A Crowning Success for Crayfish

Nature sometimes copies its own particularly successful developments. A team of scientists from the Max Planck Institute of Colloids and Interfaces in Potsdam and the Ben-Gurion University at Beer-Sheva in Israel has now found that the teeth of the Australian freshwater crayfish Cherax quadricarinatus are covered with an enamel amazingly similar to that of vertebrates. Both materials consist of calcium phosphate and are also very alike in terms of their microstructure. This extremely hard substance has apparently developed in freshwater crayfish independently from vertebrates, as it makes the teeth particularly strong.

In terms of hardness, enamel sets a unique standard, which is hardly met by any other other biological material. The hardness and strength of the outer layer of the crown of the tooth in humans and other vertebrates are due to tiny crystals of calcium phosphate, which also strengthen bones. And because the composition and structure of the enamel have made it exceptionally strong, the evolution in freshwater crayfish, too, has produced a highly mineralised protective layer for the mandibles that is very similar to enamel in vertebrates, as Barbara Aichmayer and her colleagues at the Max Planck Institute in Potsdam in cooperation with Amir Berman and Amir Sagi of the Ben-Gurion University in Beer-Sheva have now discovered. "We assume," she explains, "that in the course of their evolution both vertebrates and freshwater crayfish developed enamel-like structures independently of one another. These amazing materials are a perfect answer to similar demands on the masticatory organs."

The enamel of freshwater crayfish is heavily fluoridated by nature

The mandibles of the freshwater crayfish are part of the cuticle which, as in other crustaceans, consists essentially of a network of chitin fibres. The shell is hardened in particular by disordered calcium carbonate, which is termed amorphous by scientists. In the mandibles of freshwater crayfish, the softer compound material of chitin and amorphous calcium carbonate, however, is covered with a thin layer which, like human enamel, is composed predominantly of crystalline calcium phosphate. This is remarkable because the constituent calcium phosphate is rarely found in the exoskeleton of invertebrates. The elongated shape of the crystals and their arrangement perpendicular to the surface of the teeth, too, match the structure of human enamel to a large extent and produces similar mechanical properties. The structure makes the material extremely hard and at the same time highly resistant to crack propagation, giving the tooth perfect protection against destruction.

However, there is one aspect in which the teeth of freshwater crayfish differ from those of vertebrates: Their enamel contains a high level of fluoride that makes it much less water-soluble -- all without taking fluoride tablets. In freshwater, the habitat of the freshwater crayfish, this is particularly important, because minerals containing calcium dissolve more easily there than in salt water.

Read more at Science Daily

Rabies Evolves Slower in Hibernating Bats

The rate at which the rabies virus evolves in bats may depend heavily upon the ecological traits of its hosts, according to researchers at the University of Georgia, the U.S. Centers for Disease Control and Prevention and Katholieke Universiteit Leuven in Belgium. Their study, published May 17 in the journal PLoS Pathogens, found that the host's geographical location was the most accurate predictor of the viral rate of evolution. Rabies viruses in tropical and sub-tropical bat species evolved nearly four times faster than viral variants in bats in temperate regions.

"Species that are widely distributed can have different behaviors in different geographical areas," said Daniel Streicker, a postdoctoral associate in the UGA Odum School of Ecology and the study's leader. "Bats in the tropics are active year-round, so more rabies virus transmission events occur per year. Viruses in hibernating bats, on the other hand, might lose up to six months' worth of opportunities for transmission."

Understanding the relationship between host ecology and viral evolution rates could shed light on the transmission dynamics of other viruses, such as influenza, that occur across regions, infect multiple host species or whose transmission dynamics are impacted by anthropogenic change.

The team's findings could eventually help public health officials better predict when rabies virus transmission could happen in different environments and as environments change, but Streicker cautions that more research into the rabies virus genome and bats' overwintering ecology is needed.

"If viral evolution is faster, it could potentially lead to greater genetic diversity in crucial parts of the viral genome that allow it to shift hosts," he said. "For rabies, we don't yet know what those are, so identifying them will be key. Similarly, before understanding whether climate change will speed viral evolution, we need a better idea of how environmental changes will influence host ecology and behavior."

Evolutionary biologists have long recognized that molecular evolution proceeds in a largely clock-like manner, with mutations accumulating at a fairly constant rate over time. This "molecular clock" allows for powerful inferences -- from dating the origins of species to the origins of epidemics. However, the rate at which the clock ticks varies dramatically among species; much research has focused on what causes these differences.

For RNA viruses such as rabies, understanding the rate variability has practical implications, since faster evolution can enable viral emergence in new species or allow a virus to evade its host's immune defenses. However, nearly all past studies compared viruses of completely different families and were therefore limited to focusing on viral structural traits. Since few opportunities existed to study the evolution of similar viruses in different host species, the role of the host had been almost completely neglected.

Streicker set out to better understand the tempo of the evolution of rabies viruses in bats, and specifically what, if any, role the host species played.

To conduct the study, Streicker and his colleagues compiled a database of rabies virus genetic sequences from infected bats in the U.S. and South America, representing 21 different variants of the virus. They also collected information on the biology and ecology of the different bat species that served as viral hosts. They looked at the evolutionary history of the different bat species; their overwintering behavior (whether the bats hibernated, went through periods of torpor or remained active during the winter); their metabolic rates; and their migration habits (whether they engaged in long distance migration). They also classed the bats by climatic region and whether they were solitary or roosted in colonies.

Their analysis of this enormous database revealed extreme variability in the rate of evolution in different rabies viruses, comparable to the differences seen between viruses of entirely different families. The analysis also suggested that viral genetic traits were not chiefly responsible for this variation since rates seemed to shift freely throughout the ancestral history of the rabies virus as it jumped into new bat species.

"Earlier studies led to the conclusion that viral genomic traits are driving the evolution rate," Streicker said. "It turns out that's not the whole story. In this case, host biology plays an important role."

The trait that best correlated with the rate of viral evolution was not the host's evolutionary history. It was its climatic region, which affects the bats' behavior.

Rabies in tropical bats goes through more generations per year than in temperate bats, a mechanism also hypothesized to accelerate how quickly the molecular clock ticks in free-living tropical plants and animals. The rapid evolution in rabies viruses provided the researchers with an opportunity to examine one of the mechanisms thought to drive the differences in evolution and species diversity across latitudes from the poles to the tropics.

"This is just another example of how the fast pace of evolution in RNA viruses makes them exceptional tools for understanding simultaneously ecological and evolutionary processes," Streicker said.

Read more at Science Daily

Tyrannosaur Skeleton For Sale, But Ownership Is Questioned

The origin of a rare tyrannosaur skeleton, now sitting mounted and prepared at an auction house in New York City, has been questioned, with some saying the specimen is from Mongolia; if so, that would mean it entered the United States illegally.

The rare Tyrannosaurus bataar — standing 8 feet (2.4 meters) tall and 24 feet (7.3 m) long — is to be auctioned Sunday (May 20) by Heritage Auctions.

An email to LiveScience late on Friday afternoon claimed the Mongolian President Elbegdorj Tsakhia was raising concerns that the specimen was actually his country's property. The email contained a note signed by Mark Norell, a vertebrate paleontologist at the American Museum of Natural History in New York City.

"There is no legal mechanism (nor has there been for over 50 years) to remove vertebrate fossil material from Mongolia. These specimens are the patrimony of the Mongolian people and should be in a museum in Mongolia," the letter reads.

Norell confirmed that the letter was his.

The auction house stands by their collection, saying the items legally entered the United States.

"There is nothing from Mongolia that is legal. It's not that I am against the commercial trade of fossils, it's just different countries have different laws," Norell told LiveScience, adding that Heritage Auctions avoids giving the specific locality for the origin of the fossil in their catalog of natural history items to be auctioned.

The description, he said, only states the skeleton is from Central Asia, though if the specimen did indeed come from China, it would still be illegal.

David Herskowitz, director of natural history for Heritage Auctions, said the T. bataar skeleton entered the United States legally, adding in a statement that "no one knows where exactly it was dug up. They'd have to find the hole and match up the matrix."

While the tyrannosaur skeleton is the headliner, several other natural-history specimens are also set to be auctioned Sunday. Of these, Norell says he is also concerned an ankylosaur skull and T. bataar teeth may also be from Mongolia; the teeth described in the auction house's catalog say they came from a formation that Norell says only exists in Mongolia.

Regarding the T. bataar skeleton and the ankylosaur, Norell said, "They say they are from Central Asia, but the only places those two animals have ever been collected have been from Mongolia."

Read more at Discovery News

Tiny Deep-Sea Life Eats Dinosaur-Era Meals

Microbes living in the seabed below the deep ocean are taking the slow-food movement to extremes. According to new research, these microorganisms are subsisting on nutrients first laid down when dinosaurs still walked the Earth.

Nutrient-carrying sediment rarely makes it to the deep seafloor at the North Pacific Gyre far north of Hawaii. If a grain of sand falls to the seabed, it will be another 1,000 years before another grain lands on top of it, said Hans Røy, aquatic ecologist at Aarhus University in Denmark and leader of the new study, published Thursday (May 17) in the journal Science. And yet, an expedition to the North Pacific turned up populations of incredibly slow-living microbes in these depths.

"It's pretty amazing, because if you look at the deepest parts, these are layers that were laid down back when the dinosaurs were walking on this planet, and there has been no input of new organic material since that," Røy told LiveScience. "They've been chewing on the same bone for 86 million years."

Microbial mission

Research stretching back to the late 1980s suggests that as much as 90 percent of the Earth's microorganisms live in the seabed, Røy said. But these microbial communities remain mysterious, largely because they resist typical laboratory experiments. If you wanted to measure the metabolism (how fast the body uses energy) of microbes living in coastal mud, you'd simply take some mud and track how fast they burned through the oxygen in that sample. Because coastal seafloor organisms live in a nutrient-rich, fast-turnover world, the experiment would only take a few minutes.

To do the same thing with the slow-living bacteria found beneath the North Pacific Gyre, you'd have to wait 1,000 years to detect a change in oxygen levels, Røy said.

That's what makes the new discovery important, he said. The bacterial communities living in the Pacific have been chugging along for millions of years. All scientists have to do is go out and measure their activities.

During an expedition on the U.S. Navy research vessel R/V Knorr, Røy and his colleagues drilled long columns of sediment called cores out of the seabed. They first sampled from a long stretch along the equator, varying their distance from land, but not their latitude. Next, the vessel sailed north into the Pacific, and researchers took seabed samples at different latitudes, but all at equal distances from land.

Slow living in the seafloor

In most places, oxygen penetrates only a millimeter into the ocean bed, sometimes making it as much as about a foot and a half (0.5 meters) in deep-sea zones. But in the deep North Pacific Gyre, researchers hauled up cores 98 feet (30 m) long and found oxygen reaching all the way down.

The reason, Røy said, is that so few nutrients reach the seabed here that the microbes in the seafloor barely eat. When they don't eat, they don't use oxygen. Thus, the oxygen hangs around in the sediment for thousands of years.

The researchers aren't sure how old the individual microbes in the colonies are. It takes the microbes 1,000 years to double their biomass, they calculated. In comparison, a familiar microbe like the food-poisoning bug salmonella might take between 20 minutes and two hours to double, depending on its environment.

Cells double their biomass to divide, so the results suggest the microbes are at least 1,000 years old. But that number is a minimum, Røy said.

"Maybe they grow and divide, but the result could just as well indicate that they have a long repair cycle where over a 1,000-year period, they actually replace all the compartments of the cell," he said. "If that is the case, the cells could be much older."

Read more at Discovery News

Bronze-Age 'Facebook' Stone Conveyed 'Likes'

A Bronze Age version of Facebook has emerged from granite rocks in Russia and northern Sweden, revealing a thousands-of-years-old timeline filled with an archaic version of the Facebook "like."

Using computer modeling, Mark Sapwell, a Ph.D. archaeology student at Cambridge University, analyzed some 3,500 rock art images from Nämforsen in Northern Sweden and Zalavruga in Western Russia.

"Although this rock art has been documented from the early 1900s, the modeling has allowed a unique look at the interesting way these images have been arranged and accumulated over time," Sapwell told Discovery News.

Carved from about 4000 B.C. up to the Bronze Age, the rock art shows animals, people, boats, hunting scenes -- even very early centaurs and mermaids. It was produced by generations of semi nomadic people, who lived more inland in winter to hunt elk, and then occupied areas closer to coasts and rivers to fish.

As they were located in important and prominent locations on river crossroads, the rock art landscapes were likely very visible points where passing travellers would take notice of the traces of people who came before them, adding their own mark on the world.

"The rock art we see today is the result of a culmination of many repeated acts of carving, each responding to each other over time. Like a Facebook status invites comment, the rock art appears very social and invites addition," Sapwell said.

Usually clustered on the granite rocks, the images ranged from groups of one to two images to rock art panels with over 500 images. Larger clusters represented a greater response and conversation between people.

Read more at Discovery News

Island Platypuses Face Risky Future

Safety really is in the numbers for some of Australia's iconic animals with a new study showing small island populations of platypus are in danger of being wiped out because of a lack of genetic diversity.

The finding could help improve management of other animal populations with low genetic variation such as the koala and helps explain the decimation of the Tasmanian devils from a contagious cancer.

The paper, published this month in the Journal of Heredity, shows platypuses on the Australian mainland and in Tasmania have high levels of genetic diversity within their populations.

However those platypuses found on King Island, north-west of Tasmania, and Kangaroo Island, south-west of Adelaide, are at high risk of being wiped out.

For the study, University of Sydney doctoral student Mette Lillie, examined the immune genes of 70 platypuses from populations in Queensland, New South Wales, Victoria, Tasmania and the two smaller islands.

She says the study shows the King Island population has no diversity in its major histocompatibility complex (MHC) gene which plays a critical role in the immune system identifying pathogens and disease.

"If you have lots of variation in the MHC gene it means the populations is better able to resist disease and pathogens," Lillie says.

She says the genetic diversity has been lost because the King island population is an endemic species that has been isolated from other populations since the last Ice Age about 14,000 years ago.

Genetic diversity would have been reduced through inbreeding and random genetic drift - evolutionary forces or events that dramatically change or influence genetic diversity from generation to generation.

She says around 20 platypuses were introduced to Kangaroo Island in the 1930s and 1940s and the lack of genetic diversity is to be expected given the small size of the original population.

Read more at Discovery News

Car-Sized Turtle Found in Colombian Coal Mine

Remains of an enormous turtle, which was the size of a Smart car, have been unearthed in a Colombian coal mine.

The shell alone of the 60-million-year-old turtle, Carbonemys cofrinii aka "coal turtle," is large enough to be a small swimming pool. Its skull is roughly the size of a regulation NFL football.

The coal mine where it was found is part of northern Colombia's Cerrejon formation.

"We had recovered smaller turtle specimens from the site," Edwin Cadena, a North Carolina State doctoral student who discovered the turtle, said in a press release. "But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period -- and it gave us the first evidence of giant-ism in freshwater turtles."

The find was described in the latest Journal of Systematic Paleontology.

Relatives of Carbonemys existed alongside dinosaurs, but these turtles were much smaller. This gigantic version appeared five million years after dinos went extinct, during a period when giant varieties of many different reptiles -- including Titanoboa cerrejonensis, the largest snake ever discovered -- lived in this part of South America.

Why were the animals so big?

Cadena and other experts believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to allow these giant species to survive. Carbonemys' habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta.

Read more at Discovery News

Religion Is a Potent Force for Cooperation and Conflict, Research Shows

Across history and cultures, religion increases trust within groups but also may increase conflict with other groups, according to an article in a special issue of Science.

"Moralizing gods, emerging over the last few millennia, have enabled large-scale cooperation and sociopolitical conquest even without war," says University of Michigan anthropologist Scott Atran, lead author of the article with Jeremy Ginges of the New School for Social Research.

"Sacred values sustain intractable conflicts like those between the Israelis and the Palestinians that defy rational, business-like negotiation. But they also provide surprising opportunities for resolution."

As evidence for their claim that religion increases trust within groups but may increase conflict with other groups, Atran and Ginges cite a number of studies among different populations. These include cross-cultural surveys and experiments in dozens of societies showing that people who participate most in collective religious rituals are more likely to cooperate with others, and that groups most intensely involved in conflict have the costliest and most physically demanding rituals to galvanize group solidarity in common defense and blind group members to exit strategies. Secular social contracts are more prone to defection, they argue. Their research also indicates that participation in collective religious ritual increases parochial altruism and, in relevant contexts, support for suicide attacks.

They also identify what they call the "backfire effect," which dooms many efforts to broker peace. In many studies that Atran and Ginges carried out with colleagues in Palestine, Israel, Iran, India, Indonesia and Afghanistan, they found that offers of money or other material incentives to compromise sacred values increased anger and opposition to a deal.

"In a 2010 study, Iranians who regarded Iran's right to a nuclear program as a sacred value more violently opposed sacrificing Iran's nuclear program for conflict-resolution deals involving substantial economic aid, or relaxation of sanctions, than the same deals without aid or sanctions," they write. "In a 2005 study in the West Bank and Gaza, Palestinian refugees who held their 'right of return' to former homes in Israel as a sacred value more violently opposed abandoning this right for a Palestinian state plus substantial economic aid than the same peace deal without aid."

This dynamic is behind the paradoxical reality that the world finds itself in today: "Modern multiculturalism and global exposure to multifarious values is increasingly challenged by fundamentalist movements to revive primary group loyalties through greater ritual commitments to ideological purity."

But Atran and Ginges also offer some insights that could help to solve conflicts fueled by religious conviction. Casting these conflicts as sacred initially blocks standard business-like negotiation tactics. But making strong symbolic gestures such as sincere apologies and demonstrations of respect for the other's values generates surprising flexibility, even among militants and political leaders, and may enable subsequent material negotiations, they point out.

"In an age where religious and sacred causes are resurgent, there is urgent need for joint scientific effort to understand them," they conclude. "In-depth ethnography, combined with cognitive and behavioral experiments among diverse societies (including those lacking a world religion), can help identify and isolate the moral imperatives for decisions on war or peace."

Read more at Science Daily

Giant Galaxy-Packed Filament Revealed

A McGill-led research team using the Herschel Space Observatory has discovered a giant, galaxy-packed filament ablaze with billions of new stars. The filament connects two clusters of galaxies that, along with a third cluster, will smash together and give rise to one of the largest galaxy superclusters in the universe.

The filament is the first structure of its kind spied in a critical era of cosmic buildup when colossal collections of galaxies called superclusters began to take shape. The glowing galactic bridge offers astronomers a unique opportunity to explore how galaxies evolve and merge to form superclusters.

"We are excited about this filament, because we think the intense star formation we see in its galaxies is related to the consolidation of the surrounding supercluster," said Kristen Coppin, a postdoctoral fellow in astrophysics at McGill and lead author of a new paper in Astrophysical Journal Letters.

"This luminous bridge of star formation gives us a snapshot of how the evolution of cosmic structure on very large scales affects the evolution of the individual galaxies trapped within it," said Jim Geach, a co-author also based at McGill.

The intergalactic filament, containing hundreds of galaxies, spans 8 million light-years and links two of the three clusters that make up a supercluster known as RCS2319. This emerging supercluster is an exceptionally rare, distant object whose light has taken more than seven billion years to reach us.

RCS2319 is the subject of a huge observational study, led by Professor Tracy Webb and her group at McGill's Department of Physics. Previous observations in visible and X-ray light had found the cluster cores and hinted at the presence of a filament. It was not until astronomers trained Herschel on the region, however, that the intense star-forming activity in the filament became clear. Dust obscures much of the star-formation activity in the early universe, but telescopes like Herschel can detect the infrared glow of this dust as it is heated by nascent stars. (The Herschel Space Observatory is a European Space Agency mission with important NASA contributions.)

The amount of infrared light suggests that the galaxies in the filament are cranking out the equivalent of about 1,000 solar masses (the mass of our sun) of new stars per year. For comparison's sake, our Milky Way galaxy is producing about one solar mass-worth of new stars per year.

Researchers chalk up the blistering pace of star formation in the filament to the fact that galaxies within it are being crunched into a relatively small cosmic volume under the force of gravity. "A high rate of interactions and mergers between galaxies could be disturbing the galaxies' gas reservoirs, igniting bursts of star formation," said Geach.

By studying the filament, astronomers will be able to explore the fundamental issue of whether "nature" versus "nurture" matters more in the life progression of a galaxy. "Is the evolution of a galaxy dominated by intrinsic properties such as total mass, or do wider-scale cosmic environments largely determine how galaxies grow and change?" Geach asked. "The role of the environment in influencing galactic evolution is one of the key questions of modern astrophysics."

The galaxies in the RCS2319 filament will eventually migrate toward the center of the emerging supercluster. Over the next seven to eight billion years, astronomers think RCS2319 will come to look like gargantuan superclusters in the local universe, like the nearby Coma cluster. These advanced clusters are chock-full of "red and dead" elliptical galaxies that contain aged, reddish stars instead of young ones.

Read more at Science Daily

200-Year-Old Shipwreck Found Off Gulf Coast

Ocean researchers exploring the depths of the Gulf of Mexico have discovered a wooden shipwreck laden with anchors, navigational instruments, glass bottles, ceramic plates, cannons and boxes of muskets.

Resting on the sea bottom in about 4,000 feet of water, some 200 miles offs the northern Gulf Coast shore, the wooden-hulled vessel "is believed to have sunk as long as 200 years ago," the U.S. National Oceanic and Atmospheric Administration (NOAA) said in a statement.

"Artifacts in and around the wreck and the hull's copper sheathing may date the vessel to the early to mid-19th century," said Jack Irion, a maritime archaeologist with the Interior Department's Bureau of Ocean Energy Management.

Originally identified as an "unknown sonar contact" during a 2011 oil and gas survey for Shell Oil Company, the shipwreck site was fully investigated in a recent NOAA-funded 56-day expedition in little known regions of the Gulf.

Scientists on board the NOAA Ship Okeanos Explorer used a state-of-the-art multibeam mapping sonar and a remote-controlled underwater explorer, Little Hercules, that is equipped with lights and high definition cameras. They were able to view a variety of artifacts inside the ship's hull.

While the ship's wood has nearly disintegrated after more than a century on the seafloor, the oxidized copper sheathing remains, along with a variety of artifacts.

"Some of the more datable objects include what appears to be a type of ceramic plate that was popular between 1800 and 1830, and a wide variety of glass bottles. A rare ship's stove on the site is one of only a handful of surviving examples in the world and the second one found on a shipwreck in the Gulf of Mexico," Irion said.

Historic events in the Gulf of Mexico that may have been responsible for the sinking include the War of 1812, events leading to the Texas Revolution, and the Mexican-American War.

Read more at Discovery News