Tuesday, October 21, 2014
Thursday, October 9, 2014
Conventional estimates for the collapse of the Aegean civilization may be incorrect by up to a century, according to new radiocarbon analyses.
While historical chronologies traditionally place the end of the Greek Bronze Age at around 1025 BCE, this latest research suggests a date 70 to 100 years earlier.
Archaeologists from the University of Birmingham selected 60 samples of animal bones, plant remains and building timbers, excavated at Assiros in northern Greece, to be radiocarbon dated and correlated with 95.4% accuracy using Bayesian statistical methodology at the University of Oxford and the Akademie der Wissenschaften Heidelberg, Germany.
The findings are published in the journal PLOS One.
Dr Ken Wardle of the Department of Classics, Ancient History and Archaeology at the University of Birmingham said: 'These new results tell a story that is totally independent of and rather different from the conventional historical accounts of the date of the end of the Greek Bronze Age.
'Until very recently the chronology of the later part of the Greek Bronze Age was entirely based on historical dates derived from Egypt and the Near East with the aid of exported or imported objects such as Minoan or Mycenaean pottery or Egyptian scarabs.
'But if we accept the 14C radiocarbon dating – and there is no good reason not to – we have to rethink our understanding of a long sequence of dates from the middle of the 14th century BCE to the beginning of the 11th century BCE.
'This is a fundamental reassessment and is important not just for Greece but in the wider Mediterranean context. It affects the ways in which we understand the relationships between different areas, including the hotly debated dates of developments in Israel and Spain.'
The dates derived from the samples meticulously excavated at Assiros – 25km from modern-day Thessaloniki – represent the most complete data set for the Greek Bronze Age, covering 400 years from the mid-14th century to the 10th century BCE. They tell a similar story to those determined for the volcanic eruption in Santorini (Thera), which has been re-dated from 1525 BCE to 1625 BCE as a result of scientific evidence.
Wednesday, October 8, 2014
Friday, September 26, 2014
A new discovery of thousands of Stone Age tools has provided a major insight into human innovation 325,000 years ago and how early technological developments spread across the world, according to research published in the journal Science.
Researchers from Royal Holloway, University of London, together with an international team from across the United States and Europe, have found evidence which challenges the belief that a type of technology known as Levallois – where the flakes and blades of stones were used to make useful products such as hunting weapons – was invented in Africa and then spread to other continents as the human population expanded.
They discovered at an archaeological site in Armenia that these types of tools already existed there between 325,000 and 335,000 years ago, suggesting that local populations developed them out of a more basic type of technology, known as biface, which was also found at the site.
Dr Simon Blockley and Dr Alison MacLeod, from the Department of Geography at Royal Holloway, analysed volcanic material that preserved the archaeological site in the village of Nor Geghi, in the Kotayk Province of Armenia. By employing innovative procedures developed at Royal Holloway, they extracted suitable material to help date the Levallois tools.
"The discovery of thousands of stone artefacts preserved at this unique site provides a major new insight into how Stone Age tools developed during a period of profound human behavioural and biological change", said Dr Blockley. "The people who lived there 325,000 years ago were much more innovative than previously thought, using a combination of two different technologies to make tools that were extremely important for the mobile hunter-gatherers of the time.
"Our findings challenge the theory held by many archaeologists that Levallois technology was invented in Africa and spread to Eurasia as the human population expanded. Due to our ability to accurately date the site in Armenia, we now have the first clear evidence that this significant development in human innovation occurred independently within different populations."
Archaeologists argue that Levallois technology was a more innovative way of crafting tools, as the flakes produced during the shaping of the stone were not treated as waste but were made at predetermined shapes and sizes and used to make products that were small and easy to carry. With the more primitive biface technology, a mass of stone was shaped through the removal of flakes from two surfaces in order to produce bigger tools such as a hand axes.
Tuesday, September 23, 2014
An Impressive Compound Containing a Large Oil Press, Wine Press and Mosaics was Exposed in Bet Shemesh
Wednesday, September 17, 2014
New studies of ancient DNA are shifting scientists' ideas of how groups of people migrated across the globe and interacted with one another thousands of years ago. By comparing nine ancient genomes to those of modern humans, Howard Hughes Medical Institute (HHMI) scientists have shown that previously unrecognized groups contributed to the genetic mix now present in most modern-day Europeans.
"There are at least three major, highly differentiated populations that have contributed substantial amounts of ancestry to almost everybody that has European ancestry today," says David Reich, an HHMI investigator at Harvard Medical School. Those include hunter-gatherers from western Europe, the early farmers who brought agriculture to Europe from the Near East, and a newly identified group of ancient north Eurasians who arrived in Europe sometime after the introduction of agriculture. That means there were major movements of people into Europe later than previously thought. The team, led by Reich and Johannes Krause at the University of Tübingen in Germany, reported their findings in the September 18, 2014, issue of the journal Nature.
In the last five years, genetic evidence has demonstrated that migrants from the Near East brought agriculture with them to Europe when they arrived about 8,500 years ago. But the genomes of present-day Europeans show signs that they come from more than just the indigenous hunter-gatherers and these early farmers.
Two years ago, Reich's group uncovered genetic evidence that most present-day Europeans are a mixture of groups related to southern Europeans, Near Easterners, and a third group most closely related to Native Americans. "That was a crazy observation, but it's very strong statistically," Reich says. "We argued that this is because of the contribution of an ancient north Eurasian population some of whose members contributed to the peopling of the Americas more than 15,000 years ago, and others of which later migrated to Europe."
To clarify that early history, Reich's team, including more than 100 collaborators worldwide, collected genetic data from nine ancient skeletons and 203 present-day populations living all over the world. Collaborators isolated human DNA and sequenced the complete genomes from the bones of a 7,000-year old skeleton found in Germany and eight skeletons of hunter-gatherers who lived in Luxembourg and Sweden about 8,000 years ago. They compared those genomes to those of the 2,345 people in their contemporary populations.
That required developing new computational methods for genetic analysis. "Figuring out how these populations are related is extremely hard," Reich says. "There's a lot that happened in Europe in the last 8,000 years, and this history acts like a veil, making it difficult to discern what happened at the beginning of this period. We had to find statistics that were able to tell us what happened deep in the past without getting confused by 8,000 years of intervening history, when massive and important events occurred."
"What we find is unambiguous evidence that people in Europe today have all three of these ancestries: early European farmers who brought agriculture to Europe, the indigenous hunter-gatherers who were in Europe prior to 8,000 years ago, and these ancient north Eurasians," Reich says. Further analyses showed that describing present-day Europeans as a mixture of the three populations is a good fit for most, although not all, populations.
When the study began, the ancient north Eurasian population was a "ghost population" – identified based on genetic patterns without any ancient DNA. But in 2013, another group analyzed DNA from two skeletons found in Siberia, one from 24,000 years ago and one from 17,000 years ago, and found that it shared genetic similarities with Europeans and North Americans. The ghost, Reich says, had been found.
Although DNA from ancient north Eurasians is present in nearly all modern Europeans, Reich's team did not find it in their ancient hunter-gatherers or the ancient farmers. That means the north Eurasian line of ancestry was introduced into Europe after agriculture had been established, a scenario most archaeologists had thought unlikely.
"We have this amazing observation that only two ancestries are represented among the first farmers, from about 7,000 to 5,000 years ago. And then suddenly everybody today has ancient north Eurasian ancestry," Reich says. "So there must have been a later movement of this ancestry into Europe."
Anthropologists have long thought that densely settled populations would be resistant to the arrival of new groups. "But this is hard evidence that exactly such a major migration occurred," Reich says. "It's very important because it's a major contributor to Europeans today." The time of the ancient north Eurasians' arrival remains to be determined, but Reich says their later-than-expected movement into Europe might help explain the complex mix of languages that exists there today.
The team's data also reveals that the first farmers to reach Europe from the Near East had ancestors from a previously unidentified lineage, which Reich's group named the Basal Eurasians. Basal Eurasians were the first people to separate from the larger group of non-Africans, before other non-African groups diversified. Reich says that attempts to identify the first group to split from the non-Africans had always been puzzling: genetic evidence indicates that this is likely to be Europeans or Near Easterners, even though some archaeological evidence has indicated that people were in New Guinea and Australia before they were Europe.
The new analysis shows that the Near Easterners who came into Europe 8,000 years ago brought with them a strand of ancestry that had separated before the ancestors of Australian aborigines separated from the indigenous people of Europe. "That population must have been hanging out somewhere in the Near East for a very long time," Reich says. Now he would like to know how that population fits into the archaeological history of the region. Ancient DNA from Basal Europeans, if found, might lead to new revelations about early human history.
Tuesday, September 16, 2014
66 million years ago, a 10-km diameter chunk of rock hit the Yukatan peninsula near the site of the small town of Chicxulub with the force of 100 teratons of TNT.
It left a crater more than 150 km across, and the resulting megatsunami, wildfires, global earthquakes and volcanism are widely accepted to have wiped out the dinosaurs and made way for the rise of the mammals. But what happened to the plants on which the dinosaurs fed?
A new study led by researchers from the University of Arizona reveals that the meteorite impact that spelled doom for the dinosaurs also decimated the evergreen flowering plants to a much greater extent than their deciduous peers. They hypothesize that the properties of deciduous plants made them better able to respond rapidly to chaotically varying post-apocalyptic climate conditions. The results are publishing on September 16 in the open access journal PLOS Biology.
Applying biomechanical formulae to a treasure trove of thousands of fossilized leaves of angiosperms — flowering plants excluding conifers — the team was able to reconstruct the ecology of a diverse plant community thriving during a 2.2 million-year period spanning the cataclysmic impact event, believed to have wiped out more than half of plant species living at the time. The fossilized leaf samples span the last 1,400,000 years of the Cretaceous and the first 800,000 of the Paleogene.
The researchers found evidence that after the impact, fast-growing, deciduous angiosperms had replaced their slow-growing, evergreen peers to a large extent. Living examples of evergreen angiosperms, such as holly and ivy, tend to prefer shade, don't grow very fast and sport dark-colored leaves.
"When you look at forests around the world today, you don't see many forests dominated by evergreen flowering plants," said the study's lead author, Benjamin Blonder. "Instead, they are dominated by deciduous species, plants that lose their leaves at some point during the year."
Blonder and his colleagues studied a total of about 1,000 fossilized plant leaves collected from a location in southern North Dakota, embedded in rock layers known as the Hell Creek Formation, which at the end of the Cretaceous was a lowland floodplain crisscrossed by river channels. The collection consists of more than 10,000 identified plant fossils and is housed primarily at the Denver Museum of Nature and Science. "When you hold one of those leaves that is so exquisitely preserved in your hand knowing it's 66 million years old, it's a humbling feeling," said Blonder.
"If you think about a mass extinction caused by catastrophic event such as a meteorite impacting Earth, you might imagine all species are equally likely to die," Blonder said. "Survival of the fittest doesn't apply — the impact is like a reset button. The alternative hypothesis, however, is that some species had properties that enabled them to survive.
"Our study provides evidence of a dramatic shift from slow-growing plants to fast-growing species," he said. "This tells us that the extinction was not random, and the way in which a plant acquires resources predicts how it can respond to a major disturbance. And potentially this also tells us why we find that modern forests are generally deciduous and not evergreen."
Previously, other scientists found evidence of a dramatic drop in temperature caused by dust from the impact. "The hypothesis is that the impact winter introduced a very variable climate," Blonder said. "That would have favored plants that grew quickly and could take advantage of changing conditions, such as deciduous plants."
"We measured the mass of a given leaf in relation to its area, which tells us whether the leaf was a chunky, expensive one to make for the plant, or whether it was a more flimsy, cheap one," Blonder explained. "In other words, how much carbon the plant had invested in the leaf." In addition the researchers measured the density of the leaves' vein networks, a measure of the amount of water a plant can transpire and the rate at which it can acquire carbon.
"There is a spectrum between fast- and slow-growing species," said Blonder. "There is the 'live fast, die young' strategy and there is the 'slow but steady' strategy. You could compare it to financial strategies investing in stocks versus bonds." The analyses revealed that while slow-growing evergreens dominated the plant assemblages before the extinction event, fast-growing flowering species had taken their places afterward.