Oct 19, 2012

First Human Ancestor Looked Like a Squirrel

Newly discovered fossilized bones for the world's oldest and most primitive known primate, Purgatorius, reveal a tiny, agile animal that spent much of its time eating fruit and climbing trees, according to a study.

The fossils, described today in a presentation at the Society of Vertebrate Paleontology's 72nd Annual Meeting in Raleigh, North Carolina, are the first known below-the-head bones for Purgatorius. Previously, only teeth revealed its existence.

"The ankle bones show that it had a mobile ankle joint like primates today that live in trees," co-author Stephen Chester, a Yale University vertebrate paleontologist, told Discovery News. "This mobility would have allowed for rotating the foot in different directions as it adjusted to different angles presented by tree trunks and branches."

"It also shows that the first primates did not have elongate ankles that you see in many living primates today that are thought to be related to leaping behaviors," added Chester.

He conducted the study with colleagues Jonathan Bloch of the Florida Museum of Natural History and William Clemens, a professor emeritus at the University of California at Berkeley and a curator for the university's Museum of Paleontology.

After analyzing the fossils, the researchers believe that the specialized ankle bones of Purgatorius played a key role in the evolutionary success of early primates.

"These new fossils support the idea that the first 10 million years of primate evolution happened in the context of an intense period of similar diversification in flowering plants, including the ability to climb in branches and collect fruits and other products of the trees at the very beginning," Bloch told Discovery News.

While many questions remain unanswered about Purgatorius, this and other studies are shedding more light on the animal. Its name comes from Purgatory Hill in eastern Montana where it was first discovered.

Purgatorius lived during the Paleocene, shortly after the extinction of non-avian dinosaurs. Given the end of the Age of Dinosaurs, the new era began the mammal-dominated era, which we are still in.

This mammal is generally believed to have been small and brown, and had a bushy tail. The researchers liken it to another early primate, Dryomomys, for which more fossil material is available. Based on that and the newly found bones, Purgatorius weighed about 1.3 ounces, making it roughly the size of the smallest living primates: the mouse lemurs of Madagascar.

The mammal had a lot of teeth, including relatively low-crowned molars, which were specialized for eating fruit, although it probably ate other things too.

Tree living served this and other primates well, such that all but a few existing species remain at least partly arboreal. Humans are part of the rare exceptions, since our more recent ancestors left the trees some 60 million years after Purgatorius' lifetime.

John Fleagle, a professor in the Department of Anatomical Sciences at Stony Brook University, told Discovery News that "arboreality in Purgatorius is no great surprise," given that early other mammals, such as flying lemurs and tree shrews, had hand proportions suitable for tree navigation.

Read more at Discovery News

Prehistoric Flamingo Nest with Eggs Discovered

A fossil bird's nest has been discovered in Spain, cradling at least five eggs that scientists believe belonged to an ancient flamingo some 18 million years ago.

The nest was found in a limestone block in the Ebro Basin in northeastern Spain. The researchers think it was abandoned and sunk to the bottom of a shallow, salty lake (which once also housed snakes, turtles and crocodiles) before being covered in mud and fossilizing during the early Miocene.

Scans of the eggshell fragments revealed microscopic features that closely match that of the modern flamingo's eggs. However, the type of nest the eggs sit in is much different from the type the birds build today.

Modern flamingos make muddy volcano-shaped nests with a single, large egg in each, but this ancient nest was made from twigs and leaves and holds several eggs. The researchers said the nest actually looks more like those of modern grebes, diving birds that build floating platform nests, which typically hold three to eight eggs and are anchored to the bottom of a lake with aquatic plants.

Though they have very different reproductive and nesting behaviors, flamingos and grebes are closely related. This new fossil then might indicate that the grebe-style nest is ancestral to this group of birds and that, over time, modern flamingos diverged, developing their volcano-shaped nests, the researchers said.

Read more at Discovery News

No life found in Antarctica's buried Lake Vostok

A first analysis of ice pulled from the largest body of water buried beneath Antarctica has yielded nothing but pristine water, untouched in tens of millions of years.

But that doesn’t mean the lake is lifeless.

Sergey Bulat of Petersburg Nuclear Physics Institute in Russia presented preliminary results from a study of ice pulled from the 6,000-square-mile subglacial lake in February. He and his colleagues told the 12th European Workshop on Astrobiology that they found fewer than 10 microbes per milliliter, according to a report at Nature.

That’s equivalent to the background in their clean room, Nature said.

But the results came not from the lake water that rushed up their borehole from the lake and froze it shut again; instead the first results came from ice that froze onto the drill bit itself -- and they did find elements that likely came from the drilling oil and lubricants used to poke a hole through 13,000 feet of ice to the lake.

Bulat hopes to get clean samples from the ice frozen in the hole soon, and the lower depths of the lake itself, which scientists believe may hold microbial life that has been sealed off and isolated for as much as 20 million years.

Such unusual forms of life might give indications of what life elsewhere in the universe looks like. But Lake Vostok is an interesting spot for other reasons.

Beyond the fantastic science, Russian news agency Ria Novosti recently noted a number of rumors about the lake, including talk of a secret Nazi sub base and a rumor that the bodies of Hitler and his mistress were delivered there for cloning.

The Lake Vostok project has been years in the making, with initial drilling at the massive lake -- 6,060 square miles -- starting in 1998. The scientists were quickly able to reach 11,800 feet, but had to stop due to concerns of possible contamination of the never-before-touched lake water.

The Russian scientists came up with a clever way to make sure the water would not be contaminated: They agreed to drill until a sensor warned them of free water. At that point they took out the kerosene lubricating their drill bit and adjusted the pressure so that none of the liquids would fall into the lake, but rather lake water would rise through the hole due to pressure from below.

The Russians are not alone in such a mission: Scientists from around the world are literally racing to explore the mysteries of Antarctica. There are two other Antarctic digs underway.

Read more at Discovery News

What Makes Earth So Perfect for Life?

The closest star system to our own made headlines on Tuesday (Oct. 16) with the announcement that it hosts a planet about the mass of Earth — a tantalizing discovery so close, astronomically speaking, to us.

While the newfound planet may be Earth-sized, researchers say it is almost certainly barren.

Astronomers detected the alien world around the sunlike star Alpha Centauri B, which is a member of a three-star system only 4.3 light-years away from our solar system. This planet, known as Alpha Centauri Bb,is about as massive as Earth, but its hot surface may be covered with molten rock — its orbit takes it about 25 times closer to its star than Earth is from the sun.

"We're pretty sure there's no chance of life on this planet," said MIT planetary scientist Sara Seager.

So what makes a world such as ours able to host life? Why is Earth so special?

There are a few key ingredients that scientists often agree are needed for life to exist — but much debate remains as to what limits there actually might be on life. Even Earth hosts some strange creatures that live in extreme environments.

 Here's what makes life able to thrive on our home planet (and likely for alien life to arise on other worlds):


"First, you'd need some kind of liquid, any place where molecules can go react," Seager told OurAmazingPlanet. In such a soup, the ingredients for life as we know it, such as DNA and proteins, can swim around and interact with each other to carry out the reactions needed for life to happen.

The most common contender brought up for this solvent is the one life uses on Earth: water. Water is an excellent solvent, capable of dissolving many substances. It also floats when it is frozen, unlike many liquids, meaning that ice can insulate the underlying fluid from freezing further. If water instead sunk when frozen, this would allow another layer of water to freeze and sink, and eventually all the water would get frozen, making the chemical reactions behind life impossible.

Astronomers looking for extraterrestrial life most often focus on planets in the so-called habitable zones of their stars — orbits that are neither too hot nor too cold for liquid water to persist on the surfaces of those worlds. Earth happened to hit the Goldilocks mark, forming within the sun's habitable zone. Mars and Venus lie outside it; if Earth's orbit had been just a bit further inside or outside of where it is, life may likely never have arisen and the planet would be a cold desert like Mars or a cloudy furnace like Venus.

Of course, alien life may not play by the rules we're used to on Earth.

Astrobiologists increasingly suggest looking beyond conventional habitable zones. For instance, while liquid water might not currently persist on the surface of Mars or Venus, there may have been a time when it did. Life might have evolved on their surfaces in that time, and then either fled to safer locales on those planets, such as underground, or adapted to the environment when it became harsh, much as so-called extremophile organisms have on Earth, or both.

In addition, other solvents might host life. "Saturn's moon Titan has liquid methane and ethane." Seager said.


Second, life needs energy. Without energy, virtually nothing would happen.

The most obvious source of energy is a planet or moon's host star, as is the case on Earth, where sunlight drives photosynthesis in plants. The nutrients created by photosynthesis in turn are what the bulk of life on Earth directly or indirectly relies on for fuel.

Still, countless organisms on Earth subsist on other sources of energy as well, such as the chemicals from deep water vents.  There may be no shortage of energy sources for life to live off.


Scientists have argued that habitable worlds need stars that can live at least several billion years, long enough for life to evolve, as was the case on Earth.

Some stars only live a few million years before dying. Still, "life might originate very fast, so age is not that important," astrobiologist Jim Kasting at Pennsylvania State University told OurAmazingPlanet.

For instance, the Earth is about 4.6 billion years old. The oldest known organism first appeared on Earth about 3.5 billion years ago, meaning that life might conceivably evolve in 1.1 billion years or less. However, more complex forms of life did take longer to evolve — the first multicellular animals did not appear on Earth until about 600 million years ago. Because our sun is so long-lived, comparatively, higher orders of life, including humans, had time to evolve.


Other researchers have suggested that plate tectonics is vital for a world to host life — that is, a planet whose shell is broken up into plates that constantly move around.

"People talk about plate tectonics as essential in recycling molecules life needs," Seager said. For instance, carbon dioxide helps trap heat from the sun to keep Earth warm. This gas normally gets bound up in rocks over time, meaning the planet would eventually freeze. Plate tectonics helps ensure this rock gets dragged downward, where it melts, and this molten rock eventually releases this carbon dioxide gas back into the atmosphere through volcanoes.

"Plate tectonics is useful but probably not imperative," Kasting said. Seager agreed, saying that "volcanism might very well provide enough fresh supplies of whatever life might need."

Read more at Discovery News

Oct 18, 2012

How Dolphins Stay Awake for Two Weeks

Dolphins can stay constantly alert for more than two weeks by sleeping with only half of their brains, researchers say.

These findings suggest how dolphins can keep on the constant lookout for sharks, investigators added.

Unlike land mammals, dolphins sleep with only part of their brains at any time, past research has suggested. Half of their brains rest, while the other half remains "awake," and dolphins regularly switch which side is active.

"After being awake for many hours or days, humans and other animals are forced to stop all activity and sleep," said researcher Brian Branstetter, a marine biologist at the National Marine Mammal Foundation in San Diego. "Dolphins do not have this restriction, and if they did, they would probably drown or become easy prey."

To see just how mindful dolphins are with just half a brain, researchers tested their ability to scan the environment. Dolphins use echolocation to map the world, a biological form of sonar where they emit clicks and listen for their echoes to probe murky, dark surroundings.

The researchers set up a portable floating pen outfitted with eight modules, each consisting of an underwater sound projector and microphone. When a dolphin scanned any of these modules using echolocation clicks, they could respond with sounds mimicking echoes of those clicks from remote surfaces. Essentially, these modules could behave as "phantom targets" -- illusions that acoustically simulated physical objects.

The scientists had two dolphins -- a female, Say, and a male, Nay -- continuously scan these modules. If they detected phantom targets, they were trained over the course of a year to press a paddle to get fish. The dolphin Say often gave victory squeals whenever she succeeded.

The scientists found these dolphins could successfully use echolocation with near-perfect accuracy and no sign of deteriorating performance for up to 15 days. The researchers did not test how much longer the dolphins could have continued.

"Dolphins can continue to swim and think for days without rest or sleep, possibly indefinitely," Branstetter told LiveScience.

These findings suggest that dolphins evolved to sleep with only half their brains not only to keep from drowning, but also to remain vigilant.

"These majestic beasts are true unwavering sentinels of the sea," Branstetter said.

Future research can help verify whether the dolphins stayed awake and alert for multiple days by sleeping with half their brains. This would require monitoring their brains for electrical activity via electroencephalogram, or a EEG.

Read more at Discovery News

Ancient Tomb Found Near Sweden's 'Stonehenge'

The remains of a 5,500-year-old tomb near Ale's Stones, a megalithic monument where, according to myth, the legendary King Ale lies buried, has been discovered by Swedish archaeologists. The discovery is the product of a geophysical investigation of the area carried out in 2006.

Intrigued by a circular structure measuring about 165 feet in diameter with a rectangular feature in its center, archaeologists of the Swedish National Heritage Board decided to dig a trial trench.

"The outer circle was difficult to prove, but we did find vague traces at the spot, possibly imprints of smaller stones," archaeologist Bengt Söderberg told Discovery News.

In the middle, the researchers found "several components" that are evidence of a dolmen, a megalithic portal tomb usually made of two vertical stones supporting a large flat horizontal stone on top.

"The components consisted of imprints of large stones belonging to a central grave chamber, which was surrounded by large stones and a brim of smaller stones," Söderberg said.

Oriented north-south, the 65- by 26-foot dolmen dated to the Swedish early Neolithic period, about 5,500 years ago.

"We also found a blade, a scraper and some flakes of flint. This is not unusual when it comes to this type of graves," Söderberg said.

According to archaeologist Annika Knarrström of the Swedish National Heritage Board, the dolmen was likely "the grave of some local magnate."

 "However, we have little data to really tell who was buried there," Knarrström said.

The newly discovered dolmen lay just 130 feet from the spectacular Ales Stenar ("Ale's Stones"), also known as "Sweden's Stonehenge."

Located near the fishing village of Kåseberga, the structure consists of 59 stones, each weighing up to 4,000 pounds, that appear to form a 220-foot-long ship overlooking the Baltic Sea.

Although some researchers argue that the stone formation was assembled 2,500 years ago, during the Scandinavian Bronze Age, most scholars agree that it dates back some 1,400 years, toward the end of the Nordic Iron Age.

Like Stonehenge, the enigmatic stone ship has raised many theories about its purpose. According to local folklore, it was the final resting place of a legendary leader known as King Ale. Other theories suggest it was an ancient astronomical calendar, a cemetery, or a monument to the Vikings. The newly discovered dolmen might provide new clues on the pre-history of the monument.

Read more at Discovery News

Dome-Headed Dinos Battled With Their Heads

Fossilized skulls of dome-headed dinosaurs retain signs of injuries from violent head butting or head shoving, according to a presentation today at the Society of Vertebrate Paleontology's 72nd Annual Meeting held in Raleigh, North Carolina.

The dinosaurs, known as pachycephalosaurs (meaning "thick-headed lizards") have long puzzled paleontologists, who wondered why the heads of these dinosaurs looked to have built-in football helmets.

It's been suspected that dome-headed dinosaurs fought with their heads, but the latest investigation provides some of the most direct evidence for this antagonistic behavior.

"Aggressive behavior is rampant in modern vertebrates, and birds and crocodiles are no exception," Joseph Peterson, who led the research, told Discovery News. "While neither group has a bowling ball-like structure on top of its head, the head-slapping behavior of crocodiles and the face-pecking observed in a variety of birds suggest that 'using your head' is not unique to pachycephalosaurs and domes likely evolved in response to such behavior."

Peterson, a professor in the University of Wisconsin geology department, and his colleagues took CT scans of the skulls and compared the distribution of lesions to those on the skulls of birds, crocodilians, and mammals- particularly mammals with horns.

The investigations reveal that "larger domed pachycephalosaurs such as Pachycephalosaurus may have been head-butting like Dall sheep or head-shoving like bison, while smaller, high-domed taxa such as Stegoceras may have been flank-butting like mountain goats," Peterson said.

While the sex of the studied dinosaurs is unknown, he suspects that males were the ones fighting. As for today's head banging animals, the dinosaurs perhaps fought over mates, territory and rank.

The CT images further revealed areas of low bone density, suggesting that some of the dinosaurs' injuries were in the process of healing.

"It is not known if these injuries resulted in the death of the animal, and actually appear to be surface damage followed by a secondary infection," Peterson explained.

He added that cranial injuries have been identified in a number of ceratopsians like Triceratops. These dinosaurs are known for their stocky bodies, head horns, beaks and fondness for plants.

It is likely that these dinosaurs also fought with their heads, possibly locking horns as some horned and hoofed animals do today.

Other animals therefore might have regularly heard the sounds of dinosaur heads bashing into each other during the Jurassic and Cretaceous Eras.

"While no other animal has a head built like pachycephalosaur, cranial ornamentation ... is not all that rare in nature," he said.

Andrew Farke, curator of paleontology at the Raymond M Alf Museum of Paleontology in California, told Discovery News, "Based on all of the evidence, I think it is likely that pachycephalosaurs butted their heads against 'something' -- probably each other. Everything, including the new work from Peterson and colleagues, is consistent with this idea."

Read more at Discovery News

Alpha Centauri Bb: An Interstellar Target?

A little exoplanet living in a neighboring star system has caused a very big stir this week.

It may be too hot for life to survive on its surface, but the discovery of an Earth-sized planet orbiting Alpha Centauri B has ignited hope that the star -- one of two that orbit one another as a binary pair -- could play host to a whole system of rocky worlds.

The very fact that scientists using the European High Accuracy Radial velocity Planet Searcher (HARPS) telescope could detect the tiny gravitational tug of the orbiting world on its parent star is amazing enough, but the ramifications for the future of mankind have the potential to be nothing less than historic.

"The discovery of an Earth-sized world that is so close to us, when measured in interstellar distance scales, means that when we select target solar systems for exploration, we may not have to choose systems that are prohibitively far from our own solar system," said Richard Obousy, co-founder and president of Icarus Interstellar Inc.

Icarus Interstellar is a project to realize the possibility of sending an unmanned probe to another star system within the next century. Interstellar distances are, currently, prohibitively vast, so it's desirable to look for new worlds to explore that are located in our cosmic backyard. Now, astronomers have discovered evidence of an Earth-sized world located on our proverbial cosmic doorstep.

To bridge the gap between the stars, novel propulsion techniques will be required to accelerate a starship to an appreciable fraction of the speed of light, a challenge the Icarus team are currently investigating. For more on the projects Icarus Interstellar are developing and the technology behind them, browse our special Wide Angle: "Reaching for Interstellar Space."

A Ripe Target

Alpha Centauri is located around 4.4 light-years from our solar system and can be found in the southern constellation of Centaurus. Apart from Proxima Centauri, a small star located 4.2 light-years away and thought to be gravitationally bound to the Alpha Centauri binary, Alpha Centauri is the closest star system and a ripe target for a future interstellar probe.

There may be a small planet orbiting a nearby star, there could even be a whole as-yet-to-be-discovered system of planets, but what would be the incentive to drive us to send probes and, possibly, send humans across the interstellar expanse?

"One compelling reason is the idea of colonization of other solar systems, which would not only be a natural extension of mankind's compulsion to explore and settle new lands, but also serve as an excellent hedge for the very survival of our species should Earth experience some catastrophic event leaving it uninhabitable," Obousy said in an email to Discovery News.

"This is a tremendously exciting discovery," said Ian Crawford, professor at the Department of Earth and Planetary Sciences at Birkbeck College London and lead designer for Icarus science and target selection. "The alpha Cen system was already the front runner as an Icarus target, because of the three different types of star it contains. So the discovery of a planetary system just reinforces the system's priority as a target."

Last year, Crawford wrote a Discovery News guest article "Which Exoplanet to Visit?" detailing the priorities of target star selection for an Icarus probe. Keeping in mind that one of the design requirements for an interstellar vehicle is that it must arrive at its destination within 100 years from launch; suddenly it becomes a question of how far, realistically, could a starship go within that tight timeframe?

"It follows that the actual target will probably have to be significantly closer than 15 light-years (from Earth)," Crawford wrote in his February 2011 article. "Within 15 light-years of the sun there are approximately 56 stars, in 38 separate stellar systems."

Although many of those 56 stars hold promise, it would be wonderfully fortuitous if the star right next door played host to a bounty of Earth-sized exoplanets.

An Interstellar Demand?

"I have often imagined the day when scientists directly image an Earth-like extra-solar planet," Icarus Deputy Project Leader Robert Freeland told Discovery News. "We would be able to determine the planet's atmosphere and surface temperature from its spectrum, and we would thus know whether it might be able to sustain life as we know it. I suspect that once such a discovery hits the news, people worldwide are going to demand that we send a probe to determine whether the planet has life (of any type) and/or could be suitable for human habitation. If the latter proves true, then a manned mission would eventually follow."

Freeland added that in the case of this most recent discovery, we're not looking at a viable exploration target. This world's orbit is ten-times closer to its star as Mercury is to the sun -- it would be a hellish, (likely) rocky, molten world. Alpha Centauri Bb orbits well inside the nearest edge of the star's 'habitable zone' -- the region where liquid water can exist on the surface -- so this exoplanet is the very antithesis of 'habitable.'

"The discovery of (Alpha) Centauri Bb isn't quite as momentous as this owing to its proximity to the star, but this discovery is a warning shot that the news is coming a lot sooner than we think," he continued.

By Freeland's reckoning, when we do discover a bona fide Earth-like world encircling one of the stars in the Alpha Centauri system (i.e. a world of the approximate mass of Earth orbiting inside the habitable zone), the world's space agencies (particularly NASA) would need to be prepared, lest be caught "flat-footed" when a wave of public pressure to mount a mission to that planet demands why a plan isn't in place.

"Icarus Interstellar and its partner organizations -- the British Interplanetary Society and the Tau Zero Foundation -- have been working on interstellar mission designs for years, and we're eager to help NASA/ESA jump-start a serious, fully-funded interstellar program.

"It is my strong opinion that the quest for life on other planets should be the core mission of our major space agencies for the 21st century and beyond, and that such a mission would galvanize public support behind them," he concluded.

Read more at Discovery News

Oct 17, 2012

Complex Body Parts Could Soon Be Lab-Grown

Various groups of scientists have recently created thyroid cells in the lab, grown a new ear in the skin a woman's own arm, and won a Nobel Prize for figuring out how to reprogram cells so that they can turn into a variety of cell types.

In the future, there may be no limit to the kinds of organs and body parts that can be created from scratch.

One hope is to make donor organs obsolete, or at least far less necessary, eliminating long waiting lists for transplants. By using a patient's own cells, the new wave of regenerative medicine also circumvents ethical arguments and reduces the chance that recipients will reject their new parts.

"We now have the ability for the first time to create a virtually unlimited supply of all the cell types and building blocks we need to make what we want to make," said stem cell researcher Robert Lanza, chief scientific officer at Advanced Cell Technology, a biotechnology company in Marlborough, Mass. "Now we just have to put it all together."

The concept of growing new organs first cropped up in the scientific literature in the 1930s, said Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina. Real-life applications, however, began to appear only more recently.

With bladders grown from the cells of sick children and teenagers, Atala's group was the first to successfully implant lab-grown organs into people, beginning in 1998. In a paper in the Lancet in 2006, the team reported the promising long-term results of those procedures.

According to Atala, researchers have been able to grow and implant three kinds of parts: flat tissues like skin, tubular structures like blood vessels, and hollow organs like stomachs and bladders.

The next frontier includes solid organs, such as hearts, livers and kidneys. These structures are particularly complicated to build because they contain many different kinds of cell types and they require lots of blood vessels to carry fluids in and out.

Around the world, many groups of scientists are working aggressively on a variety of strategies to create these kinds of complex organs.

The process usually begins by extracting cells from the intended recipient. These cells often come from the part of the body that needs help. But in 2006, Shinya Yamanaka of Kyoto University, Japan, announced that he had identified genes that could be used to return mature cells to their embryonic state.

The research earned Yamanaka half of this year's Nobel Prize in Physiology or Medicine and led to an explosion of possibilities in regenerative medicine without requiring the controversial practice of extracting stem cells from embryos.

In recent years, scientists have created sperm, eggs, red blood cells, and a human trachea.

Lanza's group has made retinal cells, and in January, they reported in The Lancet that they used those cells to improve vision in two women with progressive blindness. His team has also created miniature kidneys and little patches of heart tissue that repair the organ like bicycle patches on a tire.

Read more at Discovery News

Eight-Eyed Spiders Watch Videos and People

Eight-eyed jumping spiders have a near 360-degree view of the world, according to a new study that also found these spiders can be captivated by humans and nature videos.

The study, published in the latest Royal Society Biology Letters, presents a detailed look at how each of these spiders' eight eyes works. During the experiments, the researchers also discovered that the spiders sometimes become fixated on certain nature videos, as well as people.

"Whereas many spiders, like black widows or the brown recluse, tend to avoid people, jumping spiders often seem quite fearless," co-author Elizabeth Jakob told Discovery News. "I doubt that they mistake large objects, such as people, as prey, but they are certainly interested to know whether you pose a danger."

"If you pull a thread past one, it will often attack it, much like a cat would attack a string. They make good cheap pets!" added Jakob, a professor in the University of Massachusetts Amherst Department of Psychology and a researcher in the field of organismic and evolutionary biology.

She notes that a lot of misinformation on the Web suggests that the bite of these spiders is quite dangerous. She said that the spiders rarely bite humans and, if they do, "not much happens. I got a red spot that quickly went away."

For the study, Jakob and colleagues Lauren Spano and Skye Long showed jumping spiders (family Salticidae) videos and conducted other tests to better determine how the arachnids' vision system works. Some spiders have just two eyes, but these spiders have four pairs of eyes.

Two principal eyes face forward.

"When you look at a jumping spider, and when it looks back at you, you will notice the very large principal eyes in front," she said. "These have a very unusual structure. They have a large, fixed lens and a tiny boomerang-shaped retina that provides high resolution images and sees in both color and UV."

Jakob further explained that the retina in each primary eye sits at the back of a long, moveable tube inside of the spider's head. The spider can move these tubes in order to scan all around.

"A metaphor another researcher uses that I like is that it is almost as if the spider is looking around with a flashlight," she said.

The other three pairs of eyes are, as a group, called the secondary eyes. They still have excellent vision, and are particularly good at detecting motion. Of these, one pair faces forward and to the side. One pair is very tiny and also faces to a side. The last pair is situated to the side and rear of the spider.

Jumping spiders not only have keen vision, but also a gregarious nature and a seemingly insatiable curiosity about humans and nearly everything else.

"If a spider turns to look at you, it is almost certainly a jumping spider," Jakob said, adding that they respond to their own mirror images and watch videos showing insects.

When shown videos of moving crickets, the spiders will attack the screen. Jakob said you "can hear the click of their fangs on the screen" as they try to chomp the virtual insects. In the wild, they stalk prey "much like a cat stalks a mouse, following it and tackling it."

Ximena Nelson, a senior lecturer at the University of Canterbury's School of Biological Sciences, told Discovery News that the conclusions of this new study "are very interesting."

Read more at Discovery News

Earth-Sized World Found Next Door

Scientists have found an Earth-sized planet circling a neighbor star just 4 light-years away.

No need to brush up on extraterrestrial etiquette quite yet, however. The planet, which flies around its parent star 10 times closer than Mercury orbits the sun, probably is inhospitable for life since its temperature would be more than 2,240 degrees Fahrenheit -- far too hot for liquid water to exist on the surface. Water is believed to be necessary for life.

But the newly found planet orbiting Alpha Centauri B, a sun-like star roughly 25 trillion miles away, could have better-positioned siblings.

“From statistical studies, low-mass planets are very frequently found in multiple systems,” lead researcher Xavier Dumusque, with the University of Geneva in Switzerland, wrote in an email to Discovery News.

So far, scientists have only ruled out the possibility of massive planets with orbital periods of 200 days or less around Alpha Centauri B, so that leaves plenty of room for the detection of low-mass planets in the star's so-called "habitable zone" -- the distance where water can exist on a planet's surface, Dumusque added.

Planets positioned the same distance as Earth is to the sun would take 365 days to orbit a parent star of the same type and size as the sun. Alpha Centauri B’s newly found world circles in just 3.2 days, but the star is roughly half the size of sun, which puts its habitable zone about where Venus is in our solar system. Venus orbits in 225 days.

Scientists already have found nearly 800 planets beyond the solar system, about 10 percent of which are considered low-mass worlds, meaning they are up to about 10 times the size of Earth or smaller.

“Most of the low-mass planets are in systems of two, three, up to six or seven planets, so finding in our closest neighbor one Earth-mass planet ... opens a really good prospect for detecting planets in the habitable zone in the system that is very close to us,” astronomer Stephane Udry, with Geneva University in Switzerland, told reporters at a press conference on Tuesday.

"In that sense, it is a landmark," Udry said.

Scientists using Europe’s HARPS telescope spent four years trying to ferret out telltale signs of a small planet’s gravitational tug on light coming from Alpha Centauri B.

The measurement is difficult because of variations in the star's light caused by other phenomenon, such as flares and magnetic storms, similar to sunspots on the sun.

“Trying to extract a signal that you are interested in when it is in the presence of “noise” -- in this case the variability of the star -- is difficult. One has to apply special analysis methods and tricks. The real challenge, in this particular case, was in how to analyze the data,” astronomer Artie Hatzes, with Thuringian State Observatory in Tautenburg, Germany, wrote in an email to Discovery News.

Read more at Discovery News

Could you build a city in an underground cave?

Fantasy and sci-fi are replete with underground cities: Ember, Zion, Menzoberranzan, Khazad-dûm and more. But are there any caves on Earth that are large enough to actually contain a real, functional city?

Earth's crust is riddled with massive underground spaces. There are so many that humans will probably never find them all, even though we're constantly finding new ones. In aggregate, there's certainly enough space underground to house a serious chunk of the human population. But can we find a single space large enough to house a respectable city?

The world's largest known cave system is Mammoth Cave in Kentucky. The explored and surveyed part of the system adds up to more than 300 miles of caves. The largest single chamber within Mammoth Cave is Chief Temple, 150m x 100m x 40m high. That's impressive (and I highly recommend you make a trip to Mammoth Cave some day), but it's nowhere near the largest chamber in the world.

Within a cave called Gua Nasib Bagus on the island of Borneo is Sarawak Chamber. It's 700m long, 400m wide and 70m high. When it was discovered in 1981, the explorers had no concept of how big it was, because their lights couldn't reach far enough to find the walls. Even today, after the chamber has been measured by lasers, there are few good photos of it because it's just too huge and dark.

Then there's Hang Son Doong. This cave in the jungle of Vietnam extends more than two miles. It isn't a single chamber like Sarawak, and it's obviously not as extensive as Mammoth Cave, but over the course of that two miles, Hang Son Doong encompasses a massive volume, 100m wide in places and 200m high. It's so huge that, beneath massive 100m skylights, it contains entire underground jungles nourished by sunlight glimmering down from the surface.

Now we have some idea of how large caves can get, so let's do some calculations on city size and population density. Sarawak Chamber is only 0.28 km2 (actually less because it has an irregular shape). Hang Son Doong, if we assume ideal uniform dimensions (which is certainly does not have) is somewhere around 0.4 km2.

The most densely populated cities in the world, like Mumbai and Chennai, achieve population densities of 20,000 per square km. With its height of 200 m, Hang Son Doong would not be able to fit any of the tallest 300 skyscrapers in the world, a considerable setback. Even if we assume that the cave could somehow manage a population density comparable to Mumbai, that still only amounts to 8,000 people. Not exactly a bustling urban center. Then again, 8,000 people living in a single giant cave would still be pretty amazing.

Read more at Discovery News

Oct 16, 2012

Seven Masterpieces Stolen in Dutch Museum Heist

Seven masterpieces, including paintings by Picasso, Matisse, Monet and Gauguin, were stolen in a pre-dawn heist Tuesday at Rotterdam's Kunsthal museum, the biggest such theft in the Netherlands in two decades, police said.

Alerted by an alarm but arriving on the scene after the thief or thieves had fled, police said they had launched a major investigation that includes interviewing possible witnesses and examining closed-circuit television.

"On Tuesday morning seven artworks were stolen from the Kunsthal in Rotterdam," police said in a statement, adding the burglary took place at around 3:00 a.m..

After having initially declined to name the stolen paintings, they said that after consulting with the owners, they can now release photographs of the works.

"A major investigation is under way and forensics are at the scene," Rotterdam police spokeswoman Patricia Wessels said. "We're investigating how they got access, what time it happened and who did it."

Dutch state television showed a police forensic team dusting one of the Kunsthal's outer doors for fingerprints. The museum's director is flying back from Turkey after hearing news of the theft, television said.

The NOS broadcaster said the haul was worth "millions and millions of euros", but the paintings are so famous that it will be difficult to get anything like their real value on the black market.

It is the biggest art theft in The Netherlands since 20 paintings were stolen from Amsterdam's Van Gogh museum in 1991.

The paintings are Pablo Picasso's "Tete d'Arlequin", Henri Matisse's "La Liseuse en Blanc et Jaune", Claude Monet's "Waterloo Bridge, London" and "Charing Cross Bridge, London", Paul Gauguin's "Femme Devant une Fenetre Ouverte, dite La Fiancee", Meyer de Haan's "Autoportrait" and Lucian Freud's "Woman with Eyes Closed".

"We're a bit shocked that something like this happens here and at the same time we have some respect for thieves who got away with something likes this," said student Ibo Bose, disappointed not to be able to visit the museum.

"Police are interviewing possible witnesses and examining closed-circuit video footage," the police statement said. "An initial investigation suggests that the robbery was well prepared."

The police spokeswoman said that police were alerted during the night when an alarm went off but the thief or thieves had made off by the time police arrived at the scene.

A statement on the museum's website quoted director Willem van Hassel as saying that the museum would be closed to the public on Tuesday.

The museum is in Rotterdam's museum park where few people go at night.

The works were among the 150-strong Triton Foundation's collection, which was being shown in its entirety to the public for the first time to mark the museum's 20th anniversary, the Kunsthal's website said.

Read more at Discovery News

Egyptian City Aligns with Sun on King's Birthday

The Egyptian city of Alexandria, home to one of the seven wonders of the ancient world, may have been built to align with the rising sun on the day of Alexander the Great's birth, a new study finds.

The Macedonian king, who commanded an empire that stretched from Greece to Egypt to the Indus River in what is now India, founded the city of Alexandria in 331 B.C. The town would later become hugely prosperous, home to Cleopatra, the magnificent Royal Library of Alexandria and the 450-foot-tall (140 meters) Lighthouse of Alexandria, one of the wonders of the ancient world. Today, more than 4 million people live in modern Alexandria.

Ancient Alexandria was planned around a main east-west thoroughfare called Canopic Road, said Giulio Magli, an archaeoastronomer at the Politecnico of Milan. A study of the ancient route reveals it is not laid out according to topography; for example, it doesn't run quite parallel to the coastline. But on the birthday of Alexander the Great, the rising sun of the fourth century rose "in almost perfect alignment with the road," Magli said.

The results, he added, could help researchers in the hunt for the elusive tomb of Alexander. Ancient texts hold that the king's body was placed in a gold casket in a gold sarcophagus, later replaced with glass. The tomb, located somewhere in Alexandria, has been lost for nearly 2,000 years.

Building by the stars

Magli and his colleague Luisa Ferro used computer software to simulate the sun's position in the fourth century B.C. (Because Earth's orbit isn't perfect, there is some variation in the sun's path through the sky over centuries.) Alexander the Great was born on July 20, 356 B.C. by the Julian calendar, which is slightly different than the modern, Gregorian calendar, because it does not have leap years to account for partial days in the Earth's orbit around the sun. On that day in the fourth century B.C., the researchers found, the sun rose at a spot less than half a degree off of the road's route.

"With a slight displacement of the day, the phenomenon is still enjoyable in our times," Magli told LiveScience.

A second star would have added to the effect, Magli said. The "King's Star" Regulus, which is found on the head of the lion in the constellation Leo, also rose in near-perfect alignment with Canopic Road and became visible after a period of conjunction with the sun near July 20. Earth's orbit has changed enough that this Regulus phenomenon no longer happens, Magli said.

Sun as a symbol

Architecture-by-astronomy was common in the ancient world, Magli said. The Great Pyramid of Giza, for example, is aligned with amazing precision along the compass points, which would have required the use of the stars as reference points. The Egyptians, whom Alexander conquered, had long associated the sun god Ra with their pharaohs.

"Aligning the city (of Alexandria) to the sun in the day of birth of Alexander was a way to embody in the architectural project an explicit reference to his power," Magli said. The King's Star would have only added to the mystique, he said.

Read more at Discovery News

Possible Richard III Body Almost Destroyed in 1800s

Last month, a search for King Richard III's remains turned up a human skeleton beneath a parking lot in England. Researchers have a long way to go in the lab before they can determine whether it belongs to the monarch, but they say they were lucky to have found a body at all. Evidence suggests the grave was almost razed by 19th-century builders.

"It was incredibly lucky," archaeologist Mathew Morris, said in a statement. "If the Victorians had dug down 30 cm (12 inches) more they would have built on top of the remains and destroyed them."

Leicester City Mayor Sir Peter Soulsby added that the head of the body was found "inches from the foundations of a Victorian building."

"They obviously did not discover anything and probably would not have been aware of the importance of the site," Soulsby said of the 19th-century builders. "If their plans had been just a little different, they could have destroyed a most significant historic find."

The remains were hidden within the choir of a medieval church known as Greyfriars, where many thought the English monarch was buried after his death in the Battle of Bosworth Field, part of the War of the Roses. The location of this church had been lost to history, but University of Leicester archaeologists traced the likely location to beneath the parking lot for the Leicester City Council offices.

Archaeologists began excavating the lot on Aug. 25 and soon after found what they believe is the lost church. The excavation also uncovered paving stones that may be part of the garden built by Leicester mayor Robert Herrick on top of the church where Richard III was buried. In 1612, a man named Christopher Wren reported a 3-foot (1-meter) tall stone pillar in the garden that was inscribed, "Here lies the body of Richard III sometime King of England."

Read more at Discovery News

Planet Found in Quadruple Star System

Once again the compulsive real universe upstages science fiction. Imagine Luke Skywalker watching four stars setting in the evening: a white hot globe, its diminutive red companion, and a pair of brilliant stars in the background that look like an apparition of a double Venus.

That’s the view from an obscure system of four co-orbiting stars where a gas giant planet has been found. It sets the record for the first quadruple stars system where a transiting planet – and presumably many more – is known to exist.

The gas giant whirls around a tight binary system consisting of a red dwarf and a star slightly hotter than our sun. The two stars complete an orbit about each other once every 20 days.

The other pair of stars, which are a sun-like star and red dwarf, are separate from the planet’s binary stars by a whopping 800 billion miles (or slightly over 100 solar system diameters as measured out to the radius of Neptune’s orbit).

Volunteers searching the publicly available Kepler data as part of the Planet Hunters citizen science project discovered the planet. The project uses human pattern recognition via the World Wide Web to identify the unique light curves recorded by NASA's Kepler space telescope as an object passes in front of a star. Message boards enable volunteers to discuss and analyze interesting Kepler light curves from numerous observations.

Once the planet was identified it was confirmed by spectroscopic observations at the Keck observatory to measure the stellar wobble induced by the small gravitational pull of the planet. The accompanying binary system was then discovered in residual anomalous stellar motion. This yielded telltale evidence for the pull of the distant binary. The faint duo was then visually found with Keck (photo below of the entire quad system).

Though the planet is gaseous, at half the mass of Jupiter, it could conceivably have large moons like Saturn's moon Titan. But at oven-roasting surface temperatures of 500 degrees Fahrenheit, any moons would be pretty toasty and waterless. The planet is slightly closer to the binary than Venus is too our Sun.

If anyone lived on such a moon, they would routinely see transits and eclipses of the the red dwarf and its brighter companion. Depending on orbital positions, the second, far distant stellar pair, would illuminate the night.

At an estimated age of no more than 2 billion years, the system is too young for intelligent life to exist. What’s more, the unusually rapidly spinning hot white star will burn out in just a few billion years. The red dwarf will feed off the larger companion as it swells ever bigger in its final years.

If intelligent life were to arise there billions of years from now, long after the stellar fireworks, the beings would behold a brilliant icy white dwarf and red dwarf in the daytime sky.

What makes this stellar grouping the stuff of science fiction is that at some point in the far future it is conceivable there could be at as many as three inhabitable planets or moons scattered in the system. The one binary that has two widely separated stars might posses two independent planetary systems.

If so, it is conceivable that space faring civilizations could each arise around the sun-like star, and red dwarf. Once space travel is achieved, they could physically come in contact with each other, assuming the biologies aren't so different that planet visitation isn’t practical.

Read more at Discovery News

Oct 15, 2012

Archaeologists to Mount New Expedition to Troy

The ruins of ancient Troy will be examined by a cross-disciplinary team of scientists in an expedition led by UW-Madison classics professor William Aylward.

Troy, the palatial city of prehistory, sacked by the Greeks through trickery and a fabled wooden horse, will be excavated anew beginning in 2013 by a cross-disciplinary team of archaeologists and other scientists, it was announced today (Monday, Oct. 15).

The new expedition will be led by University of Wisconsin-Madison classics Professor William Aylward, an archaeologist with long experience digging in the ruins of classical antiquity, including Troy itself. The new international project at Troy, to be conducted under the auspices of and in cooperation with Turkey's Çanakkale Onsekiz Mart University, will begin a series of summer-time expeditions beginning in 2013.

"Troy is a touchstone of Western civilization," says Aylward. "Although the site has been excavated in the past, there is much yet to be discovered. Our plan is to extend work to unexplored areas of the site and to systematically employ new technologies to extract even more information about the people who lived here thousands of years ago."

Troy and the Trojan War were immortalized in Homer's epic poem the Iliad centuries after the supposed events of the conflict. The site was occupied almost continuously for about 4,500 years, from the beginning of the Bronze Age to the 13th century A.D., when it was abandoned and consigned to myth. It was rediscovered in the 1870s by the wealthy German businessman and pioneering archaeologist Heinrich Schliemann whose work at Troy laid the foundations for modern archaeology.

"Our goal is to add a new layer of information to what we already know about Troy," says Aylward, who is contributing an international team of archaeologists and scientists to conduct what promises to be the most comprehensive dig since Troy's discovery over 140 years ago. "The archaeological record is rich. If we take a closer look with new scientific tools for study of ancient biological and cultural environments, there is much to be found for telling the story of this world heritage site."

The site of Troy is in modern Turkey and is situated on the Dardanelles, a crossroads between East and West and a flashpoint for conflict in both ancient and modern times. The archaeological site is a complex layer cake of history and prehistory, with 10 cities superimposed one atop the other, some with clear evidence for violent destruction.

Following the demise of Troy at the end of the Bronze Age, the site was re-settled by Greeks, Romans and others, who all claimed Homer's Troy and its cast of characters -- Achilles, Helen, Patroclus, Priam and Ajax -- as their own cultural heritage. The ancient city was visited by the Persian general Xerxes, Alexander the Great, and Roman emperors, including Augustus and Hadrian. Homer's epic poems about a lost age of heroes and the legendary Trojan War have endured as sources of inspiration for art and literature ever since.

Although archaeologists have been digging at Troy for almost 140 years, with the exception of a 50-year hiatus between 1938 and 1988, less than one-fifth of the site has been scientifically excavated. With about 4,500 years of nearly uninterrupted settlement at a crossroads between Europe and Asia, Troy is fundamental for questions about the development of civilization in Europe and the Near East. "Troy deserves a world-class archaeological program," says Aylward.

In its heyday, Troy's citadel, with walls 12 feet thick and more than 30 feet high, was about 6 acres in size. A walled lower town covered an expanse of 50 acres, much of which is unexplored. Mysteries abound. Ancient Troy's royal cemetery, for example, has yet to be discovered and archaeologists are eager to add to the single example of prehistoric writing known from Troy, a small bronze seal from the Bronze Age.

"Major gaps in our knowledge involve the identity of the prehistoric Trojans, the location of their principal cemeteries and the nature of their writing system," says Aylward. "The enduring question of the historicity of the Trojan War is also worthy of further exploration."

In future work at Troy, Aylward plans an array of collaborations in order to deploy powerful new scientific techniques to reveal the hidden record of the ancient city and its inhabitants. New methods to examine chemical residues on pottery from ancient kitchens and banquet halls, for example, may reveal secrets of ancient Trojan culinary proclivities, and genomic analyses of human and animal remains may shed light on diseases and afflictions at a crossroads of civilization.

Much of the new work in the area of "molecular archaeology," which includes DNA sequencing and protein analysis, will be conducted in collaboration with the UW-Madison Biotechnology Center, which has become an active partner in the new Troy project. This past summer, researchers from the center participated in reconnaissance for future studies.

Read more at Science Daily

New Way to Mimic the Color and Texture of Butterfly Wings

The colors of a butterfly's wings are unusually bright and beautiful and are the result of an unusual trait; the way they reflect light is fundamentally different from how color works most of the time.

A team of researchers at the University of Pennsylvania has found a way to generate this kind of "structural color" that has the added benefit of another trait of butterfly wings: super-hydrophobicity, or the ability to strongly repel water.

The research was led by Shu Yang, associate professor in the Department of Materials Science and Engineering at Penn's School of Engineering and Applied Science, and included other members of her group: Jie Li, Guanquan Liang and Xuelian Zhu.

Their research was published in the journal Advanced Functional Materials.

"A lot of research over the last 10 years has gone into trying to create structural colors like those found in nature, in things like butterfly wings and opals," Yang said." People have also been interested in creating superhydrophobic surfaces which is found in things like lotus leaves, and in butterfly wings, too, since they couldn't stay in air with raindrops clinging to them."

The two qualities -- structural color and superhydrophobicity -- are related by structures. Structural color is the result of periodic patterns, while superhydrophobicity is the result of surface roughness

When light strikes the surface of a periodic lattice, it's scattered, interfered or diffracted at a wavelength comparable to the lattice size, producing a particularly bright and intense color that is much stronger than color obtained from pigments or dyes.

When water lands on a hydrophobic surface, its roughness reduces the effective contact area between water and a solid area where it can adhere, resulting in an increase of water contact angle and water droplet mobility on such surface.

While trying to combine these traits, engineers have to go through complicated, multi-step processes, first to create color-providing 3D structures out of a polymer, followed by additional steps to make them rough in the nanoscale. These secondary steps, such as nanoparticle assembly, or plasma etching, must be performed very carefully as to not vary the optical property determined by the 3D periodic lattice created in the first step.

Yang's method begins with a non-conventional photolithography technique, holographic lithography, where a laser creates a cross-linked 3D network from a material called a photoresist. The photoresist material in the regions that are not exposed to the laser light are later removed by a solvent, leaving the "holes" in the 3D lattice that provides structural color.

Instead of using nanoparticles or plasma etching, Yang's team was able to add the desired nano-roughness to the structures by simply changing solvents after washing away the photoresist. The trick was to use a poor solvent; the better a solvent is, the more it tries to maximize the contact with the material. Bad solvents have the opposite effect, which the team used to its advantage at the end of the photolithography step.

"The good solvent causes the structure to swell," Yang said. "Once it has swollen, we put in the poor solvent. Because the polymer hates the poor solvent, it crunches in and shrivels, forming nanospheres within the 3D lattice.

"We found that the worse the solvent we used, the more rough we could make the structures," Yang said.

Both superhydrophobicity and structural color are in high demand for a variety of applications. Materials with structural color could be used in as light-based analogs of semiconductors, for example, for light guiding, lasing and sensing. As they repel liquids, superhydrophobic coatings are self-cleaning and waterproof. Since optical devices are highly dependent on their degree of light transmission, the ability to maintain the device surface's dryness and cleanliness will minimize the energy consumption and negative environmental impact without the use of intensive labors and chemicals. Yang has recently received a grant to develop such coatings for solar panels.

The researchers have ideas for how the two traits could be combined in one application, as well.

"Specifically, we're interested in putting this kind of material on the outside of buildings," Yang said. "The structural color we can produce is bright and highly decorative, and it won't fade away like conventional pigmentation color dies. The introduction of nano-roughness will offer additional benefits, such as energy efficiency and environmental friendliness.

Read more at Science Daily

Evolution Mostly Driven by Brawn, Not Brains, Analysis Finds

The most common measure of intelligence in animals, brain size relative to body size, may not be as dependent on evolutionary selection on the brain as previously thought, according to a new analysis by scientists.

Brain size relative to body size has been used by generations of scientists to predict an animal's intelligence. For example, although the human brain is not the largest in the animal kingdom in terms of volume or mass, it is exceptionally large considering our moderate body mass.

Now, a study by a team of scientists at UCL, the University of Konstanz, and the Max Planck Institute of Ornithology has found that the relationship between the two traits is driven by different evolutionary mechanisms in different animals.

Crucially, researchers have found that the most significant factor in determining relative brain size is often evolutionary pressure on body size, and not brain size. For example, the evolutionary history of bats reveals they decreased body size much faster than brain size, leading to an increase in relative brain size. As a result, small bats were able to evolve improved flying maneuvrability while maintaining the brainpower to handle foraging in cluttered environments.

This shows that relative brain size can not be used unequivocally as evidence of selection for intelligence. The study is published today in the Proceedings of the National Academy of Sciences.

Dr Jeroen Smaers (UCL Anthropology and UCL Genetics, Evolution & Environment), lead author of the study said: "When using brain size relative to body size as a measure of intelligence, the assumption has always been that this measure is primarily driven by changes in brain size. It now appears that the relationship between changes in brain and body size in animals is more complex than has long been assumed.

"Changes in body size often occur independently of changes in brain size and vice versa. Moreover, the nature of these independent changes in brain and body size, are different in different groups of animals."

Researchers at UCL gathered data on brain and body mass for hundreds of modern and extinct bats, carnivorans, and primates. They then charted brain and body size evolution over time for each species. Across millions of years, most animals increased body size faster than brain size, with the exception of bats.

In primate lineages decreases in brain size marginally outpaced those in body size. Carnivoran evolution has taken yet a different course, with changes generally more strongly associated with body size rather than selection on brain size and cognition.

Read more at Science Daily

Moon Made Water From Solar Wind

Blast some particles from the sun onto the seemingly dry moon and what do you get? Water, says a team of researchers who probed 43-year-old samples returned from the moon by Neil Armstrong and other Apollo astronauts.

The finding was not really a surprise, notes lead researcher Yang Liu, with the University of Tennessee in Knoxville, but it was a long time coming.

Analysis of the Apollo moon samples, which began in the 1970s, previously had uncovered the presence of hydrogen inside volcanically produced glass beads in the soil. In 2008, scientists found hydrogen in a phosphate mineral in lunar rocks, and last year found it again inside another mineral, olivine.

Three robotic probes, including NASA's LCROSS experiment, also have found evidence for water ice on the moon. But where the water came from has been a mystery.

Using two new techniques to dig down into chemistry of hydrogen inside lunar soil grains, Liu and colleagues determined that most of it came from the solar wind, a steady stream of charged particles from the sun that permeates and defines the boundaries of the solar system.

"The energy of these particles is enough to cause damage of the surface of a grain, but is low enough to be embedded and bound with oxygen on the surface," Liu wrote in an email to Discovery News.

Later, when asteroids or other bodies smashed into the lunar surface, some of the soil melted, forming glass beads laced with hydroxyl, a seemingly "dry" mineral, comprising one oxygen atom and one hydrogen, that actually can store water.

Earth's mantle, for example, holds at least one ocean's worth of water in hydroxyl minerals.

"So far, the only generally accepted way of delivering water to the inner solar system is collision with water-rich asteroids or comets that originate from the outer solar system," notes geochemist Marc Chaussidon, with Université de Lorraine in France.

"Liu and colleagues present evidence that the lunar surface contains water that originates from the solar wind -- as well as the water delivered by comets, as previously proposed."

It's too early to say how much of the moon's water can trace its origin to the solar wind.

"We have largely worked with one soil. There is about 80 ppmw (parts per million by weight) water generated by this process. For 3-meter (9-foot) deep soil covering one football field, this (translates) to about 3 metric tons of water if it could be fully extracted," Liu said.

Read more at Discovery News

Oct 14, 2012

Complex Logic Circuit Made from Bacterial Genes

By force of habit we tend to assume computers are made of silicon, but there is actually no necessary connection between the machine and the material. All that an engineer needs to do to make a computer is to find a way to build logic gates -- the elementary building blocks of digital computers -- in whatever material is handy.

So logic gates could theoretically be made of pipes of water, channels for billiard balls or even mazes for soldier crabs.

By comparison Tae Seok Moon's ambition, which is to build logic gates out of genes, seems eminently practical. As a postdoctoral fellow in the lab of Christopher Voigt, PhD, a synthetic biologist at the Massachusetts Institute of Technology, he recently made the largest gene (or genetic) circuit yet reported.

Moon, PhD, now an assistant professor of energy, environmental and chemical engineering in the School of Engineering & Applied Science at Washington University in St. Louis is the lead author of an article describing the project in the Oct. 7 issue of Nature. Voigt is the senior author.

The tiny circuits constructed from these gene gates and others like them may one day be components of engineered cells that will monitor and respond to their environments.

The number of tasks they could undertake is limited only by evolution and human ingenuity. Janitor bacteria might clean up pollutants, chemical-engineer bacteria pump out biofuels and miniature infection-control bacteria might bustle about killing pathogens.

How to make an AND gate out of genes

The basis of modern computers is the logic gate, a device that makes simple comparisons between the bits, the 1s and 0s, in which computers encode information. Each logic gate has multiple inputs and one output. The output of the gate depends on the inputs and the operation the gate performs.

An AND gate, for example, turns on only if all of its inputs are on. An OR gate turns on if any of its inputs are on.

Suggestively, genes are turned on or off when a transcription factor binds to a region of DNA adjacent to the gene called a promotor.

To make an AND gate out of genes, however, Moon had to find a gene whose activation is controlled by at least two molecules, not one. So only if both molecule 1 AND molecule 2 are present will the gene be turned on and translated into protein.

Such a genetic circuit had been identified in Salmonella typhimurium, the bacterium that causes food poisoning. In this circuit, the transcription factor can bind to the promotor of a gene only if a molecule called a chaperone is present. This meant the genetic circuit could form the basis of a two-input AND gate.

The circuit Moon eventually built consisted of four sensors for four different molecules that fed into three two-input AND gates. If all four molecules were present, all three AND gates turned on and the last one produced a reporter protein that fluoresced red, so that the operation of the circuit could be easily monitored.

In the future, Moon says, a synthetic bacterium with this circuit might sense four different cancer indicators and, in the presence of all four, release a tumor-killing factor.

Crosstalk and timing faults

There are huge differences, of course, between the floppy molecules that embody biological logic gates and the diodes and transistors that embody electronic ones.

Engineers designing biological circuits worry a great deal about crosstalk, or interference. If a circuit is to work properly, the molecules that make up one gate cannot bind to molecules that are part of another gate.

This is much more of a problem in a biological circuit than in an electronic circuit because the interior of a cell is a kind of soup where molecules mingle freely.

To ensure that there wouldn't be crosstalk among his AND gates, Moon mined parts for his gates from three different strains of bacteria: Shigella flexneri and Pseudomonas aeruginosa, as well as Salmonella.

Although the parts from the three different strains were already quite dissimilar, he made them even more so by subjecting them to error-prone copying cycles and screening the copies for ones that were even less prone to crosstalk (but still functional).

Another problem Moon faced is that biological circuits, unlike electronic ones, don't have internal clocks that keep the bits moving through the logic gates in lockstep. If signals progress through layers of gates at different speeds, the output of the entire circuit may be wrong, a problem called a timing fault.

Experiments designed to detect such faults in the synthetic circuit showed that they didn't occur, probably because the chaperones for one layer of logic gates degrades before the transcription factors for the next layer are generated, and this forces a kind of rhythm on the circuit.

Hijacking a bacterium's controller

"We're not trying to build a computer out of biological logic gates," Moon says. "You can't build a computer this way. Instead we're trying to make controllers that will allow us to access all the things biological organisms do in simple, programmable ways."

"I see the cell as a system that consists of a sensor, a controller (the logic circuit), and an actuator," he says. "This paper covers work on the controller, but eventually the controller's output will drive an actuator, something that will do work on the cell's surroundings."

Read more at Science Daily

Fly Genomes Show Natural Selection and Return to Africa

When ancestral humans walked out of Africa tens of thousands of years ago, Drosophila melanogaster fruit flies came along with them. Now the fruit flies, widely used for genetics research, are returning to Africa and establishing new populations alongside flies that never left -- offering new insights into the forces that shape genetic variation.

That's one of the findings from two new papers published this month by researchers at the University of California, Davis, and their colleagues that describe the genomes of almost 200 strains of the tiny flies.

The work reveals strong evidence of pervasive natural selection throughout the D. melanogaster genome, said Charles Langley, professor of genetics in the Department of Evolution and Ecology at UC Davis and an author on both papers. That is in striking contrast with what is known of the human genome, which shows comparatively little evidence of adaptation over the last 100,000 years.

The overall aim of the research is to better understand the forces that shape genetic variation, Langley said. Human geneticists are working to sequence a thousand human genomes to get at the same issue. The knowledge from studying fly genetics has and will help in that effort, he said.

"Most of the theory and statistical methods in human genetics were originally motivated by studies of flies, because they're easier and faster to work with," Langley said. "Model organisms like these play a critical role in developing tools and ideas."

The first paper, published Oct. 1 in the journal Genetics, reports the genomes of 37 strains of Drosophila collected in Raleigh, N.C., and six strains from the sub-Saharan nation of Malawi. The other paper, to be published in PLoS Genetics and currently available online as a preprint, describes the genomes of 139 fly strains covering 22 African and one European population.

Drosophila melanogaster, like humans, originated in Africa, and that's where they show the most genetic diversity -- just as humans do. The flies are thought to have appeared in Europe about 50,000 years ago, along with modern humans. On the way, both humans and flies squeezed through genetic bottlenecks that reduced the diversity in the population. Over generations, different fly strains evolved quite specialized niches -- such as a fondness for colonizing breweries, for example.

But the African fly genomes show that just in the past couple of decades, flies similar to those found in Europe or the U.S. have established populations back in Africa, often in new environments such as urban and industrial developments. For example, where modern breweries and bottled beer have displaced traditional African brewing, "Europeanized" brewery flies have followed.

The spread of those "European" genes is more rapid than if it were occurring by random processes, the researchers write.

"It may be that urbanization and development favor the more 'European' flies," Langley said.

UC Davis is internationally recognized for research in evolution, ecology and genetics. Campus researchers have collaborated on efforts to sequence the genomes of a wide variety of plants and animals, including wheat, rice, cucumber, horses, cats and chickens.

Langley's UC Davis-affiliated co-authors on the Genetics paper are researchers Kristian Stevens and Charis Cardeno, graduate students Yuh Chwen Lee, Sasha Langley, Charlyn Suarez and Russell Corbett-Detig, Professor David Begun, and postdoctoral researcher John Pool, all in the Department of Evolution and Ecology. Other co-authors include researchers at Indiana University, Bloomington; Lawrence Berkeley National Laboratory; University of Florida, Gainesville; UCSF; Rutgers University; Academica Sinica, Taiwan; and UC Berkeley.

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