REMAINS of the earliest human-like animal yet found suggest that hominids began walking upright two million years earlier than previously thought.
Last week, two collaborating groups of researchers, a French group led by Brigitte Senut of the National Museum of Natural History in Paris and Martin Pickford of the Coll猫ge de France, and a local group from the Community Museums of Kenya announced that they had discovered the remains of a six-million-year-old creature in Africa鈥檚 Rift Valley dubbed 鈥淢illennium Ancestor鈥�. It is 1.5 million years older than previous hominid finds.
鈥淚t鈥檚 not completely human, but definitely nothing like an ape,鈥� Senut told 麻豆传媒. 鈥淚t鈥檚 really something.鈥� The creature鈥檚 teeth and upright posture are key features linking it to humans, said Senut. The teeth are small and have thick enamel, suggesting that Millennium Ancestor enjoyed a diet of thick-skinned fruits.
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Sturdy thigh bones suggest that the hominid could walk upright on two legs, although probably not quite as we do. If correct, this means bipedalism evolved two million years earlier than previously thought, says Chris Stringer, an expert on hominids at the Natural History Museum in London. But researchers would need to study the creature鈥檚 knee joints and pelvis to confirm this, he adds. Chew marks on the bones hint that the hominid met a gruesome end-possibly in the claws of a large cat such as a leopard.
The arm and finger bones suggest that Millennium Ancestor could also climb trees-much like another famous human relative, the three-million-year-old hominid known as 鈥淟ucy鈥�. This scenario fits with the sediments in which the hominid was found, says Pickford. The formation hints at an open savannah-like environment, dotted with clumps of trees, he says. Pickford believes that the sediments, known as the Lukeino Formation, will give up many more fossils, stretching back over millions of years. 鈥淚鈥檓 sure we鈥檒l find more,鈥� he says.
The skeletons could fill a crucial gap in our understanding of human evolution. Millennium Ancestor was alive around the time researchers think the ancestors of humans and chimpanzees diverged. Studies of human and ape DNA suggest that the split occurred five to seven million years ago (see Diagram).
Other researchers are intrigued by Senut and Pickford鈥檚 findings, but hesitate to draw conclusions until they can study them in more detail. 鈥淚f what they are saying is correct, it鈥檚 really quite exciting,鈥� says Collard.