Peștera cu Oase
Revealed: the face of the first European
35 000-year-old skull fragments found in Romania are made flesh by scientists.
By Steve Connor, Science Editor, The Independent newspaper, Britain.
Text and photo for this report:
Monday, 4 May 2009
Forensic artist Richard Neave used skull and jawbone fragments found in a cave to build this likeness of an early European.
This is the face of the first anatomically-modern human to live in Europe. It belonged to a man – or woman – who inhabited the ancient forests of the Carpathian Mountains in what is now Romania about 35 000 years ago.
The artist's reconstruction – a face that could be male or female – is based on the partial skull and jawbone found in a cave where bears were known to hibernate. The facial features indicate the close affinity of these early Europeans to their immediate African ancestors, although it was still not possible to determine the person's sex.
Richard Neave, the forensic artist who reconstructed the facial features in this clay model, based his assessment on a careful measurement of the bone fragments and his long experience of how the soft tissues of the face are built around the bones of the skull.
The reconstruction was made for the forthcoming BBC 2 series The Incredible Human Journey which documents human origins and evolution, from our birthplace in Africa to the long migratory routes that led us to populate the most distant parts of the globe. It is impossible from the bones to determine the skin colour of the individual, although scientists speculate it was probably darker than modern-day Europeans, reflecting a more recent African origin.
Mr Neave's clay head of the "first modern European" now sits on the desk of Alice Roberts, the Bristol University anthropologist who will introduce the BBC series, which is scheduled for screening next Sunday evening on BBC 2. "It's really quite bizarre. I'm a scientist and objective, but I look at that face and think 'Gosh, I'm actually looking at the face of somebody from 40 000 years ago', and there's something weirdly moving about that," Dr Roberts told the Radio Times.
"Richard creates skulls of much more recent humans and he's used to looking at differences between populations. He said the skull doesn't actually look European, or Asian, or African. It looks like a mixture of all of them. And you think, well, that's probably what you'd expect of someone who was among the earliest populations to come to Europe."
Potholers discovered the lower jawbone of the first modern European in 2002 in Pestera cu Oase, the "cave with bones", located in the south-western Carpathians. The remaining fragments of skull were unearthed in 2003.
Scientists have dated the bones using radiocarbon analysis to between 34 000 and 36 000 years ago when Europe was occupied by both Neanderthal man, who had lived in the region for tens of thousands of years, and anatomically-modern humans – Homo sapiens – who had recently arrived on a migratory route from Africa via the Middle East.
Although the skull shares many modern feature of human anatomy, it also displays more archaic traits, such as very large molar teeth, which led some scientists to speculate the skull may belong to a hybrid between Homo sapiens and Neanderthals – an idea discounted by other experts.
Erik Trinkaus, professor of anthropology at Washington University in Missouri, and one of the first specialists to study the bones in detail, said the jaw was the oldest, directly-dated modern human fossil. "Taken together, the material is the first that securely documents what modern humans looked like when they spread into Europe," he said.
Caveful of Clues About Early Humans
Text below from:
By Fredric Heeren
Special to The Washington Post
Monday, September 20, 2004
"Field research" projects often require scientists to endure discomfort and danger to get where they need to be, but not many can trump this summer's expedition to what may be the world's most inaccessible human fossil site, a cave in the foothills of Romania's Carpathian Mountains.
For the seven-member team, the hazards of reaching the site, accessible only by diving using scuba gear through frigid underwater passages, including an active spring and an underground river, and also using climbing gear, were worth it. Their finds may help answer some of the most hotly debated questions about early humans: Did they make love or war with Neanderthals? Were Neanderthals intellectually inferior to our human ancestors?
Photo: A researcher shows part of a skull found in the Peștera cu Oase cave in Romania. (Erik Trinkaus And Ricardo Rodrigo)
This may be asking a lot of the scanty fossil remains of three individuals who lived 35 000 years ago, but their age makes them the earliest modern humans ever found in Europe. The uniqueness of the site, which was discovered in 2002, was motivation enough for the specially trained team to devote a month of cold and dangerous underground journeys to reach and excavate the site known as Peștera cu Oase -- Cave with Bones.
The team included a Portuguese shipwreck diver and archaeologist, a French Neanderthal specialist, a Romanian cave biologist, and the three Romanian adventurers who discovered the human fossils while exploring submerged caves.
At the start of each day's nine-hour excursion underground, team members stepped into a frigid mountain river that flows into a cave, their helmet-mounted lights piercing the perpetual fog of the cave's 100 percent humidity. As the equipment-laden crew sloshed past stalagmites, the cave narrowed and the air temperature plunged from the 90s to the upper 40s Fahrenheit.
Further in, the ceiling lowered until they were forced, first, to swim on their backs and, finally, don their diving masks and enter a narrow, 80-foot-long underwater passage called "the sump." Underwater visibility was about three feet.
Lead diver Stefan Milota warned newcomers: "Do you know how long it takes to die in the sump? Twenty, thirty seconds and you're gone."
When Milota first told biologist Oana Moldovan in 2002 that he had found a human jaw in a closed-off chamber, Moldovan wanted to see for herself -- even though she had to learn to dive to do it.
"I had to see the cave," said Moldovan, now the team's project coordinator. "So I was very motivated. But I was very scared. My first time, it was horrible."
Surfacing inside another chamber, the divers peeled off their wetsuits and changed into warm clothing. The next step was climbing "the pit," a series of underground cliff faces that the cavers scaled in dizzying climbs up a succession of ladders they had carried in earlier.
Finally, to reach the gallery of bones, they passed through "the gate," an opening that Milota had first spotted when he felt warmer air emerging. He and his explorer friends widened it just enough for the thinnest of them to squeeze through. Each day, the cavers had to plunge head-and-arms first at a slight uphill angle, then wriggle and rest, wriggle and rest, to cover the final, winding 10 feet.
Inside the final gallery, there was room for only three workers at a time because the rest of the floor was covered with thousands of fragile fossils. Most belonged to a cave bear species that became extinct 10 000 years ago -- animals almost twice as big as today's bears.
The original entrance caved in long ago, sealing off the galleries from the outside. After two labs independently yielded radiocarbon dates of about 35 000 years for the jaw, or mandible, that Milota had found, more scientists took interest. In a 2003 expedition, they found a full face and an ear region of a skull from two more individuals, with puzzling traits that suggested a mix of Neanderthal and human features, something scientists had thought impossible.
Anthropologist Erik Trinkaus of Washington University in St. Louis and Joao Zilhao of Cidade University in Lisbon joined this summer's excavation to look for more specimens and to try to find out how the human remains got into the cave. Because they turned up no sign of torches, charcoal or tools, they concluded that the human remains had washed in through fissures.
Caveful of Clues About Early Humans
The biggest payoff of the summer was the discovery of more fragments of the three individuals found earlier, which added to the evidence of hybrid traits.
Trinkaus said the Oase fossils show features of modern humans: projecting chin, no brow ridge, a high and rounded brain case. But they also have clear archaic features that place them outside the range of variation for modern humans: a huge face, a large crest of bone behind the ear and enormous teeth that get even larger toward the back.
Trinkaus made a CT scan of the face to measure the unerupted teeth. "To find wisdom teeth that big," he said, "you have to go back 500 000 years."
The team considered whether early humans might have interbred with other hominids with Neanderthal-like features, but "in this time period," said Trinkaus, "the only archaic humans those modern humans could have interbred with were Neanderthals." The mosaic of Neanderthal and modern traits remind Trinkaus and Zilhao of similar traits they found in a 25 000-year-old fossil of a child in Portugal.
Researchers pondering why the Neanderthals died out have speculated that early humans might have killed them off, and Zilhao said the signs of interbreeding do not exclude that possibility. "We know that even when people fight, the winner might kill the males and keep the females from the other side," he said.
The signs of interbreeding challenge the standard wisdom that Neanderthals were a distinct, less intelligent species.
"If you look at the archaeological evidence," argued Trinkaus, "which includes things like burials, there is very little difference between what we find associated with Neanderthals and what we find associated with early modern humans -- from the same time period."
Richard Klein of Stanford University thinks this holds true only until about 50 000 years ago, when modern human behavior changed dramatically. "There could have been interbreeding," Klein conceded. "But all the genetic evidence we have suggests that, if it occurred, it was remarkably rare."
Six years ago, Zilhao and Francesco d'Errico of the University of Bordeaux published evidence that Neanderthals independently invented and used personal ornamentation. Zilhao said these finds have changed the view that Neanderthals were an inferior species.
Klein said the picture is changing, but not in that direction. The real question today, he said, is "whether modern humans fully replaced the Neanderthals or simply swamped them" genetically, with greater numbers. "And it may never be possible to say."
Wisdom of bonesText below from: Jones, Dan, New Scientist, 02624079, 3/3/2007, Vol. 193, Issue 2593
The Lagar Velho child unearthed in Portugal isn't the only skeleton that has been identified as a possible human-Neanderthal hybrid. In the past few years Erik Trinkaus of Washington University in St Louis, Missouri, has amassed more fossil evidence that he says tells the same story.
In 2002, a team of cavers discovered a human jawbone in a cave called Peștera cu Oase ("cave with bones") in south-west Romania. Carbon dating put the remains at about 40 000 years old, which made it the earliest unambiguous modern human specimen found in Europe.
Even a single bone can contain features characteristic of either Neanderthals or modern humans. According to Trinkaus, the Oase 1 jawbone has a mixture of both. Though less dramatically a hybrid than the Lagar Velho child, the find still suggests interbreeding.
Occlusal view of the Oase 1 right mandibular molars from M1 to M3. The scale bar is in millimeters.
Further exploration of Peștera cu Oase has yielded even greater treasures. In January, Trinkaus and colleagues described a human skull which they called Oase 2 (Proceedings of the National Academy of Sciences, vol 104, p 1165). This seems to be the remains of an adolescent who also died about 40 000 years ago and, like the Oase 1 sample, has a mixture of modern and Neanderthal features.
Trinkaus has also reanalysed some 35 000-year-old human bones discovered in 1952 at another site in Romania, Peștera Muierii, and says that these too show a mosaic of features.
To Trinkaus, these finds paint a fairly clear picture of the evolution of humans in Europe. "Early European humans are basically modern -- their anatomy is overwhelmingly like that of the ancestral African population -- but in individual specimens you find features that are absent from or have already been lost from the ancestral African group," says Trinkaus. "By far the easiest way to explain this is through interbreeding."
This is not to suggest that the Lagar Velho boy or the Romanian specimens are the product of occasional, one-off meetings between Neanderthals and Cro-Magnons. Trinkaus suggests a more radical notion: the hybrids come from a population of humans that regularly interbred with Neanderthals. In other words, they are the result of generations of sex between Neanderthals and Cro-Magnons.
Not everyone agrees with his argument. Human ancestry, like beauty, is in the eye of the beholder. For instance, Chris Stringer, a palaeontologist at the Natural History Museum in London, is not convinced that the Lagar Velho boy is evidence of hybridisation. "In many respects, including face and teeth, it's a modern human; the only place where it might look archaic is in the body proportions, but to me they overlap with those of other modern humans," he says. "I just don't see the Neanderthal influence that Erik does."
Stringer believes more fossil evidence is required. "When we have a reasonable sample of early moderns dating from the same time period as the main sample of Neanderthals in Europe -- 40 000 to 70 000 years ago -- from regions such as western Asia or north Africa, then we will be able to see what their morphology was and will be able to better determine whether features have come from Neanderthal admixture."
Earliest modern humans in Europe found
By Tony Fitzpatrick
Sept. 22, 2003 -- A research team co-directed by Erik Trinkaus, Ph.D., professor of anthropology at Washington University in St. Louis, has dated a human jawbone from a Romanian bear hibernation cave to between 34 000 and 36 000 years ago. That makes it the earliest known modern human fossil in Europe.
Other human bones from the same cave -- a temporal bone, a facial skeleton and a partial braincase -- are still undergoing analysis, but are likely to be the same age. The jawbone was found in February 2002 in Peștera cu Oase — the "Cave with Bones" — located in the southwestern Carpathian Mountains. The other bones were found in June 2003.
A human jawbone (left), dated to between 34 000 and 36 000 years ago, along with a facial skeleton (center) and a temporal bone (right), both of which are still undergoing analysis, but are likely to be the same age as the jawbone.
A human jawbone (left), dated to between 34 000 and 36 000 years ago, along with a facial skeleton (center) and a temporal bone (right), both of which are still undergoing analysis, but are likely to be the same age as the jawbone.
Photo: Erik Trinkaus
Oblique view of the Oase 1 mandible.
The results on the jawbone will be published the week of Sept. 22 in the Proceedings of the National Academy of Sciences (PNAS; www.pnas.org) Online Early Edition. A report on the other bones will appear in an upcoming issue of the Journal of Human Evolution (http://www.sciencedirect.com/science/journal/00472484). The finds should shed much-needed light on early modern human biology.
"The jawbone is the oldest directly dated modern human fossil," said Trinkaus, the Mary Tileston Hemenway Professor of Anthropology in Arts & Sciences. "Taken together, the material is the first that securely documents what modern humans looked like when they spread into Europe. Although we call them 'modern humans,' they were not fully modern in the sense that we think of living people."
To determine the fossils' implications for human evolution, Trinkaus and colleagues performed radiocarbon dating of the jawbone (dating of the other remains is in progress) and a comparative anatomical analysis of the sample. The jawbone dates from between 34 000 and 36 000 years ago, placing the specimens in the period during which early modern humans overlapped with late surviving Neandertals in Europe.
Oase 1 in norma lateralis left. The scale bar is in centimeters.
Most of their anatomical characteristics are similar to those of other early modern humans found at sites in Africa, in the Middle East and later in Europe, but certain features, such as the unusual molar size and proportions, indicate their archaic human origins and a possible Neandertal connection.
The researchers document that these early modern humans retained some archaic characteristics, possibly through interbreeding with Neandertals. Nevertheless, because few well-dated remains from this period have been found, the fossil remains help to fill in an important phase in modern human emergence. Trinkaus with jaw bone David Kilper/WUSTL Photo Erik Trinkaus, professor of anthropology in Arts & Sciences at Washington University in St. Louis, with a human jawbone from a Romanian bear cave. The jawbone was dated to between 34 000 and 36 000 years ago, making it the earliest known modern human fossil in Europe.
"The specimens suggest that there have been clear changes in human anatomy since then," said Trinkaus. "The bones are also fully compatible with the blending of modern human and Neandertal populations. Not only is the face very large, but so are the jaws and the teeth, particularly the wisdom teeth. In the human fossil record, you have to go back a half-million years to find a specimen that has bigger wisdom teeth."
Medial views of the Oase 1 mandibular rami. The scale bar is in centimeters.
The jawbone was found by three Romanian cavers, who contacted Oana Moldovan, director of the Institutul de Speologie, a cave research institute in Cluj, Romania. Moldovan in turn, recognizing the importance of the jawbone, contacted Trinkaus.
The two met in Europe in May 2002, and Trinkaus brought the jawbone temporarily to Washington University for analysis. Trinkaus, Moldovan, the cavers and Ricardo Rodrigo, a Portuguese archaeologist, returned to the cave in June 2003 to produce a map and survey the cave's surface. In the process, the cavers and Rodrigo found the facial skeleton, temporal bone and other pieces that are now undergoing analysis.
Since then, Trinkaus and Moldovan have assembled an international team to document and excavate the cave and analyze the material after it comes out from the cave. The cave was primarily used for bear hibernation. It is not known how the human bones got into the cave, but Trinkaus says one possibility is that early humans used the cave as a mortuary cave for the ritual disposal of human bodies. Some of the bear bones were rearranged by humans, documenting past human activities in the cave.
"The jaw was originally found sitting by itself; the material this summer was found mixed up with bear bones," Trinkaus said. "After they found the face, they collected everything on the surface that might be human, packaged it up and brought it out of the cave. Some of the pieces that they carried out of the cave are, in fact, bear. We know that more of the skull is in the same place, but it was buried or not recognized at the time."
The team plans to return to Romania next summer to continue the scientific analysis of the cave and its contents.
Cave Diving for Europe's Past
Interview with Romanian explorer Stefan Milota
New Scientist, June 3, 2006
By Fredric Heeren
Four years ago, Romanian explorer Stefan Milota made an amazing discovery in previously unknown caves deep within his country's Carpathian mountains: a jawbone that turned out to be the oldest modern human fossil found in Europe. More surprisingly, this mandible showed features that suggested early modern humans might have interbred with Neanderthals. With his climbing buddies at the explorers' club Pro Acva Grup, Milota helped scientists make the subterranean trek to Peștera cu Oase (Cave with Bones) for three seasons of dark, 10-hour days, much of them spent climbing, swimming or diving through tight passages. Fredric Heeren followed the cave divers through the underwater passages on one such trip to ask Milota how he found the 35 000-year-old human remains — an hour’s journey deep within a Carpathian mountain.
When did you start cave diving?
In 1996 I was involved in an ecological project to clean a lake in Romania that was littered with bottles and junk. It was a karstic lake, in which limestone erosion had formed sinkholes and underground streams. At the bottom there was a cave, and I ventured inside. That was my first cave dive. After that I started diving a lot, here in Romanian caves.
And how did you discover the unexplored caves leading to the fossils?
I was with two friends who I had met in the world of climbing, and we were lucky enough to find a part of a karstic cave system in Romania that no one knew about. Most of the caves here were discovered hundreds of years ago. We spent two years exploring and mapping this system. There was a cave where water entered the mountain, and another far away where the water exits. We searched for the junction and found it, and then started finding many branches and galleries. At deeper levels there are submerged passages called sumps, and you need diving gear to explore these.
How did you find the gallery you named Peștera cu Oase?
In February 2002 I dived through a narrow sump about 25 metres long, hoping it might lead somewhere new. It led to a whole new network of caverns. I surfaced in a gallery and walked through until I saw a chimney that went up and up. I climbed a little bit but I was alone and I thought, if I fall, no one will find me. So I came back later with my friend Laurentiu Sarcina. He climbed part way up the chimney and looked up and could see it went way up to near the top of the mountain. He told me, "Wow, there's a big gallery up there." Next time we came with another guy, Adrian Bilgar, and the three of us had all the equipment we needed to climb that chimney. Then we could reach the high gallery.
What did you find there? At first we only saw a few bones of giant extinct bears, twice as big as today's bears. But then I found a small crack where I felt a current of warmer air. We dug it out and broke some stone around it until we had created a small passage. I kept wriggling further and digging because I knew from the air current that there was something big on the other side. Sure enough, when I pulled myself into the new gallery, I came face to face with three bear skulls. When I stood up, my headlamp showed the whole floor was covered with thousands of bones, partially embedded in the calcite floor.
This gallery had been closed off for a long time?
For thousands of years. The bears walked in from an entrance above, but this caved in long ago. We walked carefully around the bones — some ibex, some giant deer — and then we entered another gallery and I saw a human jawbone. It looked different from a typical human one. It was massive, but I was almost sure that it was human.
How was the jaw positioned?
That was the most bizarre thing: it was resting on top of the calcite floor, not embedded into it like the other bones. That is why most of the archaeologists didn't trust us at first. We searched but didn't find any more human fossils on that visit. We decided to leave the mandible on the cave floor just as we found it. When we came out we called researchers at the Institute of Speleology in Cluj and eventually we were put in touch with the archaeologist Joao Zilhao from the University of Bristol, in England. Joao didn't believe that we had found the skull in that position. He said, "You don't just find human mandibles lying on floors." So he sent Ricardo Rodrigo, an archaeologist based in Lisbon who dives for the Portuguese National Centre of Nautical and Underwater Archaeology, to the fossil cave with us.
How do you explain the position of the mandible?
Finally, just this season, we realised where the mandible came from. Right above where we found it there is a slope. It looks like an animal in recent times had dug a small hole in the sediment there and had displaced the mandible which had rolled down the slope to that strange position.
How old was it?
A small piece of the jawbone was sent for radiocarbon dating. Two labs agreed on a result of about 35 000 years, making it the oldest modern human fossil in Europe.
Did you find any more human remains?
Together with Ricardo Rodrigo, we searched the galleries for two weeks, but we didn't find any more human bones until the last day. Then we found the whole face of another skull. That was about midnight. When we came out of the cave Ricardo called Joao on his mobile phone. We all celebrated. No one thinks these are fakes any more. Since then we have provided support for scientists for three field seasons. Now we have an almost complete skull and other bone fragments from a second 35 000-year-old individual. The archaeologists haven't found any torches or tools to show that these people lived in the caves, so it lo0oks like they got washed in from above.
What draws you to spend these long hours climbing and diving in the cold and the dark?
It isn't just for the cave diving. I've spent a lot of time here. Too much. I've lost a girlfriend because of it. People talk about extreme sports, but for me it is not about that. It is about discovery.
When not climbing or cave diving, Stefan Milota runs Fane Holds in Timisoara, Romania, a company that designs and manufactures climbing holds. After his initial fossil find in Peștera cu Oase, he worked for three years leading scientists into the caves, where he discovered more ancient remains. For this he shared writing credit on several scientific papers. His greatest pleasure still comes from exploring caves, where he hopes he has more discoveries ahead of him.
Humanity's Strange Face
Stone Age skull stokes debate over what it takes to be human
Inside a Romanian cave last year, an explorer displays a fossil Homo sapiens skull thought to be around 35 000 years old. That discovery has fueled a debate over whether Neandertals and other ancient humanlike species interbred with Stone Age people.
Photo: Romanian Academy, http://www.fredheeren.com/new_sci.htm
In June 2003, three cave researchers prepared for what they hoped would be a return to the Stone Age. The explorers strapped on scuba gear and plunged into a lake in Romania's Carpathian Mountains. These intrepid souls, led by Stefan Milota of Pro Acva Grup in Timisoara, Romania, swam one at a time into a rocky passage that snakes up into an adjacent limestone hillside. At the top of the 80-foot-long channel, they emerged into the musky air of a pitch-dark cave that most of the group had first visited the previous year. Helmet-mounted lights cast a glow over a panorama of bones scattered across the ground.
The group had chanced upon the cave for the first time while exploring the hillside's many fluid-filled conduits. Millennia ago, the deep space would have been accessible on foot, but since then, a massive rockslide has plugged the aboveground entrance.
Upon reaching the cavern in 2002, the investigators saw cave bear bones lying everywhere. The huge creatures may have hibernated there and died after awakening, perhaps lacking the energy to lumber to the surface.
Curiously, a bear skull and leg bone lay atop separate boulders, suggesting that someone had placed them there. Proceeding into another of what turned out to be a series of chambers, the explorers collected the big prize of that first modern visit: a lower jaw that, though massive and thick, looked to be human.
Radiocarbon measurements yielded an age of about 35 000 years for the fossil, making it Europe's oldest securely dated representative of what anthropologists call modern Homo sapiens (SN: 5/10/03, p. 302: Available to subscribers at http://www.sciencenews.org/articles/20030510/note13.asp). However, closer analysis revealed a mix of primitive and modern traits, according to Erik Trinkaus, an anthropologist at Washington University in St. Louis.
Milota and his coworkers returned last year, hoping to find new fossils and map the cave they dubbed Peștera cu Oase, or cave with bones. An even bigger prize awaited them. Amid a pile of bear bones in one chamber sat a partial skull that mimicked the previous find in its mix of seemingly modern and primitive human characteristics. The face was intact, with many teeth in place, and surrounded by several pieces of the individual's brain case. The specimen even retains internal structures of the nose and ears. A piece of another person's cranium lay nearby.
Scientists have yet to establish radiocarbon ages for these fossils. But the new H. sapiens specimens are probably just as old as the Oase (pronounced wa-zee) jaw, says Trinkaus, who now leads efforts to analyze the Romanian discoveries. Together, the cave finds challenge the popular theory that people evolved into our modern form by making a neat evolutionary jump from a more primitive version of H. sapiens sometime around 50 000 years ago, Trinkaus asserted on March 31 at the Paleoanthropology Society's annual meeting in Montreal.
The Oase skull's strange combination of modern and archaic characteristics underscores scientific confusion about how to define anatomically modern humans, Trinkaus adds.
"Paleontologists have created an artificial [anatomical] Rubicon that the Oase fossils violate," he says. "The blend of traits on these specimens contradicts the existence of a straightforward evolutionary process [during the Stone Age] in which modern humans came out of Africa and replaced everyone else."
The Oase skull—which probably came from a 15- or 16-year-old male—resists easy interpretation. "The anatomy of this individual was not particularly modern, while still qualifying overall as that of a modern human," Trinkaus says.
The fossil displays a relatively narrow, high-set nose and distinct chin typical of people today. The shape and positioning of the specimen's internal ear structures also mark it as a modern H. sapiens. Another telling sign appears on the Oase skull's forehead, which lacks a brow ridge typical of Neandertals. Most researchers regard Neandertals as a separate species, Homo neanderthalensis.
Lots of lumps
The biting surface of a third molar tooth from a Homo sapiens specimen found in a Romanian cave exhibits a curious welter of protrusions, which raises questions about its evolutionary heritage.
Photo: Romanian Academy in http://www.sciencenews.org/articles/20040522/bob8.asp
Yet the Romanian fossil also flaunts some strikingly primitive traits. Its molar teeth are considerably larger than those of European H. sapiens that lived 30 000 to 20 000 years ago. In fact, Trinkaus says, the chewing surfaces of the Oase skull's molars are wider than those of the generally bulkier Neandertals.
Moreover, at the back of the Oase individual's mouth, a welter of bumps tops its third molars. No fewer than 11 protrusions of various sizes jut up from each chewing surface. Corresponding H. sapiens molars are far smoother.
A third-molar tooth from another human ancestor, which was recently unearthed in the central Asian nation of Uzbekistan, also displays nearly a dozen bumps. Preliminary work suggests that this tooth belonged to a Neandertal that lived at least 40 000 years ago. Michelle Glantz of Colorado State University in Ft. Collins described that find at the Paleoanthropology Society meeting.
Bump-covered third molars appear in some current species of mammals and may evolve as a by-product of genetic mechanisms that promote larger teeth, Trinkaus speculates.
Aside from the Oase specimen's teeth, the heft of its jaw and the shape of parts of its braincase also hark back to H. sapiens that lived 100 000 years ago or more, he says.
The mix of old and new features on the Romanian fossils adds to suspicion that, on the evolutionary path toward today's people, interbreeding occurred among H. sapiens, Neandertals, and other ancient Homo species to varying extents in different regions, according to Trinkaus and a colleague in the Oase project, Joao Zilhao of Cidade University in Lisbon, Portugal.
That theory previously received a boost with the discovery in Portugal of a 24 500-year-old skeleton that Trinkaus and Zilhao view as a prime example of interbreeding between modern H. sapiens and Neandertals. The child's bones display a potpourri of traits from both species, in the researchers' view.
The Oase fossils contain a different mosaic of characteristics, with more pieces from archaic H. sapiens than from Neandertals. If human evolution hinged on groups of various Stone Age species moving from place to place and interbreeding to some extent along the way, then unpredictable mixes of anatomical features would have been generated in any locality that attracted prehistoric crowds, Trinkaus contends.
He thus takes a skeptical view of traditional efforts to reconstruct neatly branching evolutionary trees of human ancestors by determining whether fossils contain predominantly primitive or advanced traits. Analyses of modern and ancient DNA are also incapable of unraveling the extent to which Neandertals and other Homo species interbred with H. sapiens, in Trinkaus' opinion.
That leaves a big evolutionary question mark punctuating the Romanian discoveries. "We don't fully understand what's going on with the combination of features on these bones," the St. Louis researcher says.
One way to make sense of fossils such as the Portuguese child and the Oase skull is to stop assuming that each ancient Homo species existed on a separate branch of an evolutionary tree, says Trenton W. Holliday of Tulane University in New Orleans. Instead, he proposes, think of human evolution as a braid of several large, winding tributaries, some of which are connected by small streams. Each tributary represents a Homo species; the streams signify gene flow among them.
Most of the larger channels eventually dried out, leaving only one main tributary on which H. sapiens drifted into the present.
Holliday's scenario relies on evidence that many plant and animal species remain cohesive over time, despite some interbreeding with related species that creates fertile offspring with hybrid genetics. In some instances, these offspring display a combination of anatomical features from both parent species; in others, they look like one parent species but possess a blend of DNA sequences from both species.
Interbreeding flourishes where two or more related species share common ground. Scientists refer to these areas as hybrid zones. Novel DNA arrangements can arise in hybrid zones and then spread into the larger populations of each species. In a process that's thought to be especially common among plants, a hybrid population may ultimately evolve into a new species.
Even low levels of genetic give-and-take among closely related Homo species, as suggested by a recent DNA analysis, would have yielded confusing blends of skeletal traits that vary from one region to another, Holliday asserted in the December 2003 Current Anthropology.
Other investigators doubt that interbreeding among ancient Homo species would have yielded individuals with the patchwork of traits observed on the Portuguese and Romanian fossils. Genes directly regulate the shape of only selected skeletal features, notes Daniel Lieberman of Harvard University. Bone responds to myriad influences as a person grows. Parentage from different species is thus hard to detect in fossils, Lieberman says.
The Oase skull may carry hybrid traits, according to some researchers who have received detailed information about it. For all its anatomical eccentricities, the Oase material "fits well within the envelope of modern H. sapiens," says Ian Tattersall of the American Museum of Natural History in New York City.
Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, agrees. Skulls from at least 60 000 years ago in northern Africa display primitive facial features, such as large jaws and teeth, he notes, yet they're attributed to modern H. sapiens.
Another perspective, exemplified by Milford Wolpoff of the University of Michigan in Ann Arbor, folds Neandertals and all other Homo fossils from the past 2 million years into one species, H. sapiens. If that's true, then interbreeding had nothing to do with human evolution.
The debate over the nature of modern H. sapiens doesn't end with fossils. A related issue concerns whether archaeological discoveries support the assumption that a cultural and behavioral revolution between 50 000 and 30 000 years ago set people apart from Neandertals and other species in our evolutionary family.
Western European sites from that period show many signs of cultural advances. These include art and ornaments of various kinds, graves, bone tools, and stone blades.
Christopher S. Henshilwood of the African Heritage Research Institute in Cape Town, South Africa, and Curtis Marean of Arizona State University in Tempe reviewed Stone Age finds from Europe and elsewhere in the December 2003 Current Anthropology. They concluded that modern human behavior emerged as H. sapiens evolved over the past 200 000 years, not in a late revolution.
People living in tropical parts of Africa prior to 50 000 years ago were the intellectual equals of those who later trekked into Europe, Henshilwood and Marean assert. There, a frigid climate, competition for resources in larger populations, and other environmental pressures encountered by ancient Europeans instigated innovations in tool making and hunting, these researchers propose.
They point to a growing body of evidence that many behaviors previously attributed only to late Stone Age people stretch back at least 100 000 years in Africa and occurred in European and Middle Eastern Neandertals from around 130 000 to 28 000 years ago.
In 75 000-year-old sediments at South Africa's Blombos Cave, for instance, Henshilwood has unearthed etched pieces of ocher and—as described in the April 16 Science—numerous perforated ostrich eggshell shards. Late Stone Age Europeans had no monopoly on body decorations and other symbolic products, he argues.
Although intriguing, such finds offer at best hazy glimpses of ancient societies, Trinkaus remarks. However, he suspects that cultural evolution has deep roots in the Stone Age.
Meanwhile, the fossil hunt at Oase resumes this summer. Researchers seek radiocarbon ages for the bones of bears and H. sapiens and an explanation of how people's remains ended up in the cave. "We're beyond the glory stage at Oase," Trinkaus says. "We're entering the hard-work stage."
Cave Bears may have been CarnivorousAdapted from:
Rather than being gentle giants, new research reveals that Pleistocene cave bears ate both plants and animals and competed for food with the other contemporary large carnivores of the time: hyaenas, lions, wolves, and our own human ancestors.
The study, conducted by an international group of researchers, including Erik Trinkaus, Ph.D., professor of anthropology at Washington University in St. Louis, will appear the week of Jan. 7 in the online version of the Proceedings of the National Academy of Sciences.
Cave bears (Ursus spelaeus) have long fascinated paleontologists and anthropologists, given the abundance of their large skeletal remains in Pleistocene hibernation caves across western Eurasia. For the past 30 years, studies of their bones and teeth, and especially the nitrogen isotopes in their bone protein, have concluded that they were largely vegetarian.
The interpretation of them as vegetarian has evoked an image of gentle giants, feeding on berries and roots. However, new nitrogen isotope data from the Peştera cu Oase in southwestern Romania shows otherwise. Although many of these cave bears appear to have been largely vegetarian, the Oase bears and scattered individuals from other cave sites show that they were sometimes as omnivorous as modern brown bears, including North American Kodiak and grizzly bears.
Nitrogen 15 has one more neutron than the more common nitrogen 14. Animals accumulate Nitrogen 15 in their bodies, and carnivores accumulate more of it than vegetarians do. The cave bears in Peştera cu Oase have high Nitrogen 15 levels, suggesting that they were carnivorous, or possibly cannibalistic. It may be that they got the extra Nitrogen 15 from fish, also.
Source : Washington University in St. Louis