Nov 1, 2013

Lasers Zap Heads of Flies to Expose Brains

Using lasers, scientists can now surgically blast holes thinner than a human hair in the heads of live fruit flies, allowing researchers to see how the flies' brains work.

The researchers also successfully tested this technique on worms, ants and mice.

Microscopically peering into living animals can help scientists learn more about key details of these animals' biology. For instance, tiny glass windows surgically implanted into the sides of living mice  can help researchers study how cancers develop in real time and evaluate the effectiveness of potential medicines.

Surgically preparing small live animals for such "intravital microscopy" is often time-consuming and requires considerable skill and dexterity. Now, Supriyo Sinha, a systems engineer at Stanford University in California, and his colleagues have developed a way to prepare live animals for such microscopy that is both fast -- taking less than a second -- and largely automated.

Fruit-fly brains

To conduct this procedure, scientists first cooled fruit flies to anesthetize them. Then, the researchers carefully picked up the insects with tweezers and glued them to the tops of glass fibers in order to immobilize the flies' bodies and heads. Then, using a high-energy pulsed ultraviolet laser, the researchers blasted holes measuring 12 to 350 microns wide in the flies' heads. (In comparison, the average human hair is about 100 microns wide.) They then applied a saline solution to exposed tissue to help keep the fly brains healthy. (See Experiment Video).

The scientists then microscopically analyzed brain activity in the fruit flies. The insects in the experiment were genetically modified to generate a protein that emits a green glow in the presence of calcium ions, the flow of which is key to neural activity. By looking through these "windows" into the fruit flies' heads, the researchers successfully monitored calcium-ion-based activity in neurons in response to different smells.

Using lasers enabled the researchers to create these "windows" up to 100 times faster than they could be created manually. Moreover, these laser-cut windows were apparently substantially gentler on fly health than ones created by conventional surgery -- the researchers could image brain activity for longer than they could using the conventional method, up to 18 hours, about five to 20 times longer than prior microscopy studies of living, hand-dissected flies.

"The induced trauma to the fly is minimized, and the fly can remain alive longer," Sinha told LiveScience. "Learning and memory experiments in which the brain is imaged before and after training is possible."

Prior research had tried using laser surgery to open holes in animals for intravital microscopy before. Compared to past work that used infrared, visible or larger-wavelength ultraviolet lasers, this new technique can remove tissue more quickly or cause less collateral damage in the brain.

Sinha and his colleagues also successfully tested their technique on anesthetized and immobilized ants, nematode worms and mice. "Our main motivation is to better understand neural circuits, and faster screening and imaging could better help us reverse-engineer these circuits," Sinha said.

From one to 100

The scientists are also developing a way to automatically capture, mount and align the insects for laser surgery. Their short-term goal is to build a system that can hold a dozen flies.

"We are trying to streamline the procedure such that the experimentalist only has to press one button to have the system pick and mount and align 12 flies; a second button that would surgically remove the cuticle and apply saline to the 12 flies; and a third button to start imaging the 12 flies under predetermined stimulation," Sinha said.

Ultimately the researchers would like to simultaneously image the brains of about 100 awake fruit flies with a push of a few buttons, Sinha added.

Read more at Discovery News

Finned Monster Bit Heads Off Ancient Amphibians

DENVER — Talk about a creature feature: A bizarre boomerang-headed amphibian that burrowed in a seasonal pond in what is now Texas often met its doom in the jaws of a reptilian fin-backed mammalian ancestor, new fossils reveal.

These two weird critters were residents of the Permian period 298 million to 250 million years ago, before dinosaurs roamed the Earth. Dimetrodon, the jaguar-size finback, looked like a lizard but was actually more closely related to modern mammals. Diplocaulus, the boomerang-head, was a truly strange amphibian with an impractically wide, bony skull.

"It's just so weird," said study researcher Robert Bakker, the curator of paleontology at the Houston Museum of Natural Science. "This is an example of unintelligent design."

Unintelligent though a broad head may have been for a burrowing creature, the boomerang-head managed to survive for 45 million years during the Permian, a period known for its extinctions, Bakker told LiveScience.

Bakker and his colleagues discovered the Dimetrodonand Diplocaulus interaction in the Craddock bone bed in Baylor County, Texas. The bone bed is scattered with the bodies of boomerang-heads, curled in what were once burrows. The amphibians seem to have burrowed into the mud to survive the dry season, the researchers reported here Monday (Oct. 28) at the annual meeting of the Geological Society of America.

"The bed had a reputation of just being a stewpot with everything mixed together," Bakker said. "That's totally wrong. It's beautifully layered."

The excavations revealed that boomerang-heads were common in the pond — and that something was snacking on them.

"We have hundreds of these, mostly chewed, and even the guys in burrows got attacked," Bakker said.

The shed teeth, "like bullets in a crime scene," revealed the attacker to be Dimetrodon, he said. The finback's sharp fangs and long snout would have enabled it to bite boomerang-heads hiding in burrows, perhaps after partially excavating them with its sharp, digging claws.

One cluster of eight juvenile boomerang-heads was found stacked together, suggesting they all occupied the same burrow. Dimetrodon likely killed the top three, including one whose nose was bitten clean off (taking part of the brain with it). The other five boomerang-heads survived the Dimetrodon, only to perish during the next dry season, Bakker said.

Read more at Discovery News

Supervolcanoes Found in Maine! (Yes, Maine)

Maine has supervolcanoes. Wait, Maine has volcanoes? Yes, and their eruptions could have been among the biggest ever on Earth, geoscientist Sheila Seaman reported here Tuesday (Oct. 29) at the Geological Society of America's annual meeting.

"Long before there were these things called supervolcanoes, we've known about giant, big, horrific silicic volcanic eruptions," said Seaman, of the University of Massachusetts at Amherst. The most massive of these blasts in recent history was Toba, which blew up an island in Indonesia 2.5 million years ago. The explosion heaved 700 cubic miles (2,800 cubic kilometers) of magma out of the Earth's crust.

Around 420 million years ago, a series of super-eruptions dropped thick piles of ash and lava fragments along the proto-East Coast. There are at least four volcanoes spread out along 100 miles (160 km) of Maine's coast, Seaman said.

The huge volcanic rock piles are consistent with caldera-forming eruptions, Seaman said. These explosions empty a magma chamber, leaving a gaping wound in the Earth — think Yellowstone National Park, or the San Juan volcanic field in Colorado.

Since they formed, the ancient volcanic layers have been tilted up by tectonic forces, providing a top-to-bottom slice through a supervolcano. For example, Isle au Haut, part of Acadia National Park, exposes the heart of a volcano. "The whole magma chamber is lying on its side," Seaman said.

Building on years of geologic mapping and tectonic reconstructions by other researchers, Seaman has traced a direct connection between the cooled and crystallized magma chambers, called plutons, and their enormous ash deposits.

Volcanic rock layers on Maine's Cranberry Island have a 2,300-foot-thick (700 meters) layer of welded tuff, a rock formed from volcanic ash. The welded tuff from Toba's most recent blowout is 2,000 feet (600 m) thick, Seaman said. On the remote Isle au Haut, part of Acadia National Park, the volcanic rocks are more than 3 miles (5 km) thick, Seaman said. They're capped by an immense ash flow, more than 3,200 feet (1 km) thick.

Seaman estimates the caldera at Mount Desert Island would have been about 15 miles long and 15 miles wide (25 km by 25 km). For comparison, Toba's caldera is 62 miles long and 18 miles wide (100 km by 30 km).

"The coast is so serene and so beautiful and has such a terrible, violent past," Seaman told LiveScience's OurAmazingPlanet.

Seaman thinks the super-eruptions struck between 424 million to 419 million years ago, in the Silurian period, after islands the size of Japan slammed into the eastern edge of Laurentia, the continental core of North America. Afterward, tectonic forces stretched and tore Earth's crust behind the collision zone, making space for magma to rise from the mantle, the layer beneath the crust.

Read more at Discovery News

'Hybrid' Solar Eclipse to Dazzle on Sunday

The moon will blot out the sun Sunday (Nov. 3) in an eclipse that will be visible from eastern North America to the Middle East.

Sunday's celestial event is a relatively rare occurrence known as a hybrid solar eclipse. It will begin as an annular or "ring of fire" eclipse along the path of totality, then shift to a total eclipse as the moon's shadow sweeps across our planet.

What you'll observe depends on where you live. Skywatchers in the eastern United States, northeastern South America, southern Europe, the Middle East and most of Africa will be treated to a partial solar eclipse, while people along the path of totality in central Africa will see the sun totally obscured by Earth's nearest neighbor for a few dramatic moments.

If you live in eastern North America, you'll have to get up early to enjoy the show. The partial eclipse will be visible at sunrise — about 6:30 a.m. local time — and last for about 45 minutes, experts say. Viewers in Boston and New York will see the sun more than 50 percent covered by the moon, while our star will appear 47 percent obscured from Miami and Washington, D.C.

All of the action in this part of the world will be occurring low in the sky, less than 8 degrees from the east-southeast horizon. (Your fist held at arm's length measures about 10 degrees.) So you'll want to find a spot that affords a good look at the horizon, without any buildings or hills blocking the view.

The path of totality, meanwhile, starts in the Atlantic Ocean off the eastern U.S. and runs through Gabon, the Democratic Republic of Congo, and several other African nations before petering out in southern Ethiopia and Somalia around sunset.

Read more at Discovery News

Oct 31, 2013

Viking Graves Yield Grisly Find: Sacrificed Slaves

Viking graves in Norway contain a grisly tribute: slaves who were beheaded and buried along with their masters, new research suggests.

In Flakstad, Norway, remains from 10 ancient people were buried in multiple graves, with two to three bodies in some graves and some bodies decapitated. Now, an analysis reveals the beheaded victims ate a very different diet from the people with whom they were buried.

"We propose that the people buried in double and triple burials might have come from very different strata of society, and that slaves could have been offered as grave gifts in these burials," study co-author Elise Naumann, an archaeologist at the University of Oslo in Norway, wrote in an email.

Viking age

From about the 790s until about A.D. 1100, the Vikings were fierce, sea-faring raiders and often took slaves as booty. But this vicious lifestyle wasn't a full-time job. In everyday life, many Vikings were actually farmers, relying on slaves, or thralls, for agricultural work. Though some thralls were treated well, many were forced to endure backbreaking physical labor, Naumann said. Women were often used as sex slaves, and any children who resulted could either be considered the master's children or treated as slaves themselves.

The Viking burials were first discovered in the early 1980s, but only partially excavated at the time. The ancient graves were partly damaged by modern farming and contained just a few grave artifacts, such as an amber bead, some animal bones and a few knives. At the time, archaeologists noticed that four of the bodies were beheaded whereas the rest were intact.

That led many to conclude that the decapitated bodies were those of slaves sacrificed and buried with their masters.

Different classes

To bolster that notion, Naumann and her colleagues analyzed the skeletons' mitochondrial DNA, which is passed on through the maternal line. The team found that bodies buried together were most likely not related, at least on the maternal side.

Next, they analyzed the ratio of carbon and nitrogen isotopes, or elements with different molecular weights, in the bones of the ancient Scandinavians.

Because food that comes from the sea or the land contains different proportions of heavy and light isotopes of carbon and nitrogen, the concentration of these chemicals in bones can reveal the dietary history of a people.

Results showed the beheaded people ate more fish protein, whereas the others ate land-based protein sources, such as meat and dairy products. That suggests the people buried together came from very different strata of society.

Grave gifts

Naumann proposes the beheaded victims were slaves who were sacrificed as gifts to be offered in death on behalf of their masters. Though such human sacrifice was uncommon in Viking society, it wasn't unknown.

Read more at Discovery News

Why Do We Connect Halloween and Satanism?

For most people Halloween is a fun time of dressing up, creating elaborate costumes and decorations, visiting haunted houses, taking kids trick-or-treating, and of course eating candy. It has become a heavily commercialized holiday second only to Christmas in terms of the number of people who celebrate and participate in it.

For some, however, the fears associated with Halloween go beyond fake-scary ghosts and into genuine spiritual warfare for the souls of the innocent. These people, including many fundamentalist Christians, believe that there is a dark and sinister side to the Oct. 31 festivities. Where did this belief come from?

Fear of Witches

Part of the answer lies in the reputed origins of Halloween. Many trace it back to an ancient Celtic pagan celebration called Samhain (pronounced “sah-win”). Samhain, which occurred on Halloween, the night before All Saint’s Day, was an annual communal meeting to gather resources for the winter months.

Samhain has many aspects but focused on the changing of seasons and preparing for the dormancy (and eventual rebirth) of nature as summer turned to winter. These pre-Christian practices, with their focus on nature’s cycles and many deities, were viewed as occult by the Roman Catholic Church. All Saint’s Day and Samhain, coming so close together on the calendar, influenced each other and, many believe, later combined into the celebration we now call Halloween.

Then there’s the fact that the Bible is pretty clear about its position on magic and the occult  — for example Exodus 22:18 commands that “Thou shalt not suffer a witch to live.” Because witchcraft is seen as an abomination in the eyes of God — along with other occult practices such as dowsing, astrology and Ouija boards — anything associated with it is to be shunned as evil.

Still, you may ask, what’s the big deal? What, exactly, is the link between the Devil and the day kids dress up as ghosts, Spider-Man or Shrek? Christian evangelist Phil Phillips and Joan Hake Robie, in their book “Halloween and Satanism,” explain why many fundamentalists are concerned about Halloween: “A tragic by-product of fear in the lives of children as early as pre-pubescence is the interest and involvement in supernatural occult phenomena.”

Thus, they believe, if a child is scared by a haunted house zombie or spooky witch costume, his or her natural curiosity will soon lead them to read books and watch TV programs on the things that scared them — dead bodies or witches, for example. According to Phillips and Robie, this will start children on the road to Satanic practices.

Of course, it’s true that Halloween practices — like Christmas, Thanksgiving, and other holiday practices and rituals — have a historical context and make use of certain symbols, foods, music and so on. However just because there exists a long history of real, genuine witchcraft claims — such as those that resulted in the infamous Salem witch trials of 1692 — doesn’t mean that any child who sees a green-skinned, pointy-hatted witch costume will become interested in magic or witchcraft, much less become a witch.

Unlike concerned adults who read sinister meanings into things they fear or shun, children tend to take things at face value. They are more concerned about how much candy they get — or how good their costume is — than whether their black cat lawn ornament is really an invitation for Satan.

Halloween is only a high-profile part of the problem. Role-playing games like Dungeons and Dragons, the Harry Potter books, and even popular films like “E.T.: The Extraterrestrial” and “Ghostbusters” are also gateways to sin. Rap music, violent cartoons and video games, and so on are all evidence of social moral decay leading to drug use, suicide and murder. Underlying all this is a conspiracy-theory like belief that there are hidden meanings behind everything, and powerful, sinister forces at work trying to brainwash the innocent.

Halloween, Samhain and Satan

The connection between Satanism and Halloween is even less plausible in historical context. Though a clear and direct historical connection between Halloween and Samhain has never been proven, many scholars — and the public — believe that the traditions are linked.

As for the allegedly sinister nature of that ancient Celtic feast, Nicholas Rogers, a history professor at York University and author of “Halloween: From Pagan Ritual to Party Night,” writes:

“We can dismiss the argument that Samhain was ‘satanic’ or that in some essentialist sense Halloween is a ‘satanic ritual,’ as the Reverend Pat Robertson, the founder of the Christian Coalition, declared in 1982…. Satanism is essentially a Christian creation, a travesty of Christian forms centered on the fallen rebel angel Lucifer. In fact, the early Christian church left little room for Satan… Certainly, Satanism was incompatible with the polytheism of the ancient Celts. Indeed, the belief in satanic cults blossomed only in the late medieval period — long after the demise of Samhain.”

The confusion may have arisen, in part, because Wiccan witchcraft traditions worship a horned god which superficially resembles depictions of a goat-headed Devil. This “Horned One,” however, is a god of fertility (among other things). Since these early pagans did not believe in anything resembling a Christian Satan, it could not have played a role in their rituals.

Hell Houses for Jesus

Despite no evidence that Halloween is satanic or occult, some religious organizations have tried to ban the holiday. Nicholas Rogers writes:

“Christian fundamentalists have taken exception to Halloween school parties on the grounds that they insidiously promote pagan, if not satanic, beliefs. There have been attempts to ban the annual party outright, or at the very least prevent masquerading as devils and witches.”

In fact some religious groups have co-opted Halloween for their own purposes, creating their own evangelical version called Hell House to give wayward teenagers a chance to be “scared straight.”

Read more at Discovery News

Daylight Doesn't Matter: Native Trees Need Cold

Northern native trees’ early awakening in spring may depend on chilling out during a cold winter. Whereas invading plants from the south have less need for a long winter’s nap.

Biologists recently observed that trees from further north, including syrup-dribbling sugar maples, sprouted earlier if they suffered through long cold periods. The effect of chilling exceeded that of increasing day length. The complete lack of a frigid time greatly delayed the budding of new leaves by native trees.

However, more southerly species, such as walnut and locust trees, responded to increasing day length, regardless of whether or not they had rested through a cold snap. As winters warm up, these species have been moving further north and taking turf from chill-cherishing oak and beech.

“Contrary to previous assumptions, the increasing length of the day in spring plays no big role in the timing of budding,” said lead author Julia Laube of Germany’s Technische Universitaet Muenchen in a press release. “An ample ‘cold sleep’ is what plants need in order to wake up on time in the spring.”

Climate change may give an advantage to invaders from the south. Since the newcomers get an early start in the spring, they have more time to overgrow native trees. However, nature could take revenge on these southern species. A sudden cold spell can destroy the tender buds of trees that sprang for spring too soon.

Read more at Discovery News

Redwoods Record Ancient Ocean Climate

The tallest trees on the planet, the coastal redwood, trapped a record of the Pacific Ocean within their ancient wood.

Centuries of fog from the ocean left a chemical signature in the rings of the massive redwoods (Sequoia sempervirens) that was distinct from the chemicals left by rainwater. A recent study identified that difference and used it to reconstruct the climate patterns of the past 50 years. The same method could produce a Pacific Ocean weather report stretching back to the Roman empire.

“Redwoods are restricted to a very narrow strip along the coastline,” co-author Jim Johnstone said in a press release. “They’re tied to the coastline, and they’re sensitive to marine conditions, so they actually may tell you more about what’s happening over the ocean than they do about what’s happening over land.”

Coastal redwoods can live for nearly 2,000 years. However, until now, the erratic patterns of the trees’ rings limited their usefulness in reconstructing climate from the size of growth rings, a technique known as dendrochronology. Coastal redwoods may grow incomplete rings that don’t always complete the circle around the trunk. This makes it difficult to count the rings to learn the trees’ age or measure the rings to learn about the weather in each year of the trees’ lives

Instead of counting and measuring rings, a team of scientists, measured the levels of different forms of oxygen trapped in the wood. Oxygen in the air holds more of the lighter-weight form, or isotope, of oxygen, O-16, with smaller amounts of heavier O-18.

When water evaporated off of the ocean, some of the water rains back down onto the ocean, carrying the heavier O-18 molecules with it. The rain that reaches land carries more O-16.

Fog, on the other hand, evaporates from the ocean and blows directly onto the trees where it condenses and drips down to water the trees. Since fog doesn’t condense until it reaches the trees, it carries a higher percentage of O-18.

The redwoods sucked up the water from both rain and fog. The ratio of the different types of oxygen corresponded to the varying amounts of fog and rain over the years. For example, a foggy yet dry summer would result in more O-18. Similarly, variations in carbon isotopes in the redwoods reflected changes in growth related to temperature and total moisture in the environment.

Read more at Discovery News

Sensitive Dark Matter Detector Draws a Blank

A new experiment buried deep underground has proven itself to be the most sensitive dark-matter detector ever built. But the first results from the high-tech instrument have turned up empty in its search for elusive dark matter, scientists announced today (Oct. 30).

Housed 1 mile (1.6 kilometers) underground in the Black Hills of South Dakota, the Large Underground Xenon (LUX) experiment's sensitivity makes it better at seeking out dark matter than any other detectors built for that purpose, LUX officials said. Although the powerful dark matter detector has just completed its first run, LUX has not yet found conclusive evidence of the elusive substance.

"The universe's mysterious dark sector presents us with two of the most thrilling challenges in all of physics," Saul Perlmutter, of the Lawrence Berkeley National Laboratory and a winner of the 2011 Nobel Prize in physics, said in a statement. "We call it the dark sector precisely because we don't know what accounts for most of the energy and mass in the universe. Dark energy is one challenge, and as for the other, the LUX experiment's first data now take the lead in the hunt for the dark-matter component of the dark sector."

Scientists think that dark matter makes up the majority of the matter in the universe; however, it cannot be seen or touched. Astronomers detect dark matter because they have seen its gravitational effects on galaxies and stars.

By running experiments like LUX far underground, scientists hope to shield the dark-matter detector from everything but WIMPs — weakly interacting massive particles that are thought to be the leading candidates for the particles that make up dark matter.

"LUX is the quietest place verified in the world," Rick Gaitskell, a Brown University physicist, said during a seminar on the findings. "That's how far we've had to go in order to be in a position to look for these WIMPs."

LUX is particularly adept at searching for low-mass WIMPs, which are predicted by some theoretical physics models. WIMPS are extremely difficult to find because they rarely interact with ordinary matter, except through gravity, LUX officials said.

Scientists think that WIMPs can be both low-mass and high-mass, and LUX has an enhanced sensitivity to low-mass WIMPs. The dark-matter detector recently completed its first data-collecting research run.

Through the course of the approximately three-month WIMP search, scientists did not find signals of WIMPs, although previous experiments with other detectors predicted that they would.

"Three candidate WIMP events recently reported in ultracold silicon detectors, however, would have produced more than 1,600 events in LUX's much larger detector, or one every 80 minutes in the recent run," LUX officials said in a statement. "No such signals were seen."

Read more at Discovery News

Oct 30, 2013

Largest Dino of All Time Is Digitally Recreated

A digital reconstruction of the world’s largest known land animal, the Cretaceous dinosaur Argentinosaurus, has allowed it to take its first steps -- albeit virtually -- in over 94 million years.

The recreation, outlined in PLoS ONE, is the most anatomically detailed walking simulation so far for a dinosaur, according to the researchers. The study also provides the first ever virtual trackway for Argentinosaurus.

The skeleton used in the study shows that the plant-eating dinosaur measured at least 131 feet long. The reconstruction reveals that it lumbered along at around 5 miles per hour.

“The simulation shows a slow walking gait, which is to be expected, given that the animal weighs 80 tonnes,” lead researcher Bill Sellers from the University of Manchester’s Faculty of Life Sciences, told Discovery News. “What is interesting is how well the simulated footfall pattern matches up with typical sauropod trackways.”

For the study, Sellers and his colleagues laser scanned the huge dinosaur’s skeleton. They then used an advanced computer modeling system (Sellers has his own software called Gaitsym) that involves the equivalent of 30,000 desktop computers. It virtually recreated the dinosaur, including the sauropod’s movements.

The discovery that Argentinosaurus could walk counters prior speculation that the animal could not have done so, based on previous estimations of its size.

This latest research concludes not only that Argentinosaurus could walk, but that it was also at the top of its food chain.

“Once you hit 80 tonnes, you don’t have to worry about being eaten by predators,” Sellers explained. “We don’t know whether this animal used its long neck to graze over wide areas of low-laying vegetation or for reaching the tops of trees, but from its locomotion we know that it was a slow, steady mover.”

Argentinosaurus eggs, however, were no bigger than those of many dinosaurs and large birds. It's therefore likely that Argentinosaurus young were fairly small and would have been easy prey for other carnivorous species that lived along the Cretaceous planes of what is now Patagonia, South America.

Understanding how such past animals moved may help us to better understand modern day musculoskeletal systems.

“If you are trying to understand any body system that is shared by a range of different animals then it is often extremely useful to compare this system across different species,” Sellers explained. “Vertebrate muscles, skeletons and joints work exactly the same way in everything from fish to humans.”

He continued, “The really interesting aspect of dinosaur locomotion is that you are looking at animals that test the limits of the musculoskeletal system simply by virtue of being so big. They have to make compromises and come up with ways of coping that help us to understand the limits and compromises in the human musculoskeletal system.”

Phillip Manning is head of the Paleontology Research Group at the University of Manchester and is a research associate at the American Museum of Natural History.

Manning told Discovery News that paleontology is now undergoing a renaissance, with more interdisciplinary approaches, such as this, helping to solve long-standing questions.

“To carefully break down the key components of the locomotion of such vast animals as Argentinosaurus is allowing us greater insight to the biology and physiology of such vast organisms,” Manning said. “The diverse plethora of techniques and technology available to paleontology today is changing the way we study and interpret the fossil record.”

Read more at Discovery News

Rare Roman Eagle Sculpture Found in London

Archaeologists surveying a construction site for a 16-storey hotel in London have discovered an “exceptional” Roman sculpture of an eagle holding a writhing snake in its beak.

The exquisitely chiseled statue has been hailed by experts as “the finest sculpture by a Romano-British artist ever found in London.”

“Its condition is extraordinary, as crisp as on the day it was carved,” Martin Henig, an expert on Roman art and a professor at the Institute of Archaeology at Oxford, told reporters.

Details such as the snake’s forked tongue and the eagle’s individual feathers are still clearly discernible.

The two-foot-tall sculpture is made of Cotswold limestone and dates from the late 1st or 2nd century A.D. Most likely, it adorned an imposing mausoleum, the foundations of which were also uncovered during excavation.

“The lack of weathering on the statue corroborates this theory, as does the absence of detail on the back of the sculpture; suggesting it once sat it an alcove,” the Museum of London Archaeology (MOLA), which worked on the dig, said in a statement.

Depictions of eagles are found across the Roman empire as symbols of strength and authority, but were also common in funerary settings.

“The symbolism is understood as the struggle of good, the eagle, against evil, the snake,” the MOLA said.

The sculpture was likely discarded in the ditch when the tomb of the wealthy and powerful Roman was smashed up nearly 2,000 years ago.

Read more at Discovery News

Gold Rush's Poisonous Legacy: Mercury

Even though the California Gold Rush took place more than a century ago, it left a toxic legacy of mercury pollution that will continue to be a problem for some time, scientists say.

New research shows that gold mining in the Sierra Nevada mountains between 1848 and 1884 left tons and tons of mercury-contaminated sediments in river valleys downstream, such as the Yuba River valley. About once a decade, large floods lose enough of this sediment to create a spike in mercury concentrations downriver and in the San Francisco Bay, said Michael Singer, a geologist and hydrologist with joint appointments at Scotland's University of St. Andrews and the University of California, Santa Barbara.

"This is a big deal because at the moment, there's quite a bit of mercury contamination that's in the ecosystems of the [San Francisco] Bay and Sacramento Delta," Singer told LiveScience.

Going up the food chain

It was previously thought that most of the mercury from this mining, much of which took place more than 150 years ago, had already exited the river system, Singer said. But a study by Singer and colleagues published this week in the journal Proceedings of the National Academy of Sciences showed this isn't the case. Instead, the study found that there is enough mercury-contaminated sediment to significantly add to levels of the heavy metal downriver and in the San Francisco Bay for the next 10,000 years. The sediment is washed away by large floods but also by the meandering of the river, which curves back and forth within its valley and exposes long-buried, polluted dirt, he added.

When the mercury reaches the lowlands of the Sacramento-San Joaquin River Delta, where the Yuba River and other streams that flow out of the Sierra Nevada end up, it can be converted to methylmercury by microbes. Methylmercury is the organic form of the heavy metal, which can accumulate in animals and make its way up the food chain, Singer said.

As larger animals eat smaller ones and are, in turn, eaten by even bigger creatures, mercury accumulates and increases in concentration. For this reason, predatory fish like bass and salmon in the Bay have been found to have high levels of mercury, Singer said.

This amount of mercury pollution is "already significant, and what the authors show is that it's going to get worse," said Manny Gabet, a geologist at San Jose State University who wasn't involved in the study.

Toxic legacy

Gold-rush miners sought gold by eroding entire hillsides with high-pressure water cannons, contrary to popular conceptions of panning for gold, Gabet told LiveScience. The sediment was then run through "sluice boxes," where mercury was added to bind to gold. But large quantities of the heavy metal made their way into sediment downstream. This destructive mining filled valleys with sediments that caused flooding in California's Central Valley, and in 1884, the federal government shut down much of this gold-mining activity, Singer said.

It's hard to imagine that the problem can easily be solved in the near term, because there is probably just too much mercury-tainted sediment to feasibly move, Singer said. Perhaps the sediment could be trapped in the event of large floods, or measures could be taken to prevent particularly contaminated sections of sediments from eroding, such as along the Yuba River, he said.

Read more at Discovery News

Earth's Hellish 'Twin Sister' Discovered

Two studies of an Earth-sized planet circling the sun-like star Kepler-78 show it has Earth-like amounts of iron and rock, the first world of its size that scientists have been able to calculate both density and diameter.

But don't pack your bags yet. The planet, known as Kepler-78b, circles sizzlingly close to its parent star, far from an Earth-like water-friendly orbit, a condition that is believed to be necessary for life.

"To me this means that planets like the Earth are probably not all that uncommon," astronomer Drake Deming, with the University of Maryland, told Discovery News.

"If one of the first measurements you're able to make that really pins down the density of a small, rocky planet gives you a density close to Earth's, Earth can't be that rare in terms of density," Deming said.

Two independent teams came up with nearly the same assessment of Kepler-78b, which was discovered last spring by another group of astronomers using data collected by NASA's now-defunct Kepler space telescope.

The observatory, which was sidelined by a positioning system failure in May, detected slight dips in the amount of light coming from about 150,000 target stars. Some dips were caused by orbiting planets passing by, or transiting, relative to the telescope's line of sight.

Based on how much Kepler-78's light dimmed, astronomers knew they were looking at a planet that was about the same size as Earth. To learn about its density, they followed up with ground-based telescopes to try to tease out how much gravitational tugging the little world exerted on its parent star. From that information, scientists worked out how much rock and how much iron Kepler-78b contains.

The timing of the planet's transits also revealed a startling 8.5-hour orbit, meaning Kepler-78b is almost skimming the surface of its parent star. From that location, temperatures would be about 2,000 degrees hotter than Earth, making for a molten surface and little, if any, atmosphere.

Scientists are homing in on finding Earth-sized worlds in the so-called “habitable zones” of stars similar to the sun, but figuring out those planets’ densities is beyond present-day technologies.

"If you were to take (Kepler-78b) and put it out in an Earth-like orbit, it would be undetectable with our current techniques," astronomer Andrew Howard, with the University of Hawaii at Manoa, told Discovery News.

Read more at Discovery News

Oct 29, 2013

Coral Reefs May Be Able to Adapt to Moderate Climate Change

Coral reefs may be able to adapt to moderate climate warming, improving their chance of surviving through the end of this century, if there are large reductions in carbon dioxide emissions, according to a study funded by NOAA and conducted by the agency's scientists and its academic partners. Results further suggest corals have already adapted to part of the warming that has occurred.

"Earlier modeling work suggested that coral reefs would be gone by the middle of this century. Our study shows that if corals can adapt to warming that has occurred over the past 40 to 60 years, some coral reefs may persist through the end of this century," said study lead author Cheryl Logan, Ph.D., an assistant professor in California State University Monterey Bay's Division of Science and Environmental Policy. The scientists from the university, and from the University of British Columbia, were NOAA's partners in the study.

Warm water can contribute to a potentially fatal process known as coral "bleaching," in which reef-building corals eject algae living inside their tissues. Corals bleach when oceans warm only 1-2°C (2-4°F) above normal summertime temperatures. Because those algae supply the coral with most of its food, prolonged bleaching and associated disease often kills corals.

The study, published online in the journal Global Change Biology, explores a range of possible coral adaptive responses to thermal stress previously identified by the scientific community. It suggests that coral reefs may be more resilient than previously thought due to past studies that did not consider effects of possible adaptation.

The study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100, if there are large reductions in carbon dioxide emissions.

"The hope this work brings is only achieved if there is significant reduction of human-related emissions of heat-trapping gases," said Mark Eakin, Ph.D., who serves as director of the NOAA Coral Reef Watch monitoring program, which tracks bleaching events worldwide. "Adaptation provides no significant slowing in the loss of coral reefs if we continue to increase our rate of fossil fuel use."

"Not all species will be able to adapt fast enough or to the same extent, so coral communities will look and function differently than they do today," CalState's Logan said.

While this paper focuses on ocean warming, many other general threats to coral species have been documented to exist that affect their long-term survival, such as coral disease, acidification, and sedimentation. Other threats to corals are sea-level rise, pollution, storm damage, destructive fishing practices, and direct harvest for ornamental trade.

According to the Status of Coral Reefs of the World: 2000 report, coral reefs have been lost around the world in recent decades with almost 20 percent of reefs lost globally to high temperatures during the 1998-1999 El Niño and La Niña and an 80 percent percent loss of coral cover in the Caribbean was documented in a 2003 Science paper. Both rates of decline have subsequently been documented in numerous other studies as an on-going trend.

Tropical coral reef ecosystems are among the most diverse ecosystems in the world, and provide economic and social stability to many nations in the form of food security, where reef fish provide both food and fishing jobs, and economic revenue from tourism. Mass coral bleaching and reef death has increased around the world over the past three decades, raising questions about the future of coral reef ecosystems.

In the study, researchers used global sea surface temperature output from the NOAA/GFDL Earth System Model-2 for the pre-industrial period though 2100 to project rates of coral bleaching.

Read more at Science Daily

New Species of Dolphin Found in Australian Waters

A species of humpback dolphin previously unknown to science is swimming in the waters off northern Australia, according to a team of researchers working for the Wildlife Conservation Society, the American Museum of Natural History, and numerous other groups that contributed to the study.

To determine the number of distinct species in the family of humpback dolphins (animals named for a peculiar hump just below the dorsal fin), the research team examined the evolutionary history of this family of marine mammals using both physical features and genetic data. While the Atlantic humpback dolphin is a recognized species, this work provides the best evidence to date to split the Indo-Pacific humpback dolphin into three species, one of which is completely new to science.

"Based on the findings of our combined morphological and genetic analyses, we can suggest that the humpback dolphin genus includes at least four member species," said Dr. Martin Mendez, Assistant Director of WCS's Latin America and the Caribbean Program and lead author of the study. "This discovery helps our understanding of the evolutionary history of this group and informs conservation policies to help safeguard each of the species."

The authors propose recognition of at least four species in the humpback dolphin family: the Atlantic humpback dolphin (Sousa teuszii), which occurs in the eastern Atlantic off West Africa; the Indo-Pacific humpback dolphin (Sousa plumbea), which ranges from the central to the western Indian Ocean; another species of Indo-Pacific humpback dolphin (Sousa chinensis), which inhabits the eastern Indian and western Pacific Oceans; and a fourth Sousa species found off northern Australia yet to be named (the formal adjustment of the naming and number of species occurs through a separate and complementary process based on these findings).

"New information about distinct species across the entire range of humpback dolphins will increase the number of recognized species, and provides the needed scientific evidence for management decisions aimed at protecting their unique genetic diversity and associated important habitats," said Dr. Howard Rosenbaum, Director of WCS's Ocean Giants Program and senior author on the paper.

Working to bring taxonomic clarity to a widespread yet poorly known group of dolphins, the authors assembled a large collection of physical data gathered mostly from beached dolphins and museum specimens. Specifically, the team examined features from 180 skulls covering most of the distribution area of the group in order to compare morphological characters across this region.

The researchers also collected 235 tissue samples from animals in the same areas, stretching from the eastern Atlantic to the western Pacific Oceans, analyzing both mitochondrial and nuclear DNA for significant variations between populations.

Read more at Science Daily

Saber-Toothed Attacked Each Other, Skulls Show

Distinctive bite marks on the skulls of cat-like saber-toothed predators that once skulked about North America have revealed a nasty family secret: these felines often ambushed and killed each other.

The discovery came as a result of the accidental unearthing of a new skull of what's called a nimravid -- not a true cat, but a group of cougar-like animals with large saber-like canine teeth that lived from 32 to 34 million years ago. The skull had clear signs of being mortally bitten by another nimravid.

"The nimravid skull was found in 2010 in Badlands National Park by a girl during a Junior Ranger activity right next to the visitor center," said paleontologist Clint Boyd of the South Dakota School of Mines and Technology, who was working in the park at the time. "It had a magnificent set of bite marks on it."

The skull brought to mind another found in 1936 that also had nimravid bite marks which had long been interpreted as a rare case. But the new skull raised the question of just how common these bite marks are on nimravids.

To find out, Boyd and his colleagues gathered up as many nimravids skulls as they could from collections and took a closer look at them. This included some that were on display for the public.

"Some of the best specimens with bite marks were right in front of people," he said. "Older specimens did not show the bite marks until they were cleaned up." Some actually still had dirt in the holes made by the bite marks and others had had the holes repaired by curators unaware of their significance.

"What we found is that these bite marks are a lot more common than previously thought."

In fact the bite marks make it clear that the nimravids were attacking their competitors from behind and killing by getting one fang into an eye socket or puncturing the skull.

What's even more startling is that nimravid fang marks are not found on the skull of any of their prey, said Boyd, who is presenting his results on Oct. 30 at the meeting of the Geological Society of America in Denver. That's because they used the canines to tear out the soft tissues in the throats of their prey and would have been careful not to bang them on bone, which might have damaged their most important hunting weapon.

"Damaging their canines could be a life-threatening event," said Boyd. Yet fatal nimravid bite marks are found on a surprising 10 percent of nimravid skulls in three species of nimravids over a range of four million years.

"They're still taking into consideration not damaging their canines," said Boyd, noting how the eyes are a common target with the other canine just glancing the skull. But they are definitely taking a bigger chance when they attack their own kind.

Among other things, the discovery suggests that the typical museum mural representation of nimravids facing off in battle is probably dead wrong.

"Upper canines and lower canines can be seen in the (skulls)," he said. "So all the attacks are coming from behind. This was an ambush style attack against a competitor."

The lack of any signs of healing also means that the majority of these attacks were fatal, which rules out another old hypothesis, based on the 1936 specimen (which showed some healing), that the biting might be part of a mating behavior.

Read more at Discovery News

Ghost Stories: The Science Behind Sightings

Apparitions Meet the Scientific Method

In an example of early trick photography, a ghost appears to visit a young girl beside her bed (Photo circa 1860-1869, London, England).
Ghost stories have been around as long as there have been stories themselves. The idea of apparitions from the spirit world goes back to the very beginnings of written history, and probably even farther back in oral traditions. A recent CBS News poll concluded that nearly half of all Americans believe in ghosts, and 22 percent say they have seen or felt the presence of a ghost.

And yet mainstream science has long been clear and unequivocal: There is no scientific evidence of a supernatural explanation for ghost sightings. So how do we explain those incidents when rational people sincerely believe they have seen or felt a ghost? What are some of the scientific, non-paranormal explanations for the phenomenon of ghost sightings?

Psychological States Are Important

As it turns out, there are quite a lot of real-world explanations for ghost sightings. Researcher Loyd Auerbach, author of several books on the subject of hauntings, is a believer in ghosts and has been investigating reported sightings for 30 years. Yet even he concedes that the vast majority of alleged hauntings can be explained away by natural phenomena. Chief among them is the psychological state of the person who experienced the haunting.

"It's often because people are predisposed -- they've been watching too many TV shows, or something bad is going on in their lives," Auerbach said. "Sometimes people are psychologically disturbed, but most of the time I find it's people making mistakes because they're already in a sensitized state due to something else entirely. It's people who are suggestible, and when that nail in the wall finally pops out, they ascribe significance to a mundane event."

Something Doesn't Sound Right

Sometimes a legitimate natural phenomenon, or a combination of different phenomena, can result in a "ghost sighting." For example, research dating back to the 1970s suggests that extremely low frequency (ELF) electromagnetic fields can stimulate certain parts of the brain and produce effects that are often associated with hauntings. "I had a case a couple years ago, a family had moved into a house and in a particular room, they got dizzy or got headaches," Auerbach said. "They saw shadows out of the corner of their eyes."

Auerbach investigated and found out the house was directly under high-tension wires that were emitting an electromagnetic field and a low-frequency hum. "It was in the frequency that would vibrate your eyeballs," Auerbach said. "That would cause you to see things out of the corner of your eye."

Low-frequency hums, sometimes called infrasound, can also produce feelings of fear and anxiety, Auerbach said. "Hollywood has known this since the 1950s at least, which is why you get those low frequency tones in horror movie soundtracks."

Something Doesn't Smell Right

In many cases, an alleged haunting is caused by multiple factors that seem supernatural when combined. For instance, Auerbach said that infrasound and electromagnetic waves only explained some of the issues in the house under the high-tension wires. "It wasn't just headaches, the family said they would smell noxious odors that smelled like brimstone," he said. "They would also report bursts of fire that would singe the walls."

Further investigation revealed the house was adjacent to garbage dump, and methane gas was seeping up from the ground. "That was what they were smelling, and there was so much static electricity in the house that the methane would catch fire," Auerbach said.

Don't Believe Everything You See

In an illustration from 1874, Anne Morgan -- said to have been dead for two centuries -- reveals herself under the name of "Katie King," through spiritualistic mediums to ghost seekers in Philadelphia
In cases where people claim to have seen an apparition, but there are no psychological or emitted energy factors, the "ghost" can simply be an optical illusion. Most commonly, it's an incident of light bouncing off a window or other reflecting surface. There's also the psychological phenomenon of pareidolia, where the brain gives significance to random images or patterns -- seeing faces in clouds, say, or the ghost of your grandmother in the shadows of a wardrobe closet.

Dante Centuori, director of creative productions at the Great Lakes Science Center, said that he believes alleged ghost sightings are always the result of natural phenomenon being misinterpreted. Even with incidents we can't explain, it's simply a matter of overlooking something or ascribing false significance.

"We're very error-prone in terms of observation and perception," Centuori said. "We have a predisposition to fill in the blanks with a cultural context, with the images that we're all bombarded with. We see something that doesn't add up, and we jump to: 'It's a ghost.'"

Hallucinations Aren't What They Seem

Taken in Norfolk, England, in 1936 by Capt. Hubert C. Provand, the so-called "Brown Lady Ghost" photo was published in Country Life magazine.
Visual hallucinations are often cited as the scientific explanation behind ghost sightings, and they can be caused by both psychological conditions and -- according to some research -- electromagnetic waves affecting the brain. But there's a giant gray area in this topic, Auerbach said, because an experience that could be accurately termed a hallucination can also be a genuine ghost sighting.

"The key for us is, people might have experiences that could be termed hallucinations," he said. "But if what they're seeing is historically accurate -- if they're describing things they couldn't otherwise know about -- then there's something very worthy of research."

Read more at Discovery News

Oct 28, 2013

Australia's Oldest Bird Footprints Discovered

Two thin-toed footprints pressed into a sandy riverbank more than 100 million years ago are Australia's oldest known bird tracks, researchers say.

The prints were found among the fossil-rich cliffs of Dinosaur Cove on the coast of southern Victoria. Researchers think the tracks were left by a prehistoric bird species likely the size of a great egret or a small heron during the Early Cretaceous Period.

At that time, the world was warmer and the continents were arranged in different positions than they are today. The site of Dinosaur Cove was located in a floodplain in a great rift valley that formed as the supercontinent Gondwana started breaking apart, tearing Australia away from Antarctica.

A long drag mark leading up to one of the fossilized footprints was a telltale sign that these tracks were left by flying creatures, explained study researcher Anthony Martin, a paleontologist at Emory University in Atlanta.

The bird tracks were found very close to another footprint that looks like it was left by a non-avian theropod, possibly one of the coelurosaurs, the group of dinosaurs most closely related to birds that includes beasts like the Tyrannosaurus rex.

All three ancient footprints were locked in sandstone in an area smaller than a square foot (650 square centimeters), which gives researchers insight into the types of creatures that lived together at Dinosaur Cove during the Early Cretaceous.

"These tracks are evidence that we had sizeable, flying birds living alongside other kinds of dinosaurs on these polar, river floodplains, about 105 million years ago," Martin said.

The researchers think the footprints were left at a time when the riverbank was covered in moist sand, possibly after spring and summer floodwaters had subsided. Martin said it remains unclear whether these ancient birds lived in the region during the polar winter or migrated there during the spring and summer.

The birds that left their tracks at Dinosaur Cove also had one backwards-facing toe. That feature is found on some bird feet today, and T. rex even had a vestigial rear toe. Studying the changing toe-arrangement of birds and their dinosaur cousins could give researchers insight into the evolution of these species.

Read more at Discovery News

"Lost World" Discovered in Remote Australia

An expedition to a remote part of northern Australia has uncovered three new vertebrate species isolated for millions of years, with scientists Monday calling the area a "lost world."

Conrad Hoskin from James Cook University and a National Geographic film crew were dropped by helicopter onto the rugged Cape Melville mountain range on Cape York Peninsula earlier this year and were amazed at what they found.

It included a bizarre looking leaf-tail gecko, a gold-coloured skink -- a type of lizard -- and a brown-spotted, yellow boulder-dwelling frog, none of them ever seen before.

"The top of Cape Melville is a lost world. Finding these new species up there is the discovery of a lifetime -- I'm still amazed and buzzing from it," said Hoskin, a tropical biologist from the Queensland-based university.

"Finding three new, obviously distinct vertebrates would be surprising enough in somewhere poorly explored like New Guinea, let alone in Australia, a country we think we've explored pretty well."

The virtually impassable mountain range is home to millions of black granite boulders the size of cars and houses piled hundreds of metres high, eroded in places after being thrust up through the earth millions of years ago.

While surveys had previously been conducted in the boulder-fields around the base of Cape Melville, a plateau of boulder-strewn rainforest on top, identified by satellite imagery, had remained largely unexplored, fortressed by massive boulder walls.

Within days of arriving, the team had discovered the three new species as well as a host of other interesting finds that Hoskins said may also be new to science.

The highlight was the leaf-tailed gecko, a "primitive-looking" 20 centimetre-long (7.9 inches) creature that is an ancient relic from a time when rainforest was more widespread in Australia.

The Cape Melville Leaf-tailed Gecko, which has huge eyes and a long, slender body, is highly distinct from its relatives and has been named Saltuarius eximius, Hoskin said, with the findings detailed in the latest edition of the international journal Zootaxa.

"The second I saw the gecko I knew it was a new species. Everything about it was obviously distinct," he said.

Highly camouflaged, the geckos sit motionless, head-down, waiting to ambush passing insects and spiders.

The Cape Melville Shade Skink is also restricted to moist rocky rainforest on the plateau, and is highly distinct from its relatives, which are found in rainforests to the south.

Also discovered was a small boulder-dwelling frog, the Blotched Boulder-frog, which during the dry season lives deep in the labyrinth of the boulder-field where conditions are cool and moist, allowing female frogs to lay their eggs in wet cracks in the rocks.

In the absence of water, the tadpole develops within the egg and a fully formed frog hatches out.

Once the summer wet season begins the frogs emerge on the surface of the rocks to feed and breed in the rain.

Read more at Discovery News

Lost da Vinci Artwork Unearthed Beneath Paint

Drawings sketched by Leonardo da Vinci are emerging from the walls of an Italian castle, announced restorers working on an elaborate fresco devised by the Renaissance master.

One of most original paintings of the 15th century, the mural covers the vault and walls of the Sala delle Asse in the Sforza Castle in Milan. It depticts a garden pergola made of 16 mulberry trees bound together by a golden, knotted rope. The trunk of each tree rises as a column supporting 16 half-moon-shaped spaces above a Gothic vault, producing an evocative, fictive grove.

Now restorers might be able to bring to light extra sections of the original work, possibly providing further insights into Da Vinci’s vision of the highly symbolic decoration.

The work was commissioned in 1498 by the duke of Milan, Ludovico Maria Sforza, nicknamed il Moro (the Moor) and was executed by Leonardo, who at that time was the court artist, and his assistants.

Experts agree the master's hand can be detected in a monochrome section of the fresco on the northeast and northwest corner of the room. The apparently unfinished work depicts sturdy roots bursting through rocks.

"Large parts of this mural can be recovered beneath several layers of whitewash," the Opificio Pietre Dure (OPD) the Florence based institute who is carrying out the restoration, wrote in a report.

Preliminary analysis produced "quite interesting results," lending hope that the work will recover "important parts of the preparatory drawings," Marco Ciatti, superintendent of the OPD art restoration institute, said.

Leonardo's work in the Sala delle Asse, or Room of the Planks (after the wood panels that lined it) has remained largely unknown. In 1499 Milan was conquered by the French who stormed the castle. In 1706, when Milan was under the Austrian rule, the castle became soldier barracks and the Sala delle Asse was turned into a stable, its walls covered with abundant layers of whitewash.

The arboreal decoration remained hidden beneath up to 13 layers of paint until 1893, when renovations to the castle revealed traces of frescoes.

In 1901, amid much criticism, the mural was heavily restored.

Only in 1954, the paint applied during the disastrous restoration was finally removed. But damage to Leonardo's work remained.

"The mural is covered by a thick layer of grime. However, our cleaning tests indicate that it can be easily removed. Leonardo's paint won't be damaged in the procedure," the restorers wrote.

Meanwhile, archival research also revealed the room's original name.

It was called "Camera dei Moroni" -- a clear allusion to Ludovico il Moro.

Read more at Discovery News

Ancients Painted Volcano Warning 9,000 Years Ago

A nearly 9,000-year-old mural of a village with a backdrop of an erupting volcano has now been geochemically pinned to a specific eruption of the Hasan Dağ twin-peaks volcano located about 130 km (70 miles) northeast of the ancient Çatalhöyük town site in Turkey.

The mural, painted in ocher on an adobe wall that was long buried, has long been considered the world's earliest depiction of an eruption, as well as the earliest known landscape painting, the first historical news event and the first urban plan. Until now, however the volcano it was depicting had not been confirmed with any dated samples of minerals from the volcano linking the image to a specific eruption.

"The original discoverer of the mural interpreted it as a depiction of eruption of Hasan Dağ," said volcanologist Axel Schmitt of the University of California in Los Angeles. "We're volcanologists. We're trying to find out the eruption recurrence."

Unfortunately, the archeological interpretation of the eruption made its way into the volcanological literature as evidence that Hasan Dağ is an active volcano. Then, archeologists started referring to the volcanological literature as evidence that the volcano was active -- accidentally falling into circular reasoning.

To break out of that circle, Schmitt and some colleagues, including some Turkish volcanologists, gathered volcanic pumice rock from Hasan Dağ and applied to them a new mineral dating technique using uranium-thorium-helium in zircon crystals.

“We've been pushing this dating technique to younger and younger ages,” said Schmitt. “As we do that it overlaps with archaeological timescales.”

The zircons revealed two explosive eruptions. One was about 29,000 years ago and the other at about 9,000 years ago. The latter was compared with the carbon-14 dating of artifacts at Çatalhöyük, including the strata that contains the mural.

"It agrees," Schmitt said. "It overlaps give or take 1,000 years." He will be presenting the results on October 30 at the meeting of the Geological Society of America in Denver.

Read more at Discovery News

Oct 27, 2013

Are Humans Reversing Cat Domestication?

When your cat sees a stranger, does he come and snuggle close or hiss and run away?

Whether a feline friend is a lap cat or a claws-out kitty is largely affected by their socialization as young kittens. But at least part of cats' friendliness may be in their genes. And the widespread practice of spaying or neutering cats before they are adopted may be inadvertently selecting for aloof cats, by ensuring the friendliest animals don't reproduce, one researcher says.

"The very cats that are the friendliest and the ones that don't do much hunting are the very ones we are told we should be neutering," said John Bradshaw, an anthrozoologist at the University of Bristol in England, and the author of "Cat Sense: How the New Feline Science Can Make You a Better Friend to Your Pet" (Basic Books, 2013).

But not everyone is convinced.

Domestic and feral cats are genetically indistinguishable, so spay/neuter programs are unlikely to nudge the gene pool one way or the other, said Carlos Driscoll, a University of Oxford biologist who is studying the genome of the wildcat from which the domestic cat emerged at the National Institutes of Health in Bethesda, Md.

Subtle differences

Domestic cats arose from a subspecies of cat called Felis silvestris lybica between 10,000 and 20,000 years ago in the Near East or North Africa. But the genetic differences between this wildcat ancestor and its tamer offshoot are very subtle: Wild cats and domestic cats look alike and are able to mate with one another, Driscoll said.

Just 10 to 20 gene changes may be responsible for domestication in the tame cats, though scientists don't know which ones.

Because so few genes are associated with domestication, spay and neuter policies that ensure the friendliest cats don't reproduce could be "pushing domestication backward" to a noticeable degree in the next 50 to 100 years, Bradshaw told LiveScience.

Selecting for less-friendly cats?

To support that notion, Bradshaw conducted a simple test of cat personality in Southampton, England: He had strangers enter the houses of kittens in the area, try to pick up and stroke the cats, and then watched the kitties purr or hide.

In an area where spaying and neutering rates were highest -- more than 98 percent -- kitties tended to be a bit more skittish around strangers, possibly because they have to "import" their fluffy friends since their own pals aren't able to reproduce. Less-affluent areas had bolder, friendlier cats.

"What we suggest is people [in affluent areas] are getting kittens in from the countryside from feral cats that are a little bit wilder," or from a few feral females and just a few tomcats that are "living in the shadows," Bradshaw said.

Therefore, intensive spay and neuter programs may be artificially selecting for the less-tame cats, he said.

"Neutering is -- in terms of biology, in terms of population dynamics -- a mortality factor," Bradshaw said. "If you neuter, you've removed its genes from the pools, so when you look at the next population, you have to rule it out."

The study has a few caveats: It hasn't been published in a peer-reviewed journal, and the team only looked at about 70 cats in all.

Other solutions

And even if the findings are borne out, Bradshaw isn't suggesting a return to the old days, when cats mated freely and the unwanted kittens were tossed in a sack and drowned.

Cats kill billions of animals a year, so cities rightly want to keep feral-cat colonies in check. But if that's cities' aim, Bradshaw said, they should find the ultimate source of the problem: food.

"Are there people feeding them, are they stealing the food, is it bad hygiene in restaurants?" Bradshaw said.

Reduce the available food, and the feral-cat population will naturally decrease, he said.

Read more at Discovery News

Smart Neurons: Single Neuronal Dendrites Can Perform Computations

When you look at the hands of a clock or the streets on a map, your brain is effortlessly performing computations that tell you about the orientation of these objects. New research by UCL scientists has shown that these computations can be carried out by the microscopic branches of neurons known as dendrites, which are the receiving elements of neurons.

The study, published today (Sunday) in Nature and carried out by researchers based at the Wolfson Institute for Biomedical Research at UCL, the MRC Laboratory for Molecular Biology in Cambridge and the University of North Carolina at Chapel Hill, examined neurons in areas of the mouse brain which are responsible for processing visual input from the eyes. The scientists achieved an important breakthrough: they succeeded in making incredibly challenging electrical and optical recordings directly from the tiny dendrites of neurons in the intact brain while the brain was processing visual information.

These recordings revealed that visual stimulation produces specific electrical signals in the dendrites -- bursts of spikes -- which are tuned to the properties of the visual stimulus.

The results challenge the widely held view that this kind of computation is achieved only by large numbers of neurons working together, and demonstrate how the basic components of the brain are exceptionally powerful computing devices in their own right.

Senior author Professor Michael Hausser commented: "This work shows that dendrites, long thought to simply 'funnel' incoming signals towards the soma, instead play a key role in sorting and interpreting the enormous barrage of inputs received by the neuron. Dendrites thus act as miniature computing devices for detecting and amplifying specific types of input.

"This new property of dendrites adds an important new element to the "toolkit" for computation in the brain. This kind of dendritic processing is likely to be widespread across many brain areas and indeed many different animal species, including humans."

Read more at Science Daily