Australopithecus Sediba

clip_image003Australopithecus Sediba is the name of possibly oldest direct ancestor of humans that is 1.98 million years. Australopithecus Sediba (Sediba means "well" in Soho language) was found by South African palaeo-anthropologist Lee R. Berger in Malapa Fossil Site at the Cradle of Humankind World Heritage Site in South Africa. Its. This discovery has made Malapa site one of the best dated early human sites in the world. The fossil of Australopithecus Sediba was of a male juvenile called MH 1 and the discovery was hailed as most exciting find since Lucy. In a contest to name this juvenile male, a californian student won the content to name it as Karabo.

Age of Australopithecus sediba

  • Whereas original estimates had put the age of the remains at somewhere between 1.78 and 1.95 million years old, the new analysis has narrowed this window of uncertainty to just 3,000 years. The new age is now between 1.977 and 1.98 million years old.
  • This is the time in human evolution which should be seeing the beginnings of our genus, Homo. Until now, fossils dated to 1.9 million years ago — and mostly attributed to Homo habilis and Homo rudolfensis — have been considered ancestral to Homo erectus, the earliest undisputed human ancestor.
  • Au. sediba hit headlines last year after a scientist’s nineyear-old son found the partial skeleton of a 60-pound 10 to 13-year-old male at a site Malapa.

Brain of Australopithecus sediba

  • As per the high-resolution X-ray scan of the male specimen’s skull, A. sediba‘s brain to have been about 440 cubic centimetres in volume, or about the size of a medium grapefruit.
  • This is smaller than much older fossils in the record such as the famous "Lucy" specimen, Australopithecus afarensis (3.2 million years), but, intriguingly, the shape is more human-like, especially at the front. This may hint at the start of the re-organisation of the brain that would be necessary to make us what we are today.

Pelvis:

  • The Pelvis of Australopithecus sediba is short and broad like a human pelvis.
  • It has been theoretically hypothesized that modern human pelvis evolved in tandem with the gradual growth in brain volume – facilitating the birth of babies with bigger heads.
  • But, A. sediba gives the lie to this theory because it had a modern-looking pelvis while possessing a small brain.

Hands:

  • The hands look far more like a modern human hand than an ape hand. Its fingers are shorter relative to the thumb than in a chimpanzee.
  • And yet, it appears to have possessed powerful muscles for grasping, suggesting A. sediba spent a lot of time clambering through the branches of trees.
  • The team also argues that the dexterity would have been there to make simple tools.

Foot:

  • The ankle joint is mostly human-like in form and there is some evidence for a human-like arch and Achilles tendon.
  • But A. sediba possessed an ape-like heel and lower tibia, or shin bone.
  • The scientists think this combination may have led to a distinctive type of walk when the creature was not climbing in trees.
Credits:
  • Text inputs from BBC Science News
  • Image Graphic: nationalgeographic.com

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