Absolutely fantastic! The find of the century, even greater than Dmanisi! :o
Tons of great pictures here
http://news.nationalgeographic.com/2015/09/150910-human-evolution-change/
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This Face Changes the Human Story. But How?
Scientists have discovered a new species of human ancestor deep in a South African cave, adding a baffling new branch to the family tree.
By Jamie Shreeve, National Geographic
Photographs by Robert Clark
PUBLISHED September 10, 2015
A trove of bones hidden deep within a South African cave represents a new species of human ancestor, scientists announced Thursday in the journal eLife. Homo naledi, as they call it, appears very primitive in some respects—it had a tiny brain, for instance, and apelike shoulders for climbing. But in other ways it looks remarkably like modern humans. When did it live? Where does it fit in the human family tree? And how did its bones get into the deepest hidden chamber of the cave—could such a primitive creature have been disposing of its dead intentionally?
This is the story of one of the greatest fossil discoveries of the past half century, and of what it might mean for our understanding of human evolution.
Two years ago, a pair of recreational cavers entered a cave called Rising Star, some 30 miles northwest of Johannesburg. Rising Star has been a popular draw for cavers since the 1960s, and its filigree of channels and caverns is well mapped. Steven Tucker and Rick Hunter were hoping to find some less trodden passage.
In the back of their minds was another mission. In the first half of the 20th century, this region of South Africa produced so many fossils of our early ancestors that it later became known as the Cradle of Humankind. Though the heyday of fossil hunting there was long past, the cavers knew that a scientist in Johannesburg was looking for bones. The odds of happening upon something were remote. But you never know.
Deep in the cave, Tucker and Hunter worked their way through a constriction called Superman's Crawl—because most people can fit through only by holding one arm tightly against the body and extending the other above the head, like the Man of Steel in flight. Crossing a large chamber, they climbed a jagged wall of rock called the Dragon's Back. At the top they found themselves in a pretty little cavity decorated with stalactites. Hunter got out his video camera, and to remove himself from the frame, Tucker eased himself into a fissure in the cave floor. His foot found a finger of rock, then another below it, then—empty space. Dropping down, he found himself in a narrow, vertical chute, in some places less than eight inches wide. He called to Hunter to follow him. Both men have hyper-slender frames, all bone and wiry muscle. Had their torsos been just a little bigger, they would not have fit in the chute, and what is arguably the most astonishing human fossil discovery in half a century—and undoubtedly the most perplexing—would not have occurred.
After Lucy, a Mystery
Lee Berger, the paleoanthropologist who had asked cavers to keep an eye out for fossils, is a big-boned American with a high forehead, a flushed face, and cheeks that flare out broadly when he smiles, which is a lot of the time. His unquenchable optimism has proved essential to his professional life. By the early 1990s, when Berger got a job at the University of the Witwatersrand ("Wits") and had begun to hunt for fossils, the spotlight in human evolution had long since shifted to the Great Rift Valley of East Africa.
Most researchers regarded South Africa as an interesting sidebar to the story of human evolution but not the main plot. Berger was determined to prove them wrong. But for almost 20 years, the relatively insignificant finds he made seemed only to underscore how little South Africa had left to offer.
What he most wanted to find were fossils that could shed light on the primary outstanding mystery in human evolution: the origin of our genus, Homo, between two million and three million years ago. On the far side of that divide are the apelike australopithecines, epitomized by Australopithecus afarensis and its most famous representative, Lucy, a skeleton discovered in Ethiopia in 1974. On the near side is Homo erectus, a tool-wielding, fire-making, globe-trotting species with a big brain and body proportions much like ours. Within that murky million-year gap, a bipedal animal was transformed into a nascent human being, a creature not just adapted to its environment but able to apply its mind to master it. How did that revolution happen?
The fossil record is frustratingly ambiguous. Slightly older than H. erectus is a species called Homo habilis, or "handy man"—so named by Louis Leakey and his colleagues in 1964 because they believed it responsible for the stone tools they were finding at Olduvai Gorge in Tanzania. In the 1970s teams led by Louis's son Richard found more H. habilis specimens in Kenya, and ever since, the species has provided a shaky base for the human family tree, keeping it rooted in East Africa. Before H. habilis the human story goes dark, with just a few fossil fragments of Homo too sketchy to warrant a species name. As one scientist put it, they would easily fit in a shoe box, and you'd still have room for the shoes.
Berger has long argued that H. habilis was too primitive to deserve its privileged position at the root of our genus. Some other scientists agree that it really should be called Australopithecus. But Berger has been nearly alone in arguing that South Africa was the place to look for the true earliest Homo. And for years the unchecked exuberance with which he promoted his relatively minor finds tended only to alienate some of his professional colleagues. Berger had the ambition and personality to become a famous player in his field, like Richard Leakey or Donald Johanson, who found the Lucy skeleton. Berger is a tireless fund-raiser and a master at enthralling a public audience. But he didn't have the bones.
Then, in 2008, he made a truly important discovery. While searching in a place later called Malapa, some ten miles from Rising Star, he and his nine-year-old son, Matthew, found some hominin fossils poking out of hunks of dolomite.
Over the next year Berger's team painstakingly chipped two nearly complete skeletons out of the rock. Dated to about two million years ago, they were the first major finds from South Africa published in decades. (An even more complete skeleton found earlier has yet to be described.) In most respects they were very primitive, but there were some oddly modern traits too.
Berger decided the skeletons were a new species of australopithecine, which he named Australopithecus sediba. But he also claimed they were "the Rosetta stone" to the origins of Homo. Though the doyens of paleoanthropology credited him with a "jaw-dropping" find, most dismissed his interpretation of it. A. sediba was too young, too weird, and not in the right place to be ancestral to Homo: It wasn't one of us. In another sense, neither was Berger. Since then, prominent researchers have published papers on early Homo that didn't even mention him or his find.
Berger shook off the rejection and got back to work—there were additional skeletons from Malapa to occupy him, still encased in limestone blocks in his lab. Then one night, Pedro Boshoff, a caver and geologist Berger had hired to look for fossils, knocked on his door. With him was Steven Tucker. Berger took one look at the pictures they showed him from Rising Star and realized that Malapa was going to have to take a backseat.
Skinny Individuals Wanted
After contorting themselves 40 feet down the narrow chute in the Rising Star cave, Tucker and Rick Hunter had dropped into another pretty chamber, with a cascade of white flowstones in one corner. A passageway led into a larger cavity, about 30 feet long and only a few feet wide, its walls and ceiling a bewilderment of calcite gnarls and jutting flowstone fingers. But it was what was on the floor that drew the two men's attention. There were bones everywhere. The cavers first thought they must be modern. They weren't stone heavy, like most fossils, nor were they encased in stone—they were just lying about on the surface, as if someone had tossed them in. They noticed a piece of a lower jaw, with teeth intact; it looked human.
Berger could see from the photos that the bones did not belong to a modern human being. Certain features, especially those of the jawbone and teeth, were far too primitive. The photos showed more bones waiting to be found; Berger could make out the outline of a partly buried cranium. It seemed likely that the remains represented much of a complete skeleton. He was dumbfounded. In the early hominin fossil record, the number of mostly complete skeletons, including his two from Malapa, could be counted on one hand. And now this. But what was this? How old was it? And how did it get into that cave?
Most pressing of all: how to get it out again, and quickly, before some other amateurs found their way into that chamber. (It was clear from the arrangement of the bones that someone had already been there, perhaps decades before.) Tucker and Hunter lacked the skills needed to excavate the fossils, and no scientist Berger knew—certainly not himself—had the physique to squeeze through that chute. So Berger put the word out on Facebook: Skinny individuals wanted, with scientific credentials and caving experience; must be "willing to work in cramped quarters." Within a week and a half he'd heard from nearly 60 applicants. He chose the six most qualified; all were young women. Berger called them his "underground astronauts."
With funding from National Geographic (Berger is also a National Geographic explorer-in-residence), he gathered some 60 scientists and set up an aboveground command center, a science tent, and a small village of sleeping and support tents. Local cavers helped thread two miles of communication and power cables down into the fossil chamber. Whatever was happening there could now be viewed with cameras by Berger and his team in the command center. Marina Elliott, then a graduate student at Simon Fraser University in British Columbia, was the first scientist down the chute.
"Looking down into it, I wasn't sure I'd be OK," Elliott recalled. "It was like looking into a shark's mouth. There were fingers and tongues and teeth of rock."
Elliott and two colleagues, Becca Peixotto and Hannah Morris, inched their way to the "landing zone" at the bottom, then crouched into the fossil chamber. Working in two-hour shifts with another three-woman crew, they plotted and bagged more than 400 fossils on the surface, then started carefully removing soil around the half-buried skull. There were other bones beneath and around it, densely packed. Over the next several days, while the women probed a square-yard patch around the skull, the other scientists huddled around the video feed in the command center above in a state of near-constant excitement. Berger, dressed in field khakis and a Rising Star Expedition cap, would occasionally repair to the science tent to puzzle over the accumulating bones—until a collective howl of astonishment from the command center brought him rushing back to witness another discovery. It was a glorious time.
The bones were superbly preserved, and from the duplication of body parts, it soon became clear that there was not one skeleton in the cave, but two, then three, then five ... then so many it was hard to keep a clear count. Berger had allotted three weeks for the excavation. By the end of that time, the excavators had removed some 1,200 bones, more than from any other human ancestor site in Africa—and they still hadn't exhausted the material in just the one square yard around the skull. It took another several days digging in March 2014 before its sediments ran dry, about six inches down.
There were some 1,550 specimens in all, representing at least 15 individuals. Skulls. Jaws. Ribs. Dozens of teeth. A nearly complete foot. A hand, virtually every bone intact, arranged as in life. Minuscule bones of the inner ear. Elderly adults. Juveniles. Infants, identified by their thimble-size vertebrae. Parts of the skeletons looked astonishingly modern. But others were just as astonishingly primitive—in some cases, even more apelike than the australopithecines. "We've found a most remarkable creature," Berger said. His grin went nearly to his ears.
But What Is It?
In paleoanthropology, specimens are traditionally held close to the vest until they can be carefully analyzed and the results published, with full access to them granted only to the discoverer's closest collaborators. By this protocol, answering the central mystery of the Rising Star find—What is it?—could take years, even decades. Berger wanted the work done and published by the end of the year. In his view everyone in the field should have access to important new information as quickly as possible. And maybe he liked the idea of announcing his find, which might be a new candidate for earliest Homo, in 2014— exactly 50 years after Louis Leakey published his discovery of the reigning first member of our genus, Homo habilis.
In any case there was only one way to get the analysis done quickly: Put a lot of eyes on the bones. Along with the 20-odd senior scientists who had helped him evaluate the Malapa skeletons, Berger invited more than 30 young scientists, some with the ink still wet on their Ph.D.'s, to Johannesburg from some 15 countries, for a blitzkrieg fossil fest lasting six weeks. To some older scientists who weren't involved, putting young people on the front line just to rush the papers into print seemed rash. But for the young people in question, it was "a paleofantasy come true," said Lucas Delezene, a newly appointed professor at the University of Arkansas. "In grad school you dream of a pile of fossils no one has seen before, and you get to figure it out."
The workshop took place in a newly constructed vault at Wits, a windowless room lined with glass-paneled shelves bearing fossils and casts. The analytical teams were divided by body part. The cranial specialists huddled in one corner around a large square table that was covered with skull and jaw fragments and the casts of other well-known fossil skulls. Smaller tables were devoted to hands, feet, long bones, and so on. The air was cool, the atmosphere hushed. Young scientists fiddled with bones and calipers. Berger and his close advisers circulated among them, conferring in low voices.
Delezene's own fossil pile contained 190 teeth—a critical part of any analysis, since teeth alone are often enough to identify a species. But these teeth weren't like anything the scientists in the "tooth booth" had ever seen. Some features were astonishingly humanlike—the molar crowns were small, for instance, with five cusps like ours. But the premolar roots were weirdly primitive. "We're not sure what to make of these," Delezene said. "It's crazy."
The same schizoid pattern was popping up at the other tables. A fully modern hand sported wackily curved fingers, fit for a creature climbing trees. The shoulders were apish too, and the widely flaring blades of the pelvis were as primitive as Lucy's—but the bottom of the same pelvis looked like a modern human's. The leg bones started out shaped like an australopithecine's but gathered modernity as they descended toward the ground. The feet were virtually indistinguishable from our own.
"You could almost draw a line through the hips—primitive above, modern below," said Steve Churchill, a paleontologist from Duke University. "If you'd found the foot by itself, you'd think some Bushman had died."
But then there was the head. Four partial skulls had been found—two were likely male, two female. In their general morphology they clearly looked advanced enough to be called Homo. But the braincases were tiny—a mere 560 cubic centimeters for the males and 465 for the females, far less than H. erectus's average of 900 cubic centimeters, and well under half the size of our own. A large brain is the sine qua non of humanness, the hallmark of a species that has evolved to live by its wits. These were not human beings. These were pinheads, with some humanlike body parts.
"Weird as hell," paleoanthropologist Fred Grine of the State University of New York at Stony Brook later said. "Tiny little brains stuck on these bodies that weren't tiny." The adult males were around five feet tall and a hundred pounds, the females a little shorter and lighter.
"The message we're getting is of an animal right on the cusp of the transition from Australopithecus to Homo," Berger said as the workshop began to wind down in early June. "Everything that is touching the world in a critical way is like us. The other parts retain bits of their primitive past."
In some ways the new hominin from Rising Star was even closer to modern humans than Homo erectus is. To Berger and his team, it clearly belonged in the Homo genus, but it was unlike any other member. They had no choice but to name a new species. They called it Homo naledi (pronounced na-LED-ee), tipping a hat to the cave where the bones had been found: In the local Sotho language, naledi means "star."
How Did It Get There?
Back in November, as Marina Elliott and her mates were uncovering that startling trove of bones, they were almost as surprised by what they weren't finding. "It was day three or four, and we still hadn't found any fauna," Elliott said. On the first day a few little bird bones had been found on the surface, but otherwise there was nothing but hominin bones.
That made for a mystery as perplexing as that of H. naledi's identity: How did the remains get into such an absurdly remote chamber? Clearly the individuals weren't living in the cave; there were no stone tools or remains of meals to suggest such occupation. Conceivably a group of H. naledi could have wandered into the cave one time and somehow got trapped—but the distribution of the bones seemed to indicate that they had been deposited over a long time, perhaps centuries. If carnivores had dragged hominin prey into the cave, they would have left tooth marks on the bones, and there weren't any. And finally, if the bones had been washed into the cave by flowing water, it would have carried stones and other rubble there too. But there is no rubble—only fine sediment that had weathered off the walls of the cave or sifted through tiny cracks.
"When you have eliminated the impossible," Sherlock Holmes once reminded his friend Watson, "whatever remains, however improbable, must be the truth."
Having exhausted all other explanations, Berger and his team were stuck with the improbable conclusion that bodies of H. naledi were deliberately put there, by other H. naledi. Until now only Homo sapiens, and possibly some archaic humans such as the Neanderthals, are known to have treated their dead in such a ritualized manner. The researchers don't argue that these much more primitive hominins navigated Superman's Crawl and the harrowing shark-mouth chute while dragging corpses behind them—that would go beyond improbable to incredible. Maybe back then Superman's Crawl was wide enough to be walkable, and maybe the hominins simply dropped their burden into the chute without climbing down themselves. Over time the growing pile of bones might have slowly tumbled into the neighboring chamber.
Deliberate disposal of bodies would still have required the hominins to find their way to the top of the chute through pitch-black darkness and back again, which almost surely would have required light—torches, or fires lit at intervals. The notion of such a small-brained creature exhibiting such complex behavior seems so unlikely that many other researchers have simply refused to credit it. At some earlier time, they argue, there must have been an entrance to the cave that afforded more direct access to the fossil chamber—one that probably allowed the bones to wash in. "There has to be another entrance," Richard Leakey said after he'd paid a visit to Johannesburg to see the fossils. "Lee just hasn't found it yet."
But water would inevitably have washed rubble, plant material, and other debris into the fossil chamber along with the bones, and they simply aren't there. "There isn't a lot of subjectivity here," said Eric Roberts, a geologist from James Cook University in Australia, svelte enough to have examined the chamber himself. "The sediments don't lie."
Disposal of the dead brings closure for the living, confers respect on the departed, or abets their transition to the next life. Such sentiments are a hallmark of humanity. But H. naledi, Berger emphatically stresses, was not human—which makes the behavior all the more intriguing.
"It's an animal that appears to have had the cognitive ability to recognize its separation from nature," he said.
How Old Is It?
The mysteries of what H. naledi is, and how its bones got into the cave, are inextricably knotted with the question of how old those bones are—and for the moment no one knows. In East Africa, fossils can be accurately dated when they are found above or below layers of volcanic ash, whose age can be measured from the clocklike decay of radioactive elements in the ash. At Malapa, Berger had gotten lucky: The A. sediba bones lay between two flowstones—thin layers of calcite deposited by running water—that could also be dated radiometrically. But the bones in the Rising Star chamber were just lying on the cave floor or buried in shallow, mixed sediments. When they got into the cave is an even more intractable problem to solve than how.
Most of the workshop scientists fretted over how their analysis would be received without a date attached. (As it turned out, the lack of a date would prove to be one impediment to a quick publication of the scientific papers describing the finds.) But Berger wasn't bothered one bit. If H. naledi eventually proved to be as old as its morphology suggested, then he had quite possibly found the root of the Homo family tree. But if the new species turned out to be much younger, the repercussions could be equally profound. It could mean that while our own species was evolving, a separate, small-brained, more primitive-looking Homo was loose on the landscape, as recently as anyone dared to contemplate. A hundred thousand years ago? Fifty thousand? Ten thousand? As the exhilarating workshop came to an end with that fundamental question still unresolved, Berger was sanguine as always. "No matter what the age, it will have tremendous impact," he said, shrugging.
Berger's Triumph
A few weeks later, in August of last year, he traveled to East Africa. To mark the occasion of Louis Leakey's description of H. habilis, Richard Leakey had summoned the leading thinkers on early human evolution to a symposium at the Turkana Basin Institute, the research center he (along with the State University of New York at Stony Brook) had established near the western shore of Lake Turkana in Kenya.
The purpose of the meeting was to try to come to some consensus over the confounding record of early Homo, without grandstanding or rancor—two vices endemic to paleoanthropology. Some of Lee Berger's harshest critics would be there, including some who'd written scathing reviews of his interpretation of the A. sediba fossils. To them, he was an outsider at best, a hype artist at worst. Some threatened not to attend if he were there. But given the Rising Star discovery, Leakey could hardly not invite him.
"There's no one on Earth finding fossils like Lee is now," Leakey said.
For four days the scientists huddled together in a spacious lab room, its casement windows open to the breezes, casts of all the important evidence for early Homo spread out on tables. One morning Meave Leakey (who's also a National Geographic explorer-in-residence) opened a vault to reveal brand-new specimens found on the east side of the lake, including a nearly complete foot. When it was his turn to speak, Bill Kimbel of the Institute of Human Origins described a new Homo jaw from Ethiopia dated to 2.8 million years ago—the oldest member of our genus yet. Archaeologist Sonia Harmand of Stony Brook University dropped an even bigger bombshell—the discovery of dozens of crude stone tools near Lake Turkana dating to 3.3 million years ago. If stone tools originated half a million years before the first appearance of our genus, it would be hard to argue anymore that the defining characteristic of Homo was its technological ingenuity.
Berger meanwhile was uncommonly subdued, adding little to the discussion, until the topic turned to a comparison of A. sediba and H. habilis. It was time.
"More of interest perhaps to this debate is Rising Star," he offered. For the next 20 minutes he laid out all that had happened—the serendipitous discovery of the cave, the crash analysis in June, and the gist of its findings. While he talked, a couple of casts of Rising Star skulls were passed hand to hand.
Then came the questions. Have you done a cranio-dental analysis? Yes. The H. naledi skull and teeth place it in a group with Homo erectus, Neanderthals, and modern humans. Closer to H. erectus than H. habilis is? Yes. Are there any tooth marks on the bones from carnivores? No, these are the healthiest dead individuals you'll ever see. Have you made progress on the dating? Not yet. We'll get a date sometime. Don't worry.
Then, when the questions were over, the gathered doyens did something no one expected, least of all Berger. They applauded.
The Braided Stream
When a major new find is made in human evolution—or even a minor new find—it's common to claim it overturns all previous notions of our ancestry. Perhaps having learned from past mistakes, Berger doesn't make such assertions for Homo naledi—at least not yet, with its place in time uncertain. He doesn't claim he has found the earliest Homo, or that his fossils return the title of "Cradle of Humankind" from East to South Africa. The fossils do suggest, however, that both regions, and everywhere in between, may harbor clues to a story that is more complicated than the metaphor "human family tree" would suggest.
"What naledi says to me is that you may think the record is complete enough to make up stories, and it's not," said Stony Brook's Fred Grine. Maybe early species of Homo emerged in South Africa and then moved up to East Africa. "Or maybe it's the other way around."
Berger himself thinks the right metaphor for human evolution, instead of a tree branching from a single root, is a braided stream: a river that divides into channels, only to merge again downstream. Similarly, the various hominin types that inhabited the landscapes of Africa must at some point have diverged from a common ancestor. But then farther down the river of time they may have coalesced again, so that we, at the river's mouth, carry in us today a bit of East Africa, a bit of South Africa, and a whole lot of history we have no notion of whatsoever. Because one thing is for sure: If we learned about a completely new form of hominin only because a couple of cavers were skinny enough to fit through a crack in a well-explored South African cave, we really don't have a clue what else might be out there.
It is an awesome find. Read about it in the paper this AM.
Quite the mystery. If they were deliberate 'entombments' in that cave, it would drastically revise backwards notions about the development of human-level conciousness.
Quote from: Malthus on September 10, 2015, 08:48:02 AM
It is an awesome find. Read about it in the paper this AM.
Quite the mystery. If they were deliberate 'entombments' in that cave, it would drastically revise backwards notions about the development of human-level conciousness.
Similar brain size to some of the smaller specimens of H. erectus from Dmanisi and they were empathetic enough to keep an old man alive with no teeth for years.
In fact, Tim White claims that they belong to early H. erectus.
Read about it this morning, but this article has more details :)
Thanks Tim :)
Real interesting stuff. :nerd: :cool:
Has grumbler been asked to ID the person yet?
"Where were you between 4 million and 3 million BCE?"
...
"Can you name any witnesses who can confirm that?"
Impressive find.
Good article, interesting find and info, thanks for posting that!
He looks more Asian than African. Also: Murdoch source.
Somehow I misread the last part of the title as "homo nailed". :unsure:
Some analysis by a prominent scientist not involved in the excavation.
Nice photo comparing skulls here
http://elifesciences.org/content/4/e10627
Quote
The many mysteries of Homo naledi
Chris StringerCorresponding Author
Natural History Museum, United Kingdom
DOI: http://dx.doi.org/10.7554/eLife.10627
Published September 10, 2015
Cite as eLife 2015;4:e10627
When the recovery of fossil hominin remains from the Rising Star cave system near Johannesburg in South Africa was widely publicised in 2013 and 2014, I'm sure I wasn't the only one who thought that the coverage had more hype than substance. But now, in two papers in eLife, we can see what the fuss was all about as Lee Berger of the University of the Witwatersrand, Paul Dirks of James Cook University and an international team of colleagues report the discovery of more than 1500 fossils that represent at least 15 individuals (Berger et al., 2015; Dirks et al., 2015). These remains have now been assigned to a new human species, which has been named Homo naledi. However, despite the wealth of information about the physical characteristics of H. naledi that this collection provides, many mysteries remain. How old are the fossils? Where does H. naledi fit in the scheme of human evolution? And how did the remains arrive deep within the cave system?
In the first paper, Berger et al. describe how the collection displays a unique combination of primitive and derived characteristics (Berger et al., 2015). For example, the small brain size, curved fingers and form of the shoulder, trunk and hip joint resemble the prehuman australopithecines and the early human species Homo habilis. Yet the wrist, hands, legs and feet look most like those of Neanderthals and modern humans. The teeth have some primitive features (such as increasing in size towards the back of the tooth row), but they are relatively small and simple, and set in lightly built jawbones (Figure 1). Overall, to my eye, the material looks most similar to the small-bodied examples of Homo erectus from Dmanisi in Georgia, which have been dated at ∼1.8 million years old (Lordkipanidze et al., 2013). However, the rich H. naledi sample includes bones that are poorly known in other early humans species such as Homo rudolfensis, H. habilis and H. erectus, so it is difficult at the moment to assess how similar these species were throughout the skeleton.
If H. naledi is more than 2 million years old, which Berger et al. suggest could be possible, the species might lie close to the very origin of the genus Homo. However, if the H. naledi fossils are less than 100,000 years old, it would mean that it survived until relatively recently, just like Homo floresiensis far away in Indonesia (another species which combines a small brain with small teeth; Stringer, 2014). Because H. naledi is currently only known from one site, it is unclear whether or not it was restricted to southern Africa. If it turns out that H. naledi was more widespread, its moderate body size may lead scientists to re-examine other diminutive fossils from across Africa, which have usually been attributed to a small form of H. erectus (Antón, 2004; Potts et al., 2004; Simpson et al., 2008).
In the second paper, Dirks, Berger and colleagues describe the setting of the fossils: the Dinaledi Chamber (Dirks et al., 2015). This cave chamber lies some 80 metres into the Rising Star system, and must have always been in constant darkness. This closely parallels the circumstances of a famous accumulation of ∼6500 human fossils in the Sima de los Huesos ('Pit of the Bones') in the Sierra de Atapuerca in Spain. In both cases, there is no associated evidence of human occupation. However, unlike the Dinaledi Chamber, the Sima did contain material from other large mammals. Moreover, the Atapuerca team also recovered numerous bones of the hands, feet and spine that could be articulated (or connected back together as they were in life). This led them to propose that the remains of at least 28 early Neanderthals had been intentionally thrown down into the pit, where the bodies decayed (Carbonell and Mosquera, 2006). After considering the alternative explanations, ranging from whether H. naledi occupied the caves to whether the bodies were left there by predators, Dirks et al. favour a similar scenario to that proposed for the Sima. However, they also recognise that the intentional disposal of the dead bodies is a surprisingly complex behaviour for a creature with a brain no bigger than that of H. habilis or a gorilla.
Frustratingly, the rich and informative H. naledi material remains undated. Given that this hominin material could conceivably even date within the last 100,000 years, I am puzzled by the apparent lack of attempts to estimate its age. This could have been achieved directly via radiocarbon dating (even if only to test whether the material lies beyond the effective range of that method) or indirectly based on ancient DNA samples. For example, after ancient DNA was successfully recovered from the Sima de los Huesos fossils, it was used to date them to about 400,000 years old (Meyer et al., 2014). Moreover, tests on even small fragments of bone and tooth enamel could have narrowed down the possible age range and at least ruled out either a very ancient or very young age (Grün, 2006).
Even without date information, the mosaic nature of the H. naledi skeletons provides yet another indication that the genus Homo had complex origins. The individual mix of primitive and derived characteristics in different fossils perhaps even indicates that the genus Homo might be 'polyphyletic': in other words, some members of the genus might have originated independently in different regions of Africa. If this is the case, it would mean that the species currently placed within the genus Homo would need to be reassessed (Dembo et al., 2015; Hublin, 2015). While many have concentrated on East Africa as the key and perhaps sole region for the origins of the genus Homo, the continuing surprises emerging from further south remind us that Africa is a huge continent that even now is largely unexplored for its early human fossils.
Can you say Piltdown Man
😉
He looks like Obama.
You look like Obama.
I saw that comment on a right wing news site and I couldn't resist. :blush:
Quote from: Jaron on September 11, 2015, 02:56:34 AM
I saw that comment on a right wing news site and I couldn't resist. :blush:
Why are you reading right wing news sites?
Quote from: Peter Wiggin on September 11, 2015, 03:17:53 AM
Quote from: Jaron on September 11, 2015, 02:56:34 AM
I saw that comment on a right wing news site and I couldn't resist. :blush:
Why are you reading right wing news sites?
Because he's a crypto-Mormon now? :hmm:
I subscribe to them on Facebook to raise my credibility with my co workers and neighbors.
Quote from: jimmy olsen on September 10, 2015, 06:35:42 PM
Some analysis by a prominent scientist not involved in the excavation.
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Frustratingly, the rich and informative H. naledi material remains undated. Given that this hominin material could conceivably even date within the last 100,000 years, I am puzzled by the apparent lack of attempts to estimate its age. This could have been achieved directly via radiocarbon dating (even if only to test whether the material lies beyond the effective range of that method) or indirectly based on ancient DNA samples. For example, after ancient DNA was successfully recovered from the Sima de los Huesos fossils, it was used to date them to about 400,000 years old (Meyer et al., 2014). Moreover, tests on even small fragments of bone and tooth enamel could have narrowed down the possible age range and at least ruled out either a very ancient or very young age (Grün, 2006).
There isn't any good method of dating bones estimated to be 3 million or so years old, unless you get lucky and they are covered with a layer of rock that can be dated by potassium-argon dating or some other method, or if they have DNA (most of course would not - DNA survival in material that old is rare).
Marty thought this was a typo of "homo I nailed".
PBS documentary on the excavation
http://www.pbs.org/wgbh/nova/evolution/dawn-of-humanity.html
Link to the academic article that announces the new species, for those so inclined.
http://elifesciences.org/content/4/e09560
The second author on that paper is John Hawks, those who have read my many posts on paleoanthropology may remember the many times I have quoted from his blog. Some people called me out for quoting blog posts from a random professor, but he's made the big time now! :blurgh:
His response to criticism of the paper.
http://johnhawks.net/weblog/fossils/naledi/homo-naledi-homo-erectus-2015.html
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Is Homo naledi just a primitive version of Homo erectus?
19 Sep 2015
We've gotten lots of feedback on the new species Homo naledi. Most has been enormously positive, a little bit has been critical. In particular, a few scientists have come forward with criticism of the idea that H. naledi is really a new species. Fortunately I can address those criticisms easily by pointing to some easy-to-find answers.
Is H. naledi really two species?
On one side, Jeffrey Schwartz has argued that the H. naledi remains actually represent two or more different species. Newsweek gave him an op-ed platform to make his case, "Why the Homo Naledi Discovery May Not Be Quite What it Seems".
Viewed from the side, two partial skulls are long and low, with a long gently sloping forehead that flows smoothly into the brow – nothing like us, or most specimens regarded as Homo. A third partial skull is very short and rounded, with a high-rising forehead that is distinguished from a distinct, well-defined brow by a shallow gutter – not like the other skulls, and not like us or most specimens regarded as Homo. The femur has a small head (the ball end that fits in the hip socket) that is connected to the shaft of the bone by a long neck, and, below the neck, is a "bump" of bone that points backward. These features are seen in every australopith femur. In us, and all other living primates, the head of the femur is large and the neck short, and the "bump" points inward. Further, the teeth are very similar to those from a nearby fossil site that has yielded various kinds of australopith. Even at this stage of their being publicized, the "Homo naledi" specimens reflect even greater diversity in the human fossil record than their discoverers will admit.
Homo naledi has a mosaic of features that include some that compare most closely to more primitive australopiths, and others that compare more closely to Homo. How do we know that this is one species rather than a jumble of species mixed together? Simple: every feature that is repeated in the sample is nearly identical in all individuals that preserve it. It would be very strange to have a mix of different species where all seven proximal femora come from one species, while all of a dozen lower third premolars come from a different species.
Schwartz is also totally wrong about the crania: All the frontal bones in the collection have a similar morphology with a thin supraorbital torus and slight but distinct supratoral sulcus. The variation within the collection is not high, it is extraordinarily low—in fact, the tooth size varies less than half as much as is usual in most human populations. Schwartz seems to imply in his argument that some of the Swartkrans teeth attributed to Homo are similar to H. naledi. There are some superficial similarities, but in fact we cannot find a good comparable example within the Swartkrans collection, particularly for the distinctive premolar crown and root morphology, the lower canine crown morphology, and the small molar sizes of H. naledi.
All of that is in the paper, which is open access for anyone to read anywhere in the world: "Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa". It is not really a mystery why someone like Schwartz would come forward in such a public way with criticisms that are easily answered by the open access paper—after all, it's not every day that an anthropologist is asked to write a full-page piece for Newsweek.
(https://languish.org/forums/proxy.php?request=http%3A%2F%2Fjohnhawks.net%2Fimages%2Fbanner-1500-homo-naledi-dh1-dh3-knm-er-3733.jpg&hash=3c18552544e85541236f1fed4c05931779591796)
DH1 and DH3 of Homo naledi compared to KNM-ER 3733 of Homo erectus
DH1 (left) and DH3 (center) of Homo naledi compared to KNM-ER 3733 from the Turkana Basin, usually attributed to Homo erectus. These skulls, shown to scale, illustrate the very small size of the Homo naledi cranium compared to African Homo erectus.
The "primitive small Homo erectus" story
Another criticism of Homo naledi has come from a prominent paleoanthropologist and member of the National Academy of Sciences, Tim White. White has been publicizing his theory about Homo naledi in many press interviews (e.g., "Some bones to pick"):
White: Dating is irrelevant; these are a small, primitive H. erectus, whatever the date turns out to be. This is because they are not biologically different, in any significant way, from already known H. erectus found in places like Swartkrans (800m away), eastern Africa, or the Georgian republic. Of the 80+ traits listed in the e-LIFE supplemental material, only a small fraction of them are even claimed to differentiate these fossils from earlier described H. erectus, and that fraction of characters is known to vary among members of the same species (even population) of both H. erectus and H. sapiens. In other words, the newly described "species" is an example of artificial species inflation in palaeoanthropology.
Of course, Homo erectus is a very well-known species, and we compared the Dinaledi fossils to every specimen available to us. Many of our team have studied the originals of most Homo erectus remains around the world, and I have personally examined the key cranial and postcranial specimens from Dmanisi. So we examined this question in great detail as we studied the Homo naledi material.
How are we to know that Homo naledi is not the same as a primitive, small Homo erectus? Well, for one thing, at least two H. naledi individuals have endocranial volumes around 460 cc, much smaller than any H. erectus cranium ever found. There is barely any overlap between the larger individuals and H. erectus, with only a single H. erectus specimen coming close to the H. naledi range of variation in volume.
White doesn't specify how many features would be sufficient in his view to define a species. It should be obvious that if we list 80 cranial and dental traits that are informative among all hominins, that most species will differ in only a relatively small fraction of those. Nevertheless our open access paper lists many clear differences between H. naledi and H. erectus, including aspects of premolar crown and root morphology, the crown morphology of the molars (simplified in H. naledi, invariably crenulated and complex in H. erectus), vault shape (H. naledi does not have the elongated, low cranium of H. erectus) and mandibular shape—all listed on page 10 of our open access paper. Even setting aside the postcranial skeleton and the very small endocranial volume, these show H. naledi to be distinct from H. erectus.
When we look at the postcranial skeleton, there is simply no way that H. naledi could be confused for H. erectus. H. naledi has a long, anteroposteriorally flattened and anteverted femur neck, which looks very different from African and Dmanisi femora attributed to H. erectus. The H. naledi tibia is exceptionally mediolaterally thin and long, with a rounded anterior border and tubercle for the pes anserinus tendon, all traits that we could not find in known tibiae attributed to H. erectus including Dmanisi. The H. naledi scapula has a superiorly oriented glenoid, very different from the Dmanisi scapula specimen or the Nariokotome H. erectus skeleton. The vertebrae of H. naledi do not match in proportions or morphology the comparable examples from Nariokotome or Dmanisi, and the pelvis of H. naledi exhibits a short, flared ilium unlike those known for H. erectus, including the Gona pelvic specimen.
It's just a poor match to H. erectus, so that the only way to make the H. naledi fossils fit within Homo erectus is to stretch that species beyond any other ever defined in the human lineage. There are clearly some similarities, which to us indicate something about the evolutionary relationships of H. naledi and H. erectus—but we are hesitant to go so far as to posit a unique relationship of these two species because many of their similarities also overlap with species such as H. habilis, H. rudolfensis, and even Australopithecus sediba. Figuring out those relationships will take additional research and analysis.
What a species diagnosis does
The purpose of a species diagnosis is to enable other researchers to distinguish the new species from other species they already know. The diagnosis is a taxonomic act, creating a name that can be recognized in the future by agreed-upon rules of nomenclature. The species diagnosis provides a basis for later descriptive work, which can go into much more detail about the morphology of the fossils and include comparisons with all specimens of other species rather than merely differential traits.
It has been tradition in paleoanthropology for the first diagnosis of a new hominin species to be very brief. For example, the diagnosis and description of Australopithecus ramidus (White et al. 1994) included dental, cranial and postcranial material, and was only 6 pages long. The diagnosis and description of Australopithecus garhi (Asfaw et al. 1999) was also 6 pages. The diagnosis and description of the new species Australopithecus deyiremeda (Haile-Selassie et al. 2015) is 5 pages.
Of course there is a problem with such short descriptions. How were we really to know that Australopithecus ramidus was different from Australopithecus afarensis? More to the point, a year later, when White and colleagues published an erratum to their article that named a new genus for the material, which they called Ardipithecus, how were we to know that was justifiable based on evidence? Well, in that case we waited 15 years for the publication of additional descriptive material. The description of Au. garhi is still, 16 years later, the only scientific document on those fossil remains. The description of Au. deyiremeda this spring (Haile-Selassie et al. 2015) was met with immediate criticism by Tim White, who seemingly has no time for species that he himself has not named.
Some people have become jaded about the entire idea of hominin species, cynically concluding that every new species name is just an exercise in glorifying the discoverer, or is stoked by nationalist pride. In my experience, that's rarely true. Paleoanthropologists are careful scientists who want their work to stand the test of public attention. But the field's convention of brief species diagnosis followed by long delays for more information has led to confusion and criticism.
We hope that a more open approach will lead to more productive conversations about hominin species.
With 35 text pages, not counting supplementary data, the species description of Homo naledi is around 6 times longer than has been typical in paleoanthropology. We worked to give a much broader perspective on the anatomy across the skeleton than is typical of species descriptions in our field, and we have described the differences between H. naledi and other species with much greater specificity than has been done before.
There is much work to do in describing the Homo naledi collection, and we have several publications forthcoming and in review that give more descriptive detail about the H. naledi fossils. This is just the beginning of a conversation about the form and place of this species in our evolutionary history. But we think that the data we have provided in this initial publication will allow people to know with some confidence that H. naledi is really quite different from other previously-known species.
Download them yourself!
Of course, no one has to trust what we have written about the fossils, because we have made the 3D shape files for many of them available open access through MorphoSource. Anyone can sign up for a free login and download the shape files, even print them out. It's been exciting to see anthropology departments and seminars printing the fossils and discussing them all week long!
Some senior paleoanthropologists have unfortunately been accustomed to secretive practices. They may think that people will trust their authoritative pronouncements about fossil remains because no one will ever see the data. That's an unscientific approach, and it leads to bad practices.
What we're seeing now from senior scientists like Tim White and Jeffrey Schwartz is an unfortunate pattern. These scientists are used to being able to immediately talk to their cronies in the press with a knee-jerk reaction to new fossil publications, secure in the knowledge that the authors won't release the data to contradict them. Even White, who has famously written (White 2000) that no one should publish on a fossil without seeing the original, has twice this year chased attention for his own fringe views about new species.
I hope that he'll print out the fossils and take a careful look side-by-side with his own data. Maybe someday he'll share his data with other scientists and the world so that we can have a real conversation.
References
Asfaw, Berhane, et al. "Australopithecus garhi: a new species of early hominid from Ethiopia." Science 284.5414 (1999): 629-635.
Berger, Lee R., et al. "Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa." eLife 4 (2015): e09560.
Haile-Selassie, Yohannes, et al. "New species from Ethiopia further expands Middle Pliocene hominin diversity." Nature 521.7553 (2015): 483-488.
White, Tim D., Gen Suwa, and Berhane Asfaw. "Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia." Nature 371 (1994): 306-312.
White, Tim D., Gen Suwa, and Berhane Asfaw. "Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia." Nature 375.6526 (1995): 88.
White, Tim D. News and Views: A View on the Science: Physical Anthropology at the Millennium. American Journal of Physical Anthropology 113 (2000):287–292.
Quote from: jimmy olsen on September 20, 2015, 05:50:33 AM
Some people called me out for quoting blog posts from a random professor,
Professor H. Meister?
Quote from: Peter Wiggin on September 20, 2015, 06:01:43 AM
Quote from: jimmy olsen on September 20, 2015, 05:50:33 AM
Some people called me out for quoting blog posts from a random professor,
Professor H. Meister?
Doktor of Military Science with a minor in psychology.
Great lecture by professor Hawks on the find
https://www.youtube.com/watch?v=UqMTTaR4ibk
Another good lecture by the guy who headed up the study of the leg and foot bones
https://www.youtube.com/watch?v=lZIsVI4sILU
Gotta admire your searchfu to unhearth this.
Quote from: Grinning_Colossus on September 20, 2015, 01:45:51 PM
Quote from: Peter Wiggin on September 20, 2015, 06:01:43 AM
Quote from: jimmy olsen on September 20, 2015, 05:50:33 AM
Some people called me out for quoting blog posts from a random professor,
Professor H. Meister?
Doktor of Military Science with a minor in psychology.
What ever happened to that guy? Did Cdm ban him? :hmm:
He drops in from time to time. Pretty rarely these days.
Quote from: Grey Fox on February 10, 2017, 08:02:23 AM
Gotta admire your searchfu to unhearth this.
I follow the Twitter feed of Lee Berger and John Hawks and some videos were linked in them
Found another great CARTA series of lectures at UCTV on the origins of the Genus Homo
Opening Remarks
http://www.uctv.tv/shows/Opening-Remarks-Churchill-30636
Part 1
http://www.uctv.tv/shows/CARTA-Origins-of-Genus-Homo-Homo-What-Who-When-Where-Evolution-of-Early-Human-Body-Form-Evolution-of-Human-Life-History-Patterns-30632
Part 2
http://www.uctv.tv/shows/CARTA-Origins-of-Genus-Homo-Australopithecus-and-the-Emergence-of-Earliest-Homo-Dmanisi-Variation-and-Systematics-of-Early-Homo-A-Potential-Molecular-Mechanism-for-the-Speciation-of-Genus-Homo-30634
Part 3
http://www.uctv.tv/shows/CARTA-Origins-of-Genus-Homo-Southern-Africa-and-the-Origin-of-Homo-Adaptive-Shifts-Accompanying-the-Origin-of-Homo-Energetics-and-the-Ecology-of-Early-Homo-30633
Questions and Answers
http://www.uctv.tv/search-details.aspx?showID=30646
Stunningly young age! :o
Photos can be found here.
https://www.washingtonpost.com/news/speaking-of-science/wp/2017/05/09/humanitys-strange-new-cousin-is-shockingly-young-and-shaking-up-our-family-tree/?utm_term=.53f5bf4bbf14
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Humanity's strange new cousin is shockingly young — and shaking up our family tree
By Sarah Kaplan
May 9
Homo naledi, a strange new species of human cousin found in South Africa two years ago, was unlike anything scientists had ever seen. Discovered deep in the heart of a treacherous cave system — as if they'd been placed there deliberately — were 15 ancient skeletons that showed a confusing patchwork of features. Some aspects seemed modern, almost human. But their brains were as small as a gorilla's, suggesting Homo naledi was incredibly primitive. The species was an enigma.
Now, the scientists who uncovered Homo naledi have announced two new findings: They have determined a shockingly young age for the original remains, and they found a second cavern full of skeletons. The bones are as recent as 236,000 years, meaning Homo naledi roamed Africa at about the time our own species was evolving. And the discovery of a second cave adds to the evidence that primitive Naledi may have performed a surprisingly modern behavior: burying the dead.
"This is a humbling discovery for science," said Lee Berger, a paleoanthropologist at the University of the Witwatersrand in Johannesburg. "It's reminding us that the fossil record can hide things ... we can never assume that what we have tells the whole story."
Berger and his colleagues report Naledi's age and the new chamber in two papers published Tuesday in the open-access journal eLife. In a third paper, they argue that Naledi must be a long-lasting lineage that arose 2 million years ago during the early days of the genus Homo and somehow survived long enough to coexist with modern humans, who emerged about 200,000 years ago. The species' complicated anatomy and unexpected resilience raise a number of intriguing questions, they say: Was Naledi a result of, and perhaps a contributor to, hybridization within the Homo family tree? Could Naledi be responsible for some of the stone tools found in South Africa during the period it was alive? Should paleoanthropologists shift their focus from East Africa to the continent's less-studied southern regions?
Several scientists not involved the Naledi research urged caution about some of Berger's bolder claims, including the suggestion that Naledi was burying its dead and crafting the sophisticated stone tools that characterize southern Africa's "Middle Stone Age."
But they agreed with Berger on this point: Naledi reminds us that human history is even richer than we realized.
"The past was a lot more complicated than we gave it credit for and our ancestors were a lot more resilient and lot more varied than we give them credit for," said Susan Anton, a paleoanthropologist at New York University who was not involved in the research. "We're not the pinnacle of everything that happened in the past. We just happen to be the thing that survived."
Rick Potts, director of the Human Origins Program at the Smithsonian Institution's National Museum of Natural History, said finds like this should prompt people to discard the familiar image of a stooped chimp evolving into a modern human walking upright and carrying a briefcase.
"We've had for so long this view that human evolution was a matter of inevitability represented by that march, that progress," he said. "But now that narrative of human evolution has become one of adaptability. There was a lot of evolution and extinction of populations and lineages that made it through some pretty tough times, and we're the beneficiary of that."
The original Homo naledi skeletons were discovered in 2013 in the Rising Star cave system, one of the twisted and branching limestone caverns that make up a World Heritage Site known as "the Cradle of Humankind." This same 180-square-mile region in South Africa has yielded a number of 2-million-year-old Australopithecus fossils, but Homo naledi was the first species to fit in the genus Homo.
The Dinaledi ("star" in the Sesotho language) chamber, which contained the Naledi skeletons, was so narrow and difficult to access that Berger had to seek out an all-women team of petite, extremely agile spelunkers to excavate it. What they found astonished the paleoanthropology community — not only had a new species been discovered but, with 15 skeletons, it was suddenly the best-documented species in the history of hominins.
And the Rising Star system wasn't done giving up its secrets. Spelunkers Rick Hunter and Steven Tucker, who discovered the bones in the Dinaledi chamber, had also noticed a large leg bone in a different part of the cave. They didn't think much of it at the time, but after the importance of the Dinaledi fossils became clear, they realized the bone they had passed before was probably from a hominin. As soon as the Dinaledi excavation was complete, the team went back to this second chamber, dubbed Lesedi ("light").
Lesedi was shallower and easier to access than the Dinaledi chamber, but only marginally so. It fit just one excavator at a time, working on his or her hands and knees to brush reddish brown clay from fragile bones. Berger himself only ventured into the chamber once — he got stuck coming back out of the narrow entrance and decided not to push his luck again.
Yet, somehow, more than 130 hominin bones wound up in this dark and humid cavern hundreds of thousands of years ago. The excavators uncovered remains from at least three Homo naledi individuals. One of them, an adult male they call "Neo" ("gift" in Sesotho), is arguably the most complete fossil hominin ever found.
Berger and his colleagues don't yet have an age for the Lesedi individuals, and without DNA evidence from both caverns, it will be impossible to tell whether they are related to those from Dinaledi. But he and his colleagues argue that the presence of a second cavern full of bones bolsters the theory that Homo naledi was deliberately leaving its dead in these chambers.
"One, perhaps, was a singular event," Berger said. "Two is not a coincidence."
Not everyone is convinced. Ritual disposal of the dead is an advanced behavior, suggesting that a species was capable of symbolic thought and saw itself as separate from the natural world. Only humans and Neanderthals have been conclusively found to bury their dead, and several scientists said we cannot yet rule out the possibility that the bones were deposited in the cave naturally. The Lesedi chamber also yielded some small animal fossils. (The absence of nonhuman remains in Dinaledi was considered a strong piece of evidence that the hominins were placed in the cavern intentionally, rather than falling or wandering into the cave and then dying there.)
Early humans coexisted with human-like species 300,000 years ago in Africa Play Video0:54
Scientists say new bones of homo naledi reveal they existed at about the same time homo sapiens evolved. (Reuters)
Alison Brooks, a paleoanthropologist at George Washington University and the Smithsonian Institution who was not involved in the research, suggested that the immediate ancestors of Homo sapiens might be the ones who put the bodies there. She said it is possible they dropped the bodies into the caverns through an opening that has long since closed. She noted that no artifacts were found with the caverns that might indicate how to interpret the remains. She also questioned whether the cave was really as difficult to access in the past as it is today.
But if Homo naledi was placing the bones in the cave for ritual reasons, that would mean the species was capable of something profound.
"There's a potential that we are looking at some kind of rudimentary cultural practice associated with this widely shared emotion of grief," said John Hawks, a paleoanthropologist at the University of Wisconsin at Madison who helped lead the Rising Star expedition. "It's telling us that this is something that's very deep in our history as humans. ... When you're looking at a group that takes one of their members and takes the body and put it somewhere hidden, that's like saying, 'We're different. The leopards are not going to eat you. You're one of us.' "
Yet even as the scientists puzzled over the implications of the second cave, they still had to figure out the age of the fossils in the first one. In a 2015 interview with National Geographic (which helped fund the Rising Star excavations), Berger speculated that Naledi had emerged about 2 million years ago, based on its constellation of traits, and was positioned near the root of the Homo family tree.
Homo naledi's small brain case and curved fingers suggested the species was primitive, more closely related to our Australopithecus ancestors than to us. But its long legs, small teeth and dexterous wrists appeared modern. The bones were too old to be dated using the traditional radiocarbon technique, and too poorly preserved for researchers to extract any ancient DNA.
Meanwhile the stratigraphy, or ordering of the rock layers, of the Dinaledi chamber was difficult to decipher. Water had periodically washed through the cavern during its several-hundred-thousand-year history, causing sediments to accumulate weirdly. Water also affects radiation levels in the chamber, which can throw off calculations of age based on rates of radioactive decay.
"All this gets quite, quite complicated, and this is one of the reasons why it took so long to do," said Paul Dirks, a geologist at James Cook University in Australia who led the dating effort. "We did not want to put a garbage age out there."
In the end, the research team employed six different dating techniques at 10 labs around the world. Each technique was tried independently by at least two labs to ensure that the results were as robust as possible. Based on analysis of the Naledi teeth and several measures of radioactivity in the cave, the team concluded that the fossils date back to between 236,000 and 335,000 years ago — just before the arrival of modern humans.
"Our ancestors did not live in a single species world the way we do," Brooks said. "The real take-home message of this paper is that we were not alone until very recently."
Several other hominin species roamed the globe during this period, known as the Middle Stone Age: Homo erectus in Asia; tall, large-brained Homo heidelbergensis in Africa and Europe; eventually Neanderthals and the mysterious Denisovans (who are known only from DNA and a few fossil teeth). But these species were a lot like us: They walked primarily on two feet, used tools and probably mastered fire. Even the smallest-brained species had a brain that was three-quarters the size of ours.
For years, scientists assumed that all members of the Homo genus in Africa were quite advanced by the Middle Stone Age — how else would they be able to compete with the formidable new species Homo sapiens and its direct ancestors?
Homo naledi complicates that narrative. Its limbs and teeth suggest that it had a human's walking habits and diet, and perhaps roamed the same lands and ate the same foods as our recent ancestors. But its brain was only 30 percent the size of a human's, and no bigger than that of a gorilla today.
"How the heck did these guys survive alongside of us, alongside our ancestors?" Hawks wondered.
Perhaps, he speculated, brain size is not everything. After all, Naledi was arguably able to navigate the Rising Star cave system. He and Berger both suggested the species may have been capable of other feats of intelligence, including crafting the stone tools normally attributed to Homo sapiens and our direct ancestors.
Potts of the National Museum of Natural History, compared Naledi to Homo floresiensis, the tiny, small-brained "hobbit" people who lived on the Indonesian island of Flores until about 60,000 years ago. Scientists think that the Flores people descended from taller human species but shrank as a result of "island dwarfism," the tendency of species trapped on islands with limited resources to evolve smaller stature, requiring less food. Perhaps Naledi evolved from a similar phenomenon, Potts said.
"Africa can be seen as an island of forests in a sea of grass," he said. "There are all sorts of refuges that occur and the great biodiversity of Africa emerges through that. ... Nature constantly experiments in isolated evolution, and this happens to have occurred in our own evolutionary tree, and that's just really neat."
But Berger brushed off the comparison to Homo floresiensis. Southern Africa isn't an island, he said, and Homo naledi did not evolve in isolation.
"We have a very healthy population of individuals that survived for millions of years and are clearly well adapted to their environment," Berger said. "That has profound implications. You can't just write them off."
Berger and Hawks hedged when asked where Homo naledi might fit on the human family tree.
The late age for the Dinaledi skeletons suggests that the species survived for many years, but more research is needed to pin down when it first evolved. The species may have emerged near the root of the Homo genus, during an initial phase of diversification that gave rise to Homo habilis and other primitive species. Or it could have branched off later, and may be even more closely related to Neanderthals and modern humans than Homo erectus is.
But both said it might be more accurate to think of human evolution as a stream rather than a branching tree. Tributaries may split off from the main waterway and then loop back; species may diverge, then interbreed. Naledi, with its amalgam of advanced and primitive features, could be a result of hybridization. It may also have contributed to the human gene pool: research suggests that many modern humans retain traces of an archaic species in our DNA.
In all likelihood, Hawks said, the full story of human evolution has not been uncovered yet. If a species such as Homo naledi survived for millions of years without us realizing it, what else might the fossil record be hiding?
"We keep finding stuff that we didn't think existed," Hawks said. "This is not the first, and it's not going to be the last."
You have married now Tim, you shouldn't be dating other people. Especially people so old.
Quotewas so narrow and difficult to access that Berger had to seek out an all-women team of petite, extremely agile spelunkers
:lol: Of course it was!
Quote from: Eddie Teach on February 10, 2017, 04:32:44 PM
What ever happened to that guy? Did Cdm ban him? :hmm:
Why would I ban that moron? He's still looking for Iraqi WMDs. Found some castor beans, made an 87-slide deck in .ppt about it.
I dunno.
Is lacrosse banned or did he just get bored?
Quote from: CountDeMoney on May 21, 2017, 10:26:20 AM
Quote from: Eddie Teach on February 10, 2017, 04:32:44 PM
What ever happened to that guy? Did Cdm ban him? :hmm:
Why would I ban that moron?
because you are a trigger happy mod? :)