Sediba: Man or Australopithecus

Karabo: The Australopithecus Sediba

As anthropological discoveries continue, our origins become clearer.

Australopithecus Sediba was revealed to the public in April 2011 in Minneapolis by a team led by Lee Rogers Berger during the International Anthropology Congress.

Sediba is an astonishing hominid whose extremely well-preserved fossils were discovered in a cave in Malapa, 40 km from Johannesburg (South Africa).

The species, reconstructed from a fossil, could be situated between the australopithecines and the Homo genus. Australopithecus Sediba has both a set of primitive and very modern properties.

The Australopithecines lived on the African continent 4.2 to 2.5 million years ago, while the first representatives of the Homo genus discovered in East Africa lived 2 million years ago. Sediba lived approximately 1.95 to 1.78 million years ago in South Africa.

Is Sediba on the Human Lineage?

The numerous fossil bones belong to a young individual (MH1) aged 12, named "Karabo", and a female (MH2) in her twenties. While the excavations of the Malapa Cave are not yet complete, the 2013 fossils are the richest ever obtained from a hominid species.

Australopithecus Sediba has a small brain of 420 cm³, typical of australopithecines. Comparisons of fossils between Australopithecus sediba, Australopithecus africanus, Australopithecus afarensis, Homo habilis, and Homo erectus show that Sediba is closer to Australopithecus africanus than to Australopithecus Afarensis, which includes the famous Lucy.

Sediba shows shoulder dexterity similar to that of apes, with arms still adapted for hanging from branches and thus climbing trees, but its hand with an opposable thumb is less curved than that of the chimpanzee. Its long, slender fingers indicate an evolution towards the human hand, capable of shaping tools. The female's ankle is quite modern, while the heel bone is more primitive than that of Australopithecus afarensis, which is at least a million years older.

In summary, it is not very clear which species to assign it to, likely Australopithecus africanus (2.5 to 3.5 million years ago) due to some of its properties (length of upper limbs, small brain, primitive heel bone, small body size, shapes of molars and cheekbones). Researchers face the same difficulty in defining Sediba when analyzing the lower part of the skeleton. The pelvis and legs, with long and straight bones, are adapted for bipedalism, but the feet are much more primitive, with a ground support very different from that of 'habilis and erectus'. Another species between man and apes that lived two million years ago.

N.B.: The genus Australopithecus (from Latin australis "southern" and Greek píthēkos "ape") was defined by the anthropologist Raymond Dart (1893-1988) upon the discovery of Australopithecus africanus in 1924. Sediba means "well" or "source" in Southern Sotho, a language spoken in southern Africa.

The Malapa Caves: Cradle of Humanity

The answer may still be hidden in the depths of the Malapa Cave, 40 km from Johannesburg (South Africa). Lee Berger believes that the Malapa cradle could hold the key to one of the most important chapters in the history of human evolution. The origin of the first humans, the Homo genus, may have started there.

The Malapa site is an eroded limestone cave located in a region already famous for its ancient human fossil discoveries, which is why it is often considered the cradle of humanity. Much of this reputation is based on findings from the early 1900s when South Africa held the best evidence of early human evolution, including Australopithecus africanus, our oldest known ancestor. Since then, many fossils have been discovered throughout Africa, particularly in Tanzania, Kenya, and of course, Ethiopia, the site of the famous Lucy, who is 3.2 million years old.

While anthropology is known for its controversial nature, no one disputes that the Malapa fossils are unprecedented and the richest ever obtained from a hominid species. The abundance and spectacular condition of the fossils have much to do with the unique geography of the site. Malapa was both a life-giving water source and a deadly trap.

Two million years ago, these aquifer caves were in a hilly plain with wooded hills. Some of these caves were open to the surface via vertical shafts 50 meters deep. During wet periods, when the water table was high, animals could easily drink, but during dry periods, they ventured into the darkness, attracted by the smell or sound of water, risking a fatal fall into one of the hidden shafts. The upper arm bone of Karabo, the boy, shows fractures typical of a fall from a great height.