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1. MIAMI (AFP).- The discovery of a 400,000-year-old half skull in Portugal has offered tantalizing hints about a possible ancestor of the Neanderthals, researchers said Monday.
The fossil was unearthed from the Aroeira cave site, and marks the oldest human cranium fossil ever found in Portugal, said the report in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.
But there is plenty of mystery around the skull. Researchers don't know if it was from a male or female, how the person died, or even what form of early human it was.
"There is a lot of question about which species these fossils represent. I tend to think of them as ancestors of the Neanderthals," co-author Rolf Quam, an anthropologist at Binghamton University, State University of New York, told AFP.
"It is not a Neanderthal itself," he added. "It has some features that might be related to the later Neanderthals," including a lump of bone near the ear called the mastoid process.
Researchers say this bone may be related to regulating pressure in the ear, although its exact purpose is unclear.
What researchers can say with certainty is that the skull belonged to an adult, based on the formation of the bones. A couple of teeth found with it appear worn, as if belonging to an adult rather than a child.
They also know its age -- 400,000 years -- based on precision dating of the surrounding stalagmites and sediments.
The same cannot be said for other skulls of its kind found elsewhere in Europe. Some were uncovered years ago, before modern technology existed. In other cases, conditions at the cave site did not allow for precise dating of surrounding rock and sediment.
Researchers have sometimes had to guess at the ages of these skulls, ranging from 200,000 to more than 400,000 years, according to Quam.
The Portuguese skull shares some features with bones uncovered in northern Spain that are some 430,000 years old, and in southern France dating even further back, to around 450,000 years.
"There is a lot of debate currently in the anthropological literature about what species to call these fossils. There is not a lot of agreement," said Quam, who co-authored the study with Portuguese archaeologist Joao Zilhao and colleagues.
Its location is the furthest west of any human fossil ever found in Europe during the middle Pleistocene period.
It is also one of the earliest in Europe to be associated with the Acheulean stone tool industry, a more advanced kind of toolkit than used among the earliest humans in Europe.
The Acheulean stone tools included tear-drop-shaped hand-axes that were more complex to build than previous iterations.
They originated in Africa and probably made their way into Europe via the Middle East around 500,000 years ago.
To find evidence of these tools 400,000 years ago, all the way over in western Europe, "means relatively quickly the Acheuleans spread through Europe," Quam said.
While there remains much to be learned about the skull, researchers feel lucky that they found it at all. In fact, they almost missed it.
Glimpsed as an outline of a skull in sediment as hard as cement, the skull was found on the last day of an excavation project in 2014.
"I have been studying these sites for the last 30 years and we have recovered much important archaeological data. But the discovery of a human cranium of this antiquity and importance is always a very special moment," said Zilhao in a statement.
Workers toiled for a week to cut a block out of the Earth. At one point, a heavy duty demolition hammer broke the skull into pieces.
It took two and a half years to painstakingly extract the skull itself from the block.
Images of the skull show a circular hole, which represents the damage incurred during the excavation.
The fossil will go on display in October at the Museu Nacional de Arqueologia in Lisbon.
In the coming years, experts will dive into the details of the skull and its surroundings "to give a more complete picture of life in the area, life in the cave and the evolutionary place of this human in our ancestry," said Quam.

2. Archaeologist Hipolito Collado and his team had not entered the Maltravieso Cave in the city of Caceres for close to a year to avoid damaging the 57 faded hands that adorn the walls, precious remnants of a far-flung piece of history we know little about.
Why did our ancestors or distant relatives paint hands in caves? Was it merely to make their mark, or part of a ritual to commune with spirits?
Do they tell us anything about the role of women during the Paleolithic era that ended some 10,000 years ago? And why are some fingers missing?
'Inaccessible art accessible'
In a bid to unlock some of these mysteries, Collado, head of archaeology for the government of the Extremadura region where Caceres is located, has set out to catalogue all of Europe's prehistoric painted hands.
Crouching under low hanging rocks or abseiling down crags, he and other archaeologists have been going from cave to cave, taking scans and high-resolution photos of all the hands they encounter.
They then post them in detailed, 3D format in a free-to-use online database, as part of an EU-funded project called Handpas.
The idea is for researchers anywhere in the world to be able to examine them all in one place without having to visit every cave or gain access to those closed for conservation, in the hope of producing a breakthrough.
"It's about making inaccessible art accessible," says Collado, as he checks sensors for any change in CO2 levels, temperature or humidity since he last visited the meandering, cramped cave.
Surrounded by high rises in what was a poor neighbourhood of Caceres, the cave was discovered in 1951 in a quarry but left neglected for decades, squatted by thrill-seekers, junkies and others until authorities put up a wrought-iron gate barring the entrance in the mid-1980s.
I woz ere?
According to Collado, a Spaniard who is also head of the International Federation of Rock Art Organizations, painted hands have been found in 36 caves in Europe -- all in France, Spain and Italy.
Some also contain animal drawings and fossils but his project focuses only on hands.
Further afield, hands have also been discovered in South America, Australia and Indonesia, where recent research revealed that a hand silhouette in a cave on Sulawesi island was 40,000 years old -- the world's oldest.
That was around the time when Homo sapiens -- the first modern humans -- arrived in Europe after having emerged in Africa and lived in parts of Asia.
Theories abound about what the hands mean, but with no written records, much of it is conjecture.
Researchers have tried to determine whether they were male or female, and why in some cases fingers are missing.
Was this a ritual? Did they lose them in freezing cold weather? Or -- as is more commonly believed -- did they simply fold some fingers over when painting in some sort of sign language?
What if scientists were able to determine for certain that all hands in one area were done by women?
"It could mean a matriarchal society," says Collado's colleague Jose Ramon Bello Rodrigo.
And did Homo sapiens -- or possibly Neanderthals before them -- merely wander into a cave and casually leave their hand imprint as a form of ancient "I woz ere"?
Paul Pettitt, professor of Paleolithic Archaeology at Britain's Durham University, doesn't think so.
His research focuses on where people placed their hands and he found that in some cases, fingers appeared to be deliberately placed over a bump in the wall like they were "gripping" it.
Many hands are also in the deeper recesses of the caves.
"It must have been very frightening, it must have been quite a degree of exertion, a lot of climbing in the darkness," says Pettitt.
"You don't do that for fun."
Awaiting French go-ahead
Why then would people go to such lengths to paint hands onto the walls -- be it via stencils, created by spraying pigment around an open hand, or actual handprints applied to the rock face?
French prehistorian Jean Clottes believes it may have been a form of shamanism.
"It's likely that putting paint -- what we could call sacred paint -- on the rock face introduces a link between the person who does it and the rock face, and therefore with the forces in the rock face," he says.
Collado also interprets some of the hands he has seen as warnings.
"In the La Garma Cave (in northern Spain) there is a panel with hands that is next to a big well that would be deadly," he says.
"These were definitely done to say 'stop'."
Work on documenting painted hands in two Italian caves has also begun.
But the project has come up against a major stumbling block as Collado's team has yet to get the green light to access the French caves -- 18 months after sending their first letter to the culture ministry.
"We're on standby," he concludes impatiently.
© Agence France-Presse

3. PARIS (AFP).- High-tech dating of mastodon remains found in southern California has shattered the timeline of human migration to America, pushing the presence of hominins back to 130,000 years ago rather than just 15,000 years, researchers said Wednesday.
Teeth and bones of the elephant-like creature unmistakably modified by human hands, along with stone hammers and anvils, leave no doubt that some species of early human feasted on its carcass, they reported in the journal Nature.
Discovered in 1992 during construction work to expand an expressway, the bone fragments "show clear signs of having been deliberately broken by humans with manual dexterity," said lead author Steve Holen, director of research at the Center for American Paleolithic Research.
Up to now, the earliest confirmed passage of our ancestors into North America took place about 15,000 years ago. These were modern humans -- Homo sapiens -- that probably crossed from Siberia into what is today Alaska, by land or along the coast.
There have been several other claims of an even earlier bipedal footprint on the continent, but none would take that timeline back further than 50,000 years, and all remain sharply contested.
The absence of human remains at the California site throws wide open the question of who these mysterious hunters were, as well as when -- and how -- they arrived on American shores.
One possibility that can be excluded with high confidence is that they were like us. Homo sapiens, experts say, did not exit Africa until about 80,000 to 100,000 years ago.
But that still leaves a wide range of candidates, including several other hominin species that roamed Eurasia 130,000 years ago, the authors said.
They include Homo erectus, whose earliest traces date back nearly two million years; Neanderthals, who fought and co-mingled with modern humans across Europe before dying out some 40,000 years ago; and an enigmatic species called Denisovans, whose DNA survives today in Australian aboriginals.
In a companion analysis, Holen and his team argue that -- despite rising seas 130,000 years ago due to an inter-glacial period of warming -- the overseas distances to the Americas were within the capacity of human populations at the time.
Intriguingly, in light of the new find, recent studies have also shown a genetic link between present-day Amazonian native Americans and some Asian and Australian peoples.
The picture that emerges "indicates a diverse set of founding populations of the Americas," said Erella Hovers, an anthropologist at Hebrew University of Jerusalem, who did not take part in the new study.
As for the early humans who carved up the bones at the Cerutti Mastodon site in San Diego, named for the paleontologist who discovered it, they likely died out, leaving no genetic trace in modern North Americans, the authors conjectured.
Previous attempts to accurately date artefacts at the site fell short.
Then, in 2014, co-author James Paces, a researcher with the US Geological Survey, used state-of-the-art radiometric methods to measure traces of natural uranium and its decaying by-products in the mastodon bones, which were still fresh when broken by precise blows from stone hammers.
The prehistoric butchery, he determined, took place 130,000 years ago, give or take 9,400 years, and was may have sought to extract nutritious marrow.
"Since the original discovery, dating technology has advanced to enable us to confirm with further certainty that early humans were here signficantly earlier than commonly accepted," said co-author Thomas Demere, a paleontologist at the San Diego Natural History Museum.
To strengthen the case, researchers set up an experiment to reproduce the stone-age food prep tableau unearthed from "Bed E" of the excavation site.
Using stone hammers and anvils similar to those found, they broke open large elephant bones much in the way pre-historic humans might have done. Certain blows yielded exactly the kind of strike marks, on both the hammers and the bones.
The same patterns, further tests showed, could not have emerged from natural wear-and-tear, or from the deliberate crafting of the tools, called flaking.
"This is a very old technology," said Holen. "We have people in Africa 1.5 million years ago breaking up elephant limb bones in this pattern, and as humans moved out of Africa and across the world they took this type of technology with them."
There remain nonetheless big holes in the narrative of human migration to the Americas, Hovers said, commenting in Nature.
"Time will tell whether this evidence will bring a paradigm change in our understanding of hominin dispersal and colonisation throughout the world, including in what now seems to be a not-so-new New World," she wrote.

4.BOTSWANA Dating rock art is difficult. Chips of paint—likely contaminated with all different sources of carbon due to centuries and sometimes millennia of weathering—are first removed from the delicate pieces of art. Then researchers must use these pigments to isolate dateable carbon in order to come up with an age. Laura Geggel at LiveScience reports that one researcher just spent more than seven years overcoming some of those obstacles to date rock art from the San people of southern Africa.  Her efforts paid off—her team found that some of the art is 5,000 years old, much more ancient than researchers previously thought.
According to Léa Surugue at The International Business Times, the researchers used a technique called accelerator mass spectrometry (AMS) to analyze paint chips from cave paintings in 14 sites in Botswana, Lesotho and South Africa. This newer technique allowed them to use tinier samples of the material. “With current dating methods, we need large samples—sometimes hundreds of milligrams of painting—which often means completely destroying these artworks,” explains Adelphine Bonneau, post-doctoral fellow at Laval University and first author of the article in the journal Antiquity. "We also have to consider that in many cases, the art wasn’t protected inside caves and rock shelters but created on outdoors rocks exposed to the elements and to human activity, which means that paintings are often in a bad state and cannot be dated.”
Bonneau and her colleagues selected samples made from organic materials that contained carbon, but avoided samples made from charcoal, since that material can last a very long time and paintings made with old pieces of charcoal could throw off the dates. They also worked to identify all the sources of carbon in the samples, since wind, rain, dust and all sorts of things can contaminate the paintings. Bonneau tells Geggel she’s even witnessed sheep licking the paintings.
They then examined the samples using AMS, coming up with dates for when the paintings were made. The research showed that the ancestors of the San people created their images of animals and hunters using three primary materials including charcoal, soot and carbon black, a mixture of fat. The AMS dating showed that the paintings in rock shelters in Botswana ranged from 5,000 to 2,000 years old. The Lesotho paintings were from 1,500 to 150 years old and the South African art was 2,500 to 150 years old. The dates show that the rock shelters were used over several centuries.
“For the first time, it is possible to understand how the paintings on a shelter were created,” Bonneau tells Geggel. “[It shows] when and where the artists started to paint in the shelter [and] for how long it was used. It opens up the possibility to discuss why some shelters were used for long periods and whereas other ones seem to have only one phase of paintings.”
Surugue reports that dating the paintings will allow researchers to begin associating some of the archeological artifacts found in and near the rock shelters with the people who created the cave paintings.
Even more importantly, the techniques used to date the rock art can be used in other areas of the world. For instance, rock art on the Indonesia island of Sulawesi was found to be a minimum of 40,000 years old using a technique called uranium-thorium radioisotope dating. Bonneau hopes her technique will help researchers paint a better picture of historical art by refining dating techniques even more.