Feb 8, 2014
Pacific salmon inherit magnetic sense of direction
A team of scientists last year presented evidence of a correlation between the migration patterns of ocean salmon and Earth's magnetic field, suggesting it may help explain how the fish can navigate across thousands of miles of water to find their river of origin.
This week, scientists confirmed the connection between salmon and the magnetic field following a series of experiments at the Oregon Hatchery Research Center in the Alsea River basin. Researchers exposed hundreds of juvenile Chinook salmon to different magnetic fields that exist at the latitudinal extremes of their oceanic range. Fish responded to these "simulated magnetic displacements" by swimming in the direction that would bring that toward the center of their marine feeding grounds.
The study, which was funded by Oregon Sea Grant and the Oregon Department of Fish and Wildlife, will be published this month in the forthcoming issue of Current Biology.
"What is particularly exciting about these experiments is that the fish we tested had never left the hatchery and thus we know that their responses were not learned or based on experience, but rather they were inherited," said Nathan Putman, a postdoctoral researcher at Oregon State University and lead author on the study.
"These fish are programmed to know what to do before they ever reach the ocean," he added.
To test the hypothesis, the researchers constructed a large platform with copper wires running horizontally and vertically around the perimeter. By running electrical current through the wires, the scientists could create a magnetic field and control the both the intensity and inclination angle of the field. They then placed 2-inch juvenile salmon called "parr" in 5-gallon buckets and, after an acclimation period, monitored and photographed the direction in which they were swimming.
Fish presented with a magnetic field characteristic of the northern limits of the oceanic range of Chinook salmon were more likely to swim in a southerly direction, while fish encountering a far southern field tended to swim north. In essence, fish possess a "map sense" determining where they are and which way to swim based on the magnetic fields they encounter.
"The evidence is irrefutable," said co-author David Noakes of OSU, senior scientist at the Oregon Hatchery Research Center and the 2012 recipient of the American Fisheries Society's Award of Excellence. "I tell people: The fish can detect and respond to the Earth's magnetic field. There can be no doubt of that."
Not all of the more than 1,000 fish swam in the same direction, Putman said. But there was a clear preference by the fish for swimming in the direction away from the magnetic field that was "wrong" for them. Fish that remained in the magnetic field of the testing site -- near Alsea, Ore. -- were randomly oriented, indicating that orientation of fish subjected to magnetic displacements could only be attributable to change in the magnetic field.
"What is really surprising is that these fish were only exposed to the magnetic field we created for about eight minutes," Putman pointed out. "And the field was not even strong enough to deflect a compass needle."
Putman said that salmon must be particularly sensitive because the Earth's magnetic field is relatively weak. Because of that, it may not take much to interfere with their navigational abilities. Many structures contain electrical wires or reinforcing iron that could potentially affect the orientation of fish early in their life cycle, the researchers say.
"Fish are raised in hatcheries where there are electrical and magnetic influences," Noakes said, "and some will encounter electrical fields while passing through power dams. When they reach the ocean, they may swim by structures or cables that could interfere with navigation. Do these have an impact? We don't yet know."
Putman said natural disruptions could include chunks of iron in Earth's crust, though "salmon have been dealing with that for thousands of years."
Read more at Science Daily
Red skies discovered on extreme brown dwarf
Brown dwarfs straddle the line between stars and planets. They are too big to be considered as planets; yet they do not have sufficient material to fuse hydrogen in their cores to fully develop into stars. They are midway in mass between stars, like our Sun, and giant planets, like Jupiter and Saturn. Sometimes described as failed stars, they do not have an internal source of energy -- so they are cold and very faint, and keep on cooling over time.
The brown dwarf, named ULAS J222711-004547, caught the researchers' attention for its extremely red appearance compared to "normal" brown dwarfs. Further observations with the VLT (Very Large Telescope) in Chile and the use of an innovative data analysis technique have shown that the reason for its peculiarity is the presence of a very thick layer of clouds in its upper atmosphere.
Federico Marocco, who led the research team from the University of Hertfordshire, said: "These are not the type of clouds that we are used to seeing on Earth. The thick clouds on this particular brown dwarf are mostly made of mineral dust, like enstatite and corundum.
"Not only have we been able to infer their presence, but we have also been able to estimate the size of the dust grains in the clouds."
The size of the dust grains influences the colour of the sky. In a similar way that the old saying of "Red sky at night, shepherd's delight. Red sky in the morning, shepherd's warning" is used at sunrise and sunset to indicate the changing weather, a red sky on the brown dwarf suggests an atmosphere loaded with dust and moisture particles. If our morning skies are red, it is because clear skies to the east permit the sun to light the undersides of moisture-bearing clouds coming in from the west. Conversely, in order to see red clouds in the evening, sunlight must have a clear path from the west in order to illuminate moisture-bearing clouds moving off to the east. However, the recently discovered brown dwarf ULAS J222711-004547 has a very different atmosphere where the sky is always red.
The giant planets of the Solar System, like Jupiter and Saturn, show various cloud layers including ammonia and hydrogen sulphide as well as water vapour. The atmosphere observed in this particular brown dwarf is hotter -- with water vapour, methane and probably some ammonia but, unusually, it is dominated by clay-sized mineral particles.
Getting a good understanding of how such an extreme atmosphere works will help us to better understand the range of atmospheres that can exist.
Dr Avril Day-Jones, from the University of Hertfordshire's Centre for Astrophysics Research, who contributed to the discovery and analysis said: "Being one of the reddest brown dwarfs ever observed, ULAS J222711-004547 makes an ideal target for multiple observations to understand how the weather is in such an extreme atmosphere."
Read more at Science Daily
Feb 7, 2014
Do Some Animals Get a Taste for Human Blood?
Recent killings by a tiger in northern India reveal how circumstances can cause predators to develop a taste for humans.
Certain animal predators may become serial killers of people, suggest animal experts and reports of multiple deaths inflicted by particular animals. In this case, a tigress is said to have killed nine people -- so far -- in a densely forested area near Jim Corbett National Park in Uttar Pradesh. Hunters are trying to track the animal in the forest, either to capture, but most likely to kill it.
"They do get a taste for humans," conservationist Belinda Wright from the Wildlife Protection Society of India told AFP. "But I think (attacks happen) more because we're very easy prey. As a tiger gets older, or is disabled in some way, we're just very, very easy as we bumble around on our two legs."
This tiger, one of about 200 living in the park, has terrorized local residents. Children can't venture far from their houses and farmers have stopped sleeping in their fields for fear of attack.
George Burgess, director of the Florida Program for Shark Research, told Discovery News: "It is not out of the realm of possibility that some individual animals may learn to target humans. Large cats may come to view us as easy pickings under some circumstances."
A growing taste for salt might explain the deaths.
Maheshwor Dhakal of the Department of National Parks and Wildlife Conservation in Kathmandu believes that as soon as leopards and other big cats start to prey upon humans, it is difficult to get them to stop.
"Since human blood has more salt than animal blood, once wild animals get the taste of salty blood, they do not like other animals like deer," Dhakal told CNN.
But developing a taste for humans, or anything, requires a learning process based on past experience. That isn't possible unless the predator can frequently encounter the "food source."
Johnny Rodrigues, chairman for the Zimbabwe Conservation Task Force, has told Discovery News that wild animals are often reported as being in urban areas "possibly because humans are encroaching more and more into areas previously reserved for wildlife, resulting in the destruction of their habitat."
In terms of big cats, the usual problem concerns deadly encounters with cows, sheep and other livestock. An animal that goes after humans is rare.
Burgess said that he knows of only two instances where individual sharks have repeatedly attacked humans. Both occurred in waters off of Egypt. In each instance, humans were to blame, although indirectly.
He explained that vessels from Australia and New Zealand were transporting live sheep to Egypt, since sheep are sacrificed there for a religious holiday.
"Sheep that died on the ships were tossed overboard," Burgess said. "Sheep defecate and urinate, so that waste was also being washed overboard. The result was a chum trail that likely went all the way from New Zealand to the Red Sea."
He explained that vessels from Australia and New Zealand were transporting live sheep to Egypt, since sheep are sacrificed there for a religious holiday.
"Sheep that died on the ships were tossed overboard," Burgess said. "Sheep defecate and urinate, so that waste was also being washed overboard. The result was a chum trail that likely went all the way from New Zealand to the Red Sea."
An oceanic whitetip shark and a mako shark appear to have followed this trail, winding up in more shallow water used for human recreation. Without sheep or other prey to eat, the sharks went after humans.
"So it's highly unusual for an individual shark or other animal to repeatedly prey upon humans, but it can happen," Burgess said.
Such encounters remind that humans were not always at the top of the food chain.
Kirsten Jenkins, a University of Minnesota anthropologist, explained that an early ape called Proconsul -- thought to have been an ancestor to both modern humans and chimpanzees -- was good eats for numerous predators.
"I have observed multiple tooth pits and probable beak marks on these fossil primates, which are direct evidence for creodonts and raptors consuming these primates," Jenkins told Discovery News.
Read more at Discovery News
Prehistoric Carnivore Had 'Steak Knife' Teeth
Dimetrodon lived at what are now the southwestern United States and parts of Europe between 298 million and 272 million years ago. (The first dinosaurs evolved from other animals some 40 million years later.)
Based on the new study, published in Nature Communications, we know that Dimetrodon was not afraid to bite off more than it could chew.
Its sharp, serrated teeth allowed Dimetrodon to rip into prey much larger than itself. Not surprisingly, this ravenous carnivore was at the top of the terrestrial food chain during its existence in the Early Permian Period.
“The steak knife configuration of these teeth and the architecture of the skull suggest Dimetrodon was able to grab and rip and dismember large prey,” co-author Robert Reisz, a University of Toronto Mississauga biologist, said in a press release.
“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton," he continued. "We already know from fossil evidence which animals existed at that time but now, with this type of research, we are starting to piece together how the members of these communities interacted."
Based on other known animals living at the time of Dimetrodon's existence, the toothy predator probably hunted prey such as large fish, aquatic amphibians, and certain land animals, including reptiles. It might have also snacked on insects that were around then.
Reisz and graduate student Kirstin Brink, who led the study, used high tech equipment, such as a scanning electron microscope (SEM), to get an ultra close-up look at Dimetrodon's teeth.
In addition to its ziphodont (a.k.a. steak knife) teeth, this carnivore also sported cusps -- teeth with raised points on the crown -- which are dominant in mammals.
It's now thought that this over 13-foot-long very ancient animal was a forerunner to mammals. That’s amazing to consider, given the reconstruction of Dimetrodon with its Spinosaurus-type "sail" on its back, turtle-looking head and more.
Read more at Discovery News
Earliest Human Footprints Outside Africa Found in Britain
Researchers discovered the footprints, which were left by both adults and children, in ancient estuary mud at Happisburgh in Norfolk, eastern England.
The only older footprints found so far are at Laetoli in Tanzania, at about 3.5 million years old, and at Ileret and Koobi Fora in Kenya at about 1.5 million years, they added.
"This is an extraordinarily rare discovery," said Nick Ashton of the British Museum, who led the research team, which also involved the National History Museum and Queen Mary University London.
The discovery came at an archaeological site that has yielded several previous discoveries of stone tools and fossil bones, including mammoth remains.
The researchers found the prints at low tide when waves washed away much of the beach sand to expose the silt below.
"At first we weren't sure what we were seeing but as we removed any remaining beach sand and sponged off the seawater, it was clear that the hollows resembled prints, perhaps human footprints, and that we needed to record the surface as quickly as possible before the sea eroded it away," Ashton said.
The group of early humans that left the footprints appeared to have consisted of at least one male and several smaller people believed to be females and youngsters, the researchers said.
"They are clearly a family group rather than a hunting party," said Ashton.
Analysis of the prints found that they were from a "range of adult and juvenile foot sizes" equating to modern shoe sizes of up to British 7 or 8 (US 8 or 9, European 41 or 42).
The researchers estimated that the height of the ancient humans who left the prints varied from about 0.9 meters to over 1.7 meters (2'11" to 5'6"), not far off the height of modern humans.
They were dated at 800,000 years old partly on the basis of the site's geological position beneath glacial deposits, but also because the fossils there come from now-extinct types of mammoth and horse and early forms of vole that were alive at that time.
Read more at Discovery News
The Bird That Does Unbelievable Impressions of Chainsaws, Car Alarms
Charles Darwin hated the peacock — hated it — at one point writing that he was simply sickened by its ostentatious feathers. He couldn’t for the life of him figure out why a creature would essentially beg to be hunted, seemingly in wanton disregard of his new theory of evolution, which is about the survival (not the evisceration) of the fittest.
The answer, Darwin eventually realized, is the principle of sexual selection. With its glorious plumage, the peacock is essentially saying to the peahen, “I’m healthy, and also I might have a bit of an ego problem.” It’s a drive so strong that it outweighs the risk of predation and justifies the tremendous energy the peacock puts into growing the feathers, not to mention lugging them around.
But sexual selection is far from a solely visual process. Behold the superb lyrebird, whose calls are surely the most impressive in the animal kingdom. It has the uncanny ability to perfectly mimic the sounds of the Australian forests it calls home, from camera shutters to other bird species to chainsaws, kinda like that guy from Police Academy with the funny voices, only it can’t carry a gun.
Just watch the video above. It’s real. I know because David Attenborough hosts it, and David is legit. This behavior is particularly common in captivity, where lyrebirds are inundated with decidedly unnatural sounds. And check out the second video below of a lyrebird in Australia’s Adelaide Zoo. It not only pulls off the din of a drill and hammer strikes, but the tone changes as a nail is driven home, guaranteeing that zoo employees will be annoyed by construction long after the construction itself is finished.
Physiologically, what could be driving this incredible mimicry? What makes the lyrebird so adept at impersonation? Well, according to behavioral ecologist Anastasia Dalziell of the Australian National University, we don’t really know yet. We can assume the lyrebird must have excellent hearing and memory, but what makes it so special biologically hasn’t been studied at length.
What we do know is that the lyrebird is a kind of songbird, producing sound with a vocal organ roughly equivalent to our larynx called a syrinx. (Syrinx, by the way, is Greek for “panpipe” and the name of a wood nymph who fled from the advances of Pan, who was a bit of a jackass. Beseeching assistance from water nymphs at a river’s edge, she was turned into reeds, which Pan chopped to pieces and fashioned into a flute. So … yeah.)
With lyrebirds, “it is true that their syrinx is slightly different in structure than most other songbirds,” Dalziell said in an email to WIRED. “For example, it has fewer syringeal muscles, but exactly how the structure of the syrinx allows it to produce so many sounds is not yet clear.” Strangely, notes Dalziell, having more muscles in the syrinx typically corresponds with greater vocal complexity — but the ultra-talkative lyrebirds (and parrots, as it happens) are exceptions to this rule.
In the wild, males will not only flawlessly imitate some 20 different species of birds, but multiple calls from each. They’re particularly fond of imitating Australia’s famous laughing kookaburras, and Dalziell has heard them mimicking the wing beats of small birds jetting through the forest understory. Up to 80 percent of a lyrebird’s song can consist of such mimicry, according to Dalziell, and “males imitate most often during the breeding season, particularly when females are fertile, so in this species there is strong evidence that for males mimicry is sexually selected.”
The females aren’t just looking for the best crooner, but also the best dancer and the best-dressed. So, basically, the avian opposite of me. This is where the lyrebird’s sexual dimorphism — the often dramatically different body types between females and males of a species, like in peafowl — becomes abundantly clear.
“Males have elaborate plumage, dance displays, and songs, while females are visually cryptic and a lot quieter,” said Dalziell. “Females are very independent: They defend their own territory and care for the young all by themselves (leaving males a lot of time to prance about).”
And prance about they do, in fairly remarkable fashion. During the breeding season, males clear space and build several round mounds of dirt in the forest, which they will boldly defend from other males (hey, it’s not like mounds of dirt just grow on trees). When a female takes an interest, the male will approach her with his magnificent tail slung over his head, then back up to one of the mounds.
If she follows, she’s treated to one of the more bizarre mating rituals on the planet, which you can watch below. “During these sexual displays,” said Dalziell, “male superb lyrebirds coordinate song with dance so that each different song is accompanied by a unique choreography, creating a display of a level of sophistication previously known only in humans.”
This is an extremely structured performance that Dalziell breaks into four parts, A through D. The first bit is “a laser gun-like song accompanied by a side-step, followed by a middle section of two alternating songs (B and C), followed by a ‘recapitulation’ of song A before a ‘coda’ of song D.” It’s seriously epic, like, Led Zeppelin at the Royal Albert Hall in 1970 epic.
So just as humans “waltz” to waltz music and “salsa” to salsa music, Dalziell says, “so lyrebirds step sideways with their tail spread out like a veil to song A (which sounds like a 1980s video-arcade game), but jump and flap their wings with their tail in a mohawk position while singing song C (a quiet song that sounds like ‘plinkety-plinkety-plinkety’).”
Only the fittest males, with the most impressive feathers and songs and dances, are allowed to mate and pass on their genes. This will ideally produce equally, if not more, incredible attributes in their offspring. “All females need from males is sperm,” said Dalziell, “and we know from other species of birds that this scenario can lead to intense competition among males for access to females, sometimes resulting in elaborate attempts to impress females.”
Darwin’s idea that females can drive evolution in this way wasn’t exactly popular with his critics (of which there were more than a few) in the 19th century. Not only was it preposterous for female humans to — heaven forbid — make choices, but the same went for all female creatures, even dogs and cats and stuff. But such selection is how the males and females of a given species will physically diverge over countless generations when faced with an abundance of competition.
Interestingly, though, elsewhere in nature the near lack of competition will produce the same effect, only in the sexual reverse. Take, for instance, the deep sea anglerfish, whose fearsome, gargantuan females positively dwarf males, which bite and fuse to the ladies to serve as a ready supply of sperm for the rest of their miserable lives.
Read more at Wired Science
Feb 6, 2014
Bumblebees Can Fly Higher Than Mount Everest
Bumblebees cannot survive the freezing conditions of Mt. Everest's peak. But researchers based at the University of California, Berkley simulated the low oxygen and low air density conditions of such high elevations to determine the limits of the bumblebee's flight capacity, and found the bees were capable of staying afloat at remarkably inhospitable elevations.
The team traveled to a mountain range in western China and collected six male bumblebees of the species Bombus impetuosus at about 10,660 feet (3,250 meters). The species is considered alpine, because it lives at alpine elevations, but it doesn't differ very much from similar species that live closer to sea level.
The researchers placed the bees in clear, sealed boxes and experimentally adjusted the oxygen levels and air density using a hand pump to simulate increasing elevation, while keeping temperature constant.
All of the bees were capable of flying in conditions equivalent to 13,000 feet (4,000 m), and some even made it past 30,000 feet (9,000 m) — the height of the peak of Mount Everest — the team reported Tuesday (Feb. 4) in the journal Biology Letters.
The team used a video camera to study how wing beat patterns changed to compensate for the thinner air and lower oxygen concentrations of high elevations, hypothesizing that the bees would either need to beat their wings faster or swoop them wider to keep their bodies afloat. The researchers found that, instead of beating their wings faster, the bees increased the angle at which they extended their wings with each beat, reaching closer to their heads and abdomens each time. This action increased the amount of air that they swooped, helping to boost their bodies up.
The findings suggest that bumblebees are not limited by flying capacity when searching for places to settle their colonies, but rather by something else, such as the availability of the flower nectar they feed on, study lead author Michael Dillon, who now works at the University of Wyoming, told Live Science. This could bode well for alpine bumblebees in the future, Dillon said, as climate change may force animals up to higher elevations than they once inhabited due to warming conditions at lower elevations.
Read more at Discovery News
Dwarf Whales, Twin-Tusked Walrus Once Swam West Coast
Walruses with short, twin tusks lounged on the beaches. Dwarf baleen whales, relatives of blue whales, filtered tiny creatures from the sea water. A dentally-deranged porpoise with a “chin” longer than its upper jaw shared the sea with the dwarf whales.
Primitive forms of porpoise and a dolphin related to the extinct Chinese river dolphin also lived in the region.
Along with the strange extinct beasts, modern-type species also dwelt in the region, including northern fur seals and right whales, during the late Miocene and Pliocene Epochs, which ended approximately 2.5 million years ago.
Robert Boessenecker, geology doctoral student at the university of Otago, recently published a description of the fossilized remains of the ancient northern Pacific marine animals in the journal Geodiversitas.
“The mix of marine mammals I ended up uncovering was almost completely different to that found in the North Pacific today, and to anywhere else at that time,” Boessenecker said in a press release. “At the same time as this eclectic mix of ancient and modern-type marine mammals was living together, the marine mammal fauna in the North Atlantic and Southern Ocean were already in the forms we find today.”
Read more at Discovery News
New Deep Diving Whale Discovered
The first finding of Mesoplodon hotaula came in 1963 when a 4.5 meter-long (15-foot) female washed up on the beach of Sri Lanka. Originally, the animal was described as a new species, but taxonomists later argued that the animal belonged to an already known variety, the ginko-toothed whale (Mesoplodon ginkgodens).
Since then, corpses of the whale were found on Kiribati, Palmyra Atoll, the Maldives, and the Seychelles. Genetic analysis of the whales and examination of their physical characteristics have now confirmed that Mesoplodon hotaula deserves classification as a distinct species of beaked whale. The journal Marine Mammal Science published the description of the resurrected species.
The animals swim in the deep waters off the continental shelves. They rank among Earth’s champions divers. In the Journal of Experimental Biology, scientists recorded one species, Cuvier’s beaked whale, diving to 1,888 meters (6,194 feet) and staying down for 85 minutes.
Read more at Discovery News
'Missing' Evolutionary Link for Compact Galaxies Found
My first astronomy professor put it this way: Imagine that you are part of an alien race, come down to Earth to study humanity. But, you’ve only got a few minutes to fly around the world and collect your data. How might you try and understand the life cycle of a human being? You’d have lots of pictures of small people, some so small to be almost helpless. Then there are lots of big people, too. People come in all shapes, sizes, and colors. But with that snapshot of humanity, you have to piece together the life stages of a human.
It is like this with galaxies in the Universe. We see big galaxies and small galaxies, spirals and ellipticals and irregular galaxies, too. We’ve had to put together the history of these galaxies as best we can without actually having the millions and billions of years to watch them grow up. Sometimes we get it dead wrong, as in the early 20th century it was thought that elliptical galaxies can eventually flatten out to become disks and spirals. We now know that larger galaxies are built in the mergers of smaller galaxies, but even in that paradigm there is room for diversity.
This method of galaxy building takes quite a bit of time, so you only expect to see larger galaxies nearby but not far away due to lookback time. However, some galaxies just won’t fit that mold. Some seem to defy a simple explanation.
In order to have these in existence, there must have been an incredibly powerful galaxy-building epoch even earlier, at redshifts 3 to 6, or 1 to 2 billion years after the Big Bang. Such galaxies would be full of dust and gas that would obscure their optical light, as well as being redshifted to longer wavelengths by their distance.
Such a population of galaxies has finally been uncovered and categorized by a group of astronomers led by Sune Toft, of the DARK Cosmology Center at the Niels Bohr Institute, University of Copenhagen. In a paper that contains data from many telescopes around the world and in space — including Hubble, Spitzer, Herschel, Keck, the Very Large Array, the Sub-Millimeter Array, and many more — they characterize the sample of submillimeter-emitting gas-rich galaxies that exist in the early Universe and find that it has just the right characteristics to merge and make the giant ellipticals that are “red and dead” 10 billion years ago, and even more so today.
Read more at Discovery News
Feb 5, 2014
Bees Have a Sweet Claw (Not Tooth)
Honeybees love sugar-rich nectar produced by plants, and one of the main ways they detect it is with claws on their front legs, according to a new study.
The research, published in the journal Frontiers in Behavioral Neuroscience, reveals how that works, including what happens if a bee dips one clawed leg into sugar, while another is dipped into salty water.
The tasting happens via sensilla, which are hair-like structures on the bee’s body that contain receptor nerve cells. These cells, in turn, are sensitive to particular substances, such as the bee buzz-inducing sugar.
In honeybees, the sensilla are on their little clawed legs, on their mouths, and on their antenna. With all of that potential for tasting, Gabriela de Brito Sanchez of the University of Toulouse and her colleagues wondered how the system came together.
She and her team studied hundreds of honeybees, observing what happened when sugar, bitter and salty solutions were applied to the claws (technically known as tarsomeres) of their forelegs. (This drawing allows you to see one by itself in detail.) They wanted to see if the bees would stick out their tongues- indicating something yummy is around to lap up- or if they would retract their tongues, as if to say, “Yuck.”
Everything went as planned, with the bees extending their tongue out when their claws “tasted” sugar, and doing just the opposite in the presence of bitter and salty substances.
“Honeybees rely on their color vision, memory, and sense of smell and taste to find nectar and pollen in the ever-changing environment around the colony,” co-author Martin Giurfa of the University of Toulouse said in a press release.
He continued: “The high sensitivity to salts of the tarsomeres and to sugar of the tarsal claws is impressive, given that each tarsus has fewer sensilla than the other sense organs. The claw’s sense of taste allows workers to detect nectar immediately when they land on flowers. Also, bees hovering over water ponds can promptly detect the presence of salts in water through the tarsomeres of their hanging legs.”
Read more at Discovery News
The research, published in the journal Frontiers in Behavioral Neuroscience, reveals how that works, including what happens if a bee dips one clawed leg into sugar, while another is dipped into salty water.
The tasting happens via sensilla, which are hair-like structures on the bee’s body that contain receptor nerve cells. These cells, in turn, are sensitive to particular substances, such as the bee buzz-inducing sugar.
In honeybees, the sensilla are on their little clawed legs, on their mouths, and on their antenna. With all of that potential for tasting, Gabriela de Brito Sanchez of the University of Toulouse and her colleagues wondered how the system came together.
She and her team studied hundreds of honeybees, observing what happened when sugar, bitter and salty solutions were applied to the claws (technically known as tarsomeres) of their forelegs. (This drawing allows you to see one by itself in detail.) They wanted to see if the bees would stick out their tongues- indicating something yummy is around to lap up- or if they would retract their tongues, as if to say, “Yuck.”
Everything went as planned, with the bees extending their tongue out when their claws “tasted” sugar, and doing just the opposite in the presence of bitter and salty substances.
“Honeybees rely on their color vision, memory, and sense of smell and taste to find nectar and pollen in the ever-changing environment around the colony,” co-author Martin Giurfa of the University of Toulouse said in a press release.
He continued: “The high sensitivity to salts of the tarsomeres and to sugar of the tarsal claws is impressive, given that each tarsus has fewer sensilla than the other sense organs. The claw’s sense of taste allows workers to detect nectar immediately when they land on flowers. Also, bees hovering over water ponds can promptly detect the presence of salts in water through the tarsomeres of their hanging legs.”
Read more at Discovery News
Bones of Father of Europe Found
Bones from Charlemagne's golden casket in Aachen Cathedral in Germany likely do belong to the warrior-king, say Swiss and German scientists who have studied the remains for 26 years.
"It might appear as an obvious conclusion but it isn't. Charlemagne was exhumed and reburied many times with parts of his body given away as relics, so identifying his skeleton is not an easy task," Frank Rühli, Head of the Center for Evolutionary Medicine at the University of Zurich in Switzerland, told Discovery News.
Rühli and colleagues announced the results of their research last week, 1,200 years after Charlemagne's death.
"The bones appear to belong to a single individual, an old and rather tall man. This matches contemporary descriptions of Charlemagne," Rühli said.
Charlemagne managed to forge the first empire in Europe after the demise of the Roman Empire. He died, possibly of pleurisy, after having ruled as Emperor for just over 13 years. Buried in the German Cathedral the same day as his death, on Jan. 18, 814, the father of Europe has not really rested in peace.
His tomb was first opened by the Emperor Otto III in the year 1000. According to contemporary chronicles, as Otto entered the underground chamber, he was struck by the vision of Charlemagne seated upon a throne, wearing a golden crown and holding a scepter, his fingernails sticking out the gloves.
"He had not lost any of his members to decay, except only the tip of his nose. Emperor Otto replaced this with gold, took a tooth from Charles's mouth, walled up the entrance to the chamber and withdrew," the Chronicle of Novalesia, written about 1026, reported.
In 1165, Frederick I, also known as Barbarossa, re-opened the tomb, displayed the remains as holy relics, then buried Charles in a marble sarcophagus beneath the floor of the cathedral. Fifty years later, Frederick II re-interred him in a casket made of gold and silver.
In 1349, some of Charlemagne's bones were removed and kept as relics by Holy Roman Emperor Charles IV. After five undisturbed centuries, the founder of the Holy Roman Empire was exhumed again in 1861 for research purposes.
Scientists reconstructed the skeletal remains and came to understand what may have been behind the emperor's names: Charlemagne or Carolus Magnus (meaning "Charles the Great" as well as "Charles the Big"). His skeleton suggested he was surprisingly tall for his time.
In 1988, scientists secretly opened his sarcophagus one more time to reveal 94 bones and bone fragments. The researchers also discovered bones in a golden bust that were believed to belong to the famous leader.
More recently, in 2010, Church authorities made available to Rühli and colleagues the left tibia from the Shrine.
Read more at Discovery News
"It might appear as an obvious conclusion but it isn't. Charlemagne was exhumed and reburied many times with parts of his body given away as relics, so identifying his skeleton is not an easy task," Frank Rühli, Head of the Center for Evolutionary Medicine at the University of Zurich in Switzerland, told Discovery News.
Rühli and colleagues announced the results of their research last week, 1,200 years after Charlemagne's death.
"The bones appear to belong to a single individual, an old and rather tall man. This matches contemporary descriptions of Charlemagne," Rühli said.
Charlemagne managed to forge the first empire in Europe after the demise of the Roman Empire. He died, possibly of pleurisy, after having ruled as Emperor for just over 13 years. Buried in the German Cathedral the same day as his death, on Jan. 18, 814, the father of Europe has not really rested in peace.
His tomb was first opened by the Emperor Otto III in the year 1000. According to contemporary chronicles, as Otto entered the underground chamber, he was struck by the vision of Charlemagne seated upon a throne, wearing a golden crown and holding a scepter, his fingernails sticking out the gloves.
"He had not lost any of his members to decay, except only the tip of his nose. Emperor Otto replaced this with gold, took a tooth from Charles's mouth, walled up the entrance to the chamber and withdrew," the Chronicle of Novalesia, written about 1026, reported.
In 1165, Frederick I, also known as Barbarossa, re-opened the tomb, displayed the remains as holy relics, then buried Charles in a marble sarcophagus beneath the floor of the cathedral. Fifty years later, Frederick II re-interred him in a casket made of gold and silver.
In 1349, some of Charlemagne's bones were removed and kept as relics by Holy Roman Emperor Charles IV. After five undisturbed centuries, the founder of the Holy Roman Empire was exhumed again in 1861 for research purposes.
Scientists reconstructed the skeletal remains and came to understand what may have been behind the emperor's names: Charlemagne or Carolus Magnus (meaning "Charles the Great" as well as "Charles the Big"). His skeleton suggested he was surprisingly tall for his time.
In 1988, scientists secretly opened his sarcophagus one more time to reveal 94 bones and bone fragments. The researchers also discovered bones in a golden bust that were believed to belong to the famous leader.
More recently, in 2010, Church authorities made available to Rühli and colleagues the left tibia from the Shrine.
Read more at Discovery News
How Memory Rewrites the Past
Do you remember what your mom looked like when you were 4?
Are you sure?
A study published today in the Journal of Neuroscience sheds new light on when memories remain stable and when they get overwritten with new information.
Lead author Donna Jo Bridge, a postdoctoral fellow in medical social sciences at Northwestern University Feinberg School of Medicine, and colleagues guided 17 participants through an experiment involving remembering where objects were placed on a computer screen with different backgrounds.
Participants were asked to try to remember where an object was on the original background and place it in the same spot on a new screen. Time after time, they got it wrong.
Then, when they were shown the object in three different locations on the original screen and asked to place it where they first saw it, they couldn't do that, either. They put the object where they themselves had placed it.
But, when researchers changed the experiment slightly, results improved: Researchers told the participants to put the object in a new location -- NOT the original spot. Somehow, this triggered the subjects to remember the original location.
That's an important distinction, Bridge said, in cases when you want to preserve original memories. Somehow, the hippocampus (an area of the brain critically important to memory) is deciding what's important and either building on the original memory with new information or modifying the original memory.
The participants recalled the original location, only in context of being told not to place the object there -- when a layer of instruction about that original spot was added.
"The most important function of memory is to guide future decisions and inform the present," Bridge said. "We know that memory is adaptive, changing with new circumstances, and we think it's a good thing that it doesn't stay crystallized."
Think about an ex-boyfriend or girlfriend, Bridge said. If you remembered all the positives about that person, it would be hard to move on and be happy. Instead, our memory may help us get past breakups by revising our history with the person.
The MRI scan used in the study shows that the hippocampus plays an important role both in when memories stay stable and when they're more likely to change, said Tali Sharot, principal investigator at the Affective Brain Lab at the University College London, who was not involved in the study.
Read more at Discovery News
Weird Asteroid Itokawa Has a Dual Personality
We care about how asteroids are made, in large part because if one were aiming to smash into us, we’d like to know what we can do about it. The structure of asteroids is also a matter of scientific curiosity, as it tells us a bit about the formation and evolution in our solar system. That is why it is so exciting that the most recent very delicate observations of asteroid 25143 Itokawa reveal some of its secrets.
25143 Itokawa is a relatively small near-Earth asteroid that was visited by the Japanese Habayusa spacecraft in 2005. It has also been monitored by Stephen Lowry of the University of Kent and his colleagues over a twelve year span with the 3.58 meter New Technology Telescope in La Silla, Chile. In that time span, Itokawa has made five near approaches to Earth.
By carefully studying the brightness change of the asteroid over time, Lowry and his colleagues were able to very accurately measure the change in the spin of the asteroid at different points in its orbit. These changes are incredibly minute — a 0.045 second change per year — and are caused by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect.
This multi-nomenclatured YORP effect describes how an asteroid absorbs and re-emits heat from the sun. Exactly how that absorption and re-emission happens depends on the asteroid’s size, shape, and composition. With the up-close observations from the Habayusa spacecraft, the astronomers could model the shape and thermal properties of the asteroid. What they found is that it’s not one simple object.
The asteroid appears to be composed of two different types of material that have been “mashed” together to form one peanut-shaped body. Though it has been suspected that many asteroids are collections of smaller bodies coming together from their mutual gravity (in a “rubble pile”), this is the first time we’ve actually seen it borne out of data.
Using the data and models, Lowry and his colleagues found that the center of mass of the asteroid was 21 meters away from where it was expected to be. This can occur if the two sides of the asteroid each have different densities, as demonstrated in the graphic at the top. One piece has almost twice the density of the other! This gives astronomers a clue into binary asteroid scenarios and the real composition and make-up of near Earth asteroids.
Read more at Discovery News
25143 Itokawa is a relatively small near-Earth asteroid that was visited by the Japanese Habayusa spacecraft in 2005. It has also been monitored by Stephen Lowry of the University of Kent and his colleagues over a twelve year span with the 3.58 meter New Technology Telescope in La Silla, Chile. In that time span, Itokawa has made five near approaches to Earth.
By carefully studying the brightness change of the asteroid over time, Lowry and his colleagues were able to very accurately measure the change in the spin of the asteroid at different points in its orbit. These changes are incredibly minute — a 0.045 second change per year — and are caused by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect.
This multi-nomenclatured YORP effect describes how an asteroid absorbs and re-emits heat from the sun. Exactly how that absorption and re-emission happens depends on the asteroid’s size, shape, and composition. With the up-close observations from the Habayusa spacecraft, the astronomers could model the shape and thermal properties of the asteroid. What they found is that it’s not one simple object.
The asteroid appears to be composed of two different types of material that have been “mashed” together to form one peanut-shaped body. Though it has been suspected that many asteroids are collections of smaller bodies coming together from their mutual gravity (in a “rubble pile”), this is the first time we’ve actually seen it borne out of data.
Using the data and models, Lowry and his colleagues found that the center of mass of the asteroid was 21 meters away from where it was expected to be. This can occur if the two sides of the asteroid each have different densities, as demonstrated in the graphic at the top. One piece has almost twice the density of the other! This gives astronomers a clue into binary asteroid scenarios and the real composition and make-up of near Earth asteroids.
Read more at Discovery News
Feb 4, 2014
Ultra-Sharp Images of Cells, Made Using Fluorescent DNA
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| This ultrasharp image uses a new method to simultaneously resolve microtubules (green), mitochondria (purple), Golgi apparatus (red), and peroxisomes (yellow) from a single human cell. The scale bar is 5 microns. |
By attaching colored, fluorescent tags to short stretches of DNA, a team at Harvard University’s Wyss Institute for Biologically Inspired Engineering has developed an imaging system that can resolve structures less than 10 nanometers apart.
Inside each cell in your body, a startling array of molecular machinery is whirring and humming, from the tiny factories that assemble proteins, to the furnaces that produce energy, to the skeletal fibers that help cells move and maintain their shape. Watching how these myriad operations work together — and how the system breaks down – has been both a research goal and a technology bane.
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| Scientists illustrated the new technique using synthetic DNA nanostructures that resemble numbers. This is a composite of 10 images. |
But these technologies were limited in their ability to resolve structures more than 200 nanometers apart, because light cannot illuminate anything smaller than its own wavelength.
Recently, the Wyss team figured out how to overcome this limit – inexpensively, and using normal light microscopes rather than electron or photon imaging. The method takes advantage of DNA’s ability to bind to complementary versions of itself – kind of like a molecular handshake. The team begins with short, specific sequences of DNA. These sequences are then attached to molecules, called antibodies, that recognize specific proteins or cellular structures. So, when the antibodies find and bind to their protein targets – say, the proteins making up the cell’s skeleton — they’re carrying along their DNA flags.
Next, the team introduces free-floating, complementary DNA sequences to the cell – sequences that carry a fluorescent tag. These are the sequences that will recognize and bind to the flags flown by the antibodies attached to the cell’s skeletal proteins. When these introduced DNA sequences find their partners and shake hands, the binding activates those fluorescent tags, causing them to blink on and off. By tweaking and recording this blinking, the team is able to resolve the positions of particular molecules – even those that are as close as 10 nanometers apart.
Read more at Wired Science
Animal 'Pompeii' Captured Dinos, Mammals, Birds in Death
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| Photos show the typical entombing poses of the Jehol terrestrial vertebrate fossils (a: Psittacosaurus; b-c: Confuciusornis). This boxer-like pose is typical of victims of pyroclastic density currents, resulting from postmortem tendons and muscles shortening. |
Fossils of early mammals, dinosaurs, pterosaurs, lizards, salamanders, birds, turtles, frogs, fishes and other freshwater and land animals have been found so well preserved in the rocks of the Yixian and Jiufotang rocks of southeastern Mongolia that even muscles, skin and scales are sometimes discernible after 130 million years.
The secret to that detailed preservation of what is called the Jehol Biota is that the animals were literally baked to a crisp by volcanic eruptions as they were buried.
"Fresh, hot, dry, acid volcanic ash promoted burning, charring or mummifying of soft tissues, which, as a result, became more resistant to decay and better preserved," explains Baoyu Jiang of Nanjing University who along with colleagues published their discovery in the Feb. 4 issue of the journal Nature Communication.
"The nature of the events and the mechanisms behind the exceptional preservation of the fossils, however, are poorly understood."
A closer look at the rocks themselves, along with the massive collection of animals that appear to have died at once, points to a sudden eruption of the kind that sends a tower of hot ash into the sky, which then collapses and creates a murderous landslide of volcanic ash that burns as it buries everything in its path.
Even the poses of the animals match what would be expected if they were killed suddenly, like the unfortunate Pompeii residents who died in the Mount Vesuvius eruption in 79 A.D.
"These Early Cretaceous strata in northeast China are riddled with volcanic debris, so the presence of some mass death assemblages of fossils in pyroclastic flows comes as no surprise," said paleontologist Spencer Lucas of the New Mexico Museum of Natural History.
"Sudden death and rapid burial by volcaniclastic processes certainly accounts for some of the exceptional preservation seen in the Early Cretaceous fossil assemblages in NE China, which represent one of the most remarkable records of life on land during that interval of geologic time."
Read more at Discovery News
Mysterious Iceland Pillars Not Formed by Fighting Trolls
Mysterious basalt pillars in Iceland had long been ascribed to a fight between two trolls who had thrown lumps of rock at one another. But scientists have now debunked this local lore, saying the pillars were in fact formed by an unusual geological process.
The pillars, numbering about 40 in all and measuring up to about 8.2 feet tall and 5 feet wide, are dispersed around Skaelingar Valley, where a tributary flows into the Skafta River near Iceland's southern coast. It turns out these formations were not the projectiles thrown by trolls, but were likely the result of unusual lava-water interactions on land.
Looking at the odd collection of pillars, one can imagine how the angry troll explanation may have taken root.
"It's almost an otherworldly experience to see these things for the first time because they're just not very common features," said Tracy Gregg, a volcanologist at the University at Buffalo, in a press release.
Gregg, along with graduate student Kenneth Christle, explain the hollow pillars likely formed around vertical columns of steam and superheated water venting through lava as it flowed over ground.
Gregg said the pillars resemble so-called lava trees in Hawaii, which are hollow basalt cylinders that formed as lava flowed through a forest and cooled when coming in contact with tree trunks. The tree trunks were burned up in the process, leaving the cylinders behind.
"We know that that's not what [the pillars] are in Iceland because when this lava flow erupted, there were no trees in Iceland," Gregg said.
At the Iceland location, Gregg and Christle calculated that the Skafta River Gorge became blocked during the Laki eruption of 1783. This caused the lava that had been flowing through the gorge to back up into smaller tributary valleys like the Skaelingar. As blobs of molten rock pushed up the valley, the ground surface heated up and steam and hot water rising through small gaps between the molten rock formed geysers. Lava then poured past these geysers, quickly cooled and solidified to form the pillars.
Once the jam in the main gorge broke free, the still-molten portion of lava flowed back down the valley, leaving behind the hardened pillars. The whole process likely happened in a matter of just a few hours to a few days. It was also likely a somewhat calm process, Gregg explained, since the pillars were left in tact.
Read more at Discovery News
The Ancient Meandering Rivers of Mars
Unfortunately, because Mars is so small and lacks a hefty global magnetic field to prevent its atmosphere from being ripped into space, the planet lost the majority of its atmosphere and its once-dynamic water cycle froze into its crust. However, to this day, eerie visual hints of the ancient Martian water can be seen from orbit.
With the help of the awesome High-Resolution Imaging Science Experiment (HiRISE) camera aboard NASA’s Mars Reconnaissance Orbiter, ancient meandering riverbeds that used to carve into the Martian terrain have been imaged with beautiful clarity. However, these riverbeds are now twisted ridges, created after eons of erosion processes.
“These ridges are thought to be old river channels, but wind erosion has created inverted topography,” writes Alfred McEwen, lead scientist of the HiRISE mission and geologist at the University of Arizona. “What was low (the channel bottoms) was more resistant to erosion, so now it is relatively high.”
When rivers flow, their beds accumulate sediment that becomes compressed and resistant to erosion. When they run dry, an empty trough remains. After millions of years, the surrounding landscape becomes eroded by Mars’ persistent winds, slowly wearing it away. However, the ancient riverbed erodes far more slowly (owed to it being “erosion-hardened” by the ancient flowing water), and the surrounding landscape erodes away deeper than the bottom of the ancient riverbed, creating an inverted ridge.
Interestingly, many of the features we find in terrestrial rivers can be seen in these Martian meanders.
In the image above, some extreme meanders can be seen. On Earth, at the most extreme bends in some meandering rivers, the looping beds can be “cut off” as the river relentlessly erodes its edges, eventually breaking through and leaving an oxbow lake (see the photograph below). It appears similar formations were likely created on Mars.
Read more at Discovery News
Feb 3, 2014
Baby Stars Erupt to Life in Trifid Nebula
The Trifid Nebula is located around 5,000 light-years away in the constellation Sagittarius and consists of a rare combination of an open cluster of stars, an emission nebula, a reflection nebula and a dark nebula -- the latter of which creates the dark lanes of material in the main portion to create the famous 3-lobe trifid pattern.
However, in this WISE view, the dark nebula, which consists of obscuring dust in visible wavelengths, glows bright in infrared wavelengths, creating an inverted view of the Trifid Nebula when compared with visible light imagery, as seen here:
The Trifid is alive with star formation; violent stellar winds erupt from baby stars creating large voids in the interstellar material. With the help of WISE, astronomers can dissect the region. The blue stars are comparatively old stars that lie between the nebula and Earth. The reddish region above the Trifid Nebula is dust and gas being heated by baby stars and the entire region is surrounded by the green haze of hydrogen gas.
Read more at Discovery News
Starfish Ripped Apart by Mysterious Disease
Starfish limbs wrench themselves from their bodies when suffering from a mysterious new disease. Biologists don’t know what causes the affliction or how to stop it. And the loss of tens of thousands of starfish, also known as sea stars, threatens to unbalance the ecosystems of the North American coasts.
Last summer, scientists first observed the disease at Starfish Point on Washington’s Olympic Peninsula, reported KCTS’s EarthFix. The disease also decimated starfish populations in Vancouver Harbor and Howe Sound in Canada last summer, according to the Vancouver Aquarium. Now, the disease has been spotted in patches from southern California to Alaska and on the eastern coasts of the United States.
Biologists named the mysterious illness, “starfish-wasting syndrome,” but haven’t devised a way to stop it, nor have they even determined where the disease originated, reported KCTS.
When the disease hits, starfish may develop lesions on their skin. Then their arms writhe and contort until the appendages break away from the body. Normally, starfish can regenerate lost arms, but not after the disease strikes. Instead, the lost arms allow the starfish guts to leak out from their central body cavity, killing the marine predator.
First, the sunflower star, Pycnopodia helianthoides, fell to the disease, then the purple sea star, Pisaster ochraceus. Now, at least 12 species suffer from starfish wasting syndrome.
Read more at Discovery News
Did Alien Life Evolve Just After the Big Bang?
Earthlings may be extreme latecomers to a universe full of life, with alien microbes possibly teeming on exoplanets beginning just 15 million years after the Big Bang, new research suggests.
Traditionally, astrobiologists keen on solving the mystery of the origin of life in the universe look for planets in habitable zones around stars. Also known as Goldilocks zones, these regions are considered to be just the right distance away from stars for liquid water, a pre-requisite for life as we know it, to exist.
But even exoplanets that orbit far beyond the habitable zone may have been able to support life in the distant past, warmed by the relic radiation left over from the Big Bang that created the universe 13.8 billion years ago, says Harvard astrophysicist Abraham Loeb.
For comparison, the earliest evidence of life on Earth dates from 3.8 billion years ago, about 700 million years after our planet formed.
'Warm summer day'
Just after the Big Bang, the cosmos was a much hotter place. It was filled with sizzling plasma — superheated gas — that gradually cooled. The first light produced by this plasma is the cosmic microwave background radiation (CMB) that we observe today, which dates from about 389,000 years after the Big Bang.
Now the CMB is freezing cold — around minus 454 degrees Fahrenheit (minus 270 degrees Celsius; 3 degrees Kelvin). It cooled down gradually with the expansion of the universe, and at some point during the cooling process, for a brief period of seven million years or so, the temperature was just right for life to form — between 31 and 211 degrees Fahrenheit (0 and 100 degrees Celsius; 273 and 373 degrees Kelvin).
It is the CMB's heat that would have allowed water to remain liquid on ancient exoplanets, Loeb said.
"When the universe was 15 million years old, the cosmic microwave background had a temperature of a warm summer day on Earth," he said. "If rocky planets existed at that epoch, then the CMB could have kept their surface warm even if they did not reside in the habitable zone around their parent star."
But the question is whether planets — and especially rocky planets — could already have formed at that early epoch.
According to the standard cosmological model, the very first stars started to form out of hydrogen and helium tens of millions of years after the Big Bang. No heavy elements, which are necessary for planet formation, were around yet.
But Loeb says that rare "islands" packed with denser matter may have existed in the early universe, and massive, short-lived stars could have formed in them earlier than expected. Explosions of these stars could have seeded the cosmos with heavy elements, and the very first rocky planets would have been born.
These first planets would have been bathed in the warm CMB radiation, and thus, Loeb argues, it would have been possible for them to have liquid water on their surface for several million years.
Loeb says that one way to test his theory is by searching in our Milky Way galaxy for planets around stars with almost no heavy elements. Such stars would be the nearby analogues of the early planets in the nascent universe.
Just after the Big Bang, the cosmos was a much hotter place. It was filled with sizzling plasma -- superheated gas -- that gradually cooled. The first light produced by this plasma is the cosmic microwave background radiation (CMB) that we observe today, which dates from about 389,000 years after the Big Bang.
Now the CMB is freezing cold — around minus 454 degrees Fahrenheit (minus 270 degrees Celsius; 3 degrees Kelvin). It cooled down gradually with the expansion of the universe, and at some point during the cooling process, for a brief period of seven million years or so, the temperature was just right for life to form — between 31 and 211 degrees Fahrenheit (0 and 100 degrees Celsius; 273 and 373 degrees Kelvin).
It's the CMB's heat that would have allowed water to remain liquid on ancient exoplanets, Loeb said.
"When the universe was 15 million years old, the cosmic microwave background had a temperature of a warm summer day on Earth," he said. "If rocky planets existed at that epoch, then the CMB could have kept their surface warm even if they did not reside in the habitable zone around their parent star."
But the question is whether planets -- and especially rocky planets -- could already have formed at that early epoch.
According to the standard cosmological model, the very first stars started to form out of hydrogen and helium tens of millions of years after the Big Bang. No heavy elements, which are necessary for planet formation, were around yet.
But Loeb says rare "islands" packed with denser matter may have existed in the early universe, and massive, short-lived stars could have formed in them earlier than expected. Explosions of these stars could have seeded the cosmos with heavy elements, and the very first rocky planets would have been born.
These first planets would have been bathed in the warm CMB radiation, and thus, Loeb argues, it would have been possible for them to have liquid water on their surface for several million years.
Loeb says that one way to test his theory is by searching in our Milky Way galaxy for planets around stars with almost no heavy elements. Such stars would be the nearby analogues of the early planets in the nascent universe.
Constant or not?
Based on his findings, Loeb also challenges the idea in cosmology known as the anthropic principle. This concept attempts to explain the values of fundamental parameters by arguing that humans could not have existed in a universe where these parameters were any different than they are.
So while there might be many regions in a bigger "multiverse" where the values of these parameters vary, intelligent beings are supposed to exist only in a universe like ours, where these values are exquisitely tuned for life.
For instance, Albert Einstein identified a fundamental parameter, dubbed the cosmological constant, in his theory of gravity. This constant is now thought to account for the accelerating expansion of the universe.
Also known as dark energy, this constant can be interpreted as the energy density of the vacuum, one of the fundamental parameters of our universe.
Anthropic reasoning suggests that there might be different values for this parameter in different regions of the multiverse — but our universe has been set up with just the right cosmological constant to allow our existence and to enable us to observe the cosmos around us.
Read more at Discovery News
4,600-Year-Old Step Pyramid Uncovered in Egypt
The step pyramid, which once stood as high as 43 feet (13 meters), is one of seven so-called "provincial" pyramids built by either the pharaoh Huni (reign ca. 2635-2610 B.C.) or Snefru (reign ca. 2610-2590 B.C.). Over time, the step pyramid's stone blocks were pillaged, and the monument was exposed to weathering, so today, it's only about 16 feet (5 m) tall.
Scattered throughout central and southern Egypt, the provincial pyramids are located near major settlements, have no internal chambers and were not intended for burial. Six of the seven pyramids have almost identical dimensions, including the newly uncovered one at Edfu, which is about 60 x 61 feet (18.4 x 18.6 m).
The purpose of these seven pyramids is a mystery. They may have been used as symbolic monuments dedicated to the royal cult that affirmed the power of the king in the southern provinces.
"The similarities from one pyramid to the other are really amazing, and there is definitely a common plan," said Gregory Marouard, a research associate at the University of Chicago's Oriental Institute who led the work at the Edfu pyramid. On the east side of the newly uncovered pyramid, his team found the remains of an installation where food offerings appear to have been made — a discovery that is important for understanding this kind of pyramid since it provides clues as to what they were used for.
The team also found hieroglyphic graffiti incised on the outer faces of the pyramid. The inscriptions are located beside the remains of babies and children who were buried at the foot of the pyramid. The researchers think the inscriptions and burials date to long after the pyramid was built and that the structure was not originally intended as a burial place.
Initial results of the excavation were presented at a symposium held in Toronto recently by the Society for the Study of Egyptian Antiquities.
Uncovering the pyramid
Though scholars knew of the existence of the pyramid at Edfu, the structure had never been excavated before Marouard's team started work in 2010, he said in the study. His team found that the pyramid was covered by a thick layer of sand, modern waste and remains from the pillaging of its blocks.
It didn't look like a pyramid he said, and people in a nearby village even thought the structure was the tomb of a sheikh, a local Muslim saint. As the team went to work cleaning the monument, the ancient pyramid was revealed.
Built of sandstone blocks and clay mortar, it had been constructed in the form of a three-step pyramid. A core of blocks rises up vertically, with two layers of blocks beside it, on top of each other. This made the pyramid look like it had three steps. The style is similar to that of a step pyramid built by Djoser (reign ca. 2670-2640 B.C.), the pharaoh who constructed Egypt's first pyramid at the beginning of the third ancient Egyptian dynasty. The technique is close to that used at the Meidum pyramid, which was built by either Snefru or Huni and started out as a step pyramid before being turned into a true pyramid.
"The construction itself reflects a certain care and a real expertise in the mastery of stone construction, especially for the adjustment of the most important blocks," said Marouard in his paper. Marouard also noted that the pyramid was built directly on the bedrock and was constructed entirely with local raw materials. The quarry where the sandstone was extracted was discovered in 2011, and is located only about a half mile (800 m) north of the pyramid.
The growth of a modern-day cemetery and village poses a danger to the newly uncovered pyramid. In order to help prevent further looting, a fence was built around the structure, thanks to financial assistance from the American Research Center in Egypt and the National Endowment for the Humanities.
Graffiti and child burials
As the team uncovered the pyramid, they found that inscriptions had been incised on its outer faces. They include hieroglyphic depictions of a book roll, a seated man, a four-legged animal, a reed leaf and a bird.
"These are mostly private and rough inscriptions, and certainly dedicated to the child/babies' burials located right under these inscriptions at the foot of the pyramid," Marouard told Live Science in an email. One of the inscriptions appears to mean "head of the house" and may be a reference to the mother of a buried child.
Marouard said his team would be publishing these burials and images in more detail in the future.
A pyramid abandoned
The archaeologists found that by the time of the reign of Khufu (the pharaoh who built the Great Pyramid), ca. 2590-2563 B.C., the pyramid at Edfu had been abandoned, and offerings were no longer being made. This occurred less than 50 years after its construction, Marouard said.
This suggests the seven small pyramids stopped being used when work on the Great Pyramid began. It seems Khufu no longer thought there was a need to maintain a small pyramid at Edfu, or elsewhere in southern Egypt, Marouard said. Rather, Khufu focused all the resources on building the Great Pyramid at Giza, which is close to the Egyptian capital at Memphis, he added.
Khufu may have felt politically secure in southern Egypt and saw no need to maintain or build pyramids there, Marouard said in the email. The "center of gravity of Egypt was then at Memphis for many centuries — this region draining resources and manpower from the provinces, all regions being put to use for the large construction sites of funerary complexes."
Read more at Discovery News
Feb 2, 2014
Humans are more than clever apes? Don't make me laugh
Most qualities we think of as particularly 'human' can be seen elsewhere in the animal kingdom, thanks to evolution
Just how special do you think you are? How different do you think you are from other animals? Do you think of yourself as an animal or do you see yourself, and your fellow humans, as somehow set apart from the rest of the animal kingdom?
Most of us – and I would unashamedly label us as the sensible majority of the population – accept that evolution is the best explanation for the pattern of life that we observe on the planet, both living and fossilised. However much creationists bang on about evolution being "just a theory", it beautifully explains all the evidence we have to hand (and there's masses of that: anatomical, genetic, palaeontological, embryological), without a single piece of evidence having turned up that threatens to bring the whole edifice tumbling down around our ears.
So, I'm hoping you're a sensible sort of person and that you consider evolution to be as true as the spherical nature of the Earth, or the fact that the Earth orbits the sun and not vice versa. But just how comfortable are you with the idea of being a product of evolution? I think it's still, even among the most enlightened of us, really hard to come to terms with the idea that we are just another animal. A naked ape. The third chimpanzee, even. You have to admit, science has done a very good job at bringing us down a peg or two, at knocking us off the pedestal of our own construction. We can no longer view ourselves as a special creation, something created in the image of a deity and close to angels (whatever they are or look like). We can no longer see ourselves as the ultimate destination, as the pinnacle of evolution, either. Our species is just a tiny twig on the massive, dense tree of life. But that's so difficult to stomach!
Even people undertaking research into human evolution seem to consistently fall into the trap of imagining that humans are special, and unique in a whole host of ways. But each thing we point to as utterly unique often turns out, after closer inspection, to be something shared with other animals. Or if it is a real difference, it transpires that it's often one of degree and not an absolute difference. Of course, this makes a lot of sense, as we have common ancestry with other animals, and "humanness" didn't just appear, as a package, out of nothing; it was something that happened over time, vast expanses of time.
Various features that we consider to be definitively human arrived in a piecemeal fashion. It's only with hindsight that we can say that these features gradually accumulated to the point at which we have something recognisably human. Here are a few examples of things you might think are uniquely human, but aren't.
Having fingernails rather than claws – this is a general primate characteristic. Opposable thumbs – we like to think of these as particularly human, but a quick glance at other primates reveals that most of them have got these useful thumbs as well. Bipedalism – standing and walking around on two legs – is something else that we often think of as being uniquely human (among primates at least – obviously there are other bipedal animals: kangaroos, birds and a fair few dinosaurs spring to mind). But it's simply not true that we're the only bipedal primates. Gibbons walk around on two legs quite a bit. So do the larger apes. In fact, of all the great apes, orangs are the most bipedal. They don't walk around on the ground much – but they do walk in the trees. The difference is that we are habitually bipedal on the ground.
What about smiling and laughing? Wouldn't you have thought those might be uniquely human?
But all primates have what's called a "bared teeth" expression. This seems to mean different things in different species: in some macaques, it's a sign of submission, but in gelada baboons and chimpanzees, it's more appeasing and helps social bonding – in other words, it really does seem to be the equivalent of a human smile. The "bared teeth" expression in chimpanzees certainly looks similar to a smile: the corners of the mouth are pulled up, and the lips parted. Chimpanzees also have an open-mouthed "play-face" expression that is equivalent to our laughter. While filming a Horizon programme last year, I was lucky enough to get to play with a one-year-old bonobo (or pygmy chimpanzee) called Lopori, at Twycross zoo. And when I tickled her ribs, she giggled very much like a human baby, but breathily rather than noisily.
Read more at The Guardian
Just how special do you think you are? How different do you think you are from other animals? Do you think of yourself as an animal or do you see yourself, and your fellow humans, as somehow set apart from the rest of the animal kingdom?
Most of us – and I would unashamedly label us as the sensible majority of the population – accept that evolution is the best explanation for the pattern of life that we observe on the planet, both living and fossilised. However much creationists bang on about evolution being "just a theory", it beautifully explains all the evidence we have to hand (and there's masses of that: anatomical, genetic, palaeontological, embryological), without a single piece of evidence having turned up that threatens to bring the whole edifice tumbling down around our ears.
So, I'm hoping you're a sensible sort of person and that you consider evolution to be as true as the spherical nature of the Earth, or the fact that the Earth orbits the sun and not vice versa. But just how comfortable are you with the idea of being a product of evolution? I think it's still, even among the most enlightened of us, really hard to come to terms with the idea that we are just another animal. A naked ape. The third chimpanzee, even. You have to admit, science has done a very good job at bringing us down a peg or two, at knocking us off the pedestal of our own construction. We can no longer view ourselves as a special creation, something created in the image of a deity and close to angels (whatever they are or look like). We can no longer see ourselves as the ultimate destination, as the pinnacle of evolution, either. Our species is just a tiny twig on the massive, dense tree of life. But that's so difficult to stomach!
Even people undertaking research into human evolution seem to consistently fall into the trap of imagining that humans are special, and unique in a whole host of ways. But each thing we point to as utterly unique often turns out, after closer inspection, to be something shared with other animals. Or if it is a real difference, it transpires that it's often one of degree and not an absolute difference. Of course, this makes a lot of sense, as we have common ancestry with other animals, and "humanness" didn't just appear, as a package, out of nothing; it was something that happened over time, vast expanses of time.
Various features that we consider to be definitively human arrived in a piecemeal fashion. It's only with hindsight that we can say that these features gradually accumulated to the point at which we have something recognisably human. Here are a few examples of things you might think are uniquely human, but aren't.
Having fingernails rather than claws – this is a general primate characteristic. Opposable thumbs – we like to think of these as particularly human, but a quick glance at other primates reveals that most of them have got these useful thumbs as well. Bipedalism – standing and walking around on two legs – is something else that we often think of as being uniquely human (among primates at least – obviously there are other bipedal animals: kangaroos, birds and a fair few dinosaurs spring to mind). But it's simply not true that we're the only bipedal primates. Gibbons walk around on two legs quite a bit. So do the larger apes. In fact, of all the great apes, orangs are the most bipedal. They don't walk around on the ground much – but they do walk in the trees. The difference is that we are habitually bipedal on the ground.
What about smiling and laughing? Wouldn't you have thought those might be uniquely human?
But all primates have what's called a "bared teeth" expression. This seems to mean different things in different species: in some macaques, it's a sign of submission, but in gelada baboons and chimpanzees, it's more appeasing and helps social bonding – in other words, it really does seem to be the equivalent of a human smile. The "bared teeth" expression in chimpanzees certainly looks similar to a smile: the corners of the mouth are pulled up, and the lips parted. Chimpanzees also have an open-mouthed "play-face" expression that is equivalent to our laughter. While filming a Horizon programme last year, I was lucky enough to get to play with a one-year-old bonobo (or pygmy chimpanzee) called Lopori, at Twycross zoo. And when I tickled her ribs, she giggled very much like a human baby, but breathily rather than noisily.
Read more at The Guardian
Autistic brains create more information at rest, study show
Published at the end of December in Frontiers in Neuroinformatics, this study is a follow-up to the authors' prior finding that brain connections are different in autistic children. This paper determined that the differences account for the increased complexity within their brains.
"Our results suggest that autistic children are not interested in social interactions because their brains generate more information at rest, which we interpret as more introspection in line with early descriptions of the disorder," said Roberto Fernández Galán, PhD, senior author and associate professor of neurosciences at Case Western Reserve School of Medicine.
The authors quantified information as engineers normally do but instead of applying it to signals in electronic devices, they applied it to brain activity recorded with magnetoencephalography (MEG). They showed that autistic children's brains at rest generate more information than non-autistic children. This may explain their lack of interest in external stimuli, including interactions with other people.
The researchers also quantified interactions between brain regions, i.e., the brain's functional connectivity, and determined the inputs to the brain in the resting state allowing them to interpret the children's introspection level.
"This is a novel interpretation because it is a different attempt to understand the children's cognition by analyzing their brain activity," said José L. Pérez Velázquez, PhD, first author and professor of neuroscience at University of Toronto Institute of Medical Science and Department of Pediatrics, Brain and Behavior Center. "Measuring cognitive processes is not trivial; yet, our findings indicate that this can be done to some extent with well-established mathematical tools from physics and engineering."
This study provides quantitative support for the relatively new "Intense World Theory" of autism proposed by neuroscientists Henry and Kamila Markram of the Brain Mind Institute in Switzerland, which describes the disorder as the result of hyper-functioning neural circuitry, leading to a state of over-arousal. More generally, the work of Galán and Pérez Velázquez is an initial step in the investigation of how information generation in the brain relates to cognitive/psychological traits and will begin to frame neurophysiological data into psychological aspects. The team now aims to apply a similar approach to patients with schizophrenia.
From Science Daily
Making color: When two red photons make a blue photon
Here's a question: Can scientists generate any color of light? The answer is not really, but the invention of the laser in 1960 opened new doors for this endeavor. An early experiment injected high-power laser light through quartz and out popped a different color. This sparked the field of nonlinear optics and with it, a new method of color generation became possible: frequency conversion.
Not all crystals can perform this trick and only through careful fabrication of certain materials is frequency conversion possible. In a result published in Nature Communications, scientists demonstrate a new microstructure that does what's called second harmonic generation (SHG), where the output light has twice the frequency as the input. This new device is a factor of 1000 smaller than previous frequency converters.
You can't really get something from nothing here. Physics demands that both energy and momentum are conserved in the frequency-doubling process. The energy of light is directly related to its frequency through a fundamental constant, thus this conservation law is automatically satisfied. Two photons of fixed energy pass into the conversion crystal and the output photon has a frequency, thus energy, equal to their sum.
The challenging part is momentum conservation and achieving it takes careful engineering. This difficulty arises because light has an associated direction of travel. Materials bend and delay light, and how it occurs is very material dependent. Even more, different frequencies (colors) are bent and delayed differently by a given material. This is called dispersion and is perhaps most familiar as a rainbow, where the constituent colors of sunlight are separated.
Even with dispersion, some materials have naturally occurring refractive properties that allow momentum-matching, and thus frequency conversion. Until about 20 years ago, these materials were the only option for frequency conversion. In the 1990s, scientists began to tackle the momentum conservation issue using a technique called quasi-phase matching (QPM).
When a light wave enters and moves through a crystal its properties such as velocity are altered depending on its color. In the case of second-harmonic generation, the injection light strongly interacts with the medium and a second color, having twice the frequency, is generated. Due to dispersion, the second light wave will be delayed. In QPM, scientists vary the spacing and orientation between the internal crystal layers to compensate for the delay, such that momentum conservation between the injection and output light is conserved. This method of QPM is successful but can be difficult from a fabrication point-of-view. Moreover, miniaturizing their overall size for integration onto chips is limited. This is because the frequency conversion process depends on the physical length of the interaction medium, thus scaling down these types of crystals will lead to an inherent reduction in efficiency.
Now this team has demonstrated a new, arguably simpler way, to achieve QPM and thus frequency conversion. In the new design, gallium arsenide (GaAs) is fabricated into a micrometer-sized disk 'whispering gallery' cavity. Notably, GaAs has one of the largest second-harmonic frequency conversion constants measured. Previously, scientists have harnessed its extremely nonlinear properties through the layer-varying QPM method, leading to device sizes in the centimeter range. This new device is 1000 times smaller.
In the experiment, light from a tapered optical fiber is injected into the cavity. When light travels in a loop with the proper orientation, as opposed to a linear geometry, QPM, and therefore color conversion is achieved. This team skirts around the miniaturization problem because the light can interact many times with the medium by circulating around the disk, yet the overall size can remain small. Using a cavity also means that since the power builds up in the microdisk, less injection power can be used. Think of the architectural example of a whispering gallery -- wherein sound waves add together such that small input signals (whispers) can be heard. This resonant enhancement also happens for light trapped inside microdisk cavities.
NIST scientist and author Glenn Solomon continues, "Through a combination of microcavity engineering and nonlinear optics, we can create a very small frequency conversion device that could be more easily integrated onto optical chips."
Lead author Paulina Kuo, who is currently doing research at NIST in the Information Technology Laboratory,adds, "I am excited because this method for phase-matching is brand new. It is amazing that the crystal itself can provide the phase-matching to ensure momentum conservation, and it's promising to see efficient optical frequency conversion in a really tiny volume."
Read more at Science Daily
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