Australopithecus sediba ("sediba" means fountain or wellspring in seSotho) is a recently discovered hominin (ancient human ancestor). Two well-preserved examples of Au. sediba were recovered from Malapa Cave, a dolomite cave in the Cradle of Humankind archaeological site in Guateng province near Johannesburg, South Africa. Dated using paleomagnetic and Uranium-lead techniques on flowstone and underlying sediments to 1.977 million years ago, Au. sediba is considered by some scholars to be directly ancestral to early modern humans.
Two examples of Au. sediba were recovered from sediments in-filling Malapa Cave. MH1 is a juvenile male, represented by a partial cranium (seen in the image above), a fragmentary mandible and part of the post-cranial skeleton including right leg, right arm and pelvis. Based on comparisons with modern apes and humans, he is estimated to have died at approximately 12-13 years of age. MH 2 is an adult female, represented by isolated maxillary teeth, a partial mandible and partial post-cranial skeletal remains including right leg, right arm and pelvis.
Dates reported in April 2010 placed Au. sediba within a range of 1.78-1.95 million years ago (mya), on the basis of faunal correlation, Uranium-Lead dating and paleomagnetic data. In September of 2011, a scientific team working on the hominin reported a firm date of 1.977 mya, making Au. sediba one of the oldest found in Africa to date.
Au. sediba has a small body, in comparison to H. erectus, for example, with long upper limbs, large joint surfaces and somewhat primitive limb structures. They were fully bipedal. The two hominins recovered from Malapa Cave are currently classed as Australopithecines, because their brain case is relatively small, and their arms are long for their bodies, in comparison to traditional human ancestors in the Homo group. But scholars researching Au. sediba argue that the evidence from Malapa Cave suggest a reworking of our hominid classifications may be in order.
But is it the Oldest?
Au. sediba is not the oldest hominid found to date. The Au. afarensis called Lucy is from 3.2 mya and the one called Selam from 3.4; Au. amanuensis is from 3.9-4.2 mya; Ardipithecus ramidus from 4.4 mya, and Sahelanthropus at Toumai from 6-7 mya. Au. sediba is older than almost all Homo erectus and Homo habilis found to date, except for Hadar, which is somewhat controversial but dates to 2.3 mya.
Sources
This photo essay report provides information about the context and various skeletal elements from Au. sediba. It is a part of the About.com guide to Lower Paleolithic , and the Dictionary of Archaeology.
Berger LR, De Ruiter DJ, Churchill SE, Schmid P, Carlson KJ, Dirks PHGM, and Kibii JM. 2010. Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. Science 238:195-204.
Dirks PHGM, Kibii JM, Kuhn BF, Steininger C, Churchill SE, Kramers JD, Pickering R, Farber DL, Meriaux A-S, Herries AIR et al. 2010. Geological Setting and Age of Australopithecus sediba from Southern Africa. Science 238 205-208.
