Oldest hominid discovered is 7 million years old
CHICAGO, February 27, 2008 - French fossil hunters have pinned down theage of Toumai, which they contend is the remains of the earliest human everfound, at between 6.8 and 7.2 million years old. The fossil was discovered in the Chadian desert in 2001 and an intensedebate ensued over whether the nearly complete cranium, pieces of jawbone andteeth belonged to one of our earliest ancestors. Critics said that Toumai's cranium was too squashed to be that of a hominid-- it did not have the brain capacity that gives humans primacy -- and itssmall size indicated a creature of no more than 120 centimetres (four feet) inheight, about the size of a walking chimp. In short, they said, Toumai had no right to be baptised with Frenchresearcher Michel Brunet's hominid honorific of Sahelanthropus tchadensis --he was simply a vulgar ape. Toumai's supporters used 3D computer reconstructions to show that thestructure of the cranium had clear differences from those of gorillas andchimps and indicates that Toumai was able to walk upright on two feet,something our primate cousins cannot do with ease. If Toumai is truly an early human, that means that the evolutionary splitbetween apes and humans occurred far earlier than previously thought. And pinning down his age is key to redrawing the evolutionary map. "The radiochronological data concerning Sahelanthropus tchadensis ... is animportant cornerstone both for establishing the earliest stages of hominidevolution and for new calibrations of the molecular clock," Brunet wrote in astudy which will appear in the March 4 edition of the Proceedings of theNational Academy of Sciences. "Thus, Sahelanthropus tchadensis testifies that the last divergence betweenchimps and humans is certainly not much more recent than 8 Ma (million yearsago.)" Toumai also probably lived "very close in time to this divergence contraryto the unlikely 'provocative explanation,' which recently suggested a'possible hybridization in the human-chimp lineage before finally separatingless than 6.3 (million years ago)," the authors concluded. If Toumai -- the name means "hope of life" in the local Goran language --is accepted as a human, the implications are profound. The fossil was found some 2,500 kilometers (1,500 miles) west of the GreatRift Valley. If that is still seen as humankind's ancestral home, it impliesthe early hominids ranged far wider from East Africa, and far earlier, thanpreviously thought. The discovery also implies hominids evolved quickly from apes after theysplit from a common primate ancestry. Hominids are considered the forerunners of anatomically modern humans, whoappeared on the scene about 200,000 years ago. Still unclear, though, is the exact line of genealogy from these small,rather ape-like creatures to the rise of the powerfully-brained Homo sapiens.