Toumai — or a rare greyish cast of his priceless cranium — flew a couple of thousand kilometres from the Sahara last month to visit his distant cousin Little Foot in South Africa.
Toumai, a fascinating fossil skull that was discovered in the deserts of Central Africa last year, is shaking the very roots of the human family tree. At seven million years of age, the fossil skull found by Chadian palaeoanthropologist Ahounta Djimdoumalbaye is the oldest of any human ancestor. And yet Toumai’s features appear much more human than many other ancient contenders for the title “grandfather of humanity”.
The cast came to South Africa with the leader of the Toumai dig, Michel Brunet, a professor at the University of Poitiers in France. Brunet came to see Toumai’s distant and much younger relative, the apeman skeleton of Little Foot, which is still being chipped out the hard floor of Sterkfontein Caves outside Johannesburg.
“I think it’s very important to think about the history of our history,” Brunet said at Sterkfontein recently. “The first window was opened in the 1920s in South Africa with [the discovery of the skull of] the Taung child. The second window has been opened by the Leakeys in East Africa and is continuing with the recent discovery of 160 000 year-old Homo sapein skulls in Ethiopia.
“With my team nearly 2 500km west of the Rift Valley, we have opened a third window. And you know, with each window you get a different view. If you have just one window, you have just one part of the story.”
At seven million years Toumai is the oldest known relative of the human tribe thus far discovered — and tantalisingly close to the fork in the road between apes and humans.
Toumai has a small brain, comparable to that of chimpanzees. No bones below the skull have been discovered yet, so it is not conclusively known whether Toumai walked on two feet or used his knuckles as well. Scientists in the Doubting Thomas camp say the position of the hole through which the spinal cord exits the skull suggests that it was not balanced on top of an erect body.
Brunet discounts the naysayers by showing its small canines and the shape of the skull. He points out that in 1925, when Nature magazine stunned the world with its publication of Raymond Dart’s discovery of the Taung child, a 3,3-million-year-old hominid fossil, in South Africa, critics raised their collective eyebrows and said that skull must also be that of an ape.
“Toumai is quite clearly not a chimpanzee. Not a gorilla,” he said. “It is not far from the divergence between apes and us and it means the divergence is earlier than we previously thought.”
More evidence is needed and it may appear later this year when Toumai’s trans-disciplinary team of discoverers dig at even older levels.
The cranium was recovered from the Djurab desert in northern Chad, home to bandits, huge sandstorms and very little water. Seven million years ago the environment was considerably more comfortable. Two dozen fossilised animal remains have been found there, including aquatic and amphibious vertebrates, and species inhabiting gallery forests, wooded savanna and grassland.
“We have more fauna than hominids and I think it’s very important to understand the relationship between the fauna found in South, East and Central Africa,” said Brunet.
Toumai’s deathbed is as important as his age. The location of the skull’s discovery, an astonishing 2 500km west of the Rift Valley, suggests an early, diverse and widespread hominid distribution throughout the deserts of the Sahel, as well as in East Africa.