Tuesday, November 27, 2007

Gene study: single migration across Bering Strait

Did a relatively small number of people from Siberia who trekked across a Bering Strait land bridge some 12,000 years ago give rise to the native peoples of North and South America?

Or did the ancestors of today’s native peoples come from other parts of Asia or Polynesia, arriving multiple times at several places on the two continents, by sea as well as by land, in successive migrations that began as early as 30,000 years ago?

The questions – featured on magazine covers and TV specials – have agitated anthropologists, archaeologists and others for decades.

University of Michigan scientists, working with an international team of geneticists and anthropologists, have produced new genetic evidence that’s likely to hearten proponents of the land bridge theory. The study, published online in PLoS Genetics, is one of the most comprehensive analyses so far among efforts to use genetic data to shed light on the topic.

The researchers examined genetic variation at 678 key locations or markers in the DNA of present-day members of 29 Native American populations across North, Central and South America. They also analyzed data from two Siberian groups. The analysis shows:

o genetic diversity, as well as genetic similarity to the Siberian groups, decreases the farther a native population is from the Bering Strait – adding to existing archaeological and genetic evidence that the ancestors of native North and South Americans came by the northwest route.

o a unique genetic variant is widespread in Native Americans across both American continents – suggesting that the first humans in the Americas came in a single migration or multiple waves from a single source, not in waves of migrations from different sources. The variant, which is not part of a gene and has no biological function, has not been found in genetic studies of people elsewhere in the world except eastern Siberia.

The researchers say the variant likely occurred shortly prior to migration to the Americas, or immediately afterwards.

“We have reasonably clear genetic evidence that the most likely candidate for the source of Native American populations is somewhere in east Asia,” says Noah A. Rosenberg, Ph.D., assistant professor of human genetics and assistant research professor of bioinformatics at the Center for Computational Medicine and Biology at the U-M Medical School and assistant research professor at the U-M Life Sciences Institute.

“If there were a large number of migrations, and most of the source groups didn’t have the variant, then we would not see the widespread presence of the mutation in the Americas,” he says.

Rosenberg has previously studied the same set of 678 genetic markers used in the new study in 50 populations around the world, to learn which populations are genetically similar and what migration patterns might explain the similarities. For North and South America, the current research breaks new ground by looking at a large number of native populations using a large number of markers.

The pattern the research uncovered – that as the founding populations moved south from the Bering Strait, genetic diversity declined – is what one would expect when migration is relatively recent, says Mattias Jakobsson, Ph.D., co-first author of the paper and a post-doctoral fellow in human genetics at the U-M Medical School and the U-M Center for Computational Medicine and Biology. There has not been time yet for mutations that typically occur over longer periods to diversify the gene pool.

In addition, the study’s findings hint at supporting evidence for scholars who believe early inhabitants followed the coasts to spread south into South America, rather than moving in waves across the interior.

“Assuming a migration route along the coast provides a slightly better fit with the pattern we see in genetic diversity,” Rosenberg says.

The study also found that:

Populations in the Andes and Central America showed genetic similarities.
Populations from western South America showed more genetic variation than populations from eastern South America.
Among closely related populations, the ones more similar linguistically were also more similar genetically.

Monday, November 26, 2007

Chocolate is at least 3,000 years old

The human love affair with chocolate is at least 3,000 years old -- and it began at least 500 years earlier than previously thought, according to new analyses of pottery shards from the UlĂșa Valley region of northern Honduras.

But the first people to appreciate the cacao tree were probably after a buzz of another kind -- a fermented, winelike drink, research shows -- and only later discovered the chocolaty taste we love today.

In research published in the Nov. 27 issue of the Proceedings of the National Academy of Sciences, Cornell professor of anthropology John Henderson and colleagues found traces of caffeine and theobromine, an alkaloid similar to caffeine but specific to cacao, in 11 shards dated to 1100 B.C. The samples came from excavations directed by Henderson and University of California-Berkeley anthropology professor Rosemary Joyce at a site known as Puerto Escondido.

The findings offer chemical evidence for the earliest cacao consumption anywhere in the world.

In the past, the only chemical detection of cacao in ancient pottery required an intact vessel and a substantial amount of residue, Henderson said. To detect much smaller chemical traces in broken shards, co-authors Patrick E. McGovern and Gretchen Hall at the University of Pennsylvania Museum and W. Jeffrey Hurst at Hershey Foods used new extraction techniques along with liquid chromatography, gas chromatography and mass spectrometry -- techniques that could be used for sensitive chemical testing on many more remnants in the future.

"It's not very often that you find a whole vessel," said Henderson. "Now that you can process things from people's trash piles, you can see in much better context how these things were being used."

But while cacao beans (seeds) and the spicy, frothy chocolaty drink they produced were the stuff of royal ceremonies and elite gatherings in later millennia, Henderson said, it's likely that the earliest cacao drinkers made a simpler drink by fermenting the pulp around the seeds. The result (which at least one brewing company, in collaboration with McGovern, is working to reproduce) was a brew that tasted nothing like chocolate.

Since both beverages contain theobromine and caffeine, chemistry doesn't reveal whether a vessel held a winelike quaff made from pulp or the celebrated chocolate concoction made from seeds. But while the jugs of later, chocolate-drinking periods were short and wide, with broad openings to allow for pouring back and forth to create froth, the earlier bottles had long, skinny spouts that would frustrate the most diligent Starbucks froth specialist.

Over the ensuing centuries, Henderson said, the drink was traded, shared and used in ceremonies, creating social networks across the region and beyond.

"The upwardly mobile families were using cacao, serving it as part of a strategy for distinguishing themselves," he said. "It was a way of creating social obligation and political power locally and with people in distant villages. It's that context that gives us a way of understanding how it is that potters in villages hundreds of miles apart have the same understanding of what vessels should look like."

And over time, people likely discovered that the fermented seeds, not the pulp, were the real discovery.

"If we're right about the shift from wine made from pulp to chocolate made from seeds," said Henderson, then all the pomp and luxury that surrounded chocolate in later years -- "the control of cacao plantations by kings and chiefs, all the fancy serving of chocolate in the Aztec courts that so impressed the Spaniards, and the modern chocolate industry that developed from that -- all that was an unintended consequence of some early brewing."

Tel Megiddo

Some come to dig the Tel Aviv University-directed archeological site at Tel Megiddo because they are enchanted by ancient stories of King Solomon. Others come because they believe in a New Testament prophecy that the mound of dirt will be the location of a future Judgment Day apocalyptic battle. Hence the second, rather more chilling name for the site: "Armageddon."

Tel Megiddo has been the subject of a number of decisive battles in ancient times (among the Egyptian, Hebrew and Assyrian peoples) and today it holds a venerated place in archaeology, explains site co-director and world-renowned archeologist Prof. Israel Finkelstein.

Says Prof. Finkelstein, from the Department of Archaeology and Ancient Near Eastern Cultures at Tel Aviv University, "Megiddo is one of the most interesting sites in the world for the excavation of biblical remains. Now volunteers and students from around the world can participate in the dig which lets them uncover 3,000 years worth of history -- from the late 4th millennium B.C.E. to the middle of the first millennium C.E."

rof. Finkelstein, who belongs to the Sonia and Marco Nadler Institute of Archaeology at Tel Aviv University, has been co-directing the site with Prof. David Ussishkin, also of Tel Aviv University, since 1994.

Prof. Finkelstein has co-authored a best-selling book on archaeology and biblical history (The Bible Unearthed, 2001). Earlier this month he released a book (written with A. Mazar) that contains surprising commentary on biblical archaeology and history, The Quest for Biblical Archeology, published by the Society of Biblical Literature in the United States. He is also the recipient of the prestigious international Dan David Prize in the category of Past Dimension (2005).

Likened to a "lightening rod" by the journal Science (2007), Prof. Finkelstein is famous for his unconventional way of interpreting biblical history: he puts emphasis on the days of the biblical authors in the 7th century B.C.E. and theorizes that ancient rulers such as David and Solomon, who lived centuries earlier, were "tribal chieftains ruling from a small hill town, with a modest palace and royal shrine."

Yet, "new archaeological discoveries should not erode one's sense of tradition and identity," he states.

Prof. Ze’ev Herzog, who heads the archaeology institute at Tel Aviv University, says, "There has been an important revolution in biblical history in the last decades. We are now uncovering the difference between myth and history, and between reality and ideology of the ancient authors. This is the role of our generation of archaeologists -- to unearth the real historical reality to find out why and how the biblical records were written."

The archeologists aren't the only ones looking for answers. More than one hundred volunteers come from all corners of the world to dig Megiddo alongside Prof. Finkelstein every year. They are teachers, journalists, actors, construction workers, professors and housewives, as well as archaeology, history and divinity students who dig for credit.

The Megiddo dig is offered as a three-week, four-week or seven-week program. As part of the experience, volunteers live in a nearby kibbutz and are exposed to lectures and debates about their findings. The dig is partnered with the George Washington University, represented by Prof. Eric Cline, the American associate director of the dig. This makes it an ideal stomping ground for Americans who want a hands-on education in archaeology.

"Team and staff members come from all around the world for many reasons: the adventure of foreign travel in a safe yet educational environment, intellectual stimulation, and -- yes -- even a love of digging in the dirt,” notes Prof. Finkelstein.

And those with no prior knowledge or degrees are welcome, he stresses. "We cater to all of the volunteers' backgrounds and teach them field methods, archeological techniques as well as the history of biblical archeology. It is truly a wonderful experience."

Synagogue with unique mosaic floor found in Galilee

Remains of an ancient synagogue from the Roman-Byzantine era have been revealed in excavations carried out in the Arbel National Park in the Galilee under the auspices of the Hebrew University of Jerusalem.

The excavations, in the Khirbet Wadi Hamam, were led by Dr. Uzi Leibner of the Hebrew University’s Institute of Archaeology and Scholion – Interdisciplinary Research Center in Jewish Studies.

Dr. Leibner said that the synagogue’s design is a good example of the eastern Roman architectural tradition. A unique feature of the synagogue is the design of its mosaic floor, he said.

The synagogue ruins are located at the foot of the Mt. Nitai cliffs overlooking the Sea of Galilee, amidst the remains of a large Jewish village from the Roman-Byzantine period. The first season of excavations there have revealed the northern part of the synagogue, with two rows of benches along the walls. The building is constructed of basalt and chalk stone and made use of elements from an earlier structure on the site.

Archaeologists differ among themselves as to which period the ancient Galilean synagogues belong. The generally accepted view is that they can be attributed to the later Roman period (second to fourth centuries C.E.), a time of cultural and political flowering of the Jews of the Galilee. Recently, some researchers have come to believe that these synagogues were built mainly during the Byzantine period (fifth and sixth centuries C.E.), a time in which Christianity rose to power and, it was thought, the Jews suffered from persecution. Dr. Leibner noted that this difference of scholarly opinion has great significance in perhaps redrawing the historical picture of Jews in those ancient times.

The excavators were surprised to find in the eastern aisle of the synagogue a mosaic decoration which to date has no parallels -- not in other synagogues, nor in art in Israel in general from the Roman-Byzantine period. The mosaic is made of tiny stones (four mm. in size) in a variety of colors. The scene depicted is that of a series of woodworkers who are holding various tools of their trade. Near these workers is seen a monumental structure which they are apparently building. According to Dr. Leibner, since Biblical scenes are commonly found in synagogue art, it is possible that what we see in this case is the building of the Temple, or Noah’s ark, or the tower of Babel. The mosaic floor has been removed from the excavation site and its now in the process of restoration.

The archaeologists at the site are also attempting, though their excavations, to gain a clearer picture of rural Jewish village life in Roman-era Galilee. In addition to excavating the synagogue, they also are involved in uncovering residential dwellings and other facilities at the site, such as a sophisticated olive oil press and solidly-built two-story homes.

“There are those who tend to believe that the rural Jewish villagers of that era lived in impoverished houses or in huts and that the magnificent synagogues existed in contrast to the homes that surrounded them,” said Dr. Leibner. ‘While it is true that the synagogues were built of a quality that exceeded the other structures of the village, the superior quality private dwellings here testify to the impressive economic level of the residents.”

Monday, November 19, 2007

'Noah's flood' kick-started European farming

The flood believed to be behind the Noah’s Ark myth kick-started European agriculture, according to new research by the Universities of Exeter, UK and Wollongong, Australia. Published in the journal Quaternary Science Reviews, the research paper assesses the impact of the collapse of the North American (Laurentide) Ice Sheet, 8000 years ago. The results indicate a catastrophic rise in global sea level led to the flooding of the Black Sea and drove dramatic social change across Europe. The research team argues that, in the face of rising sea levels driven by contemporary climate change, we can learn important lessons from the past.

The collapse of the Laurentide Ice Sheet released a deluge of water that increased global sea levels by up to 1.4 metres and caused the largest North Atlantic freshwater pulse of the last 100,000 years. Before this time, a ridge across the Bosporus Strait dammed the Mediterranean and kept the Black Sea as a freshwater lake. With the rise in sea level, the Bosporus Strait was breached, flooding the Black Sea. This event is now widely believed to be behind the various folk myths that led to the biblical Noah’s Ark story. Archaeological records show that around this time there was a sudden expansion of farming and pottery production across Europe, marking the end of the Mesolithic hunter-gatherer era and the start of the Neolithic. The link between rising sea levels and such massive social change has previously been unclear.

The researchers created reconstructions of the Mediterranean and Black Sea shoreline before and after the rise in sea levels. They estimated that nearly 73,000 square km of land was lost to the sea over a period of 34 years. Based on our knowledge of historical population levels, this could have led to the displacement of 145,000 people. Archaeological evidence shows that communities in southeast Europe were already practising early farming techniques and pottery production before the Flood. With the catastrophic rise in water levels it appears they moved west, taking their culture into areas inhabited by hunter-gatherer communities.

Professor Chris Turney of the University of Exeter, lead author of the paper, said: “People living in what is now southeast Europe must have felt as though the whole world had flooded. This could well have been the origin of the Noah’s Ark story. Entire coastal communities must have been displaced, forcing people to migrate in their thousands. As these agricultural communities moved west, they would have taken farming with them across Europe. It was a revolutionary time.”

The rise in global sea levels 8000 years ago is in-line with current estimates for the end of the 21st century. Professor Chris Turney continued: “This research shows how rising sea levels can cause massive social change. 8,000 years on, are we any better placed to deal with rising sea levels" The latest estimates suggest that by AD 2050, millions of people will be displaced each year by rising sea levels. For those people living in coastal communities, the omen isn’t good.”

Thursday, November 8, 2007

Maya Politics = Ancient Large-Game Decline

University of Florida Study: Maya Politics Likely Played Role in Ancient Large-Game Decline

A University of Florida study is the first to document ancient hunting effects on large-game species in the Maya lowlands of Central America, and shows political and social demands near important cities likely contributed to their population decline, especially white-tailed deer.

Additional evidence from Maya culture and social structure at the end of the Classic period (approximately 250 to 800 A.D) strongly supports this assertion. The study by Florida Museum of Natural History Assistant Curator of Environmental Archaeology Kitty Emery appears in the Oct. 31 issue of the Journal for Nature Conservation.

"We're finding declines specifically in large-game species, and particularly in the species that were politically and socially important to the Maya," Emery said. "The politically powerful elite Maya had preferential access to large game, and white-tailed deer were especially important to the Maya as food and for their symbolic power."

Emery tracked the proportion of large-game animals to all vertebrate species over time, using 78,928 animal bones found at 25 Maya archaeological sites. To tease apart specific hunting effects, she also tracked the proportion of white-tailed deer to all vertebrates. Her samples spanned 2,500 years, from about 1000 B.C. to 1500 A.D.

This period includes the collapse of the lowland Maya political and social order and the final period of Spanish colonization. Her study, funded by the National Science Foundation, is the first regional analysis of this area to interpret how humans impacted animal populations based on archaeological data of animal use by humans. She used both her own original data and existing published data.

"The data suggests the game decline was caused primarily by hunting pressure since the reduction in numbers was recorded for large vertebrates as opposed to just animals sensitive to the disappearance of forest cover or those sensitive to climate changes," Emery said. "But the effects of hunting pressure were undoubtedly exacerbated by deforestation and climate change since there is also documented evidence for these changes at the same time."

Emery said not all sites showed large-game declines despite high human population, and that the declines were most noticeable at regional capitals and large cities.

"The capital cities were home to a large and top-heavy ruling class who demanded that the regions' hunters provide them with large quantities of the best cuts of favorite meats from large game, and particularly the white-tailed deer," Emery said. "They also demanded large numbers of symbolically important species such as white-tailed deer and large wild cats like jaguar and puma, since these species were used as symbolic displays of their wealth and power, and were used in ritual interactions with the deities."

Deer also were important theatrically because actors wore costumes to portray the predator-prey relationship.

The power of the noble classes and the king was based on their perceived abilities to control ecology, but Emery said several negative environmental situations converged simultaneously, likely contributing to the collapse of Maya political stability starting around 1,200 years ago. According to current Maya archaeological theory, Maya demand for wood used in building finishes such as lime plaster combined with an exploding population base that cleared more and more land for agriculture -- resulting in deforestation. Concurrent climate change resulted in a 200-year drought which further curtailed forest regrowth.

"The rulers' response to the environmental degradation may have been to demand more large game and more deer to use in feasts and rituals where they appealed to deities for help and also to prove their status," Emery said. "As the valued resources became more scarce, they made more demands to obtain them to prove and reinforce their power."

Their demand for large game was not extreme enough to cause extinction or local exterminations, an important finding. Emery said this indicates that over the 2,500 years of this study, the ancient Maya were generally careful of their animal resources.

Brown University ancient Maya scholar Stephen Houston said Emery's "breadth of expertise" allowed her to tackle such an important review of Maya animal use.

"The lack of extinctions shows that the Maya impact on parts of their environment was not as profound as some have thought," Houston said. "That is, we don't see utter devastation to the extent that species disappeared entirely. But Emery also confirms that the Maya went after high-value, prestigious meats like deer and, through vigorous hunting, that they found such game harder and harder to find."