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Saturday, January 30, 2010

Big Freeze Plunged Europe Into Ice Age in Months

Big Freeze Plunged Europe Into Ice Age in Months


ScienceDaily (Nov. 30, 2009) — In the film The Day After Tomorrow, the
world enters the icy grip of a new glacial period within the space of
just a few weeks. Now new research shows that this scenario may not be
so far from the truth after all.


William Patterson, from the University of Saskatchewan in Canada, and
his colleagues have shown that switching off the North Atlantic
circulation can force the Northern hemisphere into a mini 'ice age' in
a matter of months. Previous work has indicated that this process
would take tens of years.


Around 12,800 years ago the northern hemisphere was hit by a mini ice-
age, known by scientists as the Younger Dryas, and nicknamed the 'Big
Freeze', which lasted around 1300 years. Geological evidence shows
that the Big Freeze was brought about by a sudden influx of
freshwater, when the glacial Lake Agassiz in North America burst its
banks and poured into the North Atlantic and Arctic Oceans. This vast
pulse, a greater volume than all of North America's Great Lakes
combined, diluted the North Atlantic conveyor belt and brought it to a
halt.


Without the warming influence of this ocean circulation temperatures
across the Northern hemisphere plummeted, ice sheets grew and human
civilisation fell apart.


Previous evidence from Greenland ice cores has indicated that this
sudden change in climate occurred over the space of a decade or so.
Now new data shows that the change was amazingly abrupt, taking place
over the course of a few months, or a year or two at most.


Patterson and his colleagues have created the highest resolution
record of the 'Big Freeze' event to date, from a mud core taken from
an ancient lake, Lough Monreach, in Ireland. Using a scalpel layers
were sliced from the core, just 0.5mm thick, representing a time
period of one to three months.


Carbon isotopes in each slice reveal how productive the lake was,
while oxygen isotopes give a picture of temperature and rainfall. At
the start of the 'Big Freeze' their new record shows that temperatures
plummeted and lake productivity stopped over the course of just a few
years. "It would be like taking Ireland today and moving it up to
Svalbard, creating icy conditions in a very short period of time,"
says Patterson, who presented the findings at the European Science
Foundation BOREAS conference on humans in the Arctic, in Rovaniemi,
Finland.


Meanwhile, their isotope record from the end of the Big Freeze shows
that it took around two centuries for the lake and climate to recover,
rather than the abrupt decade or so that ice cores indicate. "This
makes sense because it would take time for the ocean and atmospheric
circulation to turn on again," says Patterson.


Looking ahead to the future Patterson says there is no reason why a
'Big Freeze' shouldn't happen again. "If the Greenland ice sheet
melted suddenly it would be catastrophic," he says.


This study was part of a broad network of 38 individual research teams
from Europe, Russia, Canada and the USA forming the European Science
Foundation EUROCORES programme 'Histories from the North --
environments, movements, narratives' (BOREAS). This highly
interdisciplinary initiative brought together scientists from a wide
range of disciplines including humanities, social, medical,
environmental and climate sciences.
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Noah's Ark? We got a round tuit.

They were written on a tablet, which dates to around 1,700BC and was found in the Middle East during the 1940s by Leonard Simmons, who subsequently passed it on to his son Douglas.

Douglas took it to Irving Finkel, an expert at the British Museum, who "took one look at it an nearly fell off his chair". He then translated the 60 lines of script, and believes it is one of the first tablets to describe the shape of the famous ark.


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Review: Ararat by Frank Westerman"In all the images ever made people assumed the ark was, in effect, an ocean-going boat, with a pointed stem and stern for riding the waves – so that is how they portrayed it," Mr Finkel, Assistant Keeper Ancient Mesopotamian script, said. "But the ark didn't have to go anywhere, it just had to float, and the instructions are for a type of craft which they knew very well. It's still sometimes used in Iran and Iraq today, a type of round coracle which they would have known exactly how to use to transport animals across a river or floods."

The tablet describes the Mesopotamian story, which became the account in the Old Testament of Noah's Ark in the Book of Genesis.

In Mr Finkel's translation, the god speaks to Atram-Hasis, a Sumerian king who is the Noah figure in early versions of the ark story.

The tablet's translation says: "Wall, wall! Reed wall, reed wall! Atram-Hasis, pay heed to my advice, that you may live forever! Destroy your house, build a boat; despise possessions And save life! Draw out the boat that you will built with a circular design; Let its length and breadth be the same."

Mr Finkel, the curator of the recent British exhibition on ancient Babylon, believes it was during the Babylonian captivity that the exiled Jews learned of the story of Noah and incorporated it into the Old Testament.

"It is the most extraordinary thing," Douglas told The Guardian. "You hold it in your hand, and you instantly get a feeling that you are directly connected to a very ancient past – and it gives you a shiver down your spine."

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100,000 year old protofarmers

ScienceDaily (Dec. 18, 2009) — The consumption of wild cereals among prehistoric hunters and gatherers appears to be far more ancient than previously thought, according to a University of Calgary archaeologist who has found the oldest example of extensive reliance on cereal and root staples in the diet of early Homo sapiens more than 100,000 years ago.

Julio Mercader, holder of the Canada Research Chair in Tropical Archaeology in the U of C's Department of Archaeology, recovered dozens of stone tools from a deep cave in Mozambique showing that wild sorghum, the ancestor of the chief cereal consumed today in sub-Saharan Africa for flours, breads, porridges and alcoholic beverages, was in Homo sapiens' pantry along with the African wine palm, the false banana, pigeon peas, wild oranges and the African "potato." This is the earliest direct evidence of humans using pre-domesticated cereals anywhere in the world. Mercader's findings are published in the December 18 issue of the research journal Science.

"This broadens the timeline for the use of grass seeds by our species, and is proof of an expanded and sophisticated diet much earlier than we believed," Mercader said. "This happened during the Middle Stone Age, a time when the collecting of wild grains has conventionally been perceived as an irrelevant activity and not as important as that of roots, fruits and nuts."

In 2007, Mercader and colleagues from Mozambique's University of Eduardo Mondlane excavated a limestone cave near Lake Niassa that was used intermittently by ancient foragers over the course of more than 60,000 years. Deep in this cave, they uncovered dozens of stone tools, animal bones and plant remains indicative of prehistoric dietary practices. The discovery of several thousand starch grains on the excavated plant grinders and scrapers showed that wild sorghum was being brought to the cave and processed systematically.

"It has been hypothesized that starch use represents a critical step in human evolution by improving the quality of the diet in the African savannas and woodlands where the modern human line first evolved. This could be considered one of the earliest examples of this dietary transformation," Mercader said. "The inclusion of cereals in our diet is considered an important step in human evolution because of the technical complexity and the culinary manipulation that are required to turn grains into staples."

Mercader said the evidence is on par with grass seed use by hunter-gatherers in many parts of the world during the closing stages of the last Ice Age, approximately 12,000 years ago. In this case, the trend dates back to the beginnings of the Ice Age, some 90,000 years earlier.

Mercader's work was supported by the Canada Research Chairs program, Canada Foundation for Innovation, the Social Sciences and Humanities Research Council of Canada, the U of C's Faculty of Social Science and the National Geographic Society.Source
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Stone tools on Crete suggest Paleolithic sailors Options

From The Times
January 18, 2010
Tools point to early Cretan arrivals
Norman Hammond, Archaeology Correspondent


Evidence for the world’s earliest seafaring has emerged from an
archaeological survey in Crete. Tools of Lower Palaeolithic type, at
least 130,000 years old, have been found on the Greek island, which
has been isolated by the Mediterranean Sea for at least the past five
million years, so that any human ancestors must have arrived by boat.
At this date, they would have been of a pre-modern species: the
earliest Neanderthalers or even Homo heidelbergensis, the species to
which Boxgrove Man belonged, are among possible contenders, but no
such remains have so far been found on Crete.


“The early inhabitants of Crete reached the island using sea craft
capable of open-sea navigation and multiple journeys — a finding that
pushes the history of seafaring in the Mediterranean back by more than
100,000 years and has implications for the dispersal of early humans,”
Professor Curtis Runnels said. The oldest uncontested marine crossing
until recently was from Indonesia to Australia, dating to perhaps
60,000 years ago and made by anatomically modern humans of our own
species, Homo sapiens, although we now know that earlier settlement on
the island of Flores in Indonesia also necessitated a sea-crossing.


Professor Runnels, the Palaeolithic expert in the survey team, said
that the investigation was carried out along the southwestern coast of
Crete near the town of Plakias, facing Libya more than 200 miles to
the south. These first Cretans may have crossed the Libyan Sea rather
than island-hopping through the Cyclades from mainland Greece. Recent
finds of what are claimed to be Palaeolithic tools from the island of
Gavdos, off the south coast of Crete, would support this southern
approach.


The survey has focused on the area from Plakias to Ayios Pavlos,
including the Preveli Gorge, and has recovered more than 2,000 stone
artefacts from 28 sites; the early tools were found at nine of these,
eight in the area between Plakias and Preveli. “The existence of Lower
Palaeolithic artefacts in association with datable geological contexts
was a complete surprise: until now there has been no certain evidence
of Lower Palaeolithic seafaring in the Mediterranean,” Professor
Runnels said.


Early human penetration of Spain across the Strait of Gibraltar at a
much earlier Palaeolithic date has been proposed, on the basis of
occupation at Atapuerca, near Burgos, dating to at least 1.3 million
years ago. These first Europeans could also have come along the north
side of the Mediterranean from Anatolia, via Greece and the Balkans,
however. The impact of this Cretan evidence is to show that a sea-
crossing by pre-modern humans from Morocco to Spain cannot be ruled
out.


The Plakias survey team, headed by Dr Thomas Strasser, of Providence
College in Rhode Island, and Dr Eleni Panagopoulou, of the Greek
Ministry of Culture, and funded partly by the National Geographic
Society, sought caves and rock shelters near the mouths of freshwater
perennial streams and rivers emptying into the Libyan Sea and within
five kilometres of the present coast. Because erosion has cut back
many of these, the team sought artefacts on the slopes in front of
their present entrances. Much of the material was found on old marine
terraces up to 92 metres above modern sea level.


Up to 300 pieces were found at each of the early sites, and at five
sites the geological context allowed an approximate date to be
assigned. Professor Runnels considers his estimate of 130,000 years to
be a minimum and cautions that the artefacts could be much older. The
tools included handaxes, cleavers and scrapers, and the quartz rocks
used were sufficiently abundant for tools to be discarded after only
short periods of use.


What sort of water-craft might have been used remains a matter of
speculation, but it seems that our forebears were forging their way
across Homer’s “wine-dark sea” tens of millennia earlier than anybody
had supposed.
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