Many of you probably followed the discovery of a new species of Australopithecus, very likely a human ancestor, in 2010. The new species was called Australopithecus sediba. Two research articles published in Science magazine in April 2010 described a new species of Australopithecus dating from around 1.9 million years ago that casts new light on the evolution of the genus Homo. The discovery was so exciting that Science has a special feature, free to the public, on this discovery, that can be accessed here. The papers described bone fragments, including skull pieces from 2 specimens found in the Malapa cave, north of Johannesburg. The fossils have a mix of primitive features typical of australopithecines and more advanced characteristics typical of later humans. Thus, the team says, the new species may be the best candidate yet for the immediate ancestor of our genus, Homo. The claim is a big one and not all scientists agree with it, but the specimens are no doubt remarkable, look at this skull in the figure to you right! It is not too often that scientists come across 2 million year old specimens of potential human ancestors that are so well preserved.
On April 16 , 2011 (last Saturday) at a meeting of the American Association of Physical Anthropologists, more evidence from two new specimens of A. sediba ("sediba" means "wellspring" in the Sesotho language) has been presented that seems to indicate that the fossils should perhaps be classified our own genus, the genus Homo.
From ScienceNOW: In addition to the articulated partial skeletons of a youth and an older female unveiled last year in Science, the team members reported the discovery of bones of an 18-month-old infant and at least one other adult. This means they are getting a good look at Au. sediba’s development from infancy to old age. “It is going to be a remarkable record,” Berger [one of the main paleontologists in the study] said. “And we still haven’t found everything!”
The findings are exciting but the classification of the fossils is still controversial. The fossils show some surprisingly modern traits usually found only in members of our own genus. Two pelvises, in particular, are elongated and look quite Homo-like. Other modern traits include smaller teeth, short fingers, and an elongated thumb.
From Wired (and admire the amazing cranium in the photo):
It’s now clear that A. sediba shares more skeletal features with early Homo specimens than any other known Australopithecus species does, said Darryl de Ruiter of Texas A&M University in College Station. “We think A. sediba is a possible candidate ancestor for the genus Homo.” De Ruiter suspects that an isolated population of the hominid species Australopithecus africanus gradually evolved into A. sediba, resulting in a species characterized by an unusual mix of skeletal traits, some typical of Australopithecus in general and others of early Homo. That scenario, outlined in symposium presentations by De Ruiter and Lee Berger of the University of the Witwatersrand in Johannesburg, South Africa, remains controversial despite the new fossil discoveries. Ian Tattersall of the American Museum of Natural History in New York City endorsed A. sediba as a distinct species, probably closely related to A. africanus. “I wouldn’t classify it as the root of the Homo genus, though,” he commented.
As more fossils with transitional features continue to be be discovered, the picture of human evolution will become more and more clear; this of course, will have no bearing on the minds of creationists or intelligent designers who continue to deny that we indeed evolved from ape-like ancestors.
These five papers are getting A LOT of attention. From the BBC (check out that fabulous hand skeleton!):
The ancient remains of two human-like creatures found in South Africa could change the way we view our origins.
The 1.9-million-year-old fossils were first described in 2010, and given the species name Australopithecus sediba.
But the team behind the discovery has now come back with a deeper analysis.
It tells Science magazine that features seen in the brain, feet, hands and pelvis of A. sediba all suggest this species was on the direct evolutionary line to us - Homo sapiens.
"We have examined the critical areas of anatomy that have been used consistently for identifying the uniqueness of human beings," said Professor Lee Berger from the University of the Witwatersrand in Johannesburg
"Any one of these features could have evolved separately, but it is highly unlikely that all of them would have evolved together if A. sediba was not related to our lineage," the team leader informed BBC News.
It is a big claim and, if correct, would sideline other candidates in the fossil record for which similar assertions have been made in the past.
Theory holds that modern humans can trace a line back to a creature known as Homo erectus which lived more than a million years ago. This animal, according to many palaeoanthropologists, may in turn have had its origins in more primitive hominins, as they are known, such as Homo habilis or Homo rudolfensis.
The contention now made for A. sediba is that, although older than its "rivals", some of its anatomy and capabilities were more advanced than these younger forms. Put simply, it is a more credible ancestor for H. erectus, Berger's team claims.
The sediba specimens were unearthed at Malapa in the famous Cradle of Humankind World Heritage Site, just to the northwest of Jo'burg.
They were pulled from a pit - a depression left in the ground by a cave complex that had lost its roof through erosion over time.
Identified as an adult female and a juvenile male, the two individuals were quite possibly mother and son. What seems certain is that they died together in some tragic accident that saw them either fall into the cave complex or become stuck in it. After death, their bodies were washed into a pool and cemented in time along with the remains of many other animals that got trapped in the same way.
Glad you liked it!It's very exciting, like all paleoanthroplogist fights :-))
More on this story, a very good blog from Anthropology in Practice:
September 9, 2011 |
Few things remain as mysterious—or controversial—as our own history as a species. However, a series of papers released today in Science may add another piece to the puzzle: Four papers draw back the curtain on Australopithecus sediba, announced earlier this year, detailing morphological features of the hand, foot, pelvis, and skull that may establish this species within the ancestral lineage of modern humans.
In a subterranean cave at Malapa, South Africa, approximately 25 miles (40km) from Johannesburg, the remains of numerous hominins identified as Australopithecus sediba have lain between layers of flowstone—a type of rock that forms in caves, similar in composition to stalagmites and stalactites, except as the name implies, this rock forms in a layer that “flows” across the surface. Flowstone is rich in uranium, which decays into lead. By measuring the amount of uranium and lead present in the stone, scientists were able to date the flowstone to between 1.977 and 1.98 million years ago. This date has been applied to the fossils themselves (which are too old to be directly dated), making them older than the oldest known fossils of the genus Homo (1.90 Ma).
But what makes the fossils curious is their unique blend of traits. The foot and ankle, for example, suggest that Au. sediba was certainly bipedal, but it had not completely given up its arboreal tendencies. Au. sediba has a rudimentary arch and evidence indicates that it may have possessed an Achilles tendon which would have aided in bipedalism but its ape-like heel would have been poor at absorbing weight from walking or running. The ankle demonstrates less flexibility than that of apes, but more than is possible for the modern human foot. These elements in combination lead researchers to suggest that Au. sediba may have been unique in both its climbing and walking styles.
Read the rest here.
That has an easy answer: because they are fucking dumb because are blinded by faith :-)