Friday, July 18, 2014

New mosaics discovered in synagogue excavations in Galilee

 This photo shows the head of the possible Alexander figure in the mosaic.

Excavations led by a University of North Carolina at Chapel Hill faculty member revealed stunning new mosaics decorating the floor of the Late Roman (fifth century) synagogue at Huqoq, an ancient Jewish village in Israel’s Lower Galilee.

Since 2012, three well-preserved mosaics have been discovered in the same location in excavations directed by Jodi Magness, Kenan Distinguished Professor for Teaching Excellence in Early Judaism in the College of Arts and Sciences, and co-directed by Shua Kisilevitz of the Israel Antiquities Authority.

In 2012, a mosaic showing Samson and the foxes (as related in the Bible’s Judges 15:4) was discovered in the synagogue’s east aisle. Last summer (2013), a second mosaic was found which shows Samson carrying the gate of Gaza on his shoulders (Judges 16:3).

A third mosaic discovered in the synagogue’s east aisle is divided into three horizontal registers (strips), and differs in style, quality and content from the Samson scenes. It is the first time a non-biblical story has been found decorating any ancient synagogue. Portions of this mosaic were uncovered in 2013, and the rest was revealed this summer.

The lowest register shows a bull pierced by spears, with blood gushing from his wounds, and a dying or dead soldier holding a shield. The middle register depicts an arcade, with the arches framing young men arranged around a seated elderly man holding a scroll, and lighted oil lamps above each arch. The uppermost register depicts a meeting between two large male figures. A bearded, diademed soldier wearing elaborate battle dress and a purple cloak is leading a large bull by the horns, accompanied by a phalanx of soldiers and elephants with shields tied to their sides. He is meeting with a grey-haired, bearded elderly man wearing a ceremonial white tunic and mantle, accompanied by young men with sheathed swords, also wearing ceremonial white tunics and mantles.

The identification of the figures in this mosaic is unclear because there are no stories in the Hebrew Bible involving elephants, Magness said.

”Battle elephants were associated with Greek armies beginning with Alexander the Great, so this might be a depiction of a Jewish legend about the meeting between Alexander and the Jewish high priest,” Magness suggested. “Different versions of this story appear in the writings of Flavius Josephus and in rabbinic literature.”

The mosaics have been removed from the site for conservation, and the excavated areas have been backfilled. Excavations are scheduled to continue in summer 2015.

More on the excavations



Monday, July 14, 2014

Prehistoric 'bookkeeping' continued long after invention of writing






An archaeological dig in southeast Turkey has uncovered a large number of clay tokens that were used as records of trade until the advent of writing, or so it had been believed.

But the new find of tokens dates from a time when writing was commonplace – thousands of years after it was previously assumed this technology had become obsolete. Researchers compare it to the continued use of pens in the age of the word processor.

The tokens – small clay pieces in a range of simple shapes – are thought to have been used as a rudimentary bookkeeping system in prehistoric times.

One theory is that different types of tokens represented units of various commodities such as livestock and grain. These would be exchanged and later sealed in more clay as a permanent record of the trade – essentially, the world's first contract.

The system was used in the period leading up to around 3000 BC, at which point clay tablets filled with pictorial symbols drawn using triangular-tipped reeds begin to emerge: the birth of writing, and consequently history.

From this point on in the archaeological record, the tokens dwindle and then disappear, leading to the assumption that writing quickly supplanted the token system.

However, recent excavations at Ziyaret Tepe – the site of the ancient city Tušhan, a provincial capital of the Neo-Assyrian Empire – have unearthed a large quantity of tokens dating to the first millennium BC: two thousand years after 'cuneiform' – the earliest form of writing – emerged on clay tablets.

"Complex writing didn't stop the use of the abacus, just as the digital age hasn't wiped out pencils and pens," said Dr John MacGinnis from Cambridge's MacDonald Institute for Archaeological Research, who led the research.

"In fact, in a literate society there are multiple channels of recording information that can be complementary to each other. In this case both prehistoric clay tokens and cuneiform writing used together."

The tokens were discovered in the main administrative building in Tušhan's lower town, along with many cuneiform clay tablets as well as weights and clay sealings. Over 300 tokens were found in two rooms near the back of the building that MacGinnis describes as having the character of a 'delivery area', perhaps an ancient loading bay.

"We think one of two things happened here. You either have information about livestock coming through here, or flocks of animals themselves. Each farmer or herder would have a bag with tokens to represent their flock," said MacGinnis.

"The information is travelling through these rooms in token form, and ending up inscribed onto cuneiform tablets further down the line."

Archaeologists say that, while cuneiform writing was a more advanced accounting technology, by combining it with the flexibility of the tokens the ancient Assyrians created a record-keeping system of greater sophistication.

"The tokens provided a system of moveable numbers that allowed for stock to be moved and accounts to be modified and updated without committing to writing; a system that doesn't require everyone involved to be literate."

MacGinnis believes that the new evidence points to prehistoric tokens used in conjunction with cuneiform as an empire-wide 'admin' system stretching right across what is now Turkey, Syria and Iraq. In its day, roughly 900 to 600 BC, the Assyrian empire was the largest the world had ever seen.

Types of tokens ranged from basic spheres, discs and triangles to tokens that resemble oxhide and bull heads.

While the majority of the cuneiform tablets found with the tokens deal with grain trades, it's not yet known what the various tokens represent. The team say that some tokens likely stand for grain, as well as different types of livestock (such as goats and cattle), but – as they were in use at the height of the empire – tokens could have been used to represent commodities such as oil, wool and wine.

"One of my dreams is that one day we'll dig up the tablet of an accountant who was making a meticulous inventory of goods and systems, and we will be able to crack the token system's codes," said MacGinnis.

"The inventions of recording systems are milestones in the human journey, and any finds which contribute to the understanding of how they came about makes a basic contribution to mapping the progress of mankind," he said. 




Thursday, July 3, 2014

Denisovan gene helped Tibetans adapt to low oxygen at high altitudes


Tibetans were able to adapt to high altitudes thanks to a gene picked up when their ancestors mated with a species of human they helped push to extinction, according to a new report by University of California, Berkeley, scientists.

An unusual variant of a gene involved in regulating the body's production of hemoglobin – the molecule that carries oxygen in the blood – became widespread in Tibetans after they moved onto the high-altitude plateau several thousand years ago. This variant allowed them to survive despite low oxygen levels at elevations of 15,000 feet or more, whereas most people develop thick blood at high altitudes, leading to cardiovascular problems.

"We have very clear evidence that this version of the gene came from Denisovans," a mysterious human relative that went extinct 40,000-50,000 years ago, around the same time as the more well-known Neanderthals, under pressure from modern humans, said principal author Rasmus Nielsen, UC Berkeley professor of integrative biology. "This shows very clearly and directly that humans evolved and adapted to new environments by getting their genes from another species."

This is the first time a gene from another species of human has been shown unequivocally to have helped modern humans adapt to their environment, he said.

Nielsen and his colleagues at BGI-Shenzhen in China will report their findings online July 2 in advance of publication in the journal Nature.

The gene, called EPAS1, is activated when oxygen levels in the blood drop, triggering production of more hemoglobin. The gene has been referred to as the superathlete gene because at low elevations, some variants of it help athletes quickly boost hemoglobin and thus the oxygen-carrying capacity of their blood, upping endurance. At high altitude, however, the common variants of the gene boost hemoglobin and its carrier, red blood cells, too much, increasing the thickness of the blood and leading to hypertension and heart attacks as well as low-birth-weight babies and increased infant mortality. The variant or allele found in Tibetans raises hemoglobin and red blood cell levels only slightly at high elevation, avoiding the side-effects seen in most people who relocate to elevations above 13,000 feet.

"We found part of the EPAS1 gene in Tibetans is almost identical to the gene in Denisovans and very different from all other humans," Nielsen said. "We can do a statistical analysis to show that this must have come from Denisovans. There is no other way of explaining the data."

Harsh conditions on Tibetan plateau

The researchers first reported the prevalence of a high-altitude version of EPAS1 in Tibetans in 2010, based on sequencing of the genomes of numerous Han Chinese and Tibetans. Nielsen and his colleagues argued that this was the result of natural selection to adapt to about 40 percent lower oxygen levels on the Tibetan plateau. That is, people without the variant died before reproducing at a much higher rate than those with it. About 87 percent of Tibetans now have the high-altitude version, compared to only 9 percent of Han Chinese, who have the same common ancestor as Tibetans.

Nielsen and his colleagues subsequently sequenced the EPAS1 gene in an additional 40 Tibetans and 40 Han Chinese. The data revealed that the high-altitude variant of EPAS1 is so unusual that it could only have come from Denisovans. Aside from its low frequency in Han Chinese, it occurs in no other known humans, not even Melanesians, whose genomes are nearly 5 percent Denisovan. A high quality sequence of the Denisovan genome was published in 2012.

Nielsen sketched out a possible scenario leading to this result: modern humans coming out of Africa interbred with Denisovan populations in Eurasia as they passed through that area into China, and their descendants still retain a small percentage – perhaps 0.1 percent – Denisovan DNA. The group that invaded China eventually split, with one population moving into Tibet and the other, now known as Han Chinese, dominating the lower elevations.

He and his colleagues are analyzing other genomes to pin down the time of Denisovan interbreeding, which probably happened over a rather short period of time.

"There might be many other species from which we also got DNA, but we don't know because we don't have the genomes," Nielsen said. "The only reason we can say that this bit of DNA is Denisovan is because of this lucky accident of sequencing DNA from a little bone found in a cave in Siberia. We found the Denisovan species at the DNA level, but how many other species are out there that we haven't sequenced?"

Wednesday, July 2, 2014

In human evolution, changes in skin's barrier set Northern Europeans apart, not sunlight



The popular idea that Northern Europeans developed light skin to absorb more UV light so they could make more vitamin D – vital for healthy bones and immune function – is questioned by UC San Francisco researchers in a new study published online in the journal Evolutionary Biology.

Ramping up the skin's capacity to capture UV light to make vitamin D is indeed important, according to a team led by Peter Elias, MD, a UCSF professor of dermatology. However, Elias and colleagues concluded in their study that changes in the skin's function as a barrier to the elements made a greater contribution than alterations in skin pigment in the ability of Northern Europeans to make vitamin D.

Elias' team concluded that genetic mutations compromising the skin's ability to serve as a barrier allowed fair-skinned Northern Europeans to populate latitudes where too little ultraviolet B (UVB) light for vitamin D production penetrates the atmosphere.

Among scientists studying human evolution, it has been almost universally assumed that the need to make more vitamin D at Northern latitudes drove genetic mutations that reduce production of the pigment melanin, the main determinant of skin tone, according to Elias.

"At the higher latitudes of Great Britain, Scandinavia and the Baltic States, as well as Northern Germany and France, very little UVB light reaches the Earth, and it's the key wavelength required by the skin for vitamin D generation," Elias said.

"While is seems logical that the loss of the pigment melanin would serve as a compensatory mechanism, allowing for more irradiation of the skin surface and therefore more vitamin D production, this hypothesis is flawed for many reasons," he continued. "For example, recent studies show that dark-skinned humans make vitamin D after sun exposure as efficiently as lightly-pigmented humans, and osteoporosis – which can be a sign of vitamin D deficiency – is less common, rather than more common, in darkly-pigmented humans."

Furthermore, evidence for a south to north gradient in the prevalence of melanin mutations is weaker than for this alternative explanation explored by Elias and colleagues.

In earlier research, Elias began studying the role of skin as a barrier to water loss. He recently has focused on a specific skin-barrier protein called filaggrin, which is broken down into a molecule called urocanic acid – the most potent absorber of UVB light in the skin, according to Elias. "It's certainly more important than melanin in lightly-pigmented skin," he said.

In their new study, the researchers identified a strikingly higher prevalence of inborn mutations in the filaggrin gene among Northern European populations. Up to 10 percent of normal individuals carried mutations in the filaggrin gene in these northern nations, in contrast to much lower mutation rates in southern European, Asian and African populations.

Moreover, higher filaggrin mutation rates, which result in a loss of urocanic acid, correlated with higher vitamin D levels in the blood. Latitude-dependent variations in melanin genes are not similarly associated with vitamin D levels, according to Elias. This evidence suggests that changes in the skin barrier played a role in Northern European's evolutionary adaptation to Northern latitudes, the study concluded.

Yet, there was an evolutionary tradeoff for these barrier-weakening filaggrin mutations, Elias said. Mutation bearers have a tendency for very dry skin, and are vulnerable to atopic dermatitis, asthma and food allergies. But these diseases have appeared only recently, and did not become a problem until humans began to live in densely populated urban environments, Elias said.

The Elias lab has shown that pigmented skin provides a better skin barrier, which he says was critically important for protection against dehydration and infections among ancestral humans living in sub-Saharan Africa. But the need for pigment to provide this extra protection waned as modern human populations migrated northward over the past 60,000 years or so, Elias said, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago.

The data from the new study do not explain why Northern Europeans lost melanin. If the need to make more vitamin D did not drive pigment loss, what did? Elias speculates that, "Once human populations migrated northward, away from the tropical onslaught of UVB, pigment was gradually lost in service of metabolic conservation. The body will not waste precious energy and proteins to make proteins that it no longer needs."

Tuesday, July 1, 2014

A baby boom in southwestern Native Americans from 500 to 1300 A.D.




Reconstruction of life on a Hohokam platform mound in the Sonoran Desert in the 13th century A.D.

Credit: Pueblo Grande Museum, City of Phoenix

Scientists have sketched out one of the greatest baby booms in North American history, a centuries-long "growth blip" among southwestern Native Americans between 500 and 1300 A.D.

It was a time when the early features of civilization--including farming and food storage--had matured to a level where birth rates likely "exceeded the highest in the world today," the researchers report in this week's issue of the journal Proceedings of the National Academy of Sciences.

Then a crash followed, says Tim Kohler, an anthropologist at Washington State University (WSU), offering a warning sign to the modern world about the dangers of overpopulation.

"We can learn lessons from these people," says Kohler, who co-authored the paper with WSU researcher Kelsey Reese.

The study looks at a century's worth of data on thousands of human remains found at hundreds of sites across the Four Corners region of the Southwest.

"This research reconstructed the complexity of human population birth rate change and demographic variability linked with the introduction of agriculture in the Southwest U.S.," says Alan Tessier, acting deputy division director in the National Science Foundation's (NSF) Directorate for Biological Sciences, which supported the research through NSF's Dynamics of Coupled Natural and Human Systems (CNH) Program.

"It illustrates the coupling and feedbacks between human societies and their environment."

CNH is also co-funded by NSF's Directorates for Geosciences and Social, Behavioral & Economic Sciences.

While many of the remains studied have been repatriated, the data let Kohler assemble a detailed chronology of the region's Neolithic Demographic Transition, in which stone tools reflect an agricultural transition from cutting meat to pounding grain.

"It's the first step toward all the trappings of civilization that we currently see," says Kohler.

Maize, which we know as corn, was grown in the region as early as 2000 B.C.

At first, populations were slow to respond, probably because of low productivity, says Kohler. But by 400 B.C., he says, the crop provided 80 percent of the region's calories.

Crude birth rates--the number of newborns per 1,000 people per year--were by then on the rise, mounting steadily until about 500 A.D.

The growth varied across the region.

People in the Sonoran Desert and Tonto Basin, in what is today Arizona, were more culturally advanced, with irrigation, ball courts, and eventually elevated platform mounds and compounds housing elite families.

Yet birth rates were higher among people to the North and East, in the San Juan Basin and northern San Juan regions of Northwest New Mexico and Southwest Colorado.

Kohler said that the Sonoran and Tonto people eventually would have had difficulty finding new farming opportunities for many children, since corn farming required irrigation. Water from canals also may have carried harmful protozoa, bacteria and viruses.

But groups to the Northeast would have been able to expand maize production into new areas as their populations grew.

Around 900 A.D., populations remained high but birth rates began to fluctuate.

The mid-1100s saw one of the largest known droughts in the Southwest. The region likely hit its carrying capacity.

From the mid-1000s to 1280, by which time all the farmers had left, conflicts raged across the northern Southwest but birth rates remained high.

"They didn't slow down," says Kohler. "Birth rates were expanding right up to the depopulation. Why not limit growth? Maybe groups needed to be big to protect their villages and fields.

"It was a trap, however."

The northern Southwest had as many as 40,000 people in the mid-1200s, but within 30 years it was empty, leaving a mystery.

Perhaps the population had grown too large to feed itself as the climate deteriorated. Then as people began to leave, that may have made it harder to maintain the social unity needed for defense and new infrastructure, says Kohler.

Whatever the reason, he says, the ancient Puebloans show that population growth has clear consequences.

Thursday, June 26, 2014

Study provides first direct evidence of plants in the Neanderthal diet


The popular conception of the Neanderthal as a club-wielding carnivore is, well, rather primitive, according to a new study conducted at MIT. Instead, our prehistoric cousin may have had a more varied diet that, while heavy on meat, also included plant tissues, such as tubers and nuts.

Scientists from MIT and the University of La Laguna in Spain have identified human fecal remains from El Salt, a known site of Neanderthal occupation in southern Spain that dates back 50,000 years. The researchers analyzed each sample for metabolized versions of animal-derived cholesterol, as well as phytosterol, a cholesterol-like compound found in plants. While all samples contained signs of meat consumption, two samples showed traces of plants — the first direct evidence that Neanderthals may have enjoyed an omnivorous diet.

"We have passed through different phases in our interpretation of Neanderthals," says Ainara Sistiaga, a graduate student at the University of La Laguna who led the analysis as a visiting student at MIT. She and her colleagues have published their study in the journal PLoS ONE.

"It's important to understand all aspects of why humanity has come to dominate the planet the way it does," adds co-author Roger Summons, a professor of geobiology in MIT's Department of Earth, Atmospheric and Planetary Sciences. "A lot of that has to do with improved nutrition over time."

Unearthing a prehistoric meal

While scientists have attempted to reconstruct the Neanderthal diet, much of the evidence has been inconclusive. For example, researchers have analyzed bone fragments for carbon and nitrogen isotopes — signs that Neanderthals may have consumed certain prey, such as pigs versus cows. But such isotopic data only differentiate between protein sources — underestimating plant intake, and thereby depicting the Neanderthal as exclusively carnivorous.

Other researchers recently identified plant microfossils trapped in Neanderthal teeth — a finding that suggests the species may have led a more complex lifestyle, harvesting and cooking a variety of plants in addition to hunting prey. But Sistiaga says it is also possible that Neanderthals didn't eat plants directly, but consumed them through the stomach contents of their prey, leaving traces of plants in their teeth.

Equally likely, she says, is another scenario: "Sometimes in prehistoric societies, they used their teeth as tools, biting plants, among other things. We can't assume they were actually eating the plants based on finding microfossils in their teeth."

Signs in the soil

For a more direct approach, Sistiaga looked for fecal remains in El Salt, an excavation site in Alicante, Spain, where remnants of multiple Neanderthal occupations have been unearthed. Sistiaga and her colleagues dug out small samples of soil from different layers, and then worked with Summons to analyze the samples at MIT.

In the lab, Sistiaga ground the soil into a powder, then used multiple solvents to extract any organic matter from the sediment. Next, she looked for certain biomarkers in the organic residue that would signal whether the fecal remains were of human origin.

Specifically, Sistiaga looked for signs of coprostanol, a lipid formed when the gut metabolizes cholesterol. As humans are able to break down more cholesterol than any other mammal, Sistiaga looked for a certain peak level of coprostanol that would indicate the sample came from a human.

She and Summons then used the same geochemical techniques to determine the proportions of coprostanol — an animal-derived compound — to 5B-stigmastanol, a substance derived from the breakdown of phytosterol derived from plants.

Each sample contained mostly coprostanol — evidence of a largely meat-based diet. However, two samples also held biomarkers of plants, which Sistiaga says may indicate a rather significant plant intake. As she explains it, gram for gram, there is more cholesterol in meat than there is phytosterol in plants — so it would take a significant plant intake to produce even a small amount of metabolized phytosterol.

In other words, while Neanderthals had a mostly meat-based diet, they may have also consumed a fairly regular portion of plants, such as tubers, berries, and nuts.

"We believe Neanderthals probably ate what was available in different situations, seasons, and climates," Sistiaga says.

Sistiaga, Summons, and their colleagues plan to use similar geochemical biomarker techniques, coupled with micromorphological analysis, to analyze soil samples in Olduvai Gorge, Tanzania — a 1.8-million-year-old site where some of the earliest evidence of human ancestry have been discovered.

"We're working in a micro context," Sistiaga says. "Until now, people have carried out residue analysis on pots, tools, and other objects, but 90 percent of archaeology is sediment. We're opening a new window to the information that is enclosed in Paleolithic soil and sediment."



Friday, June 20, 2014

First proof of early human technology exacerbating disease burden


The discovery of a schistosomiasis parasite egg in a 6200-year-old grave at a prehistoric town by the Euphrates river in Syria may be the first evidence that agricultural irrigation systems in the Middle East contributed to disease burden, according to new Correspondence published in The Lancet Infectious Diseases.

Schistosomiasis is a disease caused by several species of flatworm parasites that live in the blood vessels of the bladder and intestines. Infection can result in anaemia, kidney failure, and bladder cancer. This research shows it may have been spread by the introduction of crop irrigation in ancient Mesopotamia, the region along the Tigris-Euphrates river system that covers parts of modern-day Iraq, Iran, Kuwait, Syria, and Turkey.

According to one of the authors Dr Piers Mitchell, at the University of Cambridge, UK, the discovery might be among the oldest evidence of man-made technology inadvertently causing disease outbreaks.

"The individual who contracted the parasite might have done so through the use of irrigation systems that were starting to be introduced in Mesopotamia around 7500 years ago. The parasite spends part of its life cycle in snails that live in warm fresh water, before leaving the snail to burrow through the skin of people wading or swimming in the water. These irrigation systems distributed water to crops and may have triggered the beginning of the enormous disease burden that schistosomiasis has caused over the past 6000 years."

The discovery at Tell Zeidan in Syria was made by an international team of archaeologists and biological anthropologists working at Cambridge (UK), The Cyprus Institute (Cyprus), and the University of Chicago's Oriental Institute (USA). It shows that the parasite infected humans there at least a thousand years earlier than has been found in Egypt. The oldest Schistosomiasis egg found previously was in Egyptian mummies from 5200 years ago.

The egg was found in the pelvic area of the burial where the intestines and bladder would have been during life. Control soil samples from the head and foot areas of the grave contained no parasitic eggs, suggesting that the gravesite was not contaminated with the parasite more recently.

"Schistosomiasis has become progressively more common over time so that it causes a huge burden across the world today, with over 200 million people infected. It causes anaemia which significantly decreases physical productivity in infected people, and may also cause bladder cancer. We would expect these consequences in ancient peoples to have had a significant impact upon early civilizations in the region"*, says Dr Mitchell.