Last year, researchers uncovered the largest virus yet discovered. With a genome that is over 700,000 base pairs long, the CroV virus has more DNA than some bacteria. Fortunately, it infects a small, unicellular organism that's very distantly related to humans. Now, the same research team is back, this time announcing that they've discovered a virus that attacks CroV, and may just have given rise to all transposable elements, sometimes known as jumping genes.
While studying CroV, the researchers discovered a much smaller virus that frequently accompanied it. The new virus, which they term Mavirus (for "Maverick virus") is still a healthy size, as far as most viruses are concerned, weighing in at just over 19,000 DNA bases, and encoding 20 genes. But Mavirus never appeared on its own; instead, it was only active in cells when the larger CroV was around, even though it could enter cells on its own. The authors conclude that it probably steals CroV's copying machinery for making more Maviruses; this is consistent with the fact that CroV infections slow down when Mavirus is around.
This isn't the first giant virus to be victimized by a smaller peer—there's even a term for this: virophage. But, when the authors looked at the 20 genes carried by Mavirus, they didn't look like the ones from another virophage; instead, they looked something like genes from a specific type of transposable element.
Transposable elements, or transposons, are stretches of DNA that can move around the genome, hopping from place to place. They're so effective at this that about a third of the human genome is composed of various forms of transposons, which don't appear to do anything very helpful, but require energy to copy.
The authors suggest, however, that transposons got their start by doing something useful. The Mavirus helps protect cells from CroV, so cells that permanently incorporate a copy into their genomes could be at a significant advantage. Once in the genome, however, the viral DNA would be free to evolve into something closer to a parasite. The authors predict that, if we look in the right places, we'll find virophages that correspond to most of the major families of transposons.
Monday, March 7, 2011
Sunday, March 6, 2011
Eastern Cougar Is Extinct, U.S. Fish and Wildlife Service Concludes
Although the eastern cougar has been on the endangered species list since 1973, its existence has long been questioned. The U.S. Fish and Wildlife Service (Service) conducted a formal review of the available information and, in a report issued March 2, 2011, concludes the eastern cougar is extinct and recommends the subspecies be removed from the endangered species list.
"We recognize that many people have seen cougars in the wild within the historical range of the eastern cougar," said the Service's Northeast Region Chief of Endangered Species Martin Miller. "However, we believe those cougars are not the eastern cougar subspecies. We found no information to support the existence of the eastern cougar."
Reports of cougars observed in the wild examined during the review process described cougars of other subspecies, often South American subspecies, that had been held in captivity and had escaped or been released to the wild, as well as wild cougars of the western United States subspecies that had migrated eastward to the Midwest.
During the review, the Service received 573 responses to a request for scientific information about the possible existence of the eastern cougar subspecies; conducted an extensive review of U.S. and Canadian scientific literature; and requested information from the 21 States within the historical range of the subspecies. No States expressed a belief in the existence of an eastern cougar population. According to Dr. Mark McCollough, the Service's lead scientist for the eastern cougar, the subspecies of eastern cougar has likely been extinct since the 1930s.
The Service initiated the review as part of its obligations under the Endangered Species Act. The Service will prepare a proposal to remove the eastern cougar from the endangered species list, since extinct animals are not eligible for protection under the Endangered Species Act. The proposal will be made available for public comment.
The Service's decision to declare the eastern cougar extinct does not affect the status of the Florida panther, another wild cat subspecies listed as endangered. Though the Florida panther once ranged throughout the Southeast, it now exists in less than five percent of its historic habitat and in only one breeding population of 120 to 160 animals in southwestern Florida.
Additional information about eastern cougars, including frequently asked questions and cougar sightings, is at: http://www.fws.gov/northeast/ecougar.
Find information about endangered species at http://www.fws.gov/endangered.
(http://www.sciencedaily.com/releases/2011/03/110302190717.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+sciencedaily+%28ScienceDaily:+Latest+Science+News%29&utm_content=Google+Feedfetcher)
"We recognize that many people have seen cougars in the wild within the historical range of the eastern cougar," said the Service's Northeast Region Chief of Endangered Species Martin Miller. "However, we believe those cougars are not the eastern cougar subspecies. We found no information to support the existence of the eastern cougar."
Reports of cougars observed in the wild examined during the review process described cougars of other subspecies, often South American subspecies, that had been held in captivity and had escaped or been released to the wild, as well as wild cougars of the western United States subspecies that had migrated eastward to the Midwest.
During the review, the Service received 573 responses to a request for scientific information about the possible existence of the eastern cougar subspecies; conducted an extensive review of U.S. and Canadian scientific literature; and requested information from the 21 States within the historical range of the subspecies. No States expressed a belief in the existence of an eastern cougar population. According to Dr. Mark McCollough, the Service's lead scientist for the eastern cougar, the subspecies of eastern cougar has likely been extinct since the 1930s.
The Service initiated the review as part of its obligations under the Endangered Species Act. The Service will prepare a proposal to remove the eastern cougar from the endangered species list, since extinct animals are not eligible for protection under the Endangered Species Act. The proposal will be made available for public comment.
The Service's decision to declare the eastern cougar extinct does not affect the status of the Florida panther, another wild cat subspecies listed as endangered. Though the Florida panther once ranged throughout the Southeast, it now exists in less than five percent of its historic habitat and in only one breeding population of 120 to 160 animals in southwestern Florida.
Additional information about eastern cougars, including frequently asked questions and cougar sightings, is at: http://www.fws.gov/northeast/ecougar.
Find information about endangered species at http://www.fws.gov/endangered.
(http://www.sciencedaily.com/releases/2011/03/110302190717.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+sciencedaily+%28ScienceDaily:+Latest+Science+News%29&utm_content=Google+Feedfetcher)
Saturday, March 5, 2011
Supercritical carbon dioxide Brayton Cycle turbines promise giant leap
ALBUQUERQUE, N.M. — Sandia National Laboratories researchers are moving into the demonstration phase of a novel gas turbine system for power generation, with the promise that thermal-to-electric conversion efficiency will be increased to as much as 50 percent — an improvement of 50 percent for nuclear power stations equipped with steam turbines, or a 40 percent improvement for simple gas turbines. The system is also very compact, meaning that capital costs would be relatively low.
Research focuses on supercritical carbon dioxide (S-CO2) Brayton-cycle turbines, which typically would be used for bulk thermal and nuclear generation of electricity, including next-generation power reactors. The goal is eventually to replace steam-driven Rankine cycle turbines, which have lower efficiency, are corrosive at high temperature and occupy 30 times as much space because of the need for very large turbines and condensers to dispose of excess steam. The Brayton cycle could yield 20 megawatts of electricity from a package with a volume as small as four cubic meters.
The Brayton cycle, named after George Brayton, originally functioned by heating air in a confined space and then releasing it in a particular direction. The same principle is used to power jet engines today.
"This machine is basically a jet engine running on a hot liquid," said principal investigator Steve Wright of Sandia's Advanced Nuclear Concepts group. "There is a tremendous amount of industrial and scientific interest in supercritical CO2 systems for power generation using all potential heat sources including solar, geothermal, fossil fuel, biofuel and nuclear."
Sandia currently has two supercritical CO2 test loops. (The term "loop" derives from the shape taken by the working fluid as it completes each circuit.) A power production loop is located at the Arvada, Colo., site of contractor Barber Nichols Inc., where it has been running and producing approximately 240 kilowatts of electricity during the developmental phase that began in March 2010. It is now being upgraded and is expected to be shipped to Sandia this summer.
A second loop, located at Sandia in Albuquerque, is used to research the unusual issues of compression, bearings, seals, and friction that exist near the critical point, where the carbon dioxide has the density of liquid but otherwise has many of the properties of a gas.
Immediate plans call for Sandia to continue to develop and operate the small test loops to identify key features and technologies. Test results will illustrate the capability of the concept, particularly its compactness, efficiency and scalability to larger systems. Future plans call for commercialization of the technology and development of an industrial demonstration plant at 10 MW of electricity.
A competing system, also at Sandia and using Brayton cycles with helium as the working fluid, is designed to operate at about 925 degrees C and is expected to produce electrical power at 43 percent to 46 percent efficiency. By contrast, the supercritical CO2 Brayton cycle provides the same efficiency as helium Brayton systems but at a considerably lower temperature (250-300 C). The S-CO2 equipment is also more compact than that of the helium cycle, which in turn is more compact than the conventional steam cycle.
Under normal conditions materials behave in a predictable, classical, "ideal" way as conditions cause them to change phase, as when water turns to steam. But this model tends not to work at lower temperatures or higher pressures than those that exist at these critical points. In the case of carbon dioxide, it becomes an unusually dense "supercritical" liquid at the point where it is held between the gas phase and liquid phase. The supercritical properties of carbon dioxide at temperatures above 500 C and pressures above 7.6 megapascals enable the system to operate with very high thermal efficiency, exceeding even those of a large coal-generated power plant and nearly twice as efficient as that of a gasoline engine (about 25 percent).
In other words, as compared with other gas turbines the S-CO2 Brayton system could increase the electrical power produced per unit of fuel by 40 percent or more. The combination of low temperatures, high efficiency and high power density allows for the development of very compact, transportable systems that are more affordable because only standard engineering materials (stainless steel) are required, less material is needed, and the small size allows for advanced-modular manufacturing processes.
"Sandia is not alone in this field, but we are in the lead," Wright said. "We're past the point of wondering if these power systems are going to be developed; the question remains of who will be first to market. Sandia and DOE have a wonderful opportunity in the commercialization effort."
Research focuses on supercritical carbon dioxide (S-CO2) Brayton-cycle turbines, which typically would be used for bulk thermal and nuclear generation of electricity, including next-generation power reactors. The goal is eventually to replace steam-driven Rankine cycle turbines, which have lower efficiency, are corrosive at high temperature and occupy 30 times as much space because of the need for very large turbines and condensers to dispose of excess steam. The Brayton cycle could yield 20 megawatts of electricity from a package with a volume as small as four cubic meters.
The Brayton cycle, named after George Brayton, originally functioned by heating air in a confined space and then releasing it in a particular direction. The same principle is used to power jet engines today.
"This machine is basically a jet engine running on a hot liquid," said principal investigator Steve Wright of Sandia's Advanced Nuclear Concepts group. "There is a tremendous amount of industrial and scientific interest in supercritical CO2 systems for power generation using all potential heat sources including solar, geothermal, fossil fuel, biofuel and nuclear."
Sandia currently has two supercritical CO2 test loops. (The term "loop" derives from the shape taken by the working fluid as it completes each circuit.) A power production loop is located at the Arvada, Colo., site of contractor Barber Nichols Inc., where it has been running and producing approximately 240 kilowatts of electricity during the developmental phase that began in March 2010. It is now being upgraded and is expected to be shipped to Sandia this summer.
A second loop, located at Sandia in Albuquerque, is used to research the unusual issues of compression, bearings, seals, and friction that exist near the critical point, where the carbon dioxide has the density of liquid but otherwise has many of the properties of a gas.
Immediate plans call for Sandia to continue to develop and operate the small test loops to identify key features and technologies. Test results will illustrate the capability of the concept, particularly its compactness, efficiency and scalability to larger systems. Future plans call for commercialization of the technology and development of an industrial demonstration plant at 10 MW of electricity.
A competing system, also at Sandia and using Brayton cycles with helium as the working fluid, is designed to operate at about 925 degrees C and is expected to produce electrical power at 43 percent to 46 percent efficiency. By contrast, the supercritical CO2 Brayton cycle provides the same efficiency as helium Brayton systems but at a considerably lower temperature (250-300 C). The S-CO2 equipment is also more compact than that of the helium cycle, which in turn is more compact than the conventional steam cycle.
Under normal conditions materials behave in a predictable, classical, "ideal" way as conditions cause them to change phase, as when water turns to steam. But this model tends not to work at lower temperatures or higher pressures than those that exist at these critical points. In the case of carbon dioxide, it becomes an unusually dense "supercritical" liquid at the point where it is held between the gas phase and liquid phase. The supercritical properties of carbon dioxide at temperatures above 500 C and pressures above 7.6 megapascals enable the system to operate with very high thermal efficiency, exceeding even those of a large coal-generated power plant and nearly twice as efficient as that of a gasoline engine (about 25 percent).
In other words, as compared with other gas turbines the S-CO2 Brayton system could increase the electrical power produced per unit of fuel by 40 percent or more. The combination of low temperatures, high efficiency and high power density allows for the development of very compact, transportable systems that are more affordable because only standard engineering materials (stainless steel) are required, less material is needed, and the small size allows for advanced-modular manufacturing processes.
"Sandia is not alone in this field, but we are in the lead," Wright said. "We're past the point of wondering if these power systems are going to be developed; the question remains of who will be first to market. Sandia and DOE have a wonderful opportunity in the commercialization effort."
Friday, March 4, 2011
Self-Doubting Monkeys Know What They Don’t Know
by Patrick Morgan
The number of traits chalked up as “distinctly human” seem to dwindle each year. And now, we can’t even say that we’re uniquely aware of the limits of our knowledge: It seems that some monkeys understand uncertainty too.
A team of researchers taught macaques how to maneuver a joystick to indicate whether the pixel density on a screen was sparse or dense. Given a pixel scenario, the monkeys would maneuver a joystick to a letter S (for sparse) or D (for dense). They were given a treat when they selected the correct answer, but when they were wrong, the game paused for a couple seconds. A third possible answer, though, allowed the monkeys to select a question mark, and thereby forgo the pause (and potentially get more treats).
And as John David Smith, a researcher at SUNY Buffalo, and Michael Beran, a researcher at Georgia State University, announced at the AAAS meeting this weekend, the macaques selected the question mark just as humans do when they encounter a mind-stumping question. As Smith told the BBC, “Monkeys apparently appreciate when they are likely to make an error…. They seem to know when they don’t know.”
These findings aren’t applicable to all species of monkeys: The researchers also trained capuchin monkeys, and this species never selected the uncertainty button. These findings may have important evolutionary implications because macaques and capuchins have different lineages: macaques are old world monkeys, and capuchins are new world monkeys.
(http://blogs.discovermagazine.com/discoblog/2011/02/22/self-doubting-monkeys-know-what-they-dont-know/)
The number of traits chalked up as “distinctly human” seem to dwindle each year. And now, we can’t even say that we’re uniquely aware of the limits of our knowledge: It seems that some monkeys understand uncertainty too.
A team of researchers taught macaques how to maneuver a joystick to indicate whether the pixel density on a screen was sparse or dense. Given a pixel scenario, the monkeys would maneuver a joystick to a letter S (for sparse) or D (for dense). They were given a treat when they selected the correct answer, but when they were wrong, the game paused for a couple seconds. A third possible answer, though, allowed the monkeys to select a question mark, and thereby forgo the pause (and potentially get more treats).
And as John David Smith, a researcher at SUNY Buffalo, and Michael Beran, a researcher at Georgia State University, announced at the AAAS meeting this weekend, the macaques selected the question mark just as humans do when they encounter a mind-stumping question. As Smith told the BBC, “Monkeys apparently appreciate when they are likely to make an error…. They seem to know when they don’t know.”
These findings aren’t applicable to all species of monkeys: The researchers also trained capuchin monkeys, and this species never selected the uncertainty button. These findings may have important evolutionary implications because macaques and capuchins have different lineages: macaques are old world monkeys, and capuchins are new world monkeys.
(http://blogs.discovermagazine.com/discoblog/2011/02/22/self-doubting-monkeys-know-what-they-dont-know/)
Thursday, March 3, 2011
Walking cactus discovered in China
By Wynne Parry
The so-called walking cactus belongs to a group of extinct worm-like creatures called lobopodians that are thought to have given rise to arthropods. Spiders and other arthropods have segmented bodies and jointed limbs covered in a hardened shell.
Before the discovery of the walking cactus, Diania cactiformis, all lobopodian remains had soft bodies and soft limbs, said Jianni Liu, the lead researcher who is affiliated with Northwest University in China and Freie University in Germany.
"Walking cactus is very important because it is sort of a missing link from lobopodians to arthropods," Liu told LiveScience. "Scientists have always suspected that arthropods evolved from somewhere amongst lobopodians, but until now we didn't have a single fossil you could point at and say that is the first one with jointed legs. And this is what walking cactus shows." [Image of walking cactus fossil]
Liu and other researchers described the extinct creature based on three complete fossils and 30 partial ones discovered in Yunnan Province in southern China. The walking cactus had a body divided into nine segments with 10 pairs of hardened, jointed legs, and it measured about 2.4 inches (6 centimeters) long.
It's not clear how the leggy worm made its living. It could have used its tube-like mouth called a proboscis to suck tiny things from the mud, or it may have used its spiny front legs to grab prey, Liu said.
Clues to arthropod evolution are preserved in modern-day velvet worms, which are considered the only living relative to all arthropods. Once mistaken for slugs, these land-dwelling worms are almost entirely soft-bodied except for hardened claws and jaws.
The discovery of the walking cactus helps fill in the evolutionary history between the velvet worms and modern arthropods, which, in terms of numbers and diversity, are the most dominant group of animals on the planet, according to Graham Budd, a professor of paleobiology at Uppsala University in Sweden, who was not involved in the current study.
The walking cactus is the first and only case of hardened, jointed limbs built for walking appearing in a creature that is not recognizable as an arthropod, Budd said.
But Budd is not convinced that, as the researchers argue, the walking cactus's hardened legs were passed directly down to modern arthropods.
"I am not persuaded that it is a direct ancestor or as closely related to living arthropods as they suggest," he told LiveScience. "I would like to see more evidence; the great thing is a lot more material keeps coming up."
For instance, it is possible that the walking cactus is less closely related to modern arthropods, and that hardened legs evolved multiple times. It is also possible that the bodies of primitive arthropods hardened before their legs did, Budd said.
New fossils, particularly from China, have helped clarify the evolutionary history of arthropods, and in the last decade or so, scientists have come to more consensus regarding that history, he added.
(http://www.csmonitor.com/Science/2011/0225/Walking-cactus-discovered-in-China)
The so-called walking cactus belongs to a group of extinct worm-like creatures called lobopodians that are thought to have given rise to arthropods. Spiders and other arthropods have segmented bodies and jointed limbs covered in a hardened shell.
Before the discovery of the walking cactus, Diania cactiformis, all lobopodian remains had soft bodies and soft limbs, said Jianni Liu, the lead researcher who is affiliated with Northwest University in China and Freie University in Germany.
"Walking cactus is very important because it is sort of a missing link from lobopodians to arthropods," Liu told LiveScience. "Scientists have always suspected that arthropods evolved from somewhere amongst lobopodians, but until now we didn't have a single fossil you could point at and say that is the first one with jointed legs. And this is what walking cactus shows." [Image of walking cactus fossil]
Liu and other researchers described the extinct creature based on three complete fossils and 30 partial ones discovered in Yunnan Province in southern China. The walking cactus had a body divided into nine segments with 10 pairs of hardened, jointed legs, and it measured about 2.4 inches (6 centimeters) long.
It's not clear how the leggy worm made its living. It could have used its tube-like mouth called a proboscis to suck tiny things from the mud, or it may have used its spiny front legs to grab prey, Liu said.
Clues to arthropod evolution are preserved in modern-day velvet worms, which are considered the only living relative to all arthropods. Once mistaken for slugs, these land-dwelling worms are almost entirely soft-bodied except for hardened claws and jaws.
The discovery of the walking cactus helps fill in the evolutionary history between the velvet worms and modern arthropods, which, in terms of numbers and diversity, are the most dominant group of animals on the planet, according to Graham Budd, a professor of paleobiology at Uppsala University in Sweden, who was not involved in the current study.
The walking cactus is the first and only case of hardened, jointed limbs built for walking appearing in a creature that is not recognizable as an arthropod, Budd said.
But Budd is not convinced that, as the researchers argue, the walking cactus's hardened legs were passed directly down to modern arthropods.
"I am not persuaded that it is a direct ancestor or as closely related to living arthropods as they suggest," he told LiveScience. "I would like to see more evidence; the great thing is a lot more material keeps coming up."
For instance, it is possible that the walking cactus is less closely related to modern arthropods, and that hardened legs evolved multiple times. It is also possible that the bodies of primitive arthropods hardened before their legs did, Budd said.
New fossils, particularly from China, have helped clarify the evolutionary history of arthropods, and in the last decade or so, scientists have come to more consensus regarding that history, he added.
(http://www.csmonitor.com/Science/2011/0225/Walking-cactus-discovered-in-China)
Wednesday, March 2, 2011
Taming the Wild -- Why Can't All Animals Be Tamed?
By Evan Ratliff
"Hello! How are you doing?" Lyudmila Trut says, reaching down to unlatch the door of a wire cage labeled "Mavrik." We're standing between two long rows of similar crates on a farm just outside the city of Novosibirsk, in southern Siberia, and the 76-year-old biologist's greeting is addressed not to me but to the cage's furry occupant. Although I don't speak Russian, I recognize in her voice the tone of maternal adoration that dog owners adopt when addressing their pets.
Mavrik, the object of Trut's attention, is about the size of a Shetland sheepdog, with chestnut orange fur and a white bib down his front. He plays his designated role in turn: wagging his tail, rolling on his back, panting eagerly in anticipation of attention. In adjacent cages lining either side of the narrow, open-sided shed, dozens of canids do the same, yelping and clamoring in an explosion of fur and unbridled excitement. "As you can see," Trut says above the din, "all of them want human contact." Today, however, Mavrik is the lucky recipient. Trut reaches in and scoops him up, then hands him over to me. Cradled in my arms, gently jawing my hand in his mouth, he's as docile as any lapdog.
Except that Mavrik, as it happens, is not a dog at all. He's a fox. Hidden away on this overgrown property, flanked by birch forests and barred by a rusty metal gate, he and several hundred of his relatives are the only population of domesticated silver foxes in the world. (Most of them are, indeed, silver or dark gray; Mavrik is rare in his chestnut fur.) And by "domesticated" I don't mean captured and tamed, or raised by humans and conditioned by food to tolerate the occasional petting. I mean bred for domestication, as tame as your tabby cat or your Labrador. In fact, says Anna Kukekova, a Cornell researcher who studies the foxes, "they remind me a lot of golden retrievers, who are basically not aware that there are good people, bad people, people that they have met before, and those they haven't." These foxes treat any human as a potential companion, a behavior that is the product of arguably the most extraordinary breeding experiment ever conducted.
It started more than a half century ago, when Trut was still a graduate student. Led by a biologist named Dmitry Belyaev, researchers at the nearby Institute of Cytology and Genetics gathered up 130 foxes from fur farms. They then began breeding them with the goal of re-creating the evolution of wolves into dogs, a transformation that began more than 15,000 years ago.
With each generation of fox kits, Belyaev and his colleagues tested their reactions to human contact, selecting those most approachable to breed for the next generation. By the mid-1960s the experiment was working beyond what he could've imagined. They were producing foxes like Mavrik, not just unafraid of humans but actively seeking to bond with them. His team even repeated the experiment in two other species, mink and rats. "One huge thing that Belyaev showed was the timescale," says Gordon Lark, a University of Utah biologist who studies dog genetics. "If you told me the animal would now come sniff you at the front of the cage, I would say it's what I expect. But that they would become that friendly toward humans that quickly… wow."
Miraculously, Belyaev had compressed thousands of years of domestication into a few years. But he wasn't just looking to prove he could create friendly foxes. He had a hunch that he could use them to unlock domestication's molecular mysteries. Domesticated animals are known to share a common set of characteristics, a fact documented by Darwin in The Variation of Animals and Plants Under Domestication. They tend to be smaller, with floppier ears and curlier tails than their untamed progenitors. Such traits tend to make animals appear appealingly juvenile to humans. Their coats are sometimes spotted—piebald, in scientific terminology—while their wild ancestors' coats are solid. These and other traits, sometimes referred to as the domestication phenotype, exist in varying degrees across a remarkably wide range of species, from dogs, pigs, and cows to some nonmammalians like chickens, and even a few fish.
Belyaev suspected that as the foxes became domesticated, they too might begin to show aspects of a domestication phenotype. He was right again: Selecting which foxes to breed based solely on how well they got along with humans seemed to alter their physical appearance along with their dispositions. After only nine generations, the researchers recorded fox kits born with floppier ears. Piebald patterns appeared on their coats. By this time the foxes were already whining and wagging their tails in response to a human presence, behaviors never seen in wild foxes.
Driving those changes, Belyaev postulated, was a collection of genes that conferred a propensity to tameness—a genotype that the foxes perhaps shared with any species that could be domesticated. Here on the fox farm, Kukekova and Trut are searching for precisely those genes today. Elsewhere, researchers are delving into the DNA of pigs, chickens, horses, and other domesticated species, looking to pinpoint the genetic differences that came to distinguish them from their ancestors. The research, accelerated by the recent advances in rapid genome sequencing, aims to answer a fundamental biological question: "How is it possible to make this huge transformation from wild animals into domestic animals?" says Leif Andersson, a professor of genome biology at Uppsala University, in Sweden. The answer has implications for understanding not just how we domesticated animals, but how we tamed the wild in ourselves as well.
The exercise of dominion over plants and animals is arguably the most consequential event in human history. Along with cultivated agriculture, the ability to raise and manage domesticated fauna—of which wolves were likely the first, but chickens, cattle, and other food species the most important—altered the human diet, paving the way for settlements and eventually nation-states to flourish. By putting humans in close contact with animals, domestication also created vectors for the diseases that shaped society.
Yet the process by which it all happened has remained stubbornly impenetrable. Animal bones and stone carvings can sometimes shed light on the when and where each species came to live side by side with humans. More difficult to untangle is the how. Did a few curious boar creep closer to human populations, feeding off their garbage and with each successive generation becoming a little more a part of our diet? Did humans capture red jungle fowl, the ancestor of the modern chicken, straight from the wild—or did the fowl make the first approach? Out of 148 large mammal species on Earth, why have no more than 15 ever been domesticated? Why have we been able to tame and breed horses for thousands of years, but never their close relative the zebra, despite numerous attempts?
In fact, scientists have even struggled to define domestication precisely. We all know that individual animals can be trained to exist in close contact with humans. A tiger cub fed by hand, imprinting on its captors, may grow up to treat them like family. But that tiger's offspring, at birth, will be just as wild as its ancestors. Domestication, by contrast, is not a quality trained into an individual, but one bred into an entire population through generations of living in proximity to humans. Many if not most of the species' wild instincts have long since been lost. Domestication, in other words, is mostly in the genes.
Yet the borders between domesticated and wild are often fluid. A growing body of evidence shows that historically, domesticated animals likely played a large part in their own taming, habituating themselves to humans before we took an active role in the process. "My working hypothesis," says Greger Larson, an expert on genetics and domestication at Durham University in the United Kingdom, "is that with most of the early animals—dogs first, then pigs, sheep, and goats—there was probably a long period of time of unintentional management by humans." The word domestication "implies something top down, something that humans did intentionally," he says. "But the complex story is so much more interesting."
(http://ngm.nationalgeographic.com/2011/03/taming-wild-animals/ratliff-text)
"Hello! How are you doing?" Lyudmila Trut says, reaching down to unlatch the door of a wire cage labeled "Mavrik." We're standing between two long rows of similar crates on a farm just outside the city of Novosibirsk, in southern Siberia, and the 76-year-old biologist's greeting is addressed not to me but to the cage's furry occupant. Although I don't speak Russian, I recognize in her voice the tone of maternal adoration that dog owners adopt when addressing their pets.
Mavrik, the object of Trut's attention, is about the size of a Shetland sheepdog, with chestnut orange fur and a white bib down his front. He plays his designated role in turn: wagging his tail, rolling on his back, panting eagerly in anticipation of attention. In adjacent cages lining either side of the narrow, open-sided shed, dozens of canids do the same, yelping and clamoring in an explosion of fur and unbridled excitement. "As you can see," Trut says above the din, "all of them want human contact." Today, however, Mavrik is the lucky recipient. Trut reaches in and scoops him up, then hands him over to me. Cradled in my arms, gently jawing my hand in his mouth, he's as docile as any lapdog.
Except that Mavrik, as it happens, is not a dog at all. He's a fox. Hidden away on this overgrown property, flanked by birch forests and barred by a rusty metal gate, he and several hundred of his relatives are the only population of domesticated silver foxes in the world. (Most of them are, indeed, silver or dark gray; Mavrik is rare in his chestnut fur.) And by "domesticated" I don't mean captured and tamed, or raised by humans and conditioned by food to tolerate the occasional petting. I mean bred for domestication, as tame as your tabby cat or your Labrador. In fact, says Anna Kukekova, a Cornell researcher who studies the foxes, "they remind me a lot of golden retrievers, who are basically not aware that there are good people, bad people, people that they have met before, and those they haven't." These foxes treat any human as a potential companion, a behavior that is the product of arguably the most extraordinary breeding experiment ever conducted.
It started more than a half century ago, when Trut was still a graduate student. Led by a biologist named Dmitry Belyaev, researchers at the nearby Institute of Cytology and Genetics gathered up 130 foxes from fur farms. They then began breeding them with the goal of re-creating the evolution of wolves into dogs, a transformation that began more than 15,000 years ago.
With each generation of fox kits, Belyaev and his colleagues tested their reactions to human contact, selecting those most approachable to breed for the next generation. By the mid-1960s the experiment was working beyond what he could've imagined. They were producing foxes like Mavrik, not just unafraid of humans but actively seeking to bond with them. His team even repeated the experiment in two other species, mink and rats. "One huge thing that Belyaev showed was the timescale," says Gordon Lark, a University of Utah biologist who studies dog genetics. "If you told me the animal would now come sniff you at the front of the cage, I would say it's what I expect. But that they would become that friendly toward humans that quickly… wow."
Miraculously, Belyaev had compressed thousands of years of domestication into a few years. But he wasn't just looking to prove he could create friendly foxes. He had a hunch that he could use them to unlock domestication's molecular mysteries. Domesticated animals are known to share a common set of characteristics, a fact documented by Darwin in The Variation of Animals and Plants Under Domestication. They tend to be smaller, with floppier ears and curlier tails than their untamed progenitors. Such traits tend to make animals appear appealingly juvenile to humans. Their coats are sometimes spotted—piebald, in scientific terminology—while their wild ancestors' coats are solid. These and other traits, sometimes referred to as the domestication phenotype, exist in varying degrees across a remarkably wide range of species, from dogs, pigs, and cows to some nonmammalians like chickens, and even a few fish.
Belyaev suspected that as the foxes became domesticated, they too might begin to show aspects of a domestication phenotype. He was right again: Selecting which foxes to breed based solely on how well they got along with humans seemed to alter their physical appearance along with their dispositions. After only nine generations, the researchers recorded fox kits born with floppier ears. Piebald patterns appeared on their coats. By this time the foxes were already whining and wagging their tails in response to a human presence, behaviors never seen in wild foxes.
Driving those changes, Belyaev postulated, was a collection of genes that conferred a propensity to tameness—a genotype that the foxes perhaps shared with any species that could be domesticated. Here on the fox farm, Kukekova and Trut are searching for precisely those genes today. Elsewhere, researchers are delving into the DNA of pigs, chickens, horses, and other domesticated species, looking to pinpoint the genetic differences that came to distinguish them from their ancestors. The research, accelerated by the recent advances in rapid genome sequencing, aims to answer a fundamental biological question: "How is it possible to make this huge transformation from wild animals into domestic animals?" says Leif Andersson, a professor of genome biology at Uppsala University, in Sweden. The answer has implications for understanding not just how we domesticated animals, but how we tamed the wild in ourselves as well.
The exercise of dominion over plants and animals is arguably the most consequential event in human history. Along with cultivated agriculture, the ability to raise and manage domesticated fauna—of which wolves were likely the first, but chickens, cattle, and other food species the most important—altered the human diet, paving the way for settlements and eventually nation-states to flourish. By putting humans in close contact with animals, domestication also created vectors for the diseases that shaped society.
Yet the process by which it all happened has remained stubbornly impenetrable. Animal bones and stone carvings can sometimes shed light on the when and where each species came to live side by side with humans. More difficult to untangle is the how. Did a few curious boar creep closer to human populations, feeding off their garbage and with each successive generation becoming a little more a part of our diet? Did humans capture red jungle fowl, the ancestor of the modern chicken, straight from the wild—or did the fowl make the first approach? Out of 148 large mammal species on Earth, why have no more than 15 ever been domesticated? Why have we been able to tame and breed horses for thousands of years, but never their close relative the zebra, despite numerous attempts?
In fact, scientists have even struggled to define domestication precisely. We all know that individual animals can be trained to exist in close contact with humans. A tiger cub fed by hand, imprinting on its captors, may grow up to treat them like family. But that tiger's offspring, at birth, will be just as wild as its ancestors. Domestication, by contrast, is not a quality trained into an individual, but one bred into an entire population through generations of living in proximity to humans. Many if not most of the species' wild instincts have long since been lost. Domestication, in other words, is mostly in the genes.
Yet the borders between domesticated and wild are often fluid. A growing body of evidence shows that historically, domesticated animals likely played a large part in their own taming, habituating themselves to humans before we took an active role in the process. "My working hypothesis," says Greger Larson, an expert on genetics and domestication at Durham University in the United Kingdom, "is that with most of the early animals—dogs first, then pigs, sheep, and goats—there was probably a long period of time of unintentional management by humans." The word domestication "implies something top down, something that humans did intentionally," he says. "But the complex story is so much more interesting."
(http://ngm.nationalgeographic.com/2011/03/taming-wild-animals/ratliff-text)
Tuesday, March 1, 2011
Cats Adore, Manipulate Women
By Jennifer Viegas
The bond between cats and their owners turns out to be far more intense than imagined, especially for cat aficionado women and their affection reciprocating felines, suggests a new study.
Cats attach to humans, and particularly women, as social partners, and it's not just for the sake of obtaining food, according to the new research, which has been accepted for publication in the journal Behavioural Processes.
The study is the first to show in detail that the dynamics underlying cat-human relationships are nearly identical to human-only bonds, with cats sometimes even becoming a furry "child" in nurturing homes.
"Food is often used as a token of affection, and the ways that cats and humans relate to food are similar in nature to the interactions seen between the human caregiver and the pre-verbal infant," co-author Jon Day, a Waltham Centre for Pet Nutrition researcher, told Discovery News. "Both cat and human infant are, at least in part, in control of when and what they are fed!"
For the study, led by Kurt Kotrschal of the Konrad Lorenz Research Station and the University of Vienna, the researchers videotaped and later analyzed interactions between 41 cats and their owners over lengthy four-part periods. Each and every behavior of both the cat and owner was noted. Owner and cat personalities were also assessed in a separate test. For the cat assessment, the authors placed a stuffed owl toy with large glass eyes on a floor so the feline would encounter it by surprise.
The researchers determined that cats and their owners strongly influenced each other, such that they were each often controlling the other's behaviors. Extroverted women with young, active cats enjoyed the greatest synchronicity, with cats in these relationships only having to use subtle cues, such as a single upright tail move, to signal desire for friendly contact.
While cats have plenty of male admirers, and vice versa, this study and others reveal that women tend to interact with their cats -- be they male or female felines -- more than men do.
"In response, the cats approach female owners more frequently, and initiate contact more frequently (such as jumping on laps) than they do with male owners," co-author Manuela Wedl of the University of Vienna told Discovery News, adding that "female owners have more intense relationships with their cats than do male owners."
Cats also seem to remember kindness and return the favors later. If owners comply with their feline's wishes to interact, then the cat will often comply with the owner's wishes at other times. The cat may also "have an edge in this negotiation," since owners are usually already motivated to establish social contact.
Although there are isolated instances of non-human animals, such as gorillas, bonding with other species, it seems to be mostly unique for humans to engage in social relationships with other animals. In this case with cats, it's for very good reason. Cats could very well be man's -- and woman's -- best friend.
"A relationship between a cat and a human can involve mutual attraction, personality compatibility, ease of interaction, play, affection and social support," co-author Dorothy Gracey of the University of Vienna explained. "A human and a cat can mutually develop complex ritualized interactions that show substantial mutual understanding of each other's inclinations and preferences."
Dennis Turner, a University of Zurich-Irchel animal behaviorist, told Discovery News the he's "very impressed with this study on human-cat interactions, in that it has taken our earlier findings a step higher, using more modern analytical techniques to get at the interplay between cat and human personalities."
Turner, who is also senior editor of The Domestic Cat: The Biology of Its Behaviour (Cambridge University Press), added that he and his colleagues "now have a new dimension to help us understand how these relationships function."
Kotrschal's team is presently involved in a long-term study of man's other well-known animal best friend: dogs.
The bond between cats and their owners turns out to be far more intense than imagined, especially for cat aficionado women and their affection reciprocating felines, suggests a new study.
Cats attach to humans, and particularly women, as social partners, and it's not just for the sake of obtaining food, according to the new research, which has been accepted for publication in the journal Behavioural Processes.
The study is the first to show in detail that the dynamics underlying cat-human relationships are nearly identical to human-only bonds, with cats sometimes even becoming a furry "child" in nurturing homes.
"Food is often used as a token of affection, and the ways that cats and humans relate to food are similar in nature to the interactions seen between the human caregiver and the pre-verbal infant," co-author Jon Day, a Waltham Centre for Pet Nutrition researcher, told Discovery News. "Both cat and human infant are, at least in part, in control of when and what they are fed!"
For the study, led by Kurt Kotrschal of the Konrad Lorenz Research Station and the University of Vienna, the researchers videotaped and later analyzed interactions between 41 cats and their owners over lengthy four-part periods. Each and every behavior of both the cat and owner was noted. Owner and cat personalities were also assessed in a separate test. For the cat assessment, the authors placed a stuffed owl toy with large glass eyes on a floor so the feline would encounter it by surprise.
The researchers determined that cats and their owners strongly influenced each other, such that they were each often controlling the other's behaviors. Extroverted women with young, active cats enjoyed the greatest synchronicity, with cats in these relationships only having to use subtle cues, such as a single upright tail move, to signal desire for friendly contact.
While cats have plenty of male admirers, and vice versa, this study and others reveal that women tend to interact with their cats -- be they male or female felines -- more than men do.
"In response, the cats approach female owners more frequently, and initiate contact more frequently (such as jumping on laps) than they do with male owners," co-author Manuela Wedl of the University of Vienna told Discovery News, adding that "female owners have more intense relationships with their cats than do male owners."
Cats also seem to remember kindness and return the favors later. If owners comply with their feline's wishes to interact, then the cat will often comply with the owner's wishes at other times. The cat may also "have an edge in this negotiation," since owners are usually already motivated to establish social contact.
Although there are isolated instances of non-human animals, such as gorillas, bonding with other species, it seems to be mostly unique for humans to engage in social relationships with other animals. In this case with cats, it's for very good reason. Cats could very well be man's -- and woman's -- best friend.
"A relationship between a cat and a human can involve mutual attraction, personality compatibility, ease of interaction, play, affection and social support," co-author Dorothy Gracey of the University of Vienna explained. "A human and a cat can mutually develop complex ritualized interactions that show substantial mutual understanding of each other's inclinations and preferences."
Dennis Turner, a University of Zurich-Irchel animal behaviorist, told Discovery News the he's "very impressed with this study on human-cat interactions, in that it has taken our earlier findings a step higher, using more modern analytical techniques to get at the interplay between cat and human personalities."
Turner, who is also senior editor of The Domestic Cat: The Biology of Its Behaviour (Cambridge University Press), added that he and his colleagues "now have a new dimension to help us understand how these relationships function."
Kotrschal's team is presently involved in a long-term study of man's other well-known animal best friend: dogs.
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