A new hominid species: Australopithecus Sediba

According to a new study published in Science, two fossil skeletons dating back to almost 2 million years ago and discovered the site of Malapa (South Africa) would be a new species of Australopithecus.

It has been dubbed Australopithecus Sediba and would be a transitional form between the 'Australopithecus africanus (Australopithecus) and' Homo habilis and Homo erectus or later (genus Homo, our own). is therefore NOT the famous missing link nor its researchers the describe in this way.

Lee Berger and his son Matthew and dog Tau, Malapa site where the fossils were found (Benedicte Kurzen for The New York Times)

"We have never seen this combination of features in any other [early humans]," says study author Lee Berger , University of the Witwatersrand in Johannesburg.

Found in a network of underground caves, the skeletal remains of Australopithecus Sediba roughly belonged to a woman of 30 years and a child of 8-13 years 1.27 meters high.

The skull of the child (Brett Eloff)

(Brett Eloff)

(Berger et al, 2010)

The couple - do not know if related in some way - apparently fell into a chasm (30-46 meters in the drawing below, under "Death Trap") in which were found remains of saber-toothed tigers and other predators.

Using a metaphor, the new species could be the "source" (wellspring, or, in the local tribal language Sotho, "Sediba") from which our ancestors originated.

Berger suggests another: "It is my opinion and that of my colleagues [l 'Australopithecus Sediba] may be the Rosetta stone that opens our knowledge of the genus Homo."

(Dirks et al, 2010)

The 'Australopithecus Sediba fact has some key features typical of a primitive man as the' Homo habilis (according to many, the first human species), that other species of Australopithecus were not.

For example, has long legs and pelvis in certain characteristics similar to those of the man who would make him the first human ancestor to walk - perhaps even to run - in an energy efficient manner (the remains of the femur and tibia are but fragmentary , and the foot is more primitive).

He was then a small teeth and a nose "modern", so to speak, other than that of chimpanzees.

Even the shapes of the two hemispheres of the brain - perceptible thanks to the "grooves" (indentations) on the left well-preserved skull - share peculiarities of human beings.

There are other features that bring the species to be included in the genus Australopithecus - and not in the genus Homo (both genera belong to the subfamily of Homininae and the family Hominidae, or hominids, see here ).

Like the other australopithecines (a term that includes Australopithecus and Paranthropus), the 'Australopithecus Sediba had a very small brain. The fossil species also had long arms similar to those of primitive apes with cuffs adapted for climbing trees.

The cave Uitkomst, near where the fossils were found (Paul Dirk)

Not all experts agree, however, the new species a transition between prehistoric apes and humans, as suggested by the study.

"I do not think we have conclusive evidence to suggest that [the 'Australopithecus Sediba] lies between the' Australopithecus and 'Homo," said anthropologist Bernard Wood of George Washington University. "It does not correspond to what our preconceptions about what they say would have been the ancestor of 'Homo".

For example, the arms of 'Australopithecus Sediba are too long - too similar to those of apes - and the species is not very well adapted to walking upright, as some scientists would expect him to be a direct ancestor of early humans.

Moreover, being dated at 1.95 - 1.78 million years ago, the fossils are not old enough to represent an ancestor of 'Homo, says anthropologist Brian Richmond , also of George Washington University.

The first members of the genus Homo are in fact much older fossils of Homo habilis are dated at 2.3 million years ago.

The anthropologist William Kimbel think this chronological conundrum can be solved by calling these new fossil Homo rather than Australopithecus: "Calling it Australopithecus and saying that it is ancestral to 'Homo, [ask yourself] as [reconcile] with the first Homo species. If [instead] you put it in the [gender] Homo, the problem vanishes. Then [became] one of several species (yes, but what then?) Of about two million years ago that are close to the base of the Homo lineage. "

Kimbel also agree with Susan Anton , an anthropologist at the University of New York, and joint editor of the Journal of Human Evolution.

So far, 130 bone fragments were recovered (Berger)

Berger replies that 's belongs to Australopithecus Sediba' Australopithecus because its anatomy suggests that even climbed up the trees. "He did not do that [change in level] to the genus Homo," he says.

About dating, Berger thinks that future discoveries may backdate the 'Australopithecus Sediba of hundreds of thousands of years - enough to make an ancestor of the first Homo species.

"This site [of discovery] is just one point in time. Is not the first appearance of this species, nor probably the last, "says Berger.

(New York Times)

Beyond the location to be given to these fossil human family tree, their importance lies in the fact that he even pose questions.

The paleontologist at Case Western Reserve University in Cleveland (Ohio), Scott Simpson , concludes: "This fossil is not responding to any specific questions. What it does is reinforce the idea that we have not even done all the right questions. "

http://ilfattostorico.com/2010/04/09/una-nuova-specie-ominide-laustralopithecus-sediba/

http://www.sciencemag.org/cgi/content/abstract/328/5975/195

http://www.sciencemag.org/extra/sediba/

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