Early human ancestor didn't have a strong jaw

Australopithecus sediba is a species of the Australopithecus of the early Pleistocene era. In 2012, a team of scientists had suggested that Australopithecus sediba subsisted mostly on hard foods which include tree barks, nuts, and fruits.

However new studies conducted by a team of researchers which included Professors Lee Berger and Kristian Carlson from the ‘Evolutionary Studies Institute (ESI)’ at the University of the Witwatersrand have revealed that Australopithecus sediba did not possess the jaw and the tooth architecture to subsist on a steady diet of hard food.

Professor David Strait, an anthropologist at Washington University in St. Louis, US reveals that australopiths had jaws, teeth, and faces which were adapted for processing food which is difficult to be chewed or crack opened. They were able to bit food with considerable force.

Co-author Dr. Justin Ledogar, who is a researcher at the University of New England in Australia, however, feels that Australopithecus sediba could be seen as closer to the ancestors of Homo, the group humans belong yet A.sediba did not have the ability to bite hard using its molar teeth.

Australopithecus sediba lived some two million years ago in southern Africa and had been pushed as a possible ancestor of Homo.

Australopiths were seen in the fossil record about four million years ago, and although they do have some human characteristics like walking on their hind legs, they lack other individual features like a large brain, small flat faces with small jaws and teeth.

Although the new study does not confirm that Australopithecus sediba is indeed a close relative of early Homo, it does hint that dietary changes shaped the paths of evolution at the beginning of humans.

Ledogar adds that humans have the drawback of not being able to bite forcefully and this drawback must have been present in previous humans also.

It means that australopith populations evolved in two directions- one evolving to maximize their capability to bite strongly, another group including A. sediba were growing in the opposite direction, and some of these ultimately gave rise to Homo.