Researchers Look at the Origins of Plate Tectonics
The mystery of what kick-started the motion of our earth’s massive tectonic plates across its surface has been explained by researchers at the Univ. of Sydney.
"Earth is the only planet in our solar system where the process of plate tectonics occurs," said Prof. Patrice Rey, from the Univ. of Sydney’s School of Geosciences. "The geological record suggests that until three billion years ago the earth’s crust was immobile so what sparked this unique phenomenon has fascinated geoscientists for decades. We suggest it was triggered by the spreading of early continents then eventually became a self-sustaining process."
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 Univ. of Tübingen in Germany, reported their findings in today’s issue of the journal Nature.
The preserved heart of composer Frederic Chopin contains signs of tuberculosis and possibly some other lung disease, medical experts said today. The findings seem to corroborate Chopin’s 1849 death certificate, which said the Polish-born musician died at the age of 39 in Paris from TB.
He rests in Paris, but in keeping with a Romanticism-era practice his heart was brought to Warsaw, where he grew up, and is kept as a national relic inside a pillar at The Holy Cross Church. Held in two cases and a sealed crystal glass jar, it was inspected in April by forensic and genetic experts to check the state of the preservation.
The meteorite impact that spelled doom for the dinosaurs 66 million years ago decimated the evergreens among the flowering plants to a much greater extent than their deciduous peers, according to a study led by Univ. of Arizona researchers. The results are published in the journal PLOS Biology.
Applying biomechanical formulas 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 researchers found evidence that, after the event, 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.
Federal researchers are exploring several underwater sites where ships sank while navigating in the treacherous waters west of San Francisco in the decades following the Gold Rush.
Over the past week, a team from the National Oceanic and Atmospheric Administration used a remote-controlled underwater vehicle, equipped with sonar and video cameras, to examine and record the historic shipwrecks.
Today in Lab History: September 16, 1885- Karen Horney
Karen Horney was a German-born American psychoanalyst, born Sept. 16, 1885, who departed from some of the basic principles of Sigmund Freud. She suggested that environmental and social conditions — rather than biological drives — determine much of an individual’s personality and are the chief causes of neuroses and personality disorders.
Conditions on Earth for the first 500 million years after it formed may have been surprisingly similar to the present day, complete with oceans, continents and active crustal plates.
This alternate view of Earth’s first geologic eon, called the Hadean, has gained substantial new support from the first detailed comparison of zircon crystals that formed more than 4 billion years ago with those formed contemporaneously in Iceland, which has been proposed as a possible geological analog for early Earth.
Today in Lab History: September 12, 1910- Alexander Langmuir
Alexander Langmuir was an American epidemiologist who created and led the Epidemic Intelligence Service for the U.S. government and was credited with saving thousands of lives with his revolutionary work. In 1949, he became director of the epidemiology branch of the National Communicable Disease Center in Atlanta, a position he held for over 20 years.
Archaeologists slowly digging through a huge 2,300-year-old tomb in northern Greece have uncovered two life-sized marble female statues flanking the entrance to one of three underground chambers.
A Culture Ministry statement says the statues show “exceptional artistic quality.” Their upper sections were discovered last week, but their bodies — in semi-transparent robes — emerged after part of a blocking wall was removed Thursday.
There is more to Stonehenge than meets a visitor’s eye. Researchers have produced digital maps of what’s beneath the World Heritage Site, using ground-penetrating radar, high-resolution magnetometers and other techniques to peer deep into the soil beneath the famous stone circle.
The project produced detailed maps of 17 previously unknown ritual monuments and a huge timber building, which is thought to have been used for burial ceremonies, Birmingham Univ. said today.
Scientist in the Spotlight: Resurrecting Extinct Predators
Russell Garwood, a research fellow at the Univ. of Manchester, England, worked with Jason Dunlop, a curator at the Museum für Naturkunde, Berlin, to create a video of the movements of an extinct arachnid. The arachnid was one of the first land predators and lived 410 million years ago. Garwood and Dunlop used exceptionally detailed fossils from the Natural History Museum in London to recreate its walking gait.
Using CT scans, mesh models and open-source CGI software, they recreated the joints in the creature’s legs and learned that the arachnid ran its prey down. The arachnids were the top of the land-dwelling food chain and the new video brings these fearsome, long-gone animals back from the dead while shedding light on their physiology and evolution.
Today in Lab History: September 9, 1853- Pierre Marie
Pierre Marie was a French neurologist, born Sept. 9, who made fundamental contributions to endocrinology. He trained at the Pitié-Salpêtrière Hospital under Jean Martin Charcot. Marie developed an early interest in nervous diseases. His doctoral thesis was on Basedow’s disease and its characteristic tremor in extended arms and fingers. He published a series of lectures he had given on diseases of the spinal cord.
Depictions of animals in ancient Egyptian artifacts have helped scientists assemble a detailed record of the large mammals that lived in the Nile Valley over the past 6,000 years. A new analysis of this record shows that species extinctions, probably caused by a drying climate and growing human population in the region, have made the ecosystem progressively less stable.
The study, published in PNAS, found that local extinctions of mammal species led to a steady decline in the stability of the animal communities in the Nile Valley. When there were many species in the community, the loss of any one species had relatively little impact on the functioning of the ecosystem, whereas it is now much more sensitive to perturbations, according to first author Justin Yeakel, who worked on the study as a graduate student at UC Santa Cruz, and is now a postdoctoral fellow at the Santa Fe Institute.
One of the most visible signs of climate change in recent years was not even visible at all until a few decades ago. The sea ice cap that covers the Arctic Ocean has been changing dramatically, especially in the last 15 years. Its ice is thinner and more vulnerable – and at its summer minimum now covers more than 1 million fewer square miles than in the late 1970s. That’s enough missing ice to cover Alaska, California and Texas.
A key part of the story of how the world was able to witness and document this change centers on meticulous work over decades by a small group of scientists at NASA’s Goddard Space Flight Center. Late nights in mainframe rooms, double- and triple-checking computer printouts, processing and re-processing data – until the first-ever accurate atlases of the world’s sea ice were published.