- Planets Align For Best Meteor Shower Of the Year Thursday Night
- New Find Pushes Age of Stone Tools Back A Million Years
- Mystery of Honeycomb Cloud Formation Solved
- Inexplicable Superconductor Fractals Hint at Higher Universal Laws
- Asteroid Crater Hunting From Your Home
- Russian Heat, Asian Floods May Be Linked
- Russian Fires Approach Nuclear Plants
- Removing a Barrier to Regrowing Organs
- Science + Geek + Beer = Awesomely Geeky Science Beer
- Finch Duets About More Than Getting the Girl
Posted: 11 Aug 2010 09:44 PM PDT
If you're looking for low-tech star gazing action, Thursday night is the time to grab a blanket and head outside.
Just after sunset Thursday evening,Venus, Saturn, Mars and the crescent moon will huddle very close together in the western sky after months of moving closer together. And as the moon sets and the sky darkens starting around 10:30 p.m. (local time), the annual Perseid meteor shower will put on its best performance of the year.
The meteor shower is a perfect time to work on your astronomical photography skills. Check out our how-to wiki on photographing the stars for some step-by-step advice.
The Perseids are visible every year in early August when the Earth moves through a cloud of dust and debris left by the Swift-Tuttle comet. The shooting stars are caused by dust and debris colliding with the Earth's atmosphere at high speeds and burning up.
At the peak of the shower under optimal conditions, you can expect to see up to 100 shooting stars per hour. The best time for seeing them will be after the moon sets, during the late night and very early morning.
Posted: 11 Aug 2010 10:45 AM PDT
Large fossilized animal bones with ends shattered for sucking out marrow and cut marks deliberately made with sharp stone tools have been found just a few hundred feet from a previously uncovered Australopithecus afarensis skeleton. The bones are roughly 3.4 million years old, and connect the earliest evidence for using stone tools and eating large game to our Lucy-like ancestors.
Previously, the earliest evidence for using tools to cut the meat off large animals was attributed to early Homo in the Gona region of Ethiopia around 2.5 million years ago. This find from a different region in Dikika, Ethiopia, , shows the behavior was around at least a million years earlier.
"It means almost everything to be able to use stone tools," said paleontologist Zeray Alemseged of the California Academy of Sciences, co-author of the discovery announced Aug. 12 in Nature. "The picture that we're going to paint of Australopithecus is being transformed completely. We can now imagine them walking around carrying their tools. Tools that were the precursor of every tool that we have today."
"Australopithecus was a very primitive, ape-like early human," said biological anthropologist Craig Stanford at University of Southern California, who edited a book on meat eating and human evolution. "The fact that they were using tools and eating meat indicates this was something that was widespread very early in human history."
The ability to carve meat off large mammal carcasses likely put Australopithecus in competition with dangerous scavengers, Alemseged says. It is unlikely they were hunting for the large game because their body shape would not have allowed them to run fast, which is necessary to chase down an antelope or similar sized animal.
But scavenging large animals still provides access to high quality, high-calorie foods that likely enabled Australopithecus to venture much further out of the forest environment into the open grassland than otherwise possible on a diet of mostly of fruit, leaves and tubers.
The two cut bones found both came from mammals. One is a rib from a cow-sized animal, and the other is a femur shaft from an antelope-sized animal. Analysis of the bones showed the cut marks were created before the bones fossilized, eliminating the possibility the marks were made recently.
While it is impossible to tell from the scratches whether Australopithecus was making stone tools or using naturally sharp rocks, the lack of adequate rock material in the immediate area where the bones were found suggests they were carrying the stones around with them from one place to another.
However, no one has yet found the stone tools themselves or where they could have come from, and at least one scientist finds this reason to be skeptical of the claims made by the discoverers.
"The fact that no single sharp-edged flaked stone has been recovered from the site makes such a claim doubtful of any hominid involvement," said paleontologist Sileshi Semaw of the Stone Age Institute, who discovered what was previously the oldest evidence for stone tool from the Gona region."Researchers who study bone surface modifications from archeological sites have shown that fresh bones trampled by animals can create marks that mimic stone tool cut marks."
"The next stage will be to really go out there and scrutinize the site to see if the tools are indeed there," said Alemseged in response. "But I wouldn't be surprised if the stone tools were archeologically invisible to us. They might have been using the tools in a sporadic way."
Images: Dikika Research Project
Citation: McPherron et. al. "Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia." Nature. August 12.
Posted: 11 Aug 2010 10:03 AM PDT
Easily spotted by their honeycomb shape, open-cell clouds are one of the most common cloud formations, found on the backside of low pressure systems and skirting the edges of every continent. Yet for all their ubiquity, they are among the more mysterious cloud formations known, and rules guiding the formation of open-cell clouds have not been quantified — until now.
Starting with a computer model of cloud formation developed at the National Center for Atmospheric Research, climate physicists refined and reconfigured its internal dynamics until they matched patterns seen in the real world. The math is complicated in detail, but simple in principle.
"Imagine you had a hosepipe, pointed it at the ground, and turned it on. The water rushes out hard, hits the ground and is forced to diverge. Now imagine you've got not just one hosepipe, but many. All these diverging flows start hitting each other. The water has to go somewhere, and the only place it can go is upwards," said Graham Feingold, a National Oceanic and Atmospheric Administration physicist.
To fit the analogy to open-cell cloud formation, replace the water with air that's pulled downwards by raindrops that cool as they evaporate. The jets of air hit the ocean, split into streams flowing across the water, and collide with other jets, driving them back up into the atmosphere. Once there, water droplets form around tiny particles of dust and biological debris, eventually coalescing into clouds. Their pattern is dictated by geometries of airstream collision far below.
Feingold's team tested their simulation against a month of real-world cloud data gathered from a site off the coast of South America by satellites, aircraft, boats, underwater and on-the-water sensors, under varying wind strengths, humidity levels and precipitation rates. At every level, the researchers' simulations matched what was observed. "We bring all these measurements to bear to look for the same signatures that we find in the models," said NOAA physicist Alan Brewer.
The findings, published August 12 in Nature, should help climate modelers improve the fine-grained dynamics of coarse-resolution models. Clouds are an especially important component, since their formation affects how much sunlight is reflected and how much hits Earth directly. Depending on the relationship between regional climates and global warming, clouds could slow rapid warming — or let it run away.
With the basic equations of open-cell cloud formation in hand, the researchers next want to study how they become "closed" cells, an inverse pattern in which the honeycomb shape is produced by dense clouds outlined by narrow gaps. "We've seen how it transitions from closed to open, but we're very unclear on how it could move back to closed," said Feingold.
The patterns of open-cell cloud formation are typical of self-organizing systems, said the researchers. Similar patterns are seen in bird flocks, crystal growth, social networks and many ecosystems. Why such different systems should display common behaviors is still being explored.
"We've also discovered that oscillations start to occur. Precipitation is synchronized. We're very fascinated by this," said Feingold. "The realm of self-organizing properties is wide open, and we'll pursue it."
More cloud images on the following page.
Posted: 11 Aug 2010 10:00 AM PDT
What seemed to be flaws in the structure of a mystery metal may have given physicists a glimpse into as-yet-undiscovered laws of the universe.
The qualities of a high-temperature superconductor — a compound in which electrons obey the spooky laws of quantum physics, and flow in perfect synchrony, without friction — appear linked to the fractal arrangements of seemingly random oxygen atoms.
Those atoms weren't thought to matter, especially not in relation to the behavior of individual electrons, which exist at a scale thousands of times smaller. The findings, published Aug. 12 in Nature, are a physics equivalent of discovering a link between two utterly separate dimensions.
"We don't know the theory for this," said physicist Antonio Bianconi of Rome's Sapienza University. "We just make the experimental observation that the two worlds seem to interfere."
Unlike semiconductors, the metals on which modern electronics rely, superconductors allow electrons to pass through without resistance. Rather than bouncing haphazardly, the electrons' movements are perfectly synchronized. They flow like a fluid, but without viscosity.
For most of the 20th century, this was possible only in certain extremely pure metals at temperatures approaching absolute zero, cold enough to quench all motion but that of quantum particles, which interact with each other in ways that defy the classic laws of space and time.
Then, in the mid-1980s, physicists Karl Muller and Johannes Bednorz discovered a class of ceramic compounds in which superconductivity was possible at much higher temperatures. The temperatures were still hundreds of degrees Fahrenheit below zero, but it wasn't even thought possible.
Muller and Bednorz soon won a Nobel Prize, but subsequent decades and thousands of researchers have not yielded a theory of high-temperature superconductivity. "High temperatures should destroy the quantum phenomenon," said Bianconi, who decided to investigate another odd property of these materials: They're not quite regular. Oxygen atoms roam inside, and assume random positions as they freeze.
"Everyone was looking at these materials as ordered and homogeneous," said Bianconi. That is not the case — but neither, he found, was the position of oxygen atoms truly random. Instead, they assumed complex geometries, possessing a fractal form: A small part of the pattern resembles a larger part, which in turn resembles a larger part, and so on.
"Such fractals are ubiquitous elsewhere in nature," wrote Leiden University theoretical physicist Jan Zaanen in an accompanying commentary, but "it comes as a complete surprise that crystal defects can accomplish this feat."
If what Zaanen described as "surprisingly beautiful" patterns were all Bianconi found, the results would have been striking enough. But they appear to have a function.
In Bianconi's samples, larger fractals correlated with higher superconductivity temperatures. When the fractal disappeared at a distance of 180 micrometers, superconductivity appeared at 32 degrees Kelvin. When it vanished at 400 micrometers, conductivity went quantum at 42 degrees Kelvin.
At -384 degrees Fahrenheit, that's still plenty cold, but it's heading towards the truly high-temperature superconductivity that Bianconi describes as "the dream" of his field, making possible miniature supercomputers that run at everyday temperatures.
However, while the arrangement of oxygen atoms appears to influence the quantum behaviors of electrons, neither Bianconi nor Zaanen have any idea how that could be. That fractal arrangements are seen in so many other systems — from leaf patterns to stock market fluctuations to the frequency of earthquakes — suggests some sort of common underlying laws, but these remain speculative.
According to Zaanen, the closest mathematical description of superconductive behavior comes from something called "Anti de Sitter space / Conformal Field Theory correspondence," a subset of string theory that attempts to describe the physics of black holes.
That's a dramatic connection. But as Zaanen wrote, "This fractal defect structure is astonishing, and there is nothing in the textbooks even hinting at an explanation."
Image: At left, the organization of oxygen atoms (blue dots) within the superconducting metal; at right, measurements of superconductivity temperature according to the distance (x- and y-axes) at which fractal organization was still evident./Nature.
Citations: "Scale-free structural organization of oxygeninterstitials in La2CuO41+y." By Michela Fratini, Nicola Poccia, Alessandro Ricci, Gaetano Campi, Manfred Burghammer, Gabriel Aeppli & Antonio Bianconi. Nature, Vol. 466 No. 7308, August 12, 2010.
"The benefit of fractal dirt." By Jan Zaanen. Nature, Vol. 466 No. 7308, August 12, 2010.
Posted: 10 Aug 2010 01:26 PM PDT
Just days after a Google Earth–aided discovery of a meteor impact was announced in Science, yet another crater has been found using Google Maps and open-access software. The age of armchair crater hunting has arrived.
Physicist Amelia Sparavigna of Politecnico di Torino in Italy found a 6-mile-wide crater in the Bayuda desert in Sudan using Google Maps, a free astronomical image-processing program she helped develop called AstroFracTool, and open source image-processing tool GIMP. The work appeared on ArXiv Aug. 3.
While no one has gone to the Bayuda crater site to confirm that it was formed by a meteor impact, the discovery demonstrates that with freely available software and a lot of spare time, anyone can become part of the search for craters.
Most of the documented impacts are in North America and Western Europe. Either space objects prefer to hit those regions, or the rest of the planet is mostly unexplored.
The best place to look for impacts is in desert regions, where the craters are better preserved. If you're ready to join the search, the Impact Database website includes a detailed description of how to contribute.
Pointers include downloading Google Earth, searching for circular features, and remembering that most circular features on earth are not from the impact of space objects.
Let us know if you have any luck!
Image: 1) Images A and C show the Bayuda desert crater images obtained directly from Google Maps, Images B and D have been processed with AstroFracTool and GIMP/ Amelia Sparavigna 2) Impact Database/David Rajmon.
Posted: 10 Aug 2010 12:59 PM PDT
Russia's killer heat wave and monster South Asian monsoon floods could be more than isolated examples of extreme weather. Though separated by a continent, they could be linked.
Monsoon rains drive air upward, and that air has to come down somewhere. It usually comes down over the Mediterranean, producing the region's hot, dry climate. This year, some of that air seems to have gone north to Russia.
"We haven't done the studies, but there's very good reason to suspect that there's a relationship," said Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research. "It's simply related to the idea that there is a monsoon with very large circulation. There's an upwards branch of it. There has to be a downwards branch somewhere else."
The Russian heat wave has persisted since late June, with daytime temperatures at least 12 Fahrenheit degrees above normal — and often much more — for over a month. In Moscow alone, an estimated 300 people a day have died. The temperatures threaten wheat harvests and have sent global prices rising in a manner reminiscent of the lead-up to 2008's global food riots.
Weather Underground meteorologist Jeff Masters called it "one of the most remarkable weather events of my lifetime," which is probably an understatement. Russian meteorologists say it's the most intense heat wave in a millennium.
Meanwhile, in South Asia and China, seasonal monsoons have been exceptionally intense, setting off the worst flooding in 80 years. Pakistan has been especially hard-hit, with 1,600 people dead and 2 million homeless in what's been dubbed "Pakistan's Katrina."
Events like these fit with general forecasts of weather trends in a warming climate. But some observers have wondered whether Russia's heat wave and Asia's floods are linked not just by a vague trend, but by specific cause-and-effect meteorological dynamics. They will undoubtedly be studied in detail for years to come, but according to Trenberth, there's good reason to think the extremes are connected.
"The two things are connected on a very large scale, through what we call an overturning or monsoonal circulation," he said. "There is a monsoon where upwards motion is being fed by the very moist air that's going onshore, and there are exceptionally heavy rains. That drives rising air. That air has to come down somewhere. Some of it comes down over the north."
Fueling the monsoons' intensity are warmer-than-usual temperatures in and above the Indian Ocean. At 2 Fahrenheit degrees above late-20th century levels, the air can hold about 8 percent more water. At higher temperatures, the air is also more buoyant, and "invigorates the storms," said Trenberth.
"Air rises faster than before. It sucks more air in. It changes moisture flow onto land even more. You can almost double the effect," he said. "From that 8 percent more water, there can be 16 percent more rainfall."
As for why some of that surging monsoon air may have fallen to Earth over Russia this year, Trenberth declined to speculate. Historical weather patterns do, however, suggest linkages across the Northern Hemisphere's middle latitudes, intermittently coupled in turn to India's summer monsoon cycles.
Russia's heat wave could simply be part of that pattern, exacerbated this year by heat absorbed in Russia's Arctic — where sunlight-reflecting sea ice is reaching all-time lows — and by heat-trapping soot particles from wildfires raging in western Russia. Trenberth added that large-scale rainfall events "tend to create more persistent weather patterns elsewhere," creating heating patterns that lock atmospheric flows into place.
Vladimir Petoukhov, a climate modeler at Germany's Potsdam Institute, agreed that a link is possible. "Different geographic locations of the Northern Hemisphere could be simultaneously subjected to drought-like and flood-like conditions," he said. "These phenomena cannot be regarded as solitary local structures."
As regional temperatures continue to rise, "the frequency of such events could markedly increase," said Petoukhov.
Images: 1) Heat anomaly map of Eurasia in late July. The darkest red areas are 22 Fahrenheit degrees warmer than usual, and the darkest blue areas are 22 degrees cooler./NASA. 2) The Indus river floodplain in Pakistan as photographed July 18 (top) and Aug. 8 (bottom)./NASA.
Posted: 10 Aug 2010 11:26 AM PDT
Russia is, at the time of writing, being consumed by wildfires caused by the worst heat wave the country has endured in a millennia. A state of emergency has been declared in 35 regions of the country — seven for the fires themselves, and another 28 for crop failures caused by the drought and heat wave.
UK media has largely ignored the disaster, but the web is alive with eye-witness accounts, photographs, videos and maps of how the flames are spreading. Most of the information is coming through blogging site LiveJournal, which has a large Russian population.
Following the July heat wave in the country, peat fires — which can smoulder for years underground — ignited forest fires in the Nizhny Novgorod Oblast, the Voronezh Oblast, and across central and western Russia. A few days later, an area of 500,000 hectares was ablaze, with Moscow shrouded in a dense, thick smoke.
Since then, the area of the fires has been brought under control, with now only about 200,000 hectares ablaze, but there are much bigger problems looming. The fires have approached the Red Forest, an area that suffered the worst of Chernobyl's fallout in 1986, with the soil still heavily contaminated by cesium-137 and strontium-90.
Similarly, the Mayak nuclear fuel reprocessing facility in Chelyabinsk Oblast is also threatened by the flames, as is a nuclear research center in Sarov, which was formerly known as the secret town Arzamas-16. If any of the structures succumb, then radionuclides could be spread widely afield, generating new zones of radioactive pollution and displacing the population of those areas.
Severe health risk
The effects of the smoke on public health could also be severe. In central Moscow, pollutants have reached 6.6 times the normal level for carbon monoxide, and 2.8 times that of suspended particulate matter. Deaths in the city have doubled, hitting about 700 people per day, and at least 53 people (and possibly hundreds) have been killed directly by the fires in other parts of the country.
To see the current status of the fires, you can view a Google Earth layer (which obviously requires Google Earth to be installed) or there's also a web version, but that's in Russian. On LiveJournal, user i-cherski has been blogging extensively about the disaster, and there are a few impressive photos of the damage on Boston.com's Big Picture. One YouTube user videoed himself driving through the inferno, which makes for some grim viewing.
However, there could be a silver lining to the disaster. In an abrupt U-turn on previous policies, Russian officials have begun linking the heat wave with climate change. President Dmitry Medvedev said in a speech published on the Kremlin's website: "Unfortunately, what is happening now in our central regions is evidence of this global climate change, because we have never in our history faced such weather conditions in the past. This means that we need to change the way we work, change the methods that we used in the past."
That contrasts dramatically with the president's previous rhetoric on the matter, which included a statement that "we will not let anyone cut our development potential," vowing not to cut carbon emissions. If this U-turn is permanent, and not just an attempt to keep the blame for the disaster away from the government's peat bog-draining policies and cuts in rural fire services, then perhaps global climate change legislation may finally be able to make some progress.
Image: Google Earth
Posted: 10 Aug 2010 10:59 AM PDT
Disabling an evolutionary backup plan for protecting against cancer could be part of a future means to regrow lost limbs or regenerate damaged organs.
A protein called ARF, which acts as a fail-safe mechanism to protect against cancer, also prevents regeneration in mammals, a study published Aug. 6 in Cell Stem Cell suggests. ARF backs up Rb, an important anticancer protein, by limiting the ability of mature cells to divide and replicate. But researchers in California have discovered that blocking ARF and Rb allowed mature muscle cells taken from mice to proliferate, something the cells normally cannot do.
The discovery is an important step in learning why mammals, including people, can't regrow or replace lost limbs and organs the way animals such as salamanders and zebrafish can. Such work may one day lead to new treatments for injuries.
Scientists have known for many years that some animals, including some fish and amphibians, can regenerate organs and limbs, but mammals can't. Therefore, at some point in evolution, mammals must have acquired proteins that halt regeneration, reasoned researchers led by Helen Blau of Stanford University and Jason Pomerantz of the University of California, San Francisco.
Other studies had shown that inactivating Rb in salamanders could kick off the regeneration process. But in mammalian cells, getting rid of Rb isn't enough to spur growth, Blau says. That's because mammal cells have ARF to take over if Rb goes down. Newts, salamanders and zebrafish don't have the ARF backup system.
"We put two and two together" and deciphered that Rb and ARF could be working together to put the brakes on regeneration, Pomerantz says.
The team tested the idea by taking muscle cells from mice and temporarily depleting the Rb and ARF inside. Cells that lacked the two cancer guards were able to replicate themselves, while normal muscle cells could not. Further experiments showed that the regenerated cells could incorporate into muscles in the mice. That finding is important because it could mean that if heart cells could be coaxed into regenerating, they might help heal injuries caused by heart attacks.
Making the protein inactivation temporary was also key. If researchers permanently removed the proteins from cells, the cells would form tumors when transplanted into mice.
But the scientists caution that real regeneration of entire limbs or organs is still a long way off. "Growing a whole limb, that's hugely complicated," says Blau.
The researchers also have not yet shown that inactivating Rb and ARF can lead to true regeneration — growing an entirely new tissue, says Kenneth Poss, a developmental biologist and Howard Hughes Medical Institute investigator at Duke University Medical Center in Durham, N.C.
"Regeneration is an extremely complex process that I don't think will boil down to just one cellular event or one molecular event," he says. In addition to being able to replicate, cells probably also need some guidance about how to reform limbs and tissues. Whether such a guidance system is at work in mammals is unknown.
"I think it will be exciting to see whether they can use these manipulations to enhance regeneration" in mammals, Poss says.
Image: Dr. Keith Melancon, left, Georgetown's kidney transplant director, is helped by other
Posted: 09 Aug 2010 05:52 PM PDT
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SAN FRANCISCO — What do you get if you cross a beer geek with a science geek? Really good beers with really geeky names.
I've already proven the connection between beer and geologists, but the number of brews out there with awesomely geeky science names suggests that the beer-science link is even more primordial. After stumbling across a few of these, like Shale Ale (named for the Burgess Shale, a famously fossiliferous outcrop) and Homo Erectus (an IPA made by Walking Man Brewing), I decided the matter required further investigation.
With the help of my friends and Twitteronia, I tracked down a bunch more science-geek beers, and a few with super-geeky tech themes (this is Wired, after all). I managed to get seven of them into Wired HQ, because, let's be honest, this was all just another elaborate excuse to make drinking beer part of my job.
Sadly, I couldn't get my hands on some of the geekiest beers. A few were short runs for special occasions, like The Empire Strikes Back All-English IPA and Galileo's Astronomical Ale (tagline: Theoretically the best beer in the universe), brewed by astronomy geek Ken Grossman of Sierra Nevada Brewing Company to celebrate the 400th anniversary of the telescope. And some are seasonal, like 21st Amendment's Spring Tweet, a beer brewed for Twitter (which brings up the obvious question: Where's Wired's beer?)
Others are only available to lucky local geeks, like the beers from Atomic Ale Brewpub in Richland, Washington, including Plutonium Porter, Half-Life Hefeweizen, Oppenheimer Oatmeal Stout and Dysprosium Dunkelweisen.
The seven beers I did obtain came to Wired in the mail from breweries and friends, on a plane in my suitcase, and one was even hand-delivered right to our doorstep. I then gathered some of the other beer lovers at Wired, and we tasted the beers. Each brew was given two scores (out of 10 balls, just like everything else we review here): one for taste and one for the geekiness of its name. The highly scientific results, based on the combined score, continue on the following pages.
No. 1: Tricerahops Double IPA
Ninkasi Brewing, Eugene, Oregon
How many aspiring geeks loved dinosaurs as kids? All of them. And how many of them still love dinosaurs? All of them. So it should come as no surprise that Ninkasi Brewery's Tricerahops Double IPA landed at the top of our list.
This beer is the descendant of Hopasaurus Rex, one of brewer Jamie Floyd's creations at a previous stint at Steelhead Brewery. But unlike their paleontological namesakes, Tricerahops could totally take H. rex.
"It's triple the hops and a double IPA, so it's a big, dangerous beer," said brewery spokesman James Book. "It's definitely a monster."
At 8.8 percent alcohol*, it really is a monster. And the Wired beer drinkers found the Tricerahops to be quite drinkable, which could have been trouble if our tasting supply had been unlimited. The beer certainly is a hoppy one, but the malt was also given a boost and balances the beer nicely and lends a subtle sweetness. Several of the reviewers commented on the staying power of the hoppy aftertaste, but couldn't agree on whether this was a good thing or a bad thing.
All in all, the beer was a hit and "would be great with a steak," according to Playbook writer Erik Malinowski. We love it when a great beer name is backed up be a great beer.
WIRED: It's named after my favorite dinosaur and is one of the least stinky double IPAs we've encountered.
TIRED: Extinction by asteroid impact.
*All alcohol contents in these reviews are percent by volume (abv).
Image: Jonathan Snyder/Wired.com
Posted: 09 Aug 2010 12:17 PM PDT
Zebra finches, at least, know how to keep the magic alive. Only after becoming a couple, in the intimacy of their nest, do they start singing to each other. That hasn't been seen in other birds. Then again, maybe we're just not looking.
"We had no idea that we would discover these private duets," said Clementine Vignal, a sensory ecologist at France's Université Jean Monnet. "Until now, only three to four percent of birds have been reported to duet. But we think that a lot of species may have been overlooked. These private duets may be common in monogamous speices."
Curious about how zebra finches communicated in nature rather than a lab, Vignal's team put microphones inside nest boxes made for wild birds. Duets were not on their mind; zebra finches don't even duet during courtship, and only males sing songs. But they soon heard the birds exchanging synchronized clicks and trills (mp3), performed when one left or returned to the nest, or was nearby while the partner remained.
In laboratories, where male zebra finch songs make them a common model for studies on neural mechanisms of learning and mechanism, the birds are kept in small spaces with no predators and plenty of food. That may reduce the need for private duets, which Vignal's team thinks are partly explained by a need to stay close and keep alert. But scientists may also have been blinded by an assumption that duets were purely a mechanism for advertising virility and reproductive health to would-be mates.
"Most of these studies have focused on display behaviors that characterize pair formation or mate choice — all these processes that interest people working on the evolutionary aspect of sexual selection. We forgot to think about what was going on after pair formation," said Vignal. "If we record inside the nests of other really common species, like tits or blackbirds, I wouldn't be surprised if we find these duets."
Were the singers human, researchers might also explain the duets in terms of affection. Since they're birds, the researchers describe the songs in terms of maintaining pair bonds, predator avoidance and conferred reproductive advantages. Vignal plans further studies of the duets, but thinks there's more than reproductive imperatives in the tiny birds' hearts and brains.
"They have emotions. They're certainly different from the ones we accept, but they do have them," said Vignal, who references studies on increasing levels of stress hormones in separated pairs. "We can imagine that this duet expresses some kind of emotion."
Image: Flickr/William Warby
Citation: "Vocal communication at the nest between mates in wild zebra Finches: a private vocal duet?" By Julie E. Elie, Mylène M. Mariette, Hédi A. Soula, Simon C. Griffith, Nicolas Mathevon, Clémentine Vignal. Animal Behavior, published online, July 24, 2010.
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