Wednesday, January 28, 2015

Ancient skull from Galilee cave offers clues to the first modern Europeans

The discovery of a 55,000-year-old partial skull in Northern Israel provides new insights into the migration of modern humans out of Africa. The rare find is reported in the journal Nature this week by an international team of Israeli, North American and European researchers.

A key event in human evolution was the expansion of modern humans of African origin across Eurasia, replacing all other forms of hominin (humans and their predecessors), around 40,000-60,000 years ago. However, due to the scarcity of human fossils from this period, these ancestors of all present-day non-African modern populations have largely remained a mystery.

Now, researchers describe a partial skull that dates to around 55,000, which was found at Manot Cave in Israel's Western Galilee. The skull has a distinctive "bun"-shaped occipital region at the back. In this way its shape resembles modern African and European skulls, but differs from other anatomically modern humans from the Levant. This suggests that the Manot people could be closely related to the first modern humans that later colonized Europe.

The specimen also provides evidence that both modern humans and Neanderthals inhabited the southern Levant during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals.

This finding represents the first fossil evidence from the critical period when genetic and archaeological models predict that African modern humans successfully migrated out of Africa and colonized Eurasia. It also represents the first fossil evidence that during the late Middle Paleolithic, the Levant was occupied not only by Neanderthals but also by modern humans.

The researchers suggest that the population from which this skull is derived had recently migrated out of Africa and established itself in the Levantine corridor during a time span that was favorable for human migration, due to warmer and wetter climatic events over the Northern Sahara and the Mediterranean.

Manot Cave 

Manot is a karstic cave in the North of Israel, very close to the Lebanese border. The first excavations began in 2010 and are continued up to day. Countless archaeological objects were discovered which document the peopling of the cave since more than 100,000 years. Around 30,000 years ago, the roof of the cave collapsed and sealed the archaeological layers until the 21st century. Beside stone tools and animal bones, some few human remains were preserved. The most spectacular finding was made on an elevated shelf within a small chamber of the cave: a very well preserved "calotte", hence the upper part of a braincase. The facial bones which contain a lot of diagnostic traits for paleoanthropologists, were, however, missing.

"Virtual Anthropology" allows identification

The traditional methods of anthropology permit to draw only a coarse picture with regard to classification if it comes to a partial braincase which features mainly smooth curvatures. By means of methods that were developed at the University of Vienna in the last 15 years it is now possible to come to much stronger statements. This "Virtual Anthropology" uses sophisticated mathematical-statistical procedures to analyse 3D data from objects. Professor Gerhard Weber from the Department of Anthropology at the University of Vienna was thus invited by the Israeli colleagues to participate. Together with his former Ph.D. student Dr. Philipp Gunz, who now works at the Max Planck Institute Leipzig, they examined carefully computer-tomographic images of the calotte. In doing so, numerous measuring points in a dense array were located on the virtual representation of Manot and on several hundreds of other braincases to capture differences and similarities. Weber states: "The shape analysis shows very clearly that Manot was a modern human. It is interesting that the most similar skulls in our sample come from recent Africans on the one hand, and on the other hand from those modern humans that lived in Europe between 20-30,000 years ago as, for instance, Mlade? 1 or P?edmostí 4 from the Czech Republic".

Absolute dating proves old age

The morphological results alone would be, however, not enough for a sensation. The Manot people could have been modern humans that later re-migrated from Europe back into the Levant. Luckily, the conditions in the flowstone-cave lead to the accumulation of several thin layers of calcite on the inner and outer surface of the skull fragment. These can be reliably dated with the uranium-thorium method. The Israeli colleagues documented an age of approximately 55,000 years. Manot is thus 10,000 years older than any modern human found in Europe, and about 5-10,000 years younger than the point when geneticists predict the appearance of our direct ancestors in Africa.

The Levant as crossing point of migration

One of the logical migration routes from Africa to Europe leads through the Levantine corridor. The age and the morphology of Manot suggest that the first modern humans took this route. At the same time, they had opportunity to meet Neandertals which occupied the Levant in this time but could never expand further south. Genetic results indicate that recent humans carry between 1-4% of Neandertal genes in their genome. So far it was speculated that admixture could have happened in Europe. Manot is changing this picture. It is likely that interbreeding happened already earlier on the way of the first modern humans through the Levant.

Manot connects

"This skull remain at Manot", Weber summarises "is exactly what we anthropologists have looked for since decades. It connects perfectly in space and time those separated parts of human history that we have known". But Manot is not only a fluke for our knowledge about human evolution. It also lead to a very successful scientific collaboration between Israeli and Austrian, respectively German, institutions. Further projects and increased exchange of know-how are on the way.

Long series of droughts doomed Mexican city 1,000 years ago

Archaeologists continue to debate the reasons for the collapse of many Central American cities and states, from Teotihuacan in Mexico to the Yucatan Maya, and climate change is considered one of the major causes.

A University of California, Berkeley, study sheds new light on this question, providing evidence that a prolonged period of below-average rainfall was partly responsible for the abandonment of one such city, Cantona, between A.D. 900 and A.D. 1050.

At its peak, Cantona, located in a dry, volcanic basin (La Cuenca Oriental) east of today's Mexico City, was one of the largest cities in the New World, with 90,000 inhabitants. The area was a major source of obsidian and the city may have played a military role alongside an important trade route from the Veracruz coast into the highlands.

To assess the climate in that area before and after Cantona's collapse, UC Berkeley geographers analyzed sediment cores from a lake located 20 miles south of the former city. They found evidence of a 650-year period of frequent droughts that extended from around A.D. 500 to about A.D. 1150. This was part of a long-term drying trend in highland Mexico that started 2,200 years ago, around 200 B.C. The climate became wetter again in about A.D. 1300, just prior to the rise of the Aztec empire.

"The decline of Cantona occurred during this dry interval, and we conclude that climate change probably played a role, at least towards the end of the city's existence," said lead author Tripti Bhattacharya, a UC Berkeley graduate student.

Surprisingly, the population of Cantona increased during the early part of the dry period, perhaps because of political upheaval elsewhere that increased the importance of the heavily fortified city, she said. Teotihuacan, less than 100 miles to the west, was in decline at the time, also possibly because of more frequent droughts.

"In a sense the area became important because of the increased frequency of drought," said UC Berkeley associate professor of geography Roger Byrne. "But when the droughts continued on such a scale, the subsistence base for the whole area changed and people just had to leave. The city was abandoned."

Bhattacharya, Byrne and their colleagues report their findings in an article appearing this week in the early edition of the journal Proceedings of the National Academy of Sciences. The UC Berkeley researchers analyzed lake cores provided by scientists at the National Autonomous University of Mexico in Juriquilla, Querétaro, Mexico and the German Research Centre for Geosciences in Potsdam, Germany.

Political upheaval and climate change

Byrne emphasized that the area's typical monsoon weather with wet summers and dry winters did not stop, but was interrupted by frequent short-term droughts, no doubt affecting crops and water supplies. Today the area is close to the northern limit of maize production without irrigation, and would have been particularly vulnerable to drier conditions, he said.

Byrne, a member of the Berkeley Initiative on Global Change Biology (BiGCB) and curator of fossil pollen in the Museum of Paleontology, has studied sediment cores from many lakes in Mexico and California, and is particularly interested in possible links between climate change and human activities.

Nearly 20 years ago, he learned of Cantona and traveled with students to the areas three times to obtain cores from lakes near the site, most of which are maar lakes created by magma explosions. They are deep and often contain undisturbed and regularly layered sediments ideal for chronological studies.

German colleagues cored this particular lake, Aljojuca, in 2007, and Bhattacharya traveled to Potsdam to collect sediment samples. Oxygen isotope ratios in carbonate sediments are correlated with the ratio of precipitation to evaporation and thus indicate aridity. Organic material in the sediments was used for accelerator mass spectroscopy carbon-14 dating.

"We can show that both the growth and decline of the site took place during a time period of frequent drought, which forces us to think in more nuanced ways about how political and social factors interact with environmental factors to cause social and cultural change," Bhattacharya said. "That makes the study particularly interesting."

Bhattacharya noted that more studies are necessary to reconstruct the prehistoric climate of highland Mexico. Such studies could reveal the causes of prehistoric climatic change and whether they were similar to the factors that regulate the region's climate today, such as the El Niño/Southern Oscillation.

Saturday, January 17, 2015

Dairying in Ireland goes back approximately 6,000 years

New research from the University of Bristol, UK has revealed the antiquity of dairy farming in a region famous for its dairy exports: Ireland.

Research published today in the Journal of Environmental Archaeology shows that dairying on the island goes back approximately 6,000 years, revealed through traces of ancient dairy fats found in pots dating to around 4,000 to 2,500 BC.

Dr Jessica Smyth of Bristol's School of Chemistry analysed nearly 500 pots from the Neolithic, the period when people switched from hunting and gathering to farming. In Britain and Ireland, this change occurred around 4,000 BC, more than 1,000 years later than on the Continent. The Bristol team use a combination of fat or lipid 'fingerprinting' and compound-specific carbon isotope techniques to identify the origin of fats preserved in the walls of prehistoric cooking pots.

Dr Smyth, who led the study, said: "We know from previous research that dairying was an important part of many early farming economies, but what was a big surprise was the prevalence of dairy residues in Irish pots. It looks to have been a very important food source."

Ninety per cent of the residues tested for fat origin were found to be dairy fats, with ten per cent found to be meat fats (beef or mutton) or a mixture of milk and meat.

Dr Smyth added: "People can obviously cook meat in other ways than boiling it in pots, and there is plenty of evidence for cereal processing at this time, but the Irish dairy signal remains very striking, particularly when you compare it with the continental European data sets. Ireland really does seem to go mad for milk in the Neolithic."

Milk is still a traditional and valuable food in Europe today, produced by over 30 million dairy cows and representing 14 per cent of the value of European agricultural production [2011 figures]. Six thousand years ago, dairying in Ireland looked very different.

Dr Smyth said: "We know that settlements were small in the Irish Neolithic, usually one or two houses, so it's likely that early farming groups had just one or two animals supporting the household with their products, which were perhaps part of a wider community herd."

Such results are even more significant given the fact that domesticated animals such as cattle, sheep and goats had to be physically shipped to Ireland as part of the process, as these animals were not native to the island.

"These are a very determined group of pioneer farmers. They are setting up everything from scratch, and taking a significant gamble with their livelihoods and those of their dependants," Dr Smyth said.

It would appear that the Irish love of dairy products is very ancient, and the suitability of the island for dairy farming was recognised early in prehistory.

Wednesday, January 14, 2015

Stone Age man wasn't necessarily more advanced than the Neanderthals

A multi-purpose bone tool dating from the Neanderthal era has been discovered by University of Montreal researchers, throwing into question our current understanding of the evolution of human behaviour. It was found at an archaeological site in France. "This is the first time a multi-purpose bone tool from this period has been discovered. It proves that Neanderthals were able to understand the mechanical properties of bone and knew how to use it to make tools, abilities usually attributed to our species, Homo sapiens," said Luc Doyon of the university's Department of Anthropology, who participated in the digs. Neanderthals lived in Europe and western Asia in the Middle Paleolithic between around 250,000 to 28,000 years ago. Homo sapiens is the scientific term for modern man.
The production of bone tools by Neanderthals is open to debate. For much of the twentieth century, prehistoric experts were reluctant to recognize the ability of this species to incorporate materials like bone into their technological know-how and likewise their ability to master the techniques needed to work bone. However, over the past two decades, many clues indicate the use of hard materials from animals by Neanderthals. "Our discovery is an additional indicator of bone work by Neanderthals and helps put into question the linear view of the evolution of human behaviour," Doyon said.
The tool in question was uncovered in June 2014 during the annual digs at the Grotte du Bison at Arcy-sur-Cure in Burgundy, France. Extremely well preserved, the tool comes from the left femur of an adult reindeer and its age is estimated between 55,000 and 60,000 years ago. Marks observed on it allow us to trace its history. Obtaining bones for the manufacture of tools was not the primary motivation for Neanderthals hunting - above all, they hunted to obtain the rich energy provided by meat and marrow. Evidence of meat butchering and bone fracturing to extract marrow are evident on the tool. Percussion marks suggest the use of the bone fragment for carved sharpening the cutting edges of stone tools. Finally, chipping and a significant polish show the use of the bone as a scraper.
"The presence of this tool at a context where stone tools are abundant suggests an opportunistic choice of the bone fragment and its intentional modification into a tool by Neanderthals," Doyon said. "It was long thought that before Homo sapiens, other species did not have the cognitive ability to produce this type of artefact. This discovery reduces the presumed gap between the two species and prevents us from saying that one was technically superior to the other.

Tuesday, January 6, 2015

New research on the collapse of the Bronze Age (beginning around 1200 BC), including the abandonment of cities


Two researchers are taking a new twist on long-published research about what an ancient civilization did for a living. W. Flint Dibble, a University of Cincinnati doctoral student in the Department of Classics, and Daniel J. Fallu, a doctoral student in archaeology at Boston University, will present their new discoveries surrounding a key site from the Greek Dark Age on Jan. 9, at the joint annual meeting of the Archaeological Institute of America (AIA) and Society for Classical Studies (SCS, formerly known as the American Philological Association), in New Orleans. 
The Greek village of Nichoria remained standing through both the Late Bronze Age and the Greek Dark Age, and previous research has suggested that Nichoria turned to cattle ranching during the region's collapse in the Dark Age. That's because the remains of cattle bones are prevalent among bone fragments in the soil. 
In a presentation titled, "The Good, the Bad and the Ugly at the Dark Age Ranch: Taphonomic Reinterpretations of Pastoralism at Nichoria, Messinia," the UC-led research suggests that soil formation after the abandonment of the site in the Dark Age led to poor preservation of the historic record, and as a result, the thicker, larger bones of animals such as cattle survived the breakdown of other bone fragments. Other possible remains would have been destroyed as a result of the more acidic soil. The researchers report that Dark Age sediments contain few visible calcite formations, indicative of poor site preservation.
The village of Nichoria in Messenia was located near the palace of Pylos during the Greek Bronze Age, when Greece was considered a Superpower of the Mediterranean. The region thrived on its trade and economic stability, culture, and art and architecture, including great monuments, palaces and writings. The collapse of the Bronze Age (beginning around 1200 BC), including the abandonment of cities and the destruction of palaces, is known as the Dark Age.
"There's no monumental architecture and little art, writing disappears and there are considerably fewer sites," says Dibble. He explains that Nichoria is one of the few settlements in Greece that remained occupied during both the Bronze Age and the Greek Dark Age. It's believed that the widespread abandonment of settlements was due to the adoption of pastoralism, making populations more mobile as they herded animals. 
The explanations for the sudden collapse of civilization in the Dark Age have ranged from believing it was the result of the invasion of another society to a catastrophic climatic event. 
"We were exploring this as evidence for a possible climate event, but the soil samples came back inconclusive," says Dibble. "We actually think that as more of these sites are abandoned in the Dark Age, the landscape becomes very stable, and the weather destroys more of what's in the top upper layers than the archaeological material buried deeper below. At this site, we have no evidence that the destruction of bone was the result of climate change."
Previous research from the first excavation of Nichoria in the late '60s - an extensive project led by the University of Minnesota - has suggested that Nichoria survived the Dark Age by turning to cattle ranching, after villagers took control of the herds of the palaces in the wake of their collapse.
Dibble says that the evolution of methods and technology has resulted in new examinations of discoveries from decades ago. "We're using modern biology to understand what is happening to ancient remains and we're finding that the bone is dissolving away. I've found teeth that are hollow because the dense enamel is still there, but the dentin is gone, which also tells me that more porous bone is dissolving away."
Dibble adds that their study is unique in that soil that was collected with the bones was also studied before being washed away to better examine the bones. Fallu conducted the examinations of the soil. Concerning the fact that many bags of bones still had dirt, Dibble says, "We got kind of lucky in a sense." 
"I want to see if this kind of soil environment that destroys bones also destroys other types of evidence, because there is bone destruction at other sites being studied from the Dark Age," says Dibble. "Bone is made up of calcium carbonate, so other carbon materials could be destroyed, such as charred plants - key to understanding agriculture at that time. Also, there are few metal objects from the Dark Age, and the soil environment might be an explanation for that."