Posted on 02/28/2008 4:21:27 AM PST by Renfield
CHICAGO (AFP) - French fossil hunters have pinned down the age of Toumai, which they contend is the remains of the earliest human ever found, at between 6.8 and 7.2 million years old.
The fossil was discovered in the Chadian desert in 2001 and an intense debate ensued over whether the nearly complete cranium, pieces of jawbone and teeth 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 its small size indicated a creature of no more than 120 centimetres (four feet) in height, about the size of a walking chimp.
In short, they said, Toumai had no right to be baptised with French researcher Michel Brunet's hominid honorific of Sahelanthropus tchadensis -- he was simply a vulgar ape.
Toumai's supporters used 3D computer reconstructions to show that the structure of the cranium had clear differences from those of gorillas and chimps 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 split between 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 an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock," Brunet wrote in a study which will appear in the March 4 edition of the Proceedings of the National Academy of Sciences.
"Thus, Sahelanthropus tchadensis testifies that the last divergence between chimps and humans is certainly not much more recent than 8 Ma (million years ago.)"
Toumai also probably lived "very close in time to this divergence contrary to the unlikely 'provocative explanation,' which recently suggested a 'possible hybridization in the human-chimp lineage before finally separating less 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 Great Rift Valley. If that is still seen as humankind's ancestral home, it implies the early hominids ranged far wider from East Africa, and far earlier, than previously thought.
The discovery also implies hominids evolved quickly from apes after they split from a common primate ancestry.
Hominids are considered the forerunners of anatomically modern humans, who appeared 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.
Undated handout photo shows the skull of Toumaï, a seven-million-year-old fossil believed to be the remains of the earliest human ever found, found in 2001. New fossil remains as well as the 3D reconstruction of the skull confirm that the creature is the oldest species of the human branch, a common ancester of the chimpanzee and of homo sapiens. (AFP/File/MFPT)
Ping
Not human. Proto-human, maybe. But no more human than the small rodents scurrying between the legs of dinosaurs. To me, “human” means the ability to comprehend “I am.” I doubt this poor creature was capable of that.
Early Democrat.
I didn't think radioisotope decay rates worked much beyond about 60,000 years. How does one infer 7 million from this kind of data? Just curious.
Helen Thomas notes
“Toumai’s supporters used 3D computer reconstructions to show that the structure of the cranium had clear differences from those of gorillas and chimps and indicates that Toumai was able to walk upright on two feet”
Yeah, right. They can tell all that from the structure of the brain.
Let’s see the rest of the skeleton and then maybe it can be determined whether it walked upright or not.
Ping
I had an amazing conversation with a friend yesterday. He’s highly educated with two advanced degrees but thought that dinosaurs and humans were both on the earth at the same time and nteracted. At first I thought he was pulling my leg but nope. Did I mention he’s a total left wing lib who thinks we should drop all sanctions against Cuba so we can import their sugar cane to make ethanol to stop global warming.
Was this before Adam and Eve?
Are they trying to prove the Bible wrong?
IB4 the Helen Thomas pic.
He wasn’t trying to prove anything and the Bible didn’t even come up. He was just ignorant. I do love the man but I know he’ll never read this.
“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.”
In other words this is a small ape which had a small brain.
But it makes for good headlines doesn’t it?
I know, just wanted to insert that. :-)
“Early Democrat.”
We must agree to differ on whether it’s Early Democrat or Future Democrat. We can only “hope”.
I dunno. If you look at a bonobo's eyes it sure looks like somebody's home. This guy might have been pretty close to a bonobo.
Let’s see the rest of the skeleton and then maybe it can be determined whether it walked upright or not.
Where the skull attaches to the spine is a pretty good indicator of bipedalism.
They just can, okay? It's scientific and stuff, just have a little faith. ;)
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