Two million years apart, two boys close the evolutionary gap

TWO million years later, a potential missing link in evolution estimated to have been nine years old when he died has been discovered by a boy of the same age.

100409 human map

TWO million years after he died in a deep death-shaft cave along with a sabre-toothed cat, a horse, wild dog, hyena and other animals, the remains of a human-like juvenile male - potentially a missing link in the evolutionary transition of apes to humans, and estimated to have been nine years old when he died - have been discovered by a boy of the same age.

The find in South Africa of the 130cm specimen, which could walk upright on its two legs like humans and swing in trees with particularly long arms and strong curved fingers, together with an adult believed to be his mother, is being hailed by scientists as one of the most extraordinary discoveries in the modern quest to understand the evolution of mankind.

The presence of two other skeletons, confirmed yesterday, has led to speculation that all four were family members who died together after entering the cave in search of water and becoming trapped, along with the animals. There is clear evidence of plaque on the teeth, and scientists are examining what may be tools.

Professor Paul Dirks, head of the School of Earth and Environmental Sciences at Queensland's James Cook University, told The Australian: "We have been incredibly fortunate. We have bumped into one of the best finds ever. It couldn't have been better orchestrated."

The initial discovery in August 2008 has been kept secret until now to allow scientific study of the site and its contents. The find occurred during a cave-mapping and fossil-searching project designed by Professor Dirks, a geologist and professor Lee Berger, colleagues at the University of Witwatersrand in Johannesburg for seven years until late last year.

Professor Berger, a controversial US paleoanthropologist whose son Matthew spotted the collarbone of the juvenile protruding from the ground in an area known as the Cradle of Humankind, said yesterday: "We have at least two more skeletons emerging - they literally are emerging."

Professor Berger described how his son had run off to an unexplored part of the cave. "After a minute and a half, he said `Dad, I've found a fossil. I was sure it would be an antelope fossil."

But when he saw the bone he realised it was the clavicle, or collarbone, of a hominin, and nearby was a block of rock containing part of its jaw and teeth.

Asked yesterday whether the find was the missing link between apes and humans, Professor Berger said that although he did not approve of the simplistic term, it appeared the species was "transitional", with a mosaic of characteristics shared by later hominins from the genus Homo and earlier hominins from the genus Australopithecus.

Professor Berger described the pelvic structure as "very advanced and very human-like".

"They could still climb trees - that was very clear with those long arms - but they were very competent walking bipeds on the ground," he said.

Although DNA has not been reliably identified beyond remains tens of thousands of years old, the scientific team, including experts from universities in Melbourne, Sydney and Townsville, is trying everything possible to recover traces of DNA from the two-million-year-old fossils.

The species, which has a brain about one-third the size of the modern human brain, has been newly named Australopithecus Sediba.

Professor Dirks said he and Professor Berger had devised a plan to rely on geology to identify locations of potential fossil-bearing caves, leading them to the cave site known as Malapa, about 40km from Johannesburg.

It is producing an astonishing wealth of fossils that are remarkably well preserved, causing scientists to reconsider the rightful place of different species in human evolution.

"They would have died within reach and within minutes or hours or days or weeks of each other," Professor Dirks said.

Describing the life of the species and how the individuals probably died in the cave, Professor Dirks paints a picture of a "death shaft" descending about 50m from the ground to the bottom: "We believe they may have gone in search of water during a calamitous drought."