‘One fossil admires another’
Cradled in the hand of an icon lies a relic of our past, an ancestor from where we might all have come. The icon’s hand is that of Desmond Tutu, and the skeletal fossil belongs to Australopithecus sediba.
This fossil hand might have once held stone tools.
On Thursday, the world was introduced to the hand, the most complete hominin hand to have been discovered. Its uniqueness is baffling the scientists who will have to ask where this individual fits into our family tree.
The discovery is forcing the focus back on South Africa as the place where humans originate, rather than East Africa, which has been in the limelight for several decades.
It was only three years ago that this ancestor of ours was discovered at Malapa, in the Cradle of Humankind, just 40km from Joburg. And it is not just the hand. Scientists at the Origins Centre at Wits University revealed other aspects of sediba never before seen in a hominin.
Their findings have been published in five papers that appear in the latest edition of the journal Science.
“We could never have imagined the (importance) of this site, when we first discovered it… the number of discoveries is unprecedented,” said Professor Lee Berger, of Wits University’s Institute for Human Evolution, who is also the research team leader.
The hand shows a mix of primitive and advanced features.
“Many of the features for tool use are present with sediba,” said Dr Job Kibii, of the Institute for Human Evolution.
Also revealed on Thursday was the most accurate scan of an early hominin brain, performed with a synchrotron scanner in Grenoble, France. Like the hand, the brain also has that curious mix of the primitive and the advanced, said Dr Kristian Carlson, also of the Institute for Human Evolution.
The brain is small, the size of a grapefruit. But there are signs of advanced development.
The scan showed development in the frontal lobes.
“The changes we see result in the culmination of the Broca’s area in human beings, which is the region for speech and language,” explained Carlson.
There is also mystery over how sediba walked. An examination of the ankle and foot suggests the hominin was 100 percent bipedal. But it has a foot that would have also been suited for tree climbing.
Scientists have also been able to reconstruct the creature’s pelvis, also similar to a human’s.
Palaeoanthropologists believed that the human pelvis evolved because of the need to deliver big-brained babies. Sediba’s modern-shaped pelvis, which was handling small-brained babies, seems to invalidate the theory.
Another first for the team is that they were also able to establish the most accurate dates ever for a palaeontological site. The two sediba specimens, an adult female and a child, died between 1.977 and 1.978 million years ago.
“This is exciting stuff, what is coming out of Malapa, and there is going to be more in the future,” said Professor Chris Stringer at the Natural History Museum in London, UK.
While Berger and the team suggest sediba might be a candidate as a direct ancestor of man, Stringer
said: “It could be that several species of Australopithecus were evolving in parallel, in Kenya, Ethiopia and South Africa, with human-like features
… but only one of these was to become our ancestor.
“If it is not our ancestor, it is still important to understand the evolutionary forces at work.” - The Star