad. They concluded that the shape of the skull meant it must have belonged to a creature that walked upright. “It’s quite a feeling to have the beginning of human origins in my hands,” one team member, Michel Brunet of the University of Poitiers, said at the time. The find made Brunet a scientific star in France, especially in Poitiers, where a street was named after him. Professor Michel Brunet, of the University of Poitiers, holds Toumaï’s skull at the University of N’Djamena in Chad. Photo: Patrick Robert/Corbis/Getty Images However, the interpretation was based solely on examination of the skull, critics said. The other bones were put aside until they were examined in 2004 by Aude Bergeret-Medina, also of the University of Poitiers. He identified a leg bone and concluded that it came from a primate that walked on all fours – not two. Most importantly, she was supported by her boss, Roberto Macchiarelli. It took Macchiarelli and Bergeret more than a decade to publish their findings. Attempts to present their findings to the Anthropological Society of Paris were blocked, they say, while Macchiarelli was accused of scientific misconduct by his opponents. A report of their work eventually concluded that it indeed showed that Tumai was a four-legged creature and unlikely to be the founder of the human lineage. “The evidence supporting bipedalism is very, very poor,” says Macchiarelli. Last month, the skull and bone explorers published their response in Nature and said examination of the bones indicated bipedalism, suggesting it was more closely related to humanity than apes. On Twitter, one of the team, Franck Guy, accused Macchiarelli and his colleagues of basing their conclusions on 5 minutes of observation and a few photos. “Our work is a five-year study,” he added. Other scientists, including Professor Bernard Wood of George Washington University, have rejected Guy’s claims while arguing that Toumaï’s bones show that he was chimpanzee-like. Professor Chris Stringer of London’s Natural History Museum was more cautious. “It’s a shame that these controversies detract from the really important findings,” he told the Observer. “Given the strange and largely unacknowledged circumstances of the discovery – the bones looked as if someone had collected them and placed them in the desert sand – we don’t even know if the skull, leg and hand bones belong together as one single person. “I would say the jury is still out on whether Toumaï was fully adapted to walking on two legs.”
