Meteorites Reveal Another Way to Make Life's Components

Creating some of life's building blocks in space may be a bit like making a sandwich -- you can make them cold or hot, according to new NASA research. This evidence that there is more than one way to make crucial components of life increases the likelihood that life emerged elsewhere in the Universe, according to the research team, and gives support to the theory that a "kit" of ready-made parts created in space and delivered to Earth by impacts from meteorites and comets assisted the origin of life.

In the study, scientists with the Astrobiology Analytical Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md., analyzed samples from fourteen carbon-rich meteorites with minerals that indicated they had experienced high temperatures -- in some cases, over 2,000 degrees Fahrenheit. They found amino acids, which are the building blocks of proteins, used by life to speed up chemical reactions and build structures like hair, skin, and nails.

Previously, the Goddard team and other researchers have found amino acids in carbon-rich meteorites with mineralogy that revealed the amino acids were created by a relatively low-temperature process involving water, aldehyde and ketone compounds, ammonia, and cyanide called "Strecker-cyanohydrin synthesis."

"Although we've found amino acids in carbon-rich meteorites before, we weren't expecting to find them in these specific groups, since the high temperatures they experienced tend to destroy amino acids," said Dr. Aaron Burton, a researcher in NASA's Postdoctoral Program stationed at NASA Goddard. "However, the kind of amino acids we discovered in these meteorites indicates that they were produced by a different, high-temperature process as their parent asteroids gradually cooled down." Burton is lead author of a paper on this discovery appearing March 9 in Meteoritics and Planetary Science.

In the new research, the team hypothesizes the amino acids were made by a high-temperature process involving gas containing hydrogen, carbon monoxide, and nitrogen called "Fischer-Tropsch" -type reactions. They occur at temperatures ranging from about 200 to 1,000 degrees Fahrenheit with minerals that facilitate the reaction. These reactions are used to make synthetic lubricating oil and other hydrocarbons; and during World War II, they were used to make gasoline from coal in an attempt to overcome a severe fuel shortage.

Researchers believe the parent asteroids of these meteorites were heated to high temperatures by collisions or the decay of radioactive elements. As the asteroid cooled, Fischer-Tropsch-type (FTT) reactions could have happened on mineral surfaces utilizing gas trapped inside small pores in the asteroid.

FTT reactions may even have created amino acids on dust grains in the solar nebula, the cloud of gas and dust that collapsed under its gravity to form the solar system. "Water, which is two hydrogen atoms bound to an oxygen atom, in liquid form is considered a critical ingredient for life. However, with FTT reactions, all that's needed is hydrogen, carbon monoxide, and nitrogen as gases, which are all very common in space. With FTT reactions, you can begin making some prebiotic components of life very early, before you have asteroids or planets with liquid water," said Burton.

In the laboratory, FTT reactions produce amino acids, and can show a preference for making straight-chain molecules. "In almost all of the 14 meteorites we analyzed, we found that most of the amino acids had these straight chains, suggesting FTT reactions could have made them," said Burton.

It's possible that both Strecker and FTT processes could have contributed to the supply of amino acids in other meteorites. However, evidence for the FTT reaction would tend to get lost because FTT reactions create them in much lower abundances than Strecker synthesis. If an asteroid with an initial amino acid supply from FTT reactions was later altered by water and Strecker synthesis, it would overwrite the small contribution from the FTT reactions, according to the team.

The team believes the majority of the amino acids they found in the 14 meteorites were truly created in space, and not the result of contamination from terrestrial life, for a few reasons. First, the amino acids in life (and in contamination from industrial products) are frequently linked together in long chains, either as proteins in biology or polymers in industrial products. Most of the amino the amino acids discovered in the new research were not bound up in proteins or polymers. In addition, the most abundant amino acids found in biology are those that are found in proteins, but such "proteinogenic" amino acids represent only a small percentage of the amino acids found in the meteorites. Finally, the team analyzed a sample of ice taken from underneath one of the meteorites. This ice had only trace levels of amino acids suggesting the meteorites are relatively pristine.

The experiments showing FTT reactions produce amino acids were performed over 40 years ago. The products have not been analyzed with modern techniques, so the exact distributions of amino acid products have not been determined. The team wants to test FTT reactions in the laboratory using a variety of ingredients and conditions to see if any produce the types of amino acids with the abundances they found in the 14 meteorites.

The team also wants to expand their search for amino acids to all known groups of carbon-rich meteorites. There are eight different groups of carbon-rich meteorites, called "carbonaceous chondrites." The new work adds two additional groups to the three previously known to have produced amino acids, leaving three groups to be tested. These three remaining groups have a high metal content as well as evidence for high temperatures. "We'll see if they have amino acids also, and hopefully gain some insight into how they were made," says Burton. When the team began looking for amino acids in carbon-rich meteorites, it was considered somewhat of a long shot, but now: "We would be surprised if we didn't discover amino acids in a carbon-rich meteorite," says Burton.

Read more at Science Daily

Storm of Spider Silk Drapes Wagga Wagga

A story that went viral this week about spider webs blanketing an Australian city is not entirely accurate.

What the spiders were doing was creating a line of silk not webs, an entomologist has told Discovery News. The arachnid at the root of the story, a wolf spider, doesn't even make webs.

So, what these images show are massive amounts of dragline silk released by the normally solitary spiders as they ran for their lives to escape rising floodwaters. According to Reuters, flooding forced more than 8000 human residents from their homes in the city of Wagga Wagga, New South Wales.

And the spider residents were equally affected too.

“Wolf spiders would rather be hiding somewhere, trying to escape birds and other predators, but when land gets so flooded the spiders are forced to flee into trees and other high things,” Steve Heydon, senior museum scientist at the Bohart Museum of Entomology, University of California at Davis, told Discovery News.

“These spiders leave behind a dragline of silk, so the spiders at these places in Australia must be nervously running into each other, marching around in search of food,” he added. “There is clearly a lot of spider activity, as evidenced by the massive amounts of silk.”

Owen Seeman, an arachnid expert at Queensland Museum, identified the spider in question as “a type of wolf spider.” These are common spiders throughout the world, with 130 species documented in Australia alone.

Wolf spiders do not make webs, which many other spiders use to capture prey.

“Wolf spiders are instead like mini tigers that run and pounce on prey at night,” Heydon said.

In some of the news stories about the Australian spider silk “storm,” at least one expert, the Australian Museum’s entomology collections manager Graham Milledge, has been quoted as saying that the spiders were “ballooning.” Andy Reynolds, a scientist at Rothamsted Research, has studied this phenomenon before.

Reynolds explained that spiders “could use ballooning to cover long distances.” Each spider casts a thread of silk into the breeze and rides wind currents away from danger or parachutes into new areas.

Reynolds said the silk “can contort and twist with turbulence, affecting its aerodynamic properties and carrying its rider unpredictable distances.”

Heydon believes it is possible that some of the images showing the spider silk after the Australian flood could indeed be evidence of ballooning. But for wolf spiders, he said, this happens more often among younger, smaller individuals.

“Ballooning is a useful technique in the spider toolkit,” he said. “Some spiders can go to the end of a blade of grass or other starting point and release silk into the air so much that wind lifts it and carries the spider off.”

Spiders “balloon” all across the United States, but many of us probably miss the activity. Heydon, however, notices it all of the time, and even at his university’s sporting events.

“At night, if you look at the big lights in our athletic fields, you can sometimes see long streamers of silk from ballooning spiders flying high into the air,” he explained.

Clearly certain parts of Australia are inundated with such spiders, resulting in the dramatic photos showing everything from a farm to a family dog covered in spider silk after the flood.

Read more at Discovery News

Tiny Dinosaur Sported Shimmery Feathers

A new fossil of a four-winged dinosaur about the size of a pigeon shows he apparently sported quite the costume, complete with glossy black feathers and a tail tipped with a pair of decorative streamer feathers.

The newly discovered fossil of Microraptor lived about 130 million years ago, during the early Cretaceous period, in what is now northeastern China. The latest depictions of the beast, whose feathery adornments may have extended to other Microraptor species, suggest it looked similar to a crow, even though non-avian dinosaurs had already separated from the ancestors of modern birds by that time.

It may have looked like a crow, but researchers also think it may have flashed its tail feathers in the manner of a peacock.

Feather comparison

The researchers analyzed the fossil feathers using a scanning electron microscope to see melanosomes, tiny structures (about one-hundredth as wide as a human hair) that give feathers their colors.

The researchers compared the arrangement of these melanosomes with those of modern birds. When melanosomes are stacked neatly, the feather looks darker; when they are more disorganized, the feather appears lighter.

From their analysis of modern birds, the researchers figured that this Microraptor fossil had black feathers. Furthermore, the narrow stacking of the melanosomes would have given the feathers iridescence. The researchers couldn't be sure of the color of the sheen, or the effect of the iridescence on the feather color, because those factors depend on the thickness of the feather's keratin coat.

"That keratin is not preserved in the fossil, so we couldn't directly infer a particular color of iridescence," said study researcher Matthew Shawkey, an assistant professor at the University of Akron, in Ohio.

For their drawings of the dinosaur, the researchers went with a middle-of-the road estimate.

Shake your tail feathers

Microraptor also had elongated tail feathers, which were much better preserved in this new specimen than in previous fossils. (The first Microraptor was unearthed in 2003.) The researchers could see these feathers were narrower and longer than previous extimates.

Read more at Discovery News

Western U.S. Will Face Tsunami. But When?

No one wants to believe that the March 11, 2011, Japan earthquake and tsunami could happen again. But it will. Somewhere.

One likely place for a repeat performance is the west coast of North America. The question is when.

Geophysicists from seven research institutions across the country are probing that question like never before, through a five-year, $4.6-million project just getting underway. Combining 1,000-times-faster computing speeds with improved methodologies, the team is creating the first unified simulation of earthquakes all along western North America.

“One of the project goals is to improve our short- and long-term earthquake forecasting capabilities,” project leader James Dieterich of the University of California, Riverside, said in a press release. “More accurate forecasting has practical advantages—earthquake insurance, for example, relies heavily on forecasts.”

The new simulation will help scientists determine the interplay between the two very different fault systems that exist along the U.S. West Coast. Californians have known to expect great lurches along the San Andreas Fault and its counterparts ever since the Great San Francisco Earthquake of 1906. But inhabitants of the U.S. Pacific Northwest face a double threat: Lurking offshore is a 600-mile-long gash in the seafloor, the Cascadia Subduction Zone, that is prone to mega-thrust earthquakes and tsunamis on the order of last year’s 9.0 tsunami-generating temblor in Japan. The last great Cascadia quake occurred in 1700, uncomfortably long ago when you consider that such events occur every 300 to 500 years.

“Observations of earthquakes go back to only about 100 years, resulting in a relatively short record,” Dieiterich said. “If we get the physics right, our simulations of plate boundary fault systems—at one-kilometer resolution for California—will span more than 10,000 years of plate motion and consist of up to a million discrete earthquake events, giving us abundant data to analyze.”

From all that new data, Dieterich and his colleagues hope to locate clues regarding the long-term processes that condition fault systems to fail in great earthquakes (greater than magnitude 8). One condition the team will be watching closely is the effect of so-called slow-slip events, a special class of subtle plate motion among the hundreds of earthquakes we cannot feel at the earth’s surface.

The existence of slow-slip events, which scientists discovered only recently, is turning out to be especially important for accurate forecasting. In a slow-slip event, movement is gradual enough not to create detectable ground motion, but the energy release can be the equivalent of a normal magnitude 6 earthquake. The big question is whether these events may transfer stress to portions of a subduction zone most prone to a violent jolt, Dieterich explained in a recent talk on the UC Riverside campus.

He pointed out that scientists reviewing the seismic recordings from Japan in early 2011 noted a slow-slip event occurred between the main shock on March 11 and its foreshock.

Read more at Discovery News

Identifying Ancient Droughts in China

Drought events are largely unknown in Earth's history, because reconstruction of ancient hydrological conditions remains difficult due to lack of proxy. New GEOLOGY research supported by China's NNSF and MS&T uses a microbial lipid proxy of highly alkaline conditions to identify enhanced aridity in Miocene sediments on the Tibetan Plateau. This enhanced aridity is associated with significant uplift of the Tibetan Plateau nine million years ago.

According to the study's lead author, Xie Shucheng of the China University of Geosciences at Wuhan, the identification of ancient droughts and associated alkaline soils is particularly challenging at the regional or local level, and is beyond the predictive capabilities of available general circulation models (GCMs). GCMs, which are used to understand physical processes in Earth surface system, are advanced tools for simulation of long-term temperature change.

This new research proposes a microbial lipid proxy of highly alkaline conditions and enhanced aridity on the basis of investigation of modern Chinese soils. In modern Chinese soils, more abundant archaeal lipids known as iGDGTs (isoprenoid glycerol dialkyl glycerol tetraethers) relative to bacterial branched GDGTs were found to be associated with alkaline conditions and enhanced aridity. As a consequence, the ratio of archaeal GDGTs to bacterial GDGTs is indicative of the occurrence of ancient alkalinity and enhanced aridity.

Xie and colleagues also used the microbial lipid proxy to identify the enhanced aridity and alkalinity of Late Miocene sediments from the Zhada basin, which is located in the southwestern Tibetan Plateau, ~1000 km west of Lhasa. They find that the highly alkaline conditions and enhanced aridity identified in these sediments are associated with the most significant uplift of the Tibetan Plateau nine million years ago. The study's findings suggest that abrupt uplifts in the Tibetan Plateau can cause enhanced aridity in central Asia and a consequential development of alkaline soils.

Read more at Science Daily

Oldest Organism With Skeleton Discovered in Australia

A team of paleontologists has discovered the oldest animal with a skeleton. Called Coronacollina acula, the organism is between 560 million and 550 million years old, which places it in the Ediacaran period, before the explosion of life and diversification of organisms took place on Earth in the Cambrian.

The finding provides insight into the evolution of life -- particularly, early life -- on the planet, why animals go extinct, and how organisms respond to environmental changes. The discovery also can help scientists recognize life elsewhere in the universe.

The Ediacaran Period, named after the Ediacara Hills of South Australia, ranges 630-542 million years ago. The Cambrian Period, marked by a rapid diversification of life-forms on Earth as well as the rise of mineralized organisms, ranges 542-488 million years ago.

The best Coronacollina specimens showing the main body with articulated spicules. Specimens originate from different field localities. Arrows indicate main body of Coronacollina. White/black bars indicate 1 cm. A, C, D and E are photographs of fossil impressions in the rock. B and F are latex casts showing how the fossils would have looked in life, after compression. Image credit: Droser lab, UC Riverside.

"Up until the Cambrian, it was understood that animals were soft bodied and had no hard parts," said Mary Droser, a professor of geology at the University of California, Riverside, whose research team made the discovery in South Australia. "But we now have an organism with individual skeletal body parts that appears before the Cambrian. It is therefore the oldest animal with hard parts, and it has a number of them -- they would have been structural supports -- essentially holding it up. This is a major innovation for animals."

Coronacollina acula is seen in the fossils as a depression measuring a few millimeters to 2 centimeters deep. But because rocks compact over time, the organism could have been bigger -- 3 to 5 centimeters tall. Notably, it is constructed in the same way that Cambrian sponges were constructed.

"It therefore provides a link between the two time intervals," Droser said. "We're calling it the 'harbinger of Cambrian constructional morphology,' which is to say it's a precursor of organisms seen in the Cambrian. This is tremendously exciting because it is the first appearance of one of the major novelties of animal evolution."

According to Droser, the appearance of Coronacollina acula signals that the initiation of skeletons was not as sudden in the Cambrian as was thought, and that Ediacaran animals like it are part of the evolutionary lineage of animals as we know them.

"The fate of the earliest Ediacaran animals has been a subject of debate, with many suggesting that they all went extinct just before the Cambrian," she said. "Our discovery shows that they did not."

Study results appeared online Feb. 14 in Geology.

The researchers note that Coronacollina acula lived on the seafloor. Shaped like a thimble to which at least four 20-40-centimeter-long needle-like "spicules" were attached, Coronacollina acula most likely held itself up by the spicules. The researchers believe it ingested food in the same manner a sponge does, and that it was incapable of locomotion. How it reproduced remains a mystery.

Coronacollina acula is so named because it translates as "little rimmed hill with needles" (corona -- rim or crown; collis -- hill; acula -- needle). The name describes the fossil organism's morphology, and, specifically, its two components: the truncated cone-shaped body, which appears in the fossils as a pit, and the long brittle spicules, which appear in the fossils as thin grooves.

Ediacaran fossils often show the imprint of the whole body of the organism. With Coronacollina acula, however, skeletal parts were found to have fallen off.

"If you have soft parts holding your body together, then, as they decay, you lose your skeletal parts," Droser explained. "Which is why it's rare to find two clam shells together in fossils. We've now found whole organisms of Coronacollina acula -- the thimble-shaped body in the center, with spicules coming off it like knitting needles. And we have found hundreds of them. They appear to have been a gregarious species, with a lot of them living together."

Droser explained that the spicules had to have been mineralized because the casts show they are ruler-straight. Moreover, they broke.

"We often associate skeletons with predation since skeletons greatly assist animals in their fight against predators," Droser said. "But Coronacollina acula used its skeleton only for support, there being no predators in the Ediacaran."

The research work began as a master's thesis project in Droser's lab. Erica Clites, now a physical science technician at Glen Canyon National Recreation Area for the National Park Service, chose to work on this project because it promised a good challenge with rewarding results.

"Every aspect of the organism's reconstruction had to be backed up by supporting statistics," said Clites, who graduated from UCR in 2009 and is the first author of the research paper. "Through painstaking measurements and detailed descriptions, the pits and needles contained in the rock were revealed as a sponge-like animal."

Read more at Science Daily

Humans and gorillas share genetic similarities

A study has shown that across 15% of their genetic code, or genome, gorillas are more like humans than chimpanzees.

In both, certain genes have also evolved at the same rate, research shows. They include genes for hearing, throwing into doubt theories linking the development of hearing and human language.

The findings emerge from the first completed genome sequence, or genetic "blueprint", of the gorilla.

Gorillas are the last of the living great apes to have their genetic codes mapped, allowing scientists to compare the genomes of humans, chimpanzees, gorillas and orang-utans.

The new research was chiefly based on DNA taken from Kamilah, a female western lowland gorilla.

Scientists at the Wellcome Trust Sanger Institute in Hinxton, Cambridgeshire, searched more than 11,000 genes in the gorilla, human and chimpanzee looking for important evolutionary differences.

In all three species, genes related to sensory perception, hearing and brain development showed accelerated evolution. But this was especially true for humans and gorillas.

Dr Chris Tyler-Smith, senior author of the research published in the journal Nature, said: "Our most significant findings reveal not only differences between the species reflecting millions of years of evolutionary divergence, but also similarities in parallel changes over time since their common ancestor.

"We found that gorillas share many parallel genetic changes with humans including the evolution of our hearing.

"Scientists had suggested that the rapid evolution of human hearing genes was linked to the evolution of language.

"Our results cast doubt on this, as hearing genes have evolved in gorillas at a similar rate to those in humans."

Gorillas separated from humans and chimpanzees on the evolutionary path around 10 million years ago, the research showed.

A more gradual divergence between eastern and western gorillas occurred much more recently in the last million years or so.

This could be compared with the split between modern humans and Neanderthals, or chimpanzees and bonobos, said the scientists.

Co-author Dr Aylwyn Scally, also from the Sanger Institute, said: "The gorilla genome is important because it sheds light on the time when our ancestors diverged from our closest evolutionary cousins.

"It also lets us explore the similarities and differences between our genes and those of gorilla, the largest living primate.

"Using DNA from Kamilah, a female western lowland gorilla, we assembled a gorilla genome sequence and compared it with the genomes of the other great apes.

Read more at The Telegraph

All Hail The New King

A new king has been added to the long list of ancient pharaohs, the Egyptian Minister of State for Antiquities, Mohamed Ibrahim, announced this week.

The king's name, Senakht-en-Re, emerged from the engraved remains of a limestone door found by a French-Egyptian team‭ ‬in the Temple of Karnak complex on Luxor’s east bank.

The archaeologists, led by French Egyptologist Christophe Thiers, of the Centre National de la Recherche Scientifique (CNRS), unearthed a fragmented lintel and an imposing door jamb during routine excavation at the temple of Ptah.

Belonging to an administrative structure dating to the enigmatic 17th Dynasty (about 1634-1543 BC) the limestone remains featured hieroglyphics which indicated that the door was dedicated to Amun-Re.‭

"They also revealed who ordered the construction of this structure. It was the pharaoh Senakht-en-Re," said a CNRS statement.

Mentioned in only three documents written one or two centuries after his reign, ‬Senakht-en-Re is regarded as one of the most obscure kings of the 17th dynasty.

No objects or monuments had ever been found bearing his name, and his tomb has yet to be discovered.

"We knew nothing‭ of this pharaoh - ‬until now. These remains are the first contemporary document of this king ever discovered in Egypt," the CNRS said.

According to the hieroglyphics, Senakht-en-Re had the monumental gateway built from limestone blocks transported from Tora (the modern Helwan, south of Cairo).

At that time, the town was under the rule of the Hyksos. Known as the "rulers of foreign countries" (probably of Asiatic roots), they infiltrated Egypt and came to dominate the Nile valley for over a century during the Second Intermediate Period (1664-1569 B.C.).

Read more at Discovery News

Researchers Capture First-Ever Image of Atoms Forming a Molecule

Researchers have recorded the first-ever image of two atoms bonding together to form a molecule.

Key to the experiment, which appears in the journal Nature, is the researchers' use of the energy of a single electron as a kind of "flash bulb" to illuminate the reaction.

The team used ultrafast laser pulses to knock one electron out of its natural orbit in one of the atoms, just as the two atoms were bonding together. When the electron fell back into place, it emitted an energy signal that scattered around the newly forming molecule as a flash of light would scatter around an object, or ripples would scatter in a pond.

Principal investigator Louis DiMauro of Ohio State University said that the feat marks a first step toward not only observing chemical reactions, but also controlling them on an atomic scale.

"Through these experiments, we realized that we can control the trajectory of the electron when it comes back to the molecule, by adjusting the orientation of the laser that launches it," said DiMauro, who is a professor of physics at Ohio State. "The next step will be to see if we can hit the electron in just the right way to actually control a chemical reaction."

A more common imaging technique involves shooting a molecule with an electron beam, bombarding it with millions of electrons per second. The researchers deemed the new single-electron approach more reliable, based on theoretical developments by the paper's coauthors at Kansas State University.

"If we shot an electron beam from outside the molecule, there would only be a certain probability that one of the electrons would scatter off the molecule," explained Ohio State postdoctoral researcher Cosmin Blaga. "But in this case, when we use a laser to launch an electron from inside the molecule we are studying, we have a 100 percent probability that it will fall back into the molecule and scatter."

The technique, called laser induced electron diffraction (LIED), is commonly used in surface science to study solid materials. This is the first time anyone has used LIED to study a single molecule as it formed.

The molecules the researchers chose to study were simple ones: they brought two nitrogen atoms together to form molecular nitrogen, or N2, then repeated the experiment with two oxygen atoms forming molecular oxygen, or O2. N2 and O2 are common atmospheric gases, and scientists already know every detail of how they form, so these two very basic reactions made good test cases for the LIED technique.

In each case, the researchers hit the forming molecule with laser light pulses of 50 femtoseconds, or quadrillionths of a second. They were able to knock a single electron out of the outer shell of one of the constituent atoms and detect the energy signal of the electron as it fell back into the molecule.

DiMauro and Blaga likened the electron signal to the diffraction pattern that light forms when it passes through slits. Given only the diffraction pattern, scientists can reconstruct the size and shape of the slits. In this case, given the diffraction pattern of the electron, the physicists reconstructed the size and shape of the molecule -- that is, the locations of the constituent atoms' nuclei and the electron shells orbiting them.

The resulting 3D image marks the first image ever recorded of bonds forming in a molecule.

Beyond its potential for controlling chemical reactions, the technique offers a new tool to study the structure and dynamics of matter, Blaga said. "Ultimately, we want to really understand how chemical reactions take place. So, long-term, there would be applications in materials science and even chemical manufacture."

"You could use this to study individual atoms," DiMauro added, "but it's safe to say that we won't learn anything new from an atomic physics standpoint. The greater impact to science will come when we can study reactions between more complex molecules. Looking at two atoms -- that's a long way from studying a more interesting molecule like a protein."

Read more at Science Daily

'Vomit Bird' Throws Up a Defense Against Predators

Offspring of the bright-blue jackdaw-sized bird -- Latin name Coracias garrulus -- throw up the repugnant fluid when they are frightened in their nests, according to a paper appearing on Wednesday in the journal Biology Letters.

Covered in vomit, the nestlings not surprisingly become less attractive as a snack, the team says.

But the smell also alerts parents, returning to the nest, that a threatening incident has happened in their absence, they believe.

The scientists tested the "olfactory cue" theory by visiting nests with 10-day-old nestlings inside.

They used a small paintbrush to daub a tiny amount of either lemon juice or vomit on the inside of the nest. Parents returning to a vomit-treated nest reacted with great caution, delaying the time when they would settle in the home.

Previous research has found that birds have a surprisingly wide range of defensive reactions.

For instance, the northern fulmar (Fulmaris glacialis) yawks up stomach oils against intruders that makes them lose their waterproof coating.

And the common eider (Somateria mollissima) and northern shoveler (Anas acuta) have the ability to spray feces on their eggs to deter mammal egg-thieves.

However, the Eurasian roller is the first bird that has been found to use a scent, derived in response to a threat, as a means of communication, says the paper.

Read more at Discovery News