- Lemur See, Lemur Do: Lower Primates Show Glimmer of Culture
- Ancient Mass Extinctions Hint at Possible Ocean Future
- Biggest-Ever Night Sky Image Released to Public
- Thunderstorms Shoot Beams of Antimatter Into Space
Posted: 11 Jan 2011 04:01 PM PST
Black-and-white ruffed lemurs can learn to do complex tasks simply by watching a fellow member of their troop.
When researchers showed one lemur how to manipulate a simple snack machine, all other lemurs in its troop successfully performed the same trick on their first try. That lemurs can learn socially like their distant primate relatives, including apes and humans, suggests they possess an underpinning to human-like culture.
"We don't really understand how culture evolved," said primatologist Tara Stoinski of Zoo Atlanta, co-author of the upcoming study in Biology Letters. "To do that, we need to look more broadly at primates and include lemurs in cognition research."
Lemurs' only natural habitat is isolated on the southern tip of Madagascar, a large island off the southeast African coast. They are members of a small group of primates called prosimians, which split off the evolutionary tree about 63 million years ago from simians, a grouping of primates that includes gorillas, chimpanzees, Old World monkeys and humans.
Most cognitive research has zeroed in on simian animals and found them to be highly adept in social learning, tool use and other essentials of human-like culture. Lemurs have been mostly excluded because studies in the 1960s suggested they weren't very bright.
"Recently, however, we've seen tool use in lemurs, and recognition of tool features," said psychologist Laurie Santos of Yale University, who studies primate cognition but wasn't involved in Stoinski's research. "For the most part, researchers just really haven't looked."
To test prosimian social learning abilities, Stoinski and her team built a snack-filled tube with two different ways to open it — a hinged door and a sliding door. They trained one lemur to open the hinged door, then had four lemurs watch their comrade repeatedly open it and get snacks inside. They trained the same lemur to use the sliding door to get snacks and exposed four different lemurs to that scene.
Both groups of lemurs emulated the trained animal on their first encounter with the snack-filled tube, and continued to use the same door even though another one existed. One group eventually figured out how to open the other door (by accident), but even so Stoinski said the experiment was one of the first controlled demonstrations of social learning in lemurs.
"This is a means of learning we take for granted as humans," Stoinski said. "We can't say this instance is culture — it's nothing like the equivalent of learning a geisha tea ceremony. But it's what allows for transmittance of cultural norms."
If more evidence piles up in favor of prosimian social learning, it's almost a given that the ability first emerged before prosimian and simian primates split about 63 million years ago, Santos said. "It's the simpler explanation. The more research we do on more distant species of primates, the better window we have to their common ancestor."
In the future, Stoinski would like to try more advanced tests of cognition. Though zoos are good places to perform the research, more studies of lemur troops in the wild would be nice, she said. But that's becoming more difficult as the primates lose their natural habitats.
"Before we can understand how rich of a society lemurs may be capable of, we may lose wild populations," Stoinski said. "If that happens, we lose the ability to answer a lot of questions about how culture emerged."
Images: 1) A baby black and white ruffed lemur. Credit: Zoo Atlanta/Tara Stoinski. 2) A lemur manipulates the device used in the two-action experiment. Credit: Zoo Atlanta/Tara Stoinski. 3) Ring-tailed lemurs sleep in a wildlife park. Credit: Flickr/Daves Portfolio
Posted: 11 Jan 2011 02:06 PM PST
In sediment traces and fossil records from one of Earth's most tumultuous periods, geologists have found a narrative linking mass extinctions with planetary biological and geological change.
After dramatic oceanic extinctions 250 million and 200 million years ago, the global carbon cycle turned chaotic. Earth's biogeochemistry went boom and bust for millions of years thereafter, as if some regulating mechanism were lost — which is exactly what happened.
"People talk about saving biodiversity, and isn't it good to have a variety of all these creatures. But the reason it matters is because ecosystem function is itself dependent on diversity in the face of normal environmental changes," said geologist Jessica Whiteside of Brown University. "Lower diversity too much, and the system will lose its resiliency. It will become a slave to otherwise minor environmental changes."
Whiteside specializes in reading the geological record of past extinctions, teasing from rocks and fossils the story of those times in Earth's history when, for one reason or another, most forms of life ceased to exist.
In the new study, published Jan. 5 in Geology, Whiteside and University of Washington biologist Peter Ward focus on two mass extinctions with especially catastrophic marine consequences: the Permian-Triassic extinction event 250 million years ago, when 96 percent of all ocean species went extinct, and the Triassic-Jurassic extinction 200 million years ago, which extinguished 20 percent of all marine families.
Scientists say that another mass extinction is now underway, with extinction rates an order of magnitude higher than normal, both on land and at sea. Studies like Whiteside's suggest what the extinction's consequences could be — not just for people, on a scale of decades or centuries, but for how the planet will work, millions of years in the future.
"Mass extinction events give us a whole suite of experiments that demonstrate what happens when you have catastrophic diversity loss," said Whiteside.
Ammonoid diversity (left) and carbon-cycle stability (right) from the end-Triassic (top) through end-Permian (bottom) mass extinctions.
She and Ward analyzed seafloor sediments from the coast of British Columbia that accumulated during and between the two extinctions, measuring the ratios of different types of carbon.
Because living creatures metabolize only certain types of carbon, the sediment record becomes a proxy for large-scale patterns in the carbon cycle. It distinguishes those eras when ocean ecosystems — which, at the most fundamental level, serve as giant conduits of carbon between the ocean floor and atmosphere — were productive, and when they were not.
Then Whiteside and Ward looked at the fossil record of ammonoids, a class of creatures that resemble shelled squid and dominated Earth's oceans from 400 million to 65 million years ago. Their fossils are common and well-preserved enough to provide not just a record of biodiversity, but of functional diversity: how different species likely occupied similar ecological niches, providing a built-in redundancy that helps ecosystems weather the loss of individual species.
After each extinction, a rich variety of ammonoid species and body plans was replaced by a few free-floating types. In tandem with this loss of diversity, global carbon cycles oscillated wildly for millions of years. The researchers don't think this was a coincidence. Ecosystems act as thermodynamic stabilizers, and "the carbon cycle integrates biological processes with physical Earth processes," Whiteside said.
As the thinner ecosystems were strained and overwhelmed by the inevitable perturbations of volcanic activity or changes in Earth's orbit, the planet went a bit haywire. The chaos lasted for about 6 million years after each extinction, until new ecosystems formed and stabilized the carbon cycle.
Even though contemporary time is just a blink in geological terms, the findings still have modern relevance, said Whiteside. One might see, at a far smaller scale, similar patterns in regions like the Sea of Japan or off the coast of North Carolina, where overfishing and pollution have produced stripped-down ecosystems devoid of the large predators needed to maintain the rich food webs crucial to a stable carbon cycle.
"What's wonderful about looking at the past is the long lens of geological history," said Whiteside. "There is evidence that food web collapse is starting to occur in some marine ecosystems. It will take a long time for systems to recover."
Images: 1) Ernst Haeckel's illustrations of ammonites./Wikimedia.org. 2) Courtesy Geology.
Citation: "Ammonoid diversity and disparity track episodes of chaotic carbon cycling during the early Mesozoic." By Jessica H. Whiteside and Peter D. Ward. Geology, online publication, Jan. 5, 2011. DOI: 10.1130/G31401.1
Posted: 11 Jan 2011 12:53 PM PST
SEATTLE — The Sloan Digital Sky Survey collaboration released the largest-ever digital color image of the sky today.
The new image consists of 1.2 trillion pixels and covers a third of the night sky, capturing half a billion individual stars and galaxies. Every yellow dot in the image (above) is a galaxy, and zooming in on each dot reveals a galaxy's detailed structure and individual star-forming regions.
"We have that sort of detail for this entire area," said astronomer Michael Blanton of New York University at a press conference here at the American Astronomical Society meeting. "It's not just really big, it's also really useful."
The survey has been taking multicolored images of the sky from a single 2.5 meter telescope in New Mexico since 1998 and releasing the photos to the public almost immediately. Its sharp shots of millions of galaxies laid the foundations for citizen science projects such as Galaxy Zoo, Google Sky and World Wide Telescope.
The first two iterations of the survey, called SDSS-I and SDSS-II, covered part of the sky called the northern galactic cap (bottom right in the image above). SDSS-III ran from July 2008 to December 2009 and completed the survey by covering the entire southern galactic cap (bottom left).
"What makes this a really special moment is that this release really completes the mission of the SDSS camera that's been going on for 11 years," Blanton said. The camera that took images in the part of the electromagnetic spectrum visible to human eyes stopped running in December 2009.
But SDSS will continue to take data in other wavelengths for several years. The new publicly available data dump (which is about 30 terabytes in size) includes spectra of millions of galaxies up to 7 billion light-years away, which will help astronomers understand the history of the universe and the effects of dark energy on cosmic structure. A survey called BOSS, which began in 2009 and will run until 2014, will convert the new 2-D image into the largest 3-D map of the distant universe.
SDSS-III also collected spectra from millions of stars as part of a survey called SEGUE-2, which will help astronomers identify streams of stars that the Milky Way stole from smaller satellite galaxies. Astronomers believe large galaxies formed by cannibalizing smaller galaxies that got too close. The remains of these hapless galaxies show up as streams of stars that still move as a flock through the Milky Way.
"For the parts of the sky where we have SEGUE-2 data, we can make a more complete census of these streams, and get a better idea of how our galaxy grew by seeing the remnants of galaxies that were torn apart by our own galaxy," said astronomer Connie Rockosi of the University of California, Santa Cruz.
"This is going to be a really unique reference for the next decade or longer," Blanton said. "It's a true legacy data set."
Image: M. Blanton and the SDSS-III
Posted: 11 Jan 2011 06:29 AM PST
SEATTLE — Forget about gamma rays from the hearts of distant galaxies. Scientists now believe gamma rays, as well as beams of energetic particles of antimatter, are common components of lightning storms right here on Earth.
In 2009, researchers announced that NASA's Fermi Gamma-ray Space Telescope had, for the first time, detected gamma rays produced by antimatter generated in terrestrial lightning storms (SN: 12/5/09, p. 9).
Now, after analyzing additional gamma-ray signals produced by terrestrial positrons — the antimatter counterpart to electrons — Michael S. Briggs of the University of Alabama in Huntsville and his colleagues think that the antimatter beams do not require special conditions to be generated. Briggs presented the latest findings during a news briefing January 10 at the winter meeting of the American Astronomical Society. Details will also appear in an upcoming Geophysical Research Letters.
"The idea that any planet has thunderstorms that not only produce antimatter but then launch it into space seems like something straight out of science fiction," commented Steven Cummer of Duke University in Durham, North Carolina, who was not part of the study. "That our own planet does this, and has probably done it for hundreds of millions of years, and that we've only just learned it, is amazing to me."
According to Briggs, positrons and electrons form in terrestrial gamma-ray flashes, short bursts of gamma rays produced inside thunderstorms. (First observed in the 1990s, gamma-ray flashes are still not well understood.) When the positrons meet up with the electrons, they annihilate each other, producing gamma rays of a specific energy: 511,000 electron volts.
The Fermi observatory has usually been located directly above thunderstorms when it has detected positron-generated gamma rays, but in four cases, the lightning storms were thousands of kilometers away from the region on Earth that the telescope was observing.
In one striking event on December 14, 2009, Fermi was orbiting over Egypt when the only active storm was in Zambia, some 4,500 kilometers to the south. Because the storm was not in Fermi's line of sight, the craft could not have detected gamma rays that came directly from the terrestrial disturbance. Yet, Fermi did record gamma rays characteristic of annihilation between electrons and positrons that lasted for 30 milliseconds, the longest it has ever recorded such terrestrial signals.
Briggs' team suggests that electrons and positrons produced in the Zambia storm surfed along Earth's magnetic field to strike the Fermi craft. Many of the electrons and positrons annihilated each other immediately, producing the telltale gamma rays. But some of the particles continued on past Fermi and were magnetically reflected back toward the craft 23 milliseconds later, only then pairing off to produce the gamma rays.
The newly discovered antimatter beams "gives us some very important information that we can use to piece together what is going on when lightning initiates and propagates," Cummer said.
Images: 1) A computer simulation shows terrestrial gamma-ray flashes (magenta), associated with lightning storms, producing a beam of high-energy electrons (yellow) and their antimatter counterparts, positrons (green). Both the electrons and positrons travel into space along Earth's magnetic field. Credit: NASA/Goddard. 2) An artist's illustration shows electrons (yellow) accelerating upward from a thunderhead. Credit: NASA/Goddard
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