Finding showing human ancestor older than previously thought offers new insights into evolution

Modern humans never co-existed with Homo erectus -- a finding counter to previous hypotheses of human evolution—new excavations in Indonesia and dating analyses show. The research, reported in the journal PLoS One, offers new insights into the nature of human evolution, suggesting a different role for Homo erectus than had been previously thought.

The work was conducted by the Solo River Terrace (SoRT) Project, an international group of scientists directed by anthropologists Etty Indriati of Gadjah Mada University in Indonesia and Susan Antón of New York University.

Homo erectus is widely considered a direct human ancestor—it resembles modern humans in many respects, except for its smaller brain and differently shaped skull—and was the first of our ancestors to migrate out of Africa, approximately 1.8 million years ago. Homo erectus went extinct in Africa and much of Asia by about 500,000 years ago, but appeared to have survived in Indonesia until about 35,000 to 50,000 years ago at the site of Ngandong on the Solo River. These late members of Homo erectus would have shared the environment with early members of our own species, Homo sapiens, who arrived in Indonesia by about 40,000 years ago.

The existence of the two species simultaneously has important implications for models about the origins of modern humans. One of the models, the Out of Africa or replacement model, predicts such overlap. However, another, the multiregional model, which posits that modern humans originated as a result of genetic contributions from hominin populations all around the Old World (Africa, Asia, Europe), does not. The late survival of Homo erectus in Indonesia has been used as one line of support for the Out of Africa model.

However, findings by the SoRT Project show that Homo erectus' time in the region ended before modern humans arrived there. The analyses suggest that Homo erectus was gone by at least 143,000 years ago—and likely by more than 550,000 years ago. This means the demise of Homo erectus occurred long before the arrival of Homo sapiens.

"Thus, Homo erectus probably did not share habitats with modern humans," said Indriati.

The SoRT Project's investigations occurred in Ngandong and Jigar, two sites in the "20-meter terrace" of the Solo River, Indonesia. The sediments in the terrace were formed by the flooding of the ancient river, but currently sit above the Solo River because the river has cut downward through time. The terrace has been a rich source for the discovery of Homo erectus and other animal fossils since the 1930s.

As recently as 1996, a research team dated these sites of hominin, or early human, fossils to as young as 35,000-50,000 years old. The analyses used a technique that dates teeth, and thus provided ages for several animals discovered at the sites. However, other scholars suggested the sites included a mixture of older hominins and younger animals, raising questions about the true age of the hominin remains.

The goal of the SoRT team, which included both members of the 1996 group and its critics, was to understand how the sites in the terrace formed, whether there was evidence for mixing of older and younger remains, and just how old the sites were.

Since 2004, team members have conducted analyses of animal remains, geological surveys, trenching, and archaeological excavations. The results from all of these provide no evidence for the mixing of older and younger remains. All the evidence suggests the sites represent just a short time period.

"The postmortem damage to the animal remains is consistent and suggests very little movement of the remains by water," explained Briana Pobiner, the project's archaeologist and a paleoanthropologist at the Smithsonian Institution's National Museum of Natural History. "This means that it is unlikely that very old remains were mixed into younger ones."

In addition, clues from the sediments exposed during excavation suggest to the projects' geoarchaeologists, Rhonda Quinn, Chris Lepre, and Craig Feibel, of Seton Hall, Columbia, and Rutgers universities, that the deposits occurred over a short time period. The teeth found in different excavation layers at Jigar are also all nearly identical in age, supporting the conclusion that mixing across geological periods did not occur.

"Whatever the geological age of the sites is, the hominins, animals, and sediments at Ngandong and Jigar are all the same age," said project co-leader Susan Antón.

The team applied two different dating techniques to the sites. Like earlier work, they used the techniques—U-series and Electron Spin Resonance, or ESR—that are applied to fossilized teeth. They also used a technique called argon-argon dating that is applied to volcanic minerals in the sediments. All three methods use radioactive decay in different ways to assess age and all yielded robust and methodologically valid results, but the ages were inconsistent with one another.

The argon-argon results yielded highly precise ages of about 550,000 years old on pumices—very light, porous volcanic products found at Ngandong and Jigar.

"Pumices are hard to rework without breaking them, and these ages are quite good, so this suggests that the hominins and fauna are this old as well," said project geochronologist Carl Swisher of Rutgers University.

By contrast, the oldest of the U-series and ESR ages, which were conducted at Australian National University by Rainer Grün, are just 143,000 years.

The difference in the ages means that one of the systems is providing an age for something other than the formation of the sites and fossils in them. One possibility is that the pumices are, in fact, reworked, or mixed in, from older rocks. The other possibility is that the ESR and U-series ages are dating an event that occurred after the sites were formed, perhaps a change in the way groundwater moved through the sites.

Either way, the ages provide a maximum and a minimum for the sites – and both of these ages are older than the earliest Homo sapiens fossils in Indonesia. Thus, the authors concluded that the idea of a population of Homo erectus surviving until late in time in Indonesia and potentially interacting with Homo sapiens seems to have been disproven.

From PhysOrg

Scientists wish to exhume da Vinci's body

The legend of Leonardo da Vinci is shrouded in mystery: How did he die? Are the remains buried in a French chateau really those of the Renaissance master? Was the "Mona Lisa" a self-portrait in disguise?

A group of Italian scientists believes the key to solving those puzzles lies with the remains — and they say they are seeking permission from French authorities to dig up the body to conduct carbon and DNA testing.

If the skull is intact, the scientists can go to the heart of a question that has fascinated scholars and the public for centuries: the identity of the "Mona Lisa." Recreating a virtual and then physical reconstruction of Leonardo's face, they can compare it with the smiling face in the painting, experts involved in the project told The Associated Press.

"We don't know what we'll find if the tomb is opened, we could even just find grains and dust," says Giorgio Gruppioni, an anthropologist who is participating in the project. "But if the remains are well kept, they are a biological archive that registers events in a person's life, and sometimes in their death."

The leader of the group, Silvano Vinceti, told the AP that he plans to press his case with the French officials in charge of the purported burial site at Amboise Castle early next week.

But the Italian enthusiasm may be premature.

In France, exhumation requires a long legal procedure, and precedent suggests it's likely to take even longer when it involves a person of great note such as Leonardo.

Jean-Louis Sureau, director of the medieval-era castle located in France's Loire Valley, said that once a formal request is made, a commission of experts would be set up. Any such request would then be discussed with the French Ministry of Culture, Sureau said.

Leonardo moved to France at the invitation of King Francis I, who named him "first painter to the king." He spent the last three years of his life there, and died in Cloux, near the monarch's summer retreat of
Amboise, in 1519 at age 67.

The artist's original burial place, the palace church of Saint Florentine, was destroyed during the French Revolution and remains that are believed to be his were eventually reburied in the Saint-Hubert Chapel near the castle.

The tombstone says simply, "Leonardo da Vinci;" a notice at the site informs visitors they are the presumed remains of the artist, as do guidebooks.

"The Amboise tomb is a symbolic tomb; it's a big question mark," said Alessandro Vezzosi, the director of a museum dedicated to Leonardo in his Tuscan hometown of Vinci.

Vezzosi, who is not involved in the project, said that investigating the tomb could help identify the artist's bones with certainty and solve other questions, such as the cause of his death. He said he asked to open the tomb in 2004 to study the remains, but the Amboise Castle turned him down.

As for the latest Italian proposal, Vinceti says preliminary conversations took place several years ago and he plans to follow up with a request next week to set up a meeting to explain the project in detail. This would pave the way for a formal request, he said.

The group of 100 experts involved in the project, called the National Committee for Historical and Artistic Heritage, was created in 2003 with the aim of "solving the great enigmas of the past," said Vinceti, who has written books on art and literature.

Arguably the world's most famous painting, the "Mona Lisa" hangs in the Louvre in Paris, where it drew some 8.5 million visitors last year. Mystery has surrounded the identity of the painting's subject for centuries, with speculation ranging from the wife of a Florentine merchant to Leonardo's own mother.

That Leonardo intended the "Mona Lisa" as a self-portrait in disguise is a possibility that has intrigued and divided scholars. Theories have abounded: Some think that Leonardo's taste for pranks and riddles might have led him to conceal his own identity behind that baffling smile; others have speculated that, given Leonardo's presumed homosexuality, the painting hid an androgynous lover.

Some have used digital analysis to superimpose Leonardo's bearded self-portrait over the "Mona Lisa" to show how the facial features perfectly aligned.

If granted access to the grave site, the Italian experts plan to use a miniature camera and ground-penetrating radar — which produces images of an underground space using radar waves_ to confirm the presence of bones. The scientists would then exhume the remains and attempt to date the bones with carbon testing.

At the heart of the proposed study is the effort to ascertain whether the remains are actually Leonardo's, including with DNA testing.

Vezzosi questions the feasibility of a DNA comparison, saying he is unaware of any direct descendants of Leonardo or of tombs that could be attributed with certainty to the artist's close relatives.

Gruppioni said DNA extracted from the bones could also eventually be compared to DNA found elsewhere. For example, Leonardo is thought to have smudged colors on the canvas with his thumb, possibly using saliva, meaning DNA might be found on his paintings, though Gruppioni conceded this was a long shot.

Even in the absence of DNA testing, other tests could provide useful information, including whether the bones belonged to a man or woman, and whether the person died young or old.

"We can have various levels of probability in the attribution of the bones," Gruppioni said. "To have a very high probability, DNA testing is necessary."

The experts would also look for any pathology or other evidence of the cause of death. Tuberculosis orsyphilis, for example, would leave significant traces in the bone structure, said Vinceti.

In the best-case scenario — that of a well-preserved skull — the group would take a CAT scan and reconstruct the face, said Francesco Mallegni, an anthropology professor who specializes in reconstructions and has recreated the faces of famous Italians, including Dante.

Even within the committee, experts are divided over the identity of the "Mona Lisa."

Vinceti believes that a tradition of considering the self-portrait to be not just a faithful imitation of one's features but a representation of one's spiritual identity may have resonated with Leonardo.

Vezzosi, the museum director, dismissed as "baseless and senseless" the idea that the "Mona Lisa" could be a self-portrait of Leonardo.

The painting is "like a mirror: Everybody starts from his own hypothesis or obsession and tries to find it there," Vezzosi said in a telephone interview.

He said most researchers believe the woman may have been either a concubine of the artist's sponsor, the Florentine nobleman Giuliano de Medici, or Lisa Gherardini, the wife of a rich silk merchant, Francesco del Giocondo. The traditional view is that the name "Mona Lisa" comes from the silk merchant's wife, as well as its Italian name: "La Gioconda."

From the Associated Press

The Science and Entertainment Exchange: Best. Idea. Ever.

The Science & Entertainment Exchange was first brought to my attention in early August when The Skeptics Guide to the Universe podcast had an interview with Jennifer Ouelette. With a background in both media and archaeology, and a passion for science education, something like this is a dream come true.

So what exactly is the Science and Entertainment Exchange? For those of you who aren’t aware, here is a bit of information:

The Science & Entertainment Exchange is a program of the National Academy of Sciences that provides entertainment industry professionals with access to top scientists and engineers to help bring the reality of cutting-edge science to creative and engaging storylines.

The portrayal of science – its practitioners, its methods, its effects – has often posed a challenge to the entertainment community. Though it has inspired some of the most intelligent and compelling storylines, science’s many complexities have confounded even the most talented writer, director, or producer, time and again pitting creative license against scientific authenticity and clarity.

Likewise, the scientific community has struggled to find an effective conduit through which it can communicate its story accurately and effectively. Though many of the world’s biggest problems require scientific solutions, finding a way to translate and depict scientific findings so that reach a wide audience has required a sounding board that has often been missing.

The Science & Entertainment Exchange bridges this gap and addresses the mutual need of the two communities by providing the credibility and the verisimilitude upon which quality entertainment depends – and which audiences have come to expect. Drawing on the deep knowledge of the scientific community, we can collaborate on narrative and visual solutions to a variety of problems while contributing directly to the creativity of the content in fresh and unexpected ways.

Spanning the range of science topics, The Exchange can find experts that will work  to identify and effectively portray the science details that complement a storyline. They can help flesh out ideas that depend upon accurate details relating to insects, extraterrestrial life, unusual Earth-based life forms, or the mysteries of oceans. They can refine concepts relating to emerging science concepts in areas such as space travel, multiple dimensions, nanotechnology, computer technology, and engineering. They can find experts in environmental and ecological issues, health, medicine, and disease, and U.S. educational practices. The Exchange is also well positioned to work  on public policy issues that relate to science such as stem cell research, global climate change, and teaching about evolution and the nature of science.

Now that is sexy!

Interested in more information?  Head over to their website or check out their blog.

Paleontologists brought to tears, laughter by Creation Museum

We found this story in the Sexy Archaeology inbox and thought it was worth sharing with all you sexy, dirt digging scientists.

For a group of paleontologists, a tour of the Creation Museum seemed like a great tongue-in-cheek way to cap off a serious conference.

But while there were a few laughs and some clowning for the camera, most left more offended than amused by the frightening way in which evolution -- and their life's work -- was attacked.

"It's sort of a monument to scientific illiteracy, isn't it?" said Jerry Lipps, professor of geology, paleontology and evolution at University of California, Berkeley.

"Like Sunday school with statues... this is a special brand of religion here. I don't think even most mainstream Christians would believe in this interpretation of Earth's history."

The 27 million dollar, 70,000-square-foot (6,500-square-metre) museum which has been dubbed a "creationist Disneyland" has attracted 715,000 visitors since it opened in mid-2007 with a vow to "bring the pages of the Bible to life."

Its presents a literal interpretation of the Bible and argues that believing otherwise leads to moral relativism and the destruction of social values.

Creationism is a theory not supported by most mainstream Christian churches.

Lisa Park of the University of Akron cried at one point as she walked a hallway full of flashing images of war, famine and natural disasters which the museum blames on belief in evolution.

"I think it's very bad science and even worse theology -- and the theology is far more offensive to me," said Park, a professor of paleontology who is an elder in the Presbyterian Church.

"I think there's a lot of focus on fear, and I don't think that's a very Christian message... I find it a malicious manipulation of the public."

Phil Jardine posed for a picture below a towering, toothy dinosaur display.

The museum argues that the fossil record has been misinterpreted and that Tyrannosaurus Rex was a vegetarian before Adam and Eve bit into that sin-inducing apple.

Jardine, a palaeobiologist graduate student from the University of Birmingham, was having fun on the tour, but told a reporter that he was disturbed by the museum's cartoonish portrayal of scientists and teachers.

"I feel very sorry for teachers when the children who come here start guessing if what they're being taught is wrong," Jardine said.

Arnie Miller, a palentologist at the University of Cincinnati who was chairman of the convention, said he hoped the tour would introduce the scientists to "the lay of the land" and show them firsthand what's being put forth in a place that has elicited vehement criticism from the scientific community.

"I think in some cases, people were surprised by the physical quality of the exhibits, but needless to say, they were unhappy with things that are inaccurately portrayed," he said.

"And there was a feeling of unhappiness, too, about the extent to which mainstream scientists and evolutionists are demonized -- that if you don't accept the Answers in Genesis vision of the history of Earth and life, you're contributing to the ills of society and of the church."

Daryl Domning, professor of anatomy at Howard University, held his chin and shook his head at several points during the tour.

"This bothers me as a scientist and as a Christian, because it's just as much a distortion and misrepresentation of Christianity as it is of science," he said.

"It's not your old-time religion by any means."

From Physorg.com