Prof Lee Berger with the Australopithecus sediba skeleton
By Itumeleng Makgobathe
In 2008, Professor Lee Berger of the University of Witwatersrand led a team of scientists to the Cradle of Humankind, where they discovered a 2-million-year-old fossil and a new species of hominid, Australopithecus sediba.
In March 2008, Berger was looking at a series of caves in the Cradle of Humankind, on the interactive web-based satellite picture application Google Earth, and noticed that they led to what looked like a vacant area.
Intrigued, on August 1, 2008, after sharing the information with other scientists and identifying almost 500 caves and 25 fossil sites that scientists had not previously identified, he took Prof Paul Dirks, at the time, head of the School of Geosciences at the University of Witwatersrand, to the area to map out the cave system.
While Dirks was doing the mapping, Berger journeyed to the uninvestigated area with his dog Tau, who has accompanied him on almost all his explorations; he almost immediately discovered a rich fossil site near another 36 caves.
A few weeks later, Berger went back to the site with his student, Dr Job Kibii, and Matthew Berger, his nine-year-old son. Just minutes after their arrival, Matthew discovered the first hominid remains, a clavicle, or collarbone.
On the opposite side of the cave, Berger discovered the jawbone of a hominid, with a canine in it. The find was later identified as part of a skeleton of a juvenile hominid, about 11 to 13 years old.
A month later Berger went back to the site, this time with a group of more than a dozen scientists, in the hopes of learning more about Matthew’s find and finding more pieces of the juvenile skeleton.
More than four hours later, the team had not discovered a single element they could conclusively identify as a hominid, so they took a break. During the break, Berger decided to go to the edge of a small pit in the middle of the site and saw a bone sticking out of a rock; the bone was a hominid humerus, an arm bone.
Berger went into the pit and as he put one hand against its wall, two hominid teeth fell out of the earth of the wall into his other hand. Remarkably, this second find was of remnants of an adult female.
In the months that followed, the site revealed two partial skeletons, a remarkable new find for science.
The partial skeletons are described in two papers in the prestigious journal, Science, as a new species of early human ancestor called Australopithecus sediba (Australopithecus meaning “southern ape” and sediba meaning “natural spring”, or “well”, in South Africa’s Sotho language). The edition containing the articles is due out on April 9, 2010.
It is suggested that these species might be candidates for the transitional species between the southern African ape-man, Australopithecus africanus (of which the Taung Child and “Mrs Ples” are examples) and either Homo habilis, or even a direct ancestor of Homo erectus (including specimens such as Turkana Boy, Java Man, Peking Man).
Lee Berger, on site, leading his team of scientists
The species has long arms, like an ape, short, powerful hands, a very advanced pelvis (hip bone) and long legs capable of striding and possibly running, like a human’s.
They are preserved in calcified clastic sediments, a hard, concrete-like substance that formed at the bottom of a shallow lake or pool that was about 30m to 50m underground about 1.9-million years ago. How the skeletons got there is a mystery, but it seems they may have fallen in.
The fossils of the juvenile male and adult female were laid down by a single debris flow, indicating the timing of their deaths was closely related and occurred shortly before the debris flow carried them to their burial spot.
The sex of the fossils could be determined from the morphology of the jaws and hips; the age of the juvenile was determined from its dentition, showing that it is around 11 to 13 years old. In contrast, the adult female had strongly worn teeth, signifying she was in her late 20s, or perhaps older. They are both around 1.27m tall.
The Cradle of Humankind is critical to our understanding of our species, as nearly a third of all the evidence for humans originating in Africa come from just a few sites in this region. It is one of the most-explored areas in Africa for evidence of human origins, having been investigated continuously since the first discoveries were made there in the 1930s.
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- Lee Berger: the man behind the Sediba fossils
- Exciting new fossil discovery published in pre-eminent journal, Science