Humans Blamed for Neanderthal Extinction

About 40,000 years ago, a huge volcanic eruption west of what is now Naples, Italy, showered ash over much of central and Eastern Europe. Some researchers have suggested that this super-eruption, combined with a sharp cold spell that hit the Northern Hemisphere at the same time, created a “volcanic winter” that did in the Neandertals. But a new study of microscopic particles of volcanic glass left behind by the explosion concludes that the eruption happened after the Neandertals were already mostly gone, putting the blame for their extinction on competition with modern humans.

Why the Neandertals disappeared is one of archaeology’s longest-running debates. Over the years, opinions have shifted back and forth between climate change, competition with modern humans, and combinations of the two. Earlier this year, the climate change contingent got a boost when a European team determined that the Italian eruption, known as the Campanian Ignimbrite (CI), was two to three times larger than previous estimates. The researchers calculated that ash and chemical aerosols released into the atmosphere by the eruption cooled the Northern Hemisphere by as much as 2°C for up to 3 years.

Modern humans entered Europe from Africa and possibly the Middle East around the time of the eruption and Neandertals’ demise, give or take several thousand years. The timing is critical. If Neandertals began disappearing before the eruption, it could not be responsible for their extinction; if their demise began at the same time or shortly afterward, the correlation with climate might still hold.

With these issues in mind, a team of more than 40 researchers from across Europe, led by geographer John Lowe of Royal Holloway, University of London in Egham, U.K., used a new technique for detecting volcanic ash across a much larger area than previously possible. The new method relies on deposits of cryptotephra, tiny particles of volcanic glass that are invisible to the naked eye. Unlike visible ash deposits, which are found over a more limited range, the much lighter cryptotephra can penetrate and be recovered from far-flung archaeological sites as well as marine, lake, and marsh environments. Moreover, by analyzing the chemical composition of the microscopic particles, researchers can trace them back to specific volcanic eruptions, in this case the CI.

The team collected samples containing CI cryptotephra from four central European caves where stone tools and other artifacts typical of Neandertals and modern humans have been found. They also gathered the particles from a modern human site in Libya and from marshland and marine sites in Greece and the Aegean Sea. The results, the team argues in a paper published online this week in the Proceedings of the National Academy of Sciences, are incompatible with the hypothesis that the CI was responsible for Neandertal extinction, at least in central Europe. The CI cryptotephra lie above, and so postdate, the transition from Neandertal to modern human stone tool types at all four central European sites, indicating that modern humans had replaced Neandertals before the catastrophic events of 40,000 years ago.

Moreover, analysis of tree pollen and other climatic indicators from the marsh and marine sediments confirmed that the CI was contemporaneous with a sharp cold spell called a Heinrich event, which is also often cited as a contributor to Neandertal extinction. So the data suggest that the eruption and the cold snap happened after the Neandertals had already vanished from central Europe.

“Climate was probably not directly responsible for Neandertal extinction, and catastrophic events most certainly were not,” says co-author William Davies, an archaeologist at the University of Southampton, Avenue Campus, in the United Kingdom. That leaves competition with modern humans as the most likely culprit, the team contends.

Nevertheless, the authors concede that their results are only directly applicable to central and probably Eastern Europe, and not to Western Europe, where some researchers have claimed that Neandertals hung on until at least 35,000 years ago in Portugal and Spain. Because the team has not been able to find cryptotephra that far west, “we cannot rule out the survival of Neandertals post-CI and post Heinrich … in refugia like the Iberian Peninsula,” says co-author Chris Stringer of the Natural History Museum in London. “But it must have been a very limited survival at best, as they headed to physical extinction.”

Read more at Wired Science

Pharaoh Snefru's Playground In the Desert

Pharaoh Snefru, the "King of the Pyramids," developed his building skills over a 2.3 square mile playground in the desert, according to a new study into the geology of the Dahshur royal necropolis in Egypt.

The first king of the 4th dynasty, Snefru (reigned 2575-2551 BC) built Egypt’s first true pyramid at Dashur, after a couple of failures. The task was overshadowed by his son Khufu, or Cheops, when he built the Great Pyramid at Giza.

More than 3.5 million cubic meters (123 million cubic feet) of building material were mined and transported at Dashur, some 20 miles from Cairo, yet very little evidence remains of what went on at the pyramid practice site some 4500 years ago. Nature wiped virtually any trace of human activity.

To expose the ancient pyramid playground, a team of Earth scientists from Germany turned to fractals.

Fractals are natural or artificially created geometric patterns that form designs. These appear to repeat themselves over and over when magnified.

Deltas created where rivers meet the ocean often display fractal properties. Dissected by river channels which drain into the floodplain of the Nile, the area around Dahshur was indeed supposed to show an abundance of natural fractals. The new study showed that was’t really the case.

Arne Ramisch of the Freie Universität Berlin in Germany and colleagues from the German Archaeological Institute in Egypt created a digital model of the topography around Dahshur and investigated the region using fractal pattern recognition analysis.

The researchers discovered distinct differences "between natural and human-shaped areas," they wrote in the journal Quaternary International.

In particular, the researchers identified a huge non-fractal footprint around the pyramids.

Read more at Discovery News

Did Ancient Warming Reunite Polar and Brown Bears?

Polar bears' past may echo their future, indicates a genetic study that finds the white-furred, sea ice-dwelling bears interbred with brown bears long after the two species separated as much as 5 million years ago.

Climate change likely drove this mixing among bears, writes the research team, noting there is evidence this is happening again.

"Maybe we're seeing a hint that in really warm times, polar bears changed their lifestyle and came into contact, and indeed interbred, with brown bears," said study researcher Stephan Schuster, a professor of biochemistry and molecular biology at Pennsylvania State University, and a research scientist at Nanyang Technological University in Singapore, in a statement.

The study estimates polar bears split from brown bears between 4 million and 5 million years ago, after which they endured fluctuations in climate, including ice ages and warmer times.

Polar bears are currently facing the effects of climate change, this time caused by humans, as the Arctic sea ice upon which they live recedes to unprecedented levels.

"If this trend continues, it is possible that future [polar bears] throughout most of their range may be forced to spend increasingly more time on land, perhaps even during the breeding season, and therefore come into contact with brown bears more frequently," the researchers write in results published today (July 23) in the journal Proceedings of the National Academy of Sciences.

"Recently, wild hybrids and even second-generation offspring have been documented in the Northern Beaufort Sea of Arctic Canada where the ranges of brown bears and [polar bears] appear to overlap, perhaps as a recent response to climatic changes," they write.

Schuster and colleagues sequenced genomes (the complete genetic blueprint) of three brown bears and a black bear and compared them with the genomes of polar bears, one modern and the other obtained from remains from a 120,000-year-old polar bear.

Read more at Discovery News

Mysterious, Colorful Lobsters Being Caught

Lobsters sporting rare, unexpected colors and patterns are becoming more common in catches, and no one knows why.

Blue, pink, orange and even calico lobsters are winding up in traps. The orange ones are perhaps causing the most problems, since some chefs think they've already been cooked. But then the live, snapping crustacean reminds them otherwise.

Maybe social media is partly to blame?

"Are we seeing more because the Twitter sphere is active and people get excited about colorful lobsters?" Michael Tlusty, research director at the New England Aquarium in Boston, told Associated Press. "Is it because we're actually seeing an upswing in them? Is it just that we're catching more lobsters so we have the opportunity to see more?"

He added, "Right now you can make a lot of explanations, but the actual data to find them out just isn't there."

Information from NOAA points out that lobsters sometimes turn an odd, different color when they eat a single type of food. (That reminds me of Willy Wonka's Violet, the Blueberry Girl.) That phenomenon, for lobsters, usually only happens in the lab, however.

In the ocean, blue lobsters appear as a genetic anomaly. I'm guessing the calico and other colored/patterned lobsters do as well. Supposedly, once cooked, they look and taste the same as a regular hued lobster.

But why are there so many unusual colored ones now?

As AP mentions:

The odds of catching a blue lobster are 1-in-2 million, while orange comes in at 1-in-10 million. Yellow and orange-and-black calico lobsters have been pegged at 1-in-30 million, split-colored varieties at 1-in-50 million, and white -- the rarest of all -- at 1-in-100 million.

Such off-colored lobsters look as bizarre to other marine life as they do to us, so they are more visible to predators.

"But with the predator population down, notably cod, there might be greater survival rates among these color morphs that are visually easier to pick out," said Diana Cowan, executive director of The Lobster Conservancy.

Read more at Discovery News

Why Does a Vivid Memory 'Feel So Real?'

Neuroscientists have found strong evidence that vivid memory and directly experiencing the real moment can trigger similar brain activation patterns.

The study, led by Baycrest's Rotman Research Institute (RRI), in collaboration with the University of Texas at Dallas, is one of the most ambitious and complex yet for elucidating the brain's ability to evoke a memory by reactivating the parts of the brain that were engaged during the original perceptual experience. Researchers found that vivid memory and real perceptual experience share "striking" similarities at the neural level, although they are not "pixel-perfect" brain pattern replications.

The study appears online this month in the Journal of Cognitive Neuroscience, ahead of print publication.

"When we mentally replay an episode we've experienced, it can feel like we are transported back in time and re-living that moment again," said Dr. Brad Buchsbaum, lead investigator and scientist with Baycrest's RRI. "Our study has confirmed that complex, multi-featured memory involves a partial reinstatement of the whole pattern of brain activity that is evoked during initial perception of the experience. This helps to explain why vivid memory can feel so real."

But vivid memory rarely fools us into believing we are in the real, external world -- and that in itself offers a very powerful clue that the two cognitive operations don't work exactly the same way in the brain, he explained.

In the study, Dr. Buchsbaum's team used functional magnetic resonance imaging (fMRI), a powerful brain scanning technology that constructs computerized images of brain areas that are active when a person is performing a specific cognitive task. A group of 20 healthy adults (aged 18 to 36) were scanned while they watched 12 video clips, each nine seconds long, sourced from YouTube.com and Vimeo.com. The clips contained a diversity of content -- such as music, faces, human emotion, animals, and outdoor scenery. Participants were instructed to pay close attention to each of the videos (which were repeated 27 times) and informed they would be tested on the content of the videos after the scan.

A subset of nine participants from the original group were then selected to complete intensive and structured memory training over several weeks that required practicing over and over again the mental replaying of videos they had watched from the first session. After the training, this group was scanned again as they mentally replayed each video clip. To trigger their memory for a particular clip, they were trained to associate a particular symbolic cue with each one. Following each mental replay, participants would push a button indicating on a scale of 1 to 4 (1 = poor memory, 4 = excellent memory) how well they thought they had recalled a particular clip.

Dr. Buchsbaum's team found "clear evidence" that patterns of distributed brain activation during vivid memory mimicked the patterns evoked during sensory perception when the videos were viewed -- by a correspondence of 91% after a principal components analysis of all the fMRI imaging data.

The so-called "hot spots," or largest pattern similarity, occurred in sensory and motor association areas of the cerebral cortex -- a region that plays a key role in memory, attention, perceptual awareness, thought, language and consciousness.

Dr. Buchsbaum suggested the imaging analysis used in his study could potentially add to the current battery of memory assessment tools available to clinicians. Brain activation patterns from fMRI data could offer an objective way of quantifying whether a patient's self-report of their memory as "being good or vivid" is accurate or not.

Read more at Science Daily

Infants Can Use Language to Learn About People's Intentions

Infants are able to detect how speech communicates unobservable intentions, researchers at New York University and McGill University have found in a study that sheds new light on how early in life we can rely on language to acquire knowledge about matters that go beyond first-hand experiences.

Their findings appear in the Proceedings of the National Academy of Sciences (PNAS).

"Much of what we know about the world does not come from our own experiences, so we have to obtain this information indirectly -- from books, the news media, and conversation," explained Athena Vouloumanos, an assistant professor at NYU and one of the study's co-authors. "Our results show infants can acquire knowledge in much the same way -- through language, or, specifically, spoken descriptions of phenomena they haven't -- or that can't be -- directly observed."

The study's other co-authors were Kristine Onishi, an associate professor in the Department of Psychology at Canada's McGill University, and Amanda Pogue, a former research assistant at NYU who is now a graduate student at the University of Waterloo.

Previous scholarship has established that infants seem to understand that speech can be used to categorize and communicate about observable entities such as objects and people. But no study has directly examined whether infants recognize that speech can communicate about unobservable aspects.

In the PNAS study, the researchers sought to determine if one-year-old infants could recognize that speech can communicate about one unobservable phenomenon that is crucial for understanding social interactions: a person's intentions.

To explore this question, the researchers had adults act out short scenarios for the infants. Some scenes ended predictably (that is, with an ending that is congruent with our understanding of the world) while others ended unpredictably (that is, incongruently).

The researchers employed a commonly used method to measure infants' detection of incongruent scenes: looking longer at an incongruent scene.

Infants saw an adult actor (the communicator) attempt, but fail, to stack a ring on a funnel because the funnel was just out of reach. Previous research showed that infants would interpret the actor's failed behavior as signaling the actor's underlying intention to stack the ring. The experimenters then introduced a second actor (the recipient) who was able to reach all the objects. In the key test scene, the communicator turned to the recipient and uttered either a novel word unknown to infants ("koba") or coughed.

Although infants always knew the communicator's intention (through observing her prior failed stacking attempts), the recipient only sometimes had the requisite information to accomplish the communicator's intended action-specifically, when the communicator vocalized appropriately using speech, but not when she coughed.

If infants understood that speech -- but not non-speech -- could transfer information about an intention, when the communicator used speech and the recipient responded by stacking the ring on the funnel, infants should treat this as a congruent outcome. Results confirmed this prediction. The infants looked longer when the recipient performed a different action, such as imitating the communicators' prior failed movements or stacking the ring somewhere other than on the funnel, suggesting they treated these as incongruent, or surprising, outcomes.

Because coughing doesn't communicate intentions, infants looked equally no matter what the recipient's response was.

"As adults, when we hear people speaking, we have the intuition that they're providing information to one another, even when we don't understand the language being spoken. And it's the same for infants," Onishi said. "Even when they don't understand the meaning of the specific words they hear, they realize that words -- like our nonsense word 'koba' -- can provide information in a way that coughing cannot."

"What's significant about this is it tells us that infants have access to another channel of communication that we previously didn't know they had," added Vouloumanos.

Read more at Science Daily

Undead: The Rabies Virus Remains a Medical Mystery

Eight years old, wiry and ponytailed, Precious Reynolds bounds from the elevator to the entrance of the pediatric intensive-care unit. She fidgets impatiently as she waits to be buzzed in, eager to return to the clinic where, by the ironclad expectations of 2,000 years of medicine, she should have died. It was nine months ago, here at the UC Davis Medical Center in Sacramento, California, that Precious survived a confirmed bout of rabies—a disease that for most of human history was considered to be fatal in 100 percent of cases.

Today, though, Precious is back just to visit. In the halls of the pediatric ward, where zoo animals cavort in backlit photos, doing their best to dispel the hospital pall, the nurses who treated Precious greet her with delight. She does not remember them at all. But she speaks shyly to each, listening as they recount to her, in turn, their roles in rescuing her. She grows more talkative when describing the life she has resumed back in Willow Creek, in the wilds of California’s Humboldt County. To get in shape for the peewee wrestling season, Precious has been running laps in the long driveway of the farm where she lives with her siblings and grandparents. She also has resumed her pursuit of “mutton bustin’,” a sport in which kids ride rodeo-style on the backs of frantic sheep for as long as they can; at a recent match, she took home the third-place purse of $23.

Precious’ brush with death began with a simple flu-like illness that soon was accompanied by some odd symptoms: head and neck pain, weakness in her legs. At the hospital, a nurse asked her to drink something, but she choked, unable to swallow the fluid. “She looked at me like ‘Grandma, please help,’” her grandmother, Shirlee Roby, recalls. “I could tell this was no damn flu.” Her symptoms were so severe that the local hospital decided to transfer her by helicopter to UC Davis. When the state health department heard the symptoms and the fact that the patient had come from rural Humboldt County, it immediately suspected rabies. Lab tests confirmed the diagnosis: Precious had antibodies against the disease in her blood serum and cerebrospinal fluid, an impossibility in the absence of infection or vaccination. As it turned out, a feral cat had bitten her a few weeks before as she played outside her elementary school. But no one had thought to treat her at the time, and now it was too late for the standard intervention against rabies—a vaccine, administered in multiple shots over the course of two weeks, that allows the body to mount an immune response before the virus reaches the brain. In Precious’ case, it was clear that her brain had already been infected.

Not long ago, the medical response to this grim situation would have been little more than “comfort care”: administration of sedatives and painkillers to ease the suffering. Untreated, this suffering can be unbearable to watch, let alone experience. That telltale difficulty in swallowing, known as hydrophobia, results in desperately thirsty patients whose bodies rebel involuntarily whenever drink is brought to their lips. Soon fevers spike, and the victims are subject to violent convulsions as well as sudden bouts of aggression; their cries of agony, as expressed through a spasming throat, can produce the impression of an almost animal bark. Eventually the part of the brain that controls autonomic functions, like respiration and circulation, stops working, and the patients either suffocate or die in cardiac arrest. A decade ago, the only choice was to sedate them so their deaths would arrive with as little misery as possible.

But today, after millennia of futility, hospitals have an actual treatment to try. It was developed in 2004 by a pediatrician in Milwaukee named Rodney Willoughby, who, like the vast majority of American doctors, had never seen a case of rabies before. (In the US, there are usually fewer than five per year.) Yet Willoughby managed to save a young rabies patient, a girl of 15, by using drugs to induce a deep, week-long coma and then carefully bringing her out of it. It was the first documented case of a human surviving rabies without at least some vaccination before the onset of symptoms. Soon Willoughby posted his regimen online, and he worked with hospitals around the world to repeat and refine its use. Now referred to as the Milwaukee protocol, his methodology has continued to show limited success: Of 41 attempts worldwide, five more patients have pulled through, including Precious, whose recovery has been the most impressive of any victim to date.

Read more at Wired Science

The Pioneer Anomaly: a Wild Goose Chase?

Everyone loves a good mystery. And, some science mysteries are so strange that they take on legendary status.

The so-called Pioneer Anomaly -- which at first seemed to challenge the laws of physics -- is a case study of when it's best to bank on the simplest explanation for even the weirdest of observations.

Small, yet odd perturbations in the velocity of a pair of Pioneer spacecraft have spawned numerous science papers and conference discussions over the past two decades. In the end, it looks like the solution is rather mundane.

Nevertheless, the Pioneer spooky story became a magnet for exotic as well as plain kooky ideas. Commentary in some discussion groups have even tried to link it to Earth's Ice Ages, and an ad hoc idea called "fractal gravity." Creationists have glommed onto the mystery to try and demonstrate that "secular" scientists are wrong for ignoring so-called biblical cosmology.

The pair of Pioneer spacecraft, launched in the early 1970s to explore the outer solar system, are among an exclusive NASA fleet of five robotic "starships" that are moving fast enough to escape the sun's gravitational pull and drift through our galaxy forever.

Pioneer has even made a cameo appearance in a Star Trek movie when the evil Klingons find it in interstellar space and shoot it for target practice.

Now over 7 billion miles from Earth (10 light-hours) Pioneer 11 and 12 serve as "test particles" for measuring the effects of gravity on manmade objects over very large distances. Such a test has never before been possible.

In the 1980s several research teams independently measured what was interpreted as an infinitesimal deceleration of both Pioneers, which are streaking away from us in nearly opposite directions. The amount was inconsequential by engineering standards, but a huge discrepancy in predictions made by the laws of gravity.

The direction of the anomalous force had also come under question: is it really in the sun's direction, or Earth's, or along the spacecraft's spin axis or velocity direction?

Scientists began toying with the exotic theories for explaining the anomaly. Perhaps the laws of gravity needed to be modified. Was dark matter in our local neighborhood tugging on the Pioneers? Or did it have an even deeper implication for cosmology? One idea was that a localized blob of dark matter could be trapped in the sun's gravitational field. Any effects from dark energy would be way to small for explaining the Pioneer motion.

The peculiar speed difference is nearly equal to the value calculated (in the same units) by multiplying speed of light by the expansion rate of the universe. Without any clear causal link, the mathematical tie can best be dismissed as coincidence. It's just pseudo-scientific numerology. For example, the ratio of the perimeter to twice the altitude of the Great Pyramid of Ghiza is equal to the mathematical value for Pi. The height of the pyramid multiplied by 100 million yields the distance from Earth to the sun. So what?

Creation scientist, Russell Humphreys, has written extensively that the Pioneer Anomaly bolsters biblical scripture by demonstrating there really is a center to the universe, and that Earth must be near it. He reasons that the starbound Pioneers are being pulled back to the center of the universe, like a hiker struggling to climb up a steep slope. He envisions the space-time fabric of an 8,000 year-old universe relaxing like a worn bed mattress, and the Pioneer velocity change reflects this. However, a century's worth of cosmological observation demonstrate that the universe has no center, and the idea is anti-Copernican to boot.

Simple explanations for the Pioneer Anomaly, dating back to the late 1990s, looked at non-gravitational forces produced by the spacecraft itself due to thermal and electrical sources. Heat from Pioneer's electronics is 100 Watts. The heat from the radioactive plutonium-238 power source on Pioneer outputs 2.5 kilowatts. The nuclear "battery" is on a boom extending from one side of the 550-pound spacecraft. This would cause "thermal recoil" as one side of the vehicle was slightly warmed (thermal model above).

Slava Turyshev of NASA’s Jet Propulsion Laboratory proposed the recoil theory several years ago. Since then he has extract more archival data from Pioneer's tracking. The smoking gun, as described in a recently published paper that the data show a drop in Pioneer's anomalous motion. This is exactly what would be predicted if thermal heating is the culprit. The 10 pounds of plutonium aboard Pioneer cools as it decays exponentially.

Both Pioneer 11 and 12 would show exactly the same anomaly because they are identically built. But what about testing other spacecraft?

The New Horizons probe blazing its way to Pluto should also have peculiarities due to heat from its nuclear power source, though its tracking is not a precise as for the Pioneers. The two Voyager spacecraft are less sensitive to the effect seen on Pioneer, because their thrusters align it along three axes, whereas the Pioneer spacecraft rely on spinning to stay stable. Other solar system spacecraft are in the wrong orbit, have larger nuclear power sources, and do frequent maneuvers.

"For the foreseeable future Pioneer 10 and 11 remain the largest scale precision gravitational experiment ever conducted," wrote Victor Toth (Perimeter Institute for Theoretical Physics, Waterloo, Ontario Canada) in 2011. "Far more likely this (Pioneer anomaly) was just a wild goose chase."

Lessons learned are that there are limits to our tracking and navigational accuracy, it is critical to archive long-term data on spacecraft, and estimates of small forces acting on a spacecraft really need to be precisely done.

Read more at Discovery News

New Clues to the Early Solar System from Ancient Meteorites

In order to understand Earth's earliest history--its formation from Solar System material into the present-day layering of metal core and mantle, and crust--scientists look to meteorites. New research from a team including Carnegie's Doug Rumble and Liping Qin focuses on one particularly old type of meteorite called diogenites. These samples were examined using an array of techniques, including precise analysis of certain elements for important clues to some of the Solar System's earliest chemical processing.

Their work is published online July 22 by Nature Geoscience.

At some point after terrestrial planets or large bodies accreted from surrounding Solar System material, they differentiate into a metallic core, asilicate mantle, and a crust. This involved a great deal of heating. The sources of this heat are the decay of short-lived radioisotopes, the energy conversion that occurs when dense metals are physically separated from lighter silicate, and the impact of large objects. Studies indicate that the Earth's and Moon's mantles may have formed more than 4.4 billion years ago, and Mars's more than 4.5 billion years ago.

Theoretically, when a planet or large body differentiates enough to form a core, certain elements including osmium, iridium, ruthenium, platinum, palladium, and rhenium -- known as highly siderophile elements -- are segregated into the core. But studies show that mantles of Earth, Moon and Mars contain more of these elements than they should. Scientists have several theories about why this is the case and the research team -- which included lead author James Day of Scripps Institution of Oceanography and Richard Walker of the University of Maryland -- set out to explore these theories by looking at diogenite meteorites.

Diogenites are a kind of meteorite that may have come from the asteroid Vesta, or a similar body. They represent some of the Solar System's oldest existing examples of heat-related chemical processing. What's more, Vesta or their other parent bodies were large enough to have undergone a similar degree of differentiation to Earth, thus forming a kind of scale model of a terrestrial planet.

The team examined seven diogenites from Antarctica and two that landed in the African desert. They were able to confirm that these samples came from no fewer than two parent bodies and that the crystallization of their minerals occurred about 4.6 billion years ago, only 2 million years after condensation of the oldest solids in the Solar System.

Examination of the samples determined that the highly siderophile elements present in the diogenite meteorites were present during formation of the rocks, which could only occur if late addition or 'accretion' of these elements after core formation had taken place. This timing of late accretion is earlier than previously thought, and much earlier than similar processes are thought to have occurred on Earth, Mars, or the Moon.

Remarkably, these results demonstrate that accretion, core formation, primary differentiation, and late accretion were all accomplished in just over 2 to 3 million years on some parent bodies. In the case of Earth, there followed crust formation, the development of an atmosphere, and plate tectonics, among other geologic processes, so the evidence for this early period is no longer preserved.

Read more at Science Daily

Behold, the Artificial Jellyfish: Researchers Create Moving Model, Using Silicone Polymer and Heart Muscle Cells

Using recent advances in marine biomechanics, materials science, and tissue engineering, a team of researchers at Harvard University and the California Institute of Technology (Caltech) have turned inanimate silicone and living cardiac muscle cells into a freely swimming "jellyfish."

The finding serves as a proof of concept for reverse engineering a variety of muscular organs and simple life forms. It also suggests a broader definition of what counts as synthetic life in an emerging field that has primarily focused on replicating life's building blocks.

The researchers' method for building the tissue-engineered jellyfish, dubbed "Medusoid," was published in a Nature Biotechnology paper on July 22.

An expert in cell- and tissue-powered actuators, coauthor Kevin Kit Parker has previously demonstrated bioengineered constructs that can grip, pump, and even walk. The inspiration to raise the bar and mimic a jellyfish came out of his own frustration with the state of the cardiac field.

Similar to the way a human heart moves blood throughout the body, jellyfish propel themselves through the water by pumping. In figuring out how to take apart and then rebuild the primary motor function of a jellyfish, the aim was to gain new insights into how such pumps really worked.

"It occurred to me in 2007 that we might have failed to understand the fundamental laws of muscular pumps," says Parker, Tarr Family Professor of Bioengineering and Applied Physics at the Harvard School of Engineering and Applied Sciences (SEAS) and a Core Faculty Member at the Wyss Institute for Biologically Inspired Engineering at Harvard. "I started looking at marine organisms that pump to survive. Then I saw a jellyfish at the New England Aquarium and I immediately noted both similarities and differences between how the jellyfish and the human heart pump."

To build the Medusoid, Parker collaborated with Janna Nawroth, a doctoral student in biology at Caltech and lead author of the study, who performed the work as a visiting researcher in Parker's lab. They also worked with Nawroth's adviser, John Dabiri, a professor of aeronautics and bioengineering at Caltech, who is an expert in biological propulsion.

"A big goal of our study was to advance tissue engineering," says Nawroth. "In many ways, it is still a very qualitative art, with people trying to copy a tissue or organ just based on what they think is important or what they see as the major components -- without necessarily understanding if those components are relevant to the desired function or without analyzing first how different materials could be used."

It turned out that jellyfish, believed to be the oldest multi-organ animals in the world, were an ideal subject, as they use muscles to pump their way through water, and their basic morphology is similar to that of a beating human heart.

To reverse engineer a medusa jellyfish, the investigators used analysis tools borrowed from the fields of law enforcement biometrics and crystallography to make maps of the alignment of subcellular protein networks within all of the muscle cells within the animal. They then conducted studies to understand the electrophysiological triggering of jellyfish propulsion and the biomechanics of the propulsive stroke itself.

Based on such understanding, it turned out that a sheet of cultured rat heart muscle tissue that would contract when electrically stimulated in a liquid environment was the perfect raw material to create an ersatz jellyfish. The team then incorporated a silicone polymer that fashions the body of the artificial creature into a thin membrane that resembles a small jellyfish, with eight arm-like appendages.

Using the same analysis tools, the investigators were able to quantitatively match the subcellular, cellular, and supracellular architecture of the jellyfish musculature with the rat heart muscle cells.

The artificial construct was placed in container of ocean-like salt water and shocked into swimming with synchronized muscle contractions that mimic those of real jellyfish. (In fact, the muscle cells started to contract a bit on their own even before the electrical current was applied.)

"I was surprised that with relatively few components -- a silicone base and cells that we arranged -- we were able to reproduce some pretty complex swimming and feeding behaviors that you see in biological jellyfish," says Dabiri.

Their design strategy, they say, will be broadly applicable to the reverse engineering of muscular organs in humans.

"As engineers, we are very comfortable with building things out of steel, copper, concrete," says Parker. "I think of cells as another kind of building substrate, but we need rigorous quantitative design specs to move tissue engineering to a reproducible type of engineering. The jellyfish provides a design algorithm for reverse engineering an organ's function and developing quantitative design and performance specifications. We can complete the full exercise of the engineer's design process: design, build, and test."

In addition to advancing the field of tissue engineering, Parker adds that he took on the challenge of building a creature to challenge the traditional view of synthetic biology which is "focused on genetic manipulations of cells." Instead of building just a cell, he sought to "build a beast."

Looking forward, the researchers aim to further evolve the artificial jellyfish, allowing it to turn and move in a particular direction, and even incorporating a simple "brain" so it can respond to its environment and replicate more advanced behaviors like heading toward a light source and seeking energy or food.

Read more at Science Daily