A new species of Australopithecus discovered in S. Africa
And......
THE two-million-year-old skeletal remains of a juvenile male and an adult female, discovered in a South African cave, may be those of the direct ancestors of the first humans to walk the earth. The claim -- from an international team led by James Cook University geologist Paul Dirks and Lee Berger, a paleoanthropologist at Johannesburg's Witwatersrand University -- is a big one.
The newfound species has been named Australopithecus sediba, a blend of the established Latin term for "southern ape" and the word for "wellspring" in the SeSotho language.
What sets Au sediba apart from previous early ancestral humans is the fact that the bipedal hominin shares a mix of primitive features common to the ape-like Australopithecines and to more advanced proto-humans such as "handy man" Homo habalis , and "upright man" Homo erectus.
"These fossils give us an extraordinarily detailed look into a new chapter of human evolution and provide a window into a critical period when (hominins) made the committed change from dependency on life in the trees to life on the ground," Professor Berger said.
In two reports published overnight in the journal Science, Professor Dirks, Professor Berger and their colleagues report that the fossils were found close together in cave deposits at Malapa, South Africa, along with the remains of up to 25 animals, among them a sabre-toothed cat, a horse, a hyena, an ancient pig and rabbits.
The two partial skeletons include most of a skull, teeth, pelvis and ankle of the new species.
The researchers found, but have not yet analysed, the bones of at least two other individuals, including an infant and another adult female. Those fossils were also embedded in cave sediment.
William Jungers, head of anatomical sciences at New York State's Stony Brook University Medical Centre, said: "Great new fossils, fabulous preservation, and with associated craniodental and postcranial elements -- it doesn't get much better than that."
But along with all the experts The Australian contacted, Professor Jungers -- an expert in locomotion skills of hominins like "Lucy", a 3.5 million-year-old Australopithecus afarensis, and the hobbit Homo floresiensis, the puzzling hominin found by Australian and Indonesian experts in a cave on the Indonesian island of Flores in 2003 -- is sceptical of the claim that Au sediba is the direct ancestor of all members of the human family's genus, or group, Homo.
By the time the new hominin lived, 1.95 million to 1.78 million years ago, members of the Homo clan had been around for at least half a million years in east Africa.
And ancestral humans such as H. erectus and Homo ergaster had left Africa, arriving in eastern Europe and western Asia at least 1.8 million years ago.
"Fundamentally, this is just another wonderful australopith," Professor Jungers said.
Peter Brown, the University of New England paleoanthropologist who first analysed the hobbit remains, said working out where this australopithecine fits in the family tree would not be easy.
"Between five million and two million years ago, our ancestor evolved into something we would recognise as increasingly human, both in appearance and behaviour," he said. "Unfortunately, while there are hundreds of hominin fossils, particularly from south and east Africa, from this time period, preservation is poor."
That's frustrating for experts such as Professor Brown, since it makes it difficult to work out the processes driving the emergence of the behavioural and biological traits that distinguish humans from other primates such as chimpanzees and gorillas -- in particular, modern humanity's gait, reproductive strategy, growth rate and big brain.
Professor Brown is optimistic the newfound fossils will help put together some of the pieces of the evolutionary puzzle. "But the fragmentary and geographically dispersed nature of the hominin fossil record makes picking the winners and losers in the evolutionary lottery difficult," he said.
Au sediba could easily be an evolutionary dead end.
Professors Dirks and Berger and colleagues acknowledged this in their report.
"The possibility that A sediba split from A africanus before the earliest appearance of Homo cannot be discounted," they wrote.
There's another difficulty with the team's earliest-ancestor claim, one that will only be resolved with the discovery and analysis of more Au sediba remains.
As University of California, Berkeley, paleoanthropologist Tim White told Science, the characteristics shared by Au sediba and Homo could be due to normal variation among australopithecines or because of the young male's juvenile status.
Professor White said of Au sediba: "Given its late age and Australopithecus-grade anatomy, it contributes little to the understanding of the origins of the genus Homo."
Paleoanthropologist Matthew Tocheri of the Human Origins Program at the Smithsonian's National Museum of Natural History in Washington agreed.
"It remains to be seen which presently known -- that is Au afarensis or Au africanus -- or perhaps yet-to-be-discovered hominin is the last common ancestor of the genus Homo," he said.
Sorting that out won't be a straightforward process of finding lots of new fossils and deciding which ancient species looked more like us than another.
For instance, like Professor Jungers, Dr Tocheri has studied the hobbit. He noted there were resemblances between it and Au sediba, among them a small brain size and similar limbs.
"But since these shared primitive characteristics have been in the hominin lineage for a long time, more than three million years, they do not provide the necessary information about which later hominins are more closely related to each other," Dr Tocheri said.
So as with every discovery in human evolution, they not only add new clues, they toss up new questions.
Understanding of the human journey was complicated last March when a group led by evolutionary geneticist Savante Paabo of Germany's Max Planck Institute in Leipzig announced it had genetic evidence that a previously unknown species -- nicknamed X woman -- lived at the same time as modern people and neanderthals, sharing a common ancestor with both species.
Mike Morwood, a University of Wollongong archeologist and co-leader of the hobbit discovery team, said that along with the hobbit, X woman was further evidence that humanity's family tree was really a family bush.
Speaking of the age when australopithecines and early Homo species lived, he said: "This was obviously a period of evolutionary ferment for hominins, and the time when the ancestors of H. floresiense probably dispersed out of Africa."
That fits neatly with what evolutionary biologists know of the emergence of species generally. Nature tosses up a variety of experiments. Some win, some lose. The winners evolve into another species, the losers become extinct.
The question is, what was Au sediba: late surviving australopithecine, late surviving member of a species that earlier gave rise to Homo, or oddball Homo?
Professor Brown's answer: "As in most matters to do with interpretation of the hominin fossil record, history will be the judge."
Source:
http://www.theaustralian.com.au/news...-1225851589086
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Scientists come face to face with 2 million-year-old 'missing link'
HE WAS less than 13 years old when he met a sudden death, apparently plummeting tens of metres into a deep cave in southern Africa.
There he lay for almost two million years, until a nine-year-old boy searching for fossils with his archaeologist father spotted a piece of human-like collar bone.
The unearthing of the ancient child's skull and skeletal remains, and those nearby of an older female - perhaps his mother - is being hailed as one of the most significant discoveries in human archaeology and one that could rewrite our evolutionary past.
Revealed today, the African fossils represent a new species of early human ancestor that could be a missing link, or ''transitional'' species, between ape-men and the first members of the human family.
They had a small brain, long arms like an ape and short powerful hands. But they also had small teeth and walked upright, with long legs capable of striding, and possibly running, like a human.
The find follows the discovery last month of a new human species that lived in Siberia 40,000 years ago dubbed X-woman.
Lee Berger, of the University of Witwatersrand in Johannesburg, who found the extremely well-preserved fossils with the help of his son, Matthew, said they provided a window into a critical period when early human ancestors moved down from the trees to a life on the ground.
Their physical features suggest they were ''comfortable in both worlds'', he said.
The two partial skeletons - the most complete by far from this period - were dated to between 1.78 and 1.95 million years old by an international team including researchers from three Australian universities.
''It's an absolutely staggering find,'' said team member and dating expert, Andy Herries, of the University of NSW.
Paul Dirks, of James Cook University, a co-leader of the project, said his team's research suggests the female, who was in her late 20s or early 30s, had fallen into the cave about the same time as the boy.
''The timing of their deaths were closely related,'' he said.
The new species, found at Malapa, about 40 kilometres from Johannesburg in the Cradle of Humankind World Heritage Site, and reported in the journal Science, has been named Australopithecus sediba.
Australopithecus means southern ape, and sediba means fountain or wellspring in Sotho, a South African language.
''Sediba was deemed an appropriate name for a species that might be the point from which the genus Homo arises,'' Professor Berger said.
''I believe this is a good candidate for being the transitional species between the southern African ape-man, Australopithecus africanus, and either Homo habilis, or even a direct ancestor of Homo erectus.''
However, scientific debate about where the new species fits on the family tree has already begun.
Colin Groves, of the Australian National University, said it was a ''magnificent discovery'', but the new species was not an Australopithecine as claimed.
Rather, it was probably a sister species to Homo habilis that lived in Africa at that time, Professor Groves said.
While most scientists believe early humans evolved from Australopithecines about 2 million years ago, the fossils from this time period are so few they would fit onto a small table, Professor Berger said.
''With the discovery of Australopithecus sediba and the wealth of fossils we've recovered - and are recovering - that has changed dramatically.''
He said the skeletons are thought to be so well preserved because the two ancient humans fell into a cave, perhaps 50 metres deep, where they lay for a few days or weeks, free from scavengers.
Their relatively intact bodies were then washed into an underground pool, where they were solidified ''as if thrown into quick-setting concrete''.
Professor Berger said it was likely the two knew each other in life and could have been related.
About 130 caves and 20 fossil deposits had been identified in the area before Professor Berger and Professor Dirks began searching it using Google Earth at the start of 2008.
They uncovered almost 500 more caves and more than 25 new fossil sites, including the small pit where the new species was found in August that year.
Dr Herries said it had been impossible until recently to precisely date South African cave sites. Several new techniques were used in this case, including his specialty, palaeomagnetism - the effect of changes in the Earth's magnetic field on the alignment of minerals.
Darren Curnoe, of the University of NSW, said the fossil discovery was ''rare and truly amazing'', but ''surrounded by hype and over-interpretation in terms of its significance''.
Dr Curnoe said: ''It is way too primitive to be the ancestor of the human genus, Homo, one of our direct ancestors.''
Dr Herries said different interpretations of the fossils were expected. ''I think it will end up being hugely debated.''
The child's brain was a third to a quarter the size of a human's, but its shape was more advanced than that of Australopithecines.
VIDEO IS INSIDE THE SOURCE LINK
Source: http://www.smh.com.au/world/science/...ml?autostart=1
Clips can be found here:South African fossils could be new hominid species
The remarkable remains of two ancient human-like creatures (hominids) have been found in South Africa.
The fossils of a female adult and a juvenile male - perhaps mother and son - are just under two million years old.
They were uncovered in cave deposits at Malapa not far from Johannesburg.
Researchers tell the journal Science that the creatures fill an important gap between older hominids and the group of more modern species known as Homo, which includes our own kind.
The team has assigned the name Australopithecus sediba to their finds.
"It's at the point where we transition from an ape that walks on two legs to, effectively, us," lead scientist Professor Lee Berger of the University of the Witwatersrand told BBC News.
"I think that probably everyone is aware that this period of time - that period between 1.8 and just over two million years [ago] - is one of the most poorly represented in the entire early hominid fossil record. You're talking about a very small, very fragmentary record," he explained.
Rapid burial
Many scientists regard the Australopithecines as being directly ancestral to Homo but the precise placement of A. sediba in the human family tree is already proving controversial, with some scientists arguing the species may well be a Homo itself.
The Malapa creatures lived right on the cusp of the emergence of Homo species. Indeed, there are some fossils from East Africa thought to be Homo that are slightly older than the new specimens.
A. sediba has a fascinating mix of features - some archaic, some modern.
Its small teeth, projecting nose, very advanced pelvis, and long legs throw forward to more modern forms. And yet its very long arms and small brain case might echo the much older Australopithecine group to which Professor Berger and colleagues have assigned it.
The Malapa fossils were unearthed in the famous Cradle of Humankind World Heritage Site, which has yielded many fine fossils down the years.
They were pulled from a pit - what is left of a cave complex that has lost its roof through erosion over time.
The bones were located within a metre or so of each other, suggesting they died at the same time or very soon after one another. It is entirely possible they were mother and son, says Professor Berger's group. At the very least, it seem reasonable to assume they knew each other and belonged to the same troupe, the team adds.
The scientists speculate the creatures either fell into the cave complex or became stuck in it. It is likely their bodies were then swept into an underground lake or pool, perhaps during a rainstorm.
Their bones were laid down with the remains of other dead animals, including a sabre-toothed cat, antelope, mice and rabbits. The fact that none of the bodies appear to have been scavenged indicates that all died suddenly and were entombed rapidly.
"We think that there must have been some sort of calamity taking place at the time that caused all of these fossils to come down together into the cave where they got trapped and ultimately buried," said team-member Professor Paul Dirks from James Cook University in Queensland, Australia.
All were preserved in the hard calcified clastic sediment that formed at the bottom of a pool of water.
A view across the Cradle of Humankind landscape
Vigorous debate about the significance of finds in the field of palaeoanthropology is common, and A. sediba has already generated much comment within the scientific community.
Professor Colin Groves, from the Australian National University, said his assessment of the Malapa hominids led him to conclude that they were actually a new species of Homo, not Australopithecus.
"In fact, the authors themselves pointed to certain similarities with early Homo, seeming even to admit that the predominance of its features were with Homo, only the small cranial capacity being really an "australopithecine" feature," he commented.
"But we now know of [the Indonesian 'Hobbit' species] Homo floresiensis with the cranial capacity more or less the same as the new species."
Paul Dirks stands in the Malapa pit that was once a deep cave complex
The richness of the fossil finds means the Malapa cave complex is likely to keep scientists busy for many years.
In addition to the two hominids reported in the journal Science, the remains of two further individuals are in the process of excavation.
The site was found by the team thanks to the "virtual globe" software Google Earth, which allowed the group to map and visualise the most promising fossil grounds in the World Heritage Site.
The first discovery of A. sediba remains was made in August 2008. The very first bone was picked up by Professor Berger's nine-year-old son, Matthew.
"I turned the rock over and I saw the clavicle sticking out - that's the collar bone. I didn't know what it was at first; I thought it was just an antelope," the youngster told BBC News.
"So I called my dad over and about five metres away he started swearing, and I was like 'what did I do wrong?' and he's like, 'nothing, nothing - you found a hominid'."
The scientists say they will hold a competition in South Africa to give the juvenile specimen a name, to help people identify better with the species, just as they can with the 3.2-million-year-old Australopithecus afarensis creature found in Ethiopia and known to the world simply as "Lucy".
The name "sediba" means "fountain" or "wellspring" in the Sesotho language spoken in South Africa
Source: http://news.bbc.co.uk/2/hi/science/nature/8609192.stm
http://news.bbc.co.uk/2/hi/science/nature/8609192.stm
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http://www.smh.com.au/world/science/...ml?autostart=1
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