It is August 15 2008. On the ground, amid the long, dry grass of the Highveld, two men, a boy and a dog are staring at an object the boy is holding.
It is a rock — but one with a difference. It contains fossilised hominid bones, the “most sought-after objects on Earth”.
Professor Lee Berger, palaeoanthropologist and reader in human evolution at the Institute for Human Evolution at Wits University, has struck fossil gold.
An American who relocated to Johannesburg in 1989 to do his doctorate, Berger has spent most of the past 19 years exploring the Cradle of Humankind at Sterkfontein, particularly the Gladysvale site.
“I thought I knew the area as well as you can know one,” he says, laughing.
Beginning in the December holidays of 2007 and continuing the next year, Berger began to explore the dolomite rocks in the Krugersdorp and Pretoria areas.
Using maps downloaded from Google Earth (“which I was the last adult human being on Earth to discover”) and GPS coordinates, he began to walk the area, accompanied by his dog, Tau.
He soon called in the help of Professor Paul Dirks, a geologist and former head of the Wits school of geosciences, to map out the anomalies they were finding in the rock systems.
By July 2008 they had discovered hundreds of new cave sites.
“And this is in one of the most explored areas in the world,” Berger says. “They had never been seen before.”
Accompanied by Tau and Dirks, Berger found that the Gladysvale area was rich in fossils, with nearly 40 unexplored caves. In particular, he noticed a line of caves that seemed to point to a telltale cluster of trees.
In mid-August he returned to the site, this time with his nine-year-old son, Matthew, and post-doctoral research student Joe Kibii.
They followed a hidden mining track to the grove about 50m from the road. There, in the middle of the site, they found a pit that was not much bigger than a couple of two-seater couches. “And I told them, ‘Go look for fossils!'” says Berger.
Minutes later Matthew called his father to look at a rock he had stumbled on.
“I thought he’d found an antelope — we always find them. When you look at a fossil, instead of trying to argue why it’s hominid, you have to argue why it’s not an antelope,” Berger says.
“And there was this rock with a clavicle sticking out of it. Very few creatures have clavicles: bats, moles and primates, which includes us. And I could see immediately it wasn’t a bat or mole.” S-shaped, it also pointed to the long-dead creature’s upright stance.
Berger counts himself an expert on the collarbone. “I did my PhD on it in 1994,” he says. “Of course, it was mostly used as a doorstop for years.”
Fossil clavicles are “never found”, he says. But articulated remains, such as the mandible and canine his son had found on the other side of the rock, are even rarer.
“There are probably fewer than two dozen out there. But partial skeletons — and we’re generous with that term — well, if there were 10, it would be a lot.”
A partial skeleton is a fossil where any part of the head can be linked to any part of the body.
“I knew we had something big.”
Berger immediately contacted the South African Heritage Resources Agency for a permit to work on the site. By law, all fossils found in South Africa belong to the country’s people.
On September 4 2008, after hearing that a permit had been awarded, almost every member of Berger’s department joined the expedition to the site. “We were all thinking: ‘Well, if that’s what a nine-year-old can find after a minute and a half, the place must be fossil-rich,'” says Berger.
But after more than four hours of searching, they had nothing to show Â- and Berger was close to desperation. “I was feeling just devastated, because the possibility was that our rock had been moved there by miners — in which case we had no context.
“And I was staring at the back wall of the pit when the sun fell on it. I realised a humerus [upper arm bone] was sticking out of the solid rock.”
On closer inspection, Berger saw that the bone was articulated with a shoulder blade. “It was unbelievable. No one ever finds scapulas — they’re paper-thin. If you hold one up to the light you can see right through it.”
As he put his hand up to the wall — “to steady myself” — two fossil teeth fell from the rock into his hand.
At that point he realised there were at least two skeletons — the teeth were so worn they could not belong to the other skeletal remains they had uncovered.
No fieldworker has ever found two fossil hominid skeletons together before.
The site is just 300m from where Berger spent most of his professional life working. And in a further historical irony, Gladysvale was well known to earlier pioneering researchers, including Robert Broom, Phillip Tobias — who took this first group of students there — and Bob Brain.
“This is not the end of the story. There are other skeletons in the site,” Berger says, leaning forward, his eyes shining with barely contained excitement. “You can see them. I’ve seen them. They’re down there.”