It is a dispute that has taken a long time to reach a boiling point. Seven million years after an ape-like creature, since nicknamed Toumaï, swept across the landscape of the modern age. Chad, their means of mobility has sparked a dispute among fossil experts. Some claim that this was the oldest member of the human lineage. Others that it was just an old monkey.
The anger, lit by a role in Naturelast week led scientists to denounce opponents while others accused rivals of building theories on “less than five minutes of observation.”
The core of the dispute is simple. Could Toumaï, which means “hope of life” in the local Daza language of Chad, walk on two feet, an ability that suggests he might be the oldest member of the human family? The scientists who unearthed the fossil remains believe this to be the case.
Others vehemently disagree. They say that 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 dispute is acrimonious even for paleontology, a field known for its bitter controversies over the interpretation of ancient skulls and bones. In this case, the dispute began with the 2001 discovery in the Djurab desert of a distorted skull and other bones by paleontologists from France and Chad. They concluded that the shape of the skull meant that it must have belonged to a creature that walked upright.
“It’s very exciting to have the beginning of the human lineage in my hands,” team member Michel Brunet of the University of Poitiers said at the time. The finding made Brunet a scientific star in Franceespecially in Poitiers, where a street bears his name.
However, the interpretation was based solely on examination of the skull, critics said. The other bones had been left out until they were examined in 2004 by Aude Bergeret-Medina, also from the University of Poitiers. She recognized a leg bone and concluded that it came from a primate that walked on all fours, not two. Basically, she had the support of her supervisor, Roberto Macchiarelli.
Macchiarelli and Bergeret took more than a decade to publish their conclusions. Attempts to present his findings at the Paris Anthropological Society were blocked, they say, while Macchiarelli was accused of scientific misconduct by his opponents.
A report of his work ultimately concluded that it did indicate that Toumaï was a four-legged creature and unlikely to have been one of the founders of the human lineage. “The evidence to support bipedalism is very, very poor,” says Macchiarelli.
Last month, the skull and bones seekers posted their answer on Nature and such examination of the bones pointed to bipedalism, suggesting that it had a closer relationship with humanity than the apes. On Twitter, one of the team members, Franck Guy, accused Macchiarelli and his colleagues of basing his conclusions on 5 minutes of observation and some photos. “Our article is a five-year study,” he added.
Other scientists, including Professor Bernard Wood of George Washington University, have openly rejected Guy’s claims while supporting the argument that Toumaï’s bones indicate it was chimpanzee-like.
Professor Chris Stringer of the Natural History Museum in London was more cautious. “It’s a shame that these disputes detract from really important findings,” he told the Observer. “Given the peculiar and largely unknown circumstances of the discovery (the bones appeared to have been collected by someone and placed in desert sand), we don’t even know if the skull, leg, and arm bones belong together as a single individual.” .
“I would say the jury is still out on whether Toumaï was fully adapted to walk on two legs.”
