Skull bones of the earliest known ancestor of humankind have emerged from the swirling sand dunes of Chad -- a fossil more than 6 million years old that will revolutionize the scientific understanding of human beginnings, researchers announced yesterday.
The nearly complete cranium, fractured jaw bones and teeth -- 3 million years older than any other hominid skull discovered to date -- offer experts the first glimpse of a mysterious period of evolution between 6 million and 7 million years ago when the earliest ancestors of humankind first branched off from chimpanzees, gorillas and other great apes.
As the first and only tangible evidence of hominids from such an important period, the new fossils illuminate that crucial epoch like a single candle burning in the dark basement of time.
"Unquestionably, this is one of the most important fossil discoveries of the last 100 years," said Harvard University anthropologist Daniel Lieberman. "It is the oldest skull by far of a human ancestor. This will have the scientific impact of a small nuclear bomb."
Details of the find were announced in Chad yesterday and published today in the British research journal Nature.
The discovery suggests that human roots go deeper than previously thought, said experts in England, Japan and the United States who have examined the fossils. The first pre-humans may have branched off from the ancestors of chimps and other apes a million years earlier than genetic evidence of molecular DNA has hinted.
"This is the closest we have gotten to the last common ancestor" between humans and their closest modern relative, chimpanzees, said University of California, Berkeley anthropologist Tim D. White.
The creature's teeth, brain case and facial features also appear "incredibly modern," suggesting this diminutive lake-shore dweller could easily be a direct ancestor of contemporary humanity. It is evidence that the earliest human ancestors bore little resemblance to any modern ape.
And because the fossils were found so far from the East African Rift Valley long considered the cradle of humanity, scientists conclude that these first primitive hominids, as the early ancestors of humanity are called, ranged much more widely than researchers had expected.
"It is of tremendous significance for its age, its completeness, the location where it was found, and its fascinating combination of features," said David Pilbeam, an authority on human beginnings at Harvard and a member of the research team. "It is a stunning find."
The fossil fragments from the newly named species were unearthed last July in the scorching Djurab desert of Chad in Central Africa, by the Mission Paleoanthropologique Franco-Tchadienne, or MPFT, a team of 40 researchers from 10 countries led by French paleontologist Michel Brunet at the University of Poitiers, who has explored the region for 30 years.
"It's a lot of emotion to have in my hand the beginning of the human lineage," Brunet said in a statement released in Chad. "I have been looking for this for so long."
The cranium itself was first spotted protruding from the crumbling sandstone by a student at the University of N'Djamena named Ahounta Djimdoumalbaye.
The fossilized remains belong to a small-brained creature not much taller than a chimp that was neither ape nor completely human.
The newly discovered species "shows a mix of primitive and evolved characteristics never seen before and that are surprising to see 6 million years ago," said paleontologist Chris Stringer at the Natural History Museum in London. "It had an ape-like brain size and skull shape, combined with a more humanlike face and teeth. Its discovery shows how much evidence has been missing up to now."
Taken together, the combination of features appears so unusual that the French researchers assigned the creature to its own new genus and species called "Sahelanthropus tchadensis."
