Since its discovery in August 2008, the site of Malapa has yielded well over 240 bones of early hominins representing more than five individuals, including the remains of babies, juveniles and adults. Given the open access policy of the team, Sediba is already one of the best studied hominin species yet discovered.
The team studying these fossils is one of the largest ever assembled in the history of archaeology or palaeontology. With more than 80 scientists, students and technicians from across the globe involved in the study, the team includes expert geologists, computer specialists, functional morphologists, anatomists and physicists.
The team announced the first direct evidence of what our earliest ancestors actually ate, in Nature on, Wednesday, 27 June 2012, which has been discovered due to a two million-year-old mishap that befell two early members of the human family tree. The find has provided the most robust evidence to date of what at least one pair of hominins ate.
An international team of researchers studying the remarkable find was led by Professor Lee Berger, Reader in Human Evolution and the Public Understanding of Science at the Institute for Human Evolution at the University of the Witwatersrand.
The team comprised nine scientists from across the globe.
Q: How was the site and the fossils discovered?
A: In the middle 1990s, Lee Berger had conducted an expedition across southern Africa, funded by the National Geographic Society designed to map fossil sites using the then relatively new technology of GPS to discover new sites. While the expedition discovered many new caves and fossil bearing localities (over 100 caves and four new fossil sites in the Cradle of Humankind World Heritage Site alone), it was somewhat of a disappointment in not yielding any significant discoveries. In addition, without him knowing, the result was erroneous due to deliberate error being placed in the GPS signal in the late 1990s. In early 2008, using Google Earth to spot caves in the Cradle of Humankind World Heritage Site, and to correct the errors in these earlier maps, Berger renewed the exploration programme in the area. With the assistance of these new technologies, Berger discovered, over a few months, more than 600 caves and more than three dozen new fossil sites in one of the most explored areas on the planet. On the 1st of August 2008, while mapping with his dog Tau, he discovered the fossil site of Malapa. On the 15th of August he returned to the site with Dr Job Kibii, Tau and his then 9-year-old son Matthew. Within minutes Matthew had discovered the first piece of hominid, belonging to the MH-1 skeleton. Two weeks later, Berger discovered the remains of the adult female skeleton MH-2 and since then, the site has yielded one of the most remarkable records of early human origins of any site on the planet.
Q: What does Australopithecus sediba mean?
A: Australopithecus means “southern ape”, after the genus of the Taung child, named by Prof. Raymond Dart, also from the University of the Witwatersrand, Johannesburg. Sediba means natural spring, fountain or wellspring in Sotho, an appropriate name for a species that might be the point from which the genus Homo arises. As the hominids were also found preserved in an ancient underground lake or spring, the name also relates to their place of discovery.
Q: What is a hominid/hominin?
A: A hominid is a member of the taxonomic family that includes humans, chimpanzees, gorillas and their extinct ancestors. Hominins are members of the human branch after the human lineage split from that of chimpanzees, and thus include living humans and extinct human ancestors, such as the Australopiths. Hominins are characterised by bipedal locomotion, although this may not have been the case for the very earliest members of the group, and relatively small canine teeth. Later members of this group (those in the genus, Homo) are characterised by larger brains than those of living apes like chimpanzees, bonobos, gorillas, orangutans and gibbons.
Q: How were the individuals preserved?
A: The site where the fossils were discovered is technically the infill of a de-roofed cave that was about 30 to 50 metres underground just under two million years ago. The individuals appear to have fallen, along with other animals, into a deep cave, landing up on the floor for a few days or weeks. The bodies were then washed into an underground lake or pool probably pushed there by a large rainstorm. They did not travel far, maybe a few metres, where they were solidified into the rock, as if thrown into quick setting concrete. The rock they are preserved in is called calcified clastic sediment. Over the past two million years the land has eroded to expose the fossil bearing sediments.
Q: Did they die at the same time, or was it a catastrophe?
A: The hominin skeletons were found with the bones either in partial articulation or in close anatomical association, which suggests that the bodies were only partially decomposed at the time of deposition in the lower chamber. This further suggests that they died very close in time to each other, either at the same time, or hours, days or weeks apart. Other animals have been found with them – equally complete – including sabre-toothed cats, hyenas, antelopes, mice, birds and even snails. There is also plant material that has been found.
Q: Is there organic preservation like plant remains or skin?
A: The preservation at Malapa is so good that there are certainly organic remains preserved like plant remains. There are some indications that even soft tissues of animals are preserved, including possibly skin. This material is presently under study by a world-wide based team of experts, who are attempting to prove or disprove the existence of such important material and develop ways to study things that have never been found before in the early hominin record. The plant material described in this paper are small silica bodies called phytoliths which form part of the support and defence structure of plants, and can be used to identify plants to their families, and sometimes even the species. Different parts of the plants even produce different, identifiable phytoliths.
Q: Will there be more discoveries from Malapa?
A: Malapa is already one of the richest early hominin sites ever discovered but excavations have not yet commenced. When they do, later this year, we expect to make even more remarkable finds at the site.
For more information, visit www.wits.ac.za/ihe