Thursday, November 25, 2010

DARWIN'S THEORY OF GRADUAL EVOLUTION NOT SUPPORTED BY GEOLOGICAL HISTORY

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Charles Darwin's theory of gradual evolution is not supported by geological history, New York University Geologist Michael Rampino concludes in an essay in the journal Historical Biology. In fact, Rampino notes that a more accurate theory of gradual evolution, positing that long periods of evolutionary stability are disrupted by catastrophic mass extinctions of life, was put forth by Scottish horticulturalist Patrick Matthew prior to Darwin's published work on the topic.

"Matthew discovered and clearly stated the idea of natural selection, applied it to the origin of species, and placed it in the context of a geologic record marked by catastrophic mass extinctions followed by relatively rapid adaptations," says Rampino, whose research on catastrophic events includes studies on volcano eruptions and asteroid impacts. "In light of the recent acceptance of the importance of catastrophic mass extinctions in the history of life, it may be time to reconsider the evolutionary views of Patrick Matthew as much more in line with present ideas regarding biological evolution than the Darwin view."

Matthew (1790-1874), Rampino notes, published a statement of the law of natural selection in a little-read Appendix to his 1831 book Naval Timber and Arboriculture. Even though both Darwin and his colleague Alfred Russel Wallace acknowledged that Matthew was the first to put forth the theory of natural selection, historians have attributed the unveiling of the theory to Darwin and Wallace. Darwin's notebooks show that he arrived at the idea in 1838, and he composed an essay on natural selection as early as 1842—years after Matthew's work appeared. Darwin and Wallace's theory was formally presented in 1858 at a science society meeting in London. Darwin's Origin of Species appeared a year later.

In the Appendix of Naval Timber and Arboriculture, Matthew described the theory of natural selection in a way that Darwin later echoed: "There is a natural law universal in nature, tending to render every reproductive being the best possibly suited to its condition…As the field of existence is limited and pre-occupied, it is only the hardier, more robust, better suited to circumstance individuals, who are able to struggle forward to maturity…"

However, in explaining the forces that influenced this process, Matthew saw catastrophic events as a prime factor, maintaining that mass extinctions were crucial to the process of evolution: "...all living things must have reduced existence so much, that an unoccupied field would be formed for new diverging ramifications of life... these remnants, in the course of time moulding and accommodating ... to the change in circumstances."

When Darwin published his Origin of Species nearly three decades later, he explicitly rejected the role of catastrophic change in natural selection: "The old notion of all the inhabitants of the Earth having been swept away by catastrophes at successive periods is very generally given up," he wrote. Instead, Darwin outlined a theory of evolution based on the ongoing struggle for survival among individuals within populations of existing species. This process of natural selection, he argued, should lead to gradual changes in the characteristics of surviving organisms.

However, as Rampino notes, geological history is now commonly understood to be marked by long periods of stability punctuated by major ecological changes that occur both episodically and rapidly, casting doubt on Darwin's theory that "most evolutionary change was accomplished very gradually by competition between organisms and by becoming better adapted to a relatively stable environment."

"Matthew's contribution was largely ignored at the time, and, with few exceptions, generally merits only a footnote in modern discussions of the discovery of natural selection," Rampino concludes. "Others have said that Matthew's thesis was published in too obscure a place to be noticed by the scientific community, or that the idea was so far ahead of its time that it could not be connected to generally accepted knowledge. As a result, his discovery was consigned to the dustbin of premature and unappreciated scientific ideas."

New York University

BILINGUAL BENEFITS REACH BEYOND COMMUNICATION

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Speaking two languages can be handy when traveling abroad, applying for jobs, and working with international colleagues, but how does bilingualism influence the way we think?

In the current issue of Psychological Science in the Public Interest, a journal of the Association for Psychological Science, Ellen Bialystok (York University), Fergus I.M. Craik (Rotman Research Institute), David W. Green (University College London), and Tamar H. Gollan (University of California, San Diego) review the latest research on bilingualism and ways in which knowing two languages can change brain function, even affecting brain areas not directly involved in communication.

Children learning two languages from birth achieve the same basic milestones (e.g., their first word) as monolinguals do, but they may use different strategies for language acquisition. Although bilinguals tend to have smaller vocabularies in each language than do children who know one language, bilinguals may have an advantage when it comes to certain nonverbal cognitive tasks. Bilinguals tend to perform better than monolinguals on exercises that require blocking out distractions and switching between two or more different tasks. The authors note that “when a bilingual speaks two languages regularly, speaking in just one of these languages requires use of the control network to limit interference from the other language and to ensure the continued dominance of the intended language.” The bilingual advantage in attention and cognitive control may have important, long-term benefits. Preliminary evidence even suggests that their increased use of these systems may protect bilinguals against Alzheimer’s.

The differences between monolinguals and bilinguals have important clinical implications. For example, vocabulary tests are commonly used in psychologists’ offices and bilinguals’ scores may not accurately reflect their language ability. According to the authors, “Bilinguals who score below average may be inaccurately diagnosed with impairment when none is present, or could be diagnosed as ‘normal for a bilingual’ even though impairment is in fact present and treatment is needed.” Clinicians need to be aware of the potential to misinterpret bilinguals’ test scores. Developing tests that specifically target bilingual populations may result in better outcomes for these patients.

Association for Psychological Science

THE MIND USES SYNTAX TO INTERPRET ACTIONS

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Most people are familiar with the concept that sentences have syntax. A verb, a subject, and an object come together in predictable patterns. But actions have syntax, too; when we watch someone else do something, we assemble their actions to mean something, according to a new study published in Psychological Science, a journal of the Association for Psychological Science.

“There are oceans and oceans of work on how we understand languages and how we interpret the things other people say,” says Matthew Botvinick of Princeton University, who cowrote the paper with his colleagues Kachina Allen, Steven Ibara, Amy Seymour, and Natalia Cordova. They thought the same principle might be applied to understanding actions. For example, if you see someone buy a ticket, give it to the attendant, and ride on the carousel, you understand that exchanging money for a piece of paper gave him the right to get on the round thing and go around in circles.

Botvinick and his colleagues focused on action sequences that followed two contrasting kinds of syntax—a linear syntax, in which action A (buying a ticket) leads to action B (giving the ticket to the attendant), which leads to outcome C (riding the carousel), and another syntax in which actions A and B both independently lead to outcome C. They were testing whether the difference in structure affected the way that people read about the actions.

The experiments were based on studies suggesting that people read a sentence faster if it comes after a sentence with the same grammatical form. But in this case, the scientists varied relationships between actions rather than the order of parts of speech. In one experiment, volunteers read sentences that described three actions. They took one of two forms: either one action leads to the next action, which leads to the outcome, such as “John purchased a carousel ticket, gave it to the attendant, and went for a ride,” or sentences like “John sliced up some tomatoes, rinsed off some lettuce, and tossed together a salad”—in which both of the first two actions lead to the result, without the second depending on the first.

Indeed, people were able to read a sentence more quickly if it followed a set of actions arranged the same way than if it followed a sentence of the other type. This indicates that readers’ minds had some kind of abstract representation of the ways goals and actions relate, says Botvinick. “It’s the underlying knowledge structure that kind of glues actions together. Otherwise, you could watch somebody do something and say it’s just a random sequence of actions.”

In the carousel example, a Martian might not understand why John exchanges paper for another piece of paper, why he gives the paper to the other man, why he goes around and around in circles, and what relationship there is between these actions. As humans, we’ve worked all of those things out, and Botvinick thinks he’s a step closer to understanding the process.

Association for Psychological Science

THE EMERGENCE OF HOLOGRAPHIC VIDEO

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Researchers at the University of Arizona (UA), Tucson, have developed a holographic system that can transmit a series of 3D images in near-real-time, a precursor to holographic videoconferencing.

The system incorporates a novel, photorefractive polymer--one that can rapidly refresh holographic images and is scalable for production--coupled to a unique system for recording and transmitting 3D images of individuals and objects via Ethernet.

Lead author Pierre-Alexandre Blanche and his colleagues from the university and Nitto Denko Technical Corp. of Oceanside, Calif., describe the breakthrough in the cover story of the Nov. 4, 2010, issue of Nature.

"This advance brings us a step closer to the ultimate goal of realistic holographic telepresence with high-resolution, full-color, human-size, 3D images that can be sent at video refresh rates from one part of the world to the other," says co-author and project lead Nasser Peyghambarian of UA and the Director of NSF's multi-institution Engineering Research Center for Integrated Access Networks (CIAN).

The researchers had previously demonstrated a refreshable polymer display system, but it could refresh images only once every four minutes. The new system can refresh images every two seconds; while not yet ideal for a display, the rate is more than one hundred times faster.

Additionally, using a single-laser system for writing the images onto the photorefractive polymer, the researchers can display visuals in color. While the current refresh rate for multi-color display is even slower than for monochromatic images, the development suggests a true 3D, multicolor system may be feasible.

"This breakthrough opens new opportunities for optics as a means to transport images in real time," says Lynn Preston, director of the NSF Engineering Research Centers program that supports CIAN. "Such a system can have an important impact on telepresence, telemedicine, engineering design and manufacturing, and other applications. This is an early and tremendously important outcome from this three-year old center."

(Photo: University of Arizona)

National Science Foundation

GRAVITY EASES ITS PULL

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A Newcastle University scientist has provided new insights into the way that electromagnetic forces interact with gravity.

The nature of gravity has baffled scientists through the ages and has proved a major stumbling block to the creation of a single 'theory of everything'.

But a new analysis by Dr David Toms, a theoretical physicist at Newcastle University, now shows that gravity may at least make some fundamental calculations more manageable.

He has found that gravity seems to calm the electromagnetic force at high energies. The finding could make some calculations easier, and is a rare case in which gravity seems to work in harmony with quantum mechanics, the theory of small particles. His full paper is published today in Nature.

Dr Toms explains: "The basic idea is that the value of the electric charge depends on how close you are to that charge.

"The number for the electric charge that you look up in the back of a textbook assumes that you are a very large distance - on the atomic scale - from the charge. The reason that the value changes with energy has to do with quantum mechanics.

"My research shows conclusively that charge is affected by gravity, and that it tends to make the charge weaker as you proceed to smaller distances. This is unexpected because in the complete absence of gravity the charge gets larger as the distance decreases."

In Dr Toms work, gravity seems to smoothe the interaction, making the force between the electron and photon nearly zero at high energies. This weakening of the force means that theorists can calculate the behaviour of high-energy electrons and photons after all.

"What gravity seems to do is make things better for you but there is still a lot of work to do", he warns.

Newcastle University

THE BRAINS OF NEANDERTHALS AND MODERN HUMANS DEVELOPED DIFFERENTLY

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Researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany have documented species differences in the pattern of brain development after birth that are likely to contribute to cognitive differences between modern humans and Neanderthals.

Whether cognitive differences exist between modern humans and Neanderthals is the subject of contentious disputes in anthropology and archaeology. Because the brain size range of modern humans and Neanderthals overlap, many researchers previously assumed that the cognitive capabilities of these two species were similar. Among humans, however, the internal organization of the brain is more important for cognitive abilities than its absolute size is. The brain’s internal organization depends on the tempo and mode of brain development.

Based on detailed measurements of internal shape changes of the braincase during individual growth, a team of scientists from the MPI has shown that these are differences in the patterns of brain development between humans and Neanderthals during a critical phase for cognitive development.

Discussions about the cognitive abilities of fossil humans usually focus on material culture (e.g. the complexity of the stone tool production process) and endocranial volumes. "The interpretation of the archaeological evidence remains controversial, and the brain-size ranges of Neanderthals and modern humans overlap," says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA in Leipzig where the research was conducted. Hublin adds, "our findings show how biological differences between modern humans and Neanderthals may be linked to behavioural differences inferred from the archaeological record."

Nature of the evidence: As the brain does not fossilize, for fossil skulls, only the imprints of the brain and its surrounding structures in the bone (so called "endocasts") can be studied. The researchers used state-of-the-art statistical methods to compare shape changes of virtual endocasts extracted from computed-tomographic scans. The distinct globular shape of the braincase of adult Homo sapiens is largely the result of a brain development phase that is not present in Neanderthals.

One of the key pieces of evidence was the skull reconstruction of a Neanderthal newborn. In 1914, a team of French archaeologists had excavated the skeleton of a Neanderthal baby at the rock shelter of Le Moustier in the Dordogne. The original bones of the skeleton had been lost to science for more than 90 years, until they were rediscovered among museum collections by Bruno Maureille and the museum staff. The restored original baby bones are now on permanent display at the Musée National de Préhistoire in Les Eyzies-de-Tayac-Sireuil. The museum’s director Jean-Jacques Cleyet-Merle made it possible to scan the delicate fragments using a high-resolution computed-tomographic scanner (µCT). Using computers at the Max Planck Institute’s virtual reality lab in Leipzig, Philipp Gunz and Simon Neubauer then reconstructed the Neanderthal baby from the digital pieces, like in a three-dimensional jigsaw puzzle. "When we compare the skulls of a Neanderthal and a modern human newborn, the Neanderthal’s face is already larger at the time of birth. However, most shape differences of the internal braincase develop after birth," explains Gunz. Both Neanderthals and modern human neonates have elongated braincases at the time of birth, but only modern human endocasts change to a more globular shape in the first year of life. Modern humans and Neanderthals therefore reach large adult brain sizes via different developmental pathways.

In a related study the same team of MPI researchers had previously shown that the developmental patterns of the brain were remarkably similar between chimpanzees and humans after the first year of life, but differed markedly directly after birth. "We interpret those aspects of development that are shared between modern humans, Neanderthals, and chimpanzees as conserved," explains Simon Neubauer. "This developmental pattern has probably not changed since the last common ancestor of chimpanzees and humans several million years ago." In the first year of life, modern humans, but not Neanderthals, depart from this ancestral pattern of brain development.

Establishing when the species differences between Neanderthal and modern human adults emerge during development was critical for understanding whether differences in the pattern of brain development might underlie potential cognitive differences. As the differences between modern humans and Neanderthals are most prominent in the period directly after birth, they likely have implications for the neuronal and synaptic organization of the developing brain.

The development of cognitive abilities during individual growth is linked to the maturation of the underlying wiring pattern of the brain; around the time of birth, the neural circuitry is sparse in humans, and clinical studies have linked even subtle alterations in early brain development to changes in the neural wiring patterns that affect behaviour and cognition. The connections between diverse brain regions that are established during this period in modern humans are important for higher-order social, emotional, and communication functions. It is therefore unlikely that Neanderthals saw the world as we do.

The new study shows that modern humans have a unique pattern of brain development after birth, which separates us from our closest relatives, the Neanderthals. This uniquely modern human pattern of early brain development is particularly interesting in light of the recent breakthroughs in the Neanderthal genome project. A comparison of Neanderthal and modern human genomes revealed several regions with strong evidence for positive selection within Homo sapiens, i.e. the selection occurred after the split between modern humans and Neanderthals. Three among these are likely to be critical for brain development, as they affect mental and cognitive development.

"Our findings have two important implications," says Philipp Gunz. "We have discovered differences in the patterns of brain development that might contribute to cognitive differences between modern humans and Neanderthals. Maybe more importantly, however, this discovery will tell us more about our own species than about Neanderthals; we hope that our findings will help to identify the function of some genes that show evidence for recent selection in modern humans."

(Photo: Max Planck Institute for Evolutionary Anthropology)

Max Planck Institute

CAVEMAN BEHAVIOURAL TRAITS MIGHT KICK IN AT DINNER TABLE BEFORE EATING

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Frank Kachanoff was surprised. He thought the sight of meat on the table would make people more aggressive, not less. After all, don’t football coaches feed their players big hunks of red meat before a game in hopes of pumping them up? And what about our images of a grunting or growling animal snarling at anyone who dares take their meat away from them? Wouldn’t that go for humans, too?

Kachanoff, a researcher with a special interest in evolution at McGill University’s Department of Psychology, has discovered quite the reverse. According to research presented at a recent symposium at McGill, seeing meat appears to make human beings significantly less aggressive. “I was inspired by research on priming and aggression, that has shown that just looking at an object which is learned to be associated with aggression, such as a gun, can make someone more likely to behave aggressively. I wanted to know if we might respond aggressively to certain stimuli in our environment not because of learned associations, but because of an innate predisposition. I wanted to know if just looking at the meat would suffice to provoke an aggressive behavior.”

The idea that meat would illicit aggressive behaviour makes sense, as it would have helped our primate ancestors with hunting, co-opting and protecting their meat resources. Kachanoff believed that humans may therefore have evolved an innate predisposition to respond aggressively towards meat, and recruited 82 males to test his theory, using long-established techniques for provoking and measuring aggression. The experiment itself was quite simple – subjects had to punish a script reader every time he made an error while sorting photos, some with pictures of meat, and others with neutral imagery. The subjects believed that they could inflict various volumes of sound, including “painful,” to the script reader, which he would hear after his performance. While the research team figured that the group sorting pictures of meat would inflict more discomfort on the reader, they were very surprised by the results.

“We used imagery of meat that was ready to eat. In terms of behaviour, with the benefit of hindsight, it would make sense that our ancestors would be calm, as they would be surrounded by friends and family at meal time,” Kachanoff explained. “I would like to run this experiment again, using hunting images. Perhaps Thanksgiving next year will be a great opportunity for a do-over!”

Evolutionary psychologists believe it is useful to look at innate reflexes in order to better understand societal trends and personal behavior. Kachanoff’s research is important because it looks at ways society may influence environmental factors to decrease the likelihood of aggressive behavior. His research was carried out under the direction of Dr. Donald Taylor and Ph.D student, Ms. Julie Caouette of McGill’s Department of Psychology, and was presented at the university’s annual undergraduate science symposium.

McGill University

FAT CELLS REACH THEIR LIMIT AND TRIGGER CHANGES LINKED TO TYPE 2 DIABETES

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Scientists have found that the fat cells and tissues of morbidly obese people and animals can reach a limit in their ability to store fat appropriately. Beyond this limit several biological processes conspire to prevent further expansion of fat tissue and in the process may trigger other health problems.

Research funded by the Biotechnology and Biological Sciences Research Council (BBSRC), the Medical Research Council (MRC) and the European Union Sixth Framework Programme, shows that a protein called secreted frizzled-related protein 1 (SFRP1) is produced by fat cells and may be involved in changes to our metabolism that could increase the risk of diabetes and cardiovascular disease. The work was carried out at the University of Cambridge and will be published in a future edition of the International Journal of Obesity.

Professor Antonio Vidal-Puig from the Institute of Metabolic Science, University of Cambridge said "We have known for some time that many obese individuals are at greater risk of developing diabetes, cardiovascular disease and also cancer. But this is not true for all obese people."

Dr Jaswinder Sethi, also from the Institute of Metabolic Sciences, University of Cambridge added "What we still do not fully understand, is how the expansion of fat tissue is regulated in healthy people and how this process of regulation might be different in those obese people who have health problems such as the metabolic syndrome."

One hypothesis is that storing surplus fat in itself may not lead to metabolic syndrome but there may be a maximum limit of how much fat a person can store safely before the body's natural responses lead to the debilitating chronic health problems often associated with obesity.

Dr Sethi continued "To investigate this we have been using a combination of molecular cell biology, human gene profiling and mouse genetics as tools to understand what is happening as fat cells and tissues develop and then, in some very obese people, lose their normal process of regulation."

The researchers have found that the level of SFRP1 increases as fat cells and tissues increase in volume until it peaks at about the point of mild obesity. There is evidence that SFRP1 is involved in recruiting new fat cells, thereby facilitating the expansion of fat tissue up until this point where it peaks.

"SFRP1 seems to be very closely linked to some sort of tipping point, after which the way in which our fat tissue is regulated changes significantly and there are knock-on consequences to our wider metabolism. We think that in very obese people this may be an early event that triggers metabolic syndrome and the chronic health problems associated with it, such as diabetes and cardiovascular disease," said Dr Sethi.

The fat tissue of people who are obese and also have diabetes shows signs of not being regulated as it usually would be. In this tissue, the researchers also see the levels of SFRP1 begin to fall so as to prevent further expansion of the tissue. It is this fall in SFRP1 that has knock-on effects on metabolism that may in part explain the link between morbid obesity and metabolic syndrome.

The researchers believe that SFRP1 works in concert with other molecules to respond to the availability, or not, of energy. Together these molecules also determine to what extent our fat tissue can continue to expand as we consume more calories than we burn.

Professor Douglas Kell, BBSRC Chief Executive said: "Research such as this leads to better understanding of the biochemistry that drives normal human physiology. In particular we can see how we usually respond to extremes brought on by the various onslaughts of our lifestyles and environments. Increasing our understanding of the fundamentals of metabolic signalling is an important part of working towards an increase in health span to match our increasing life spans."

Biological Sciences Research Council

SKELETONS FROM THE 18TH CENTURY REVEAL TYPHUS EPIDEMIC FROM SPAIN

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By studying the dental pulp of skeletons buried in Douai (northern France), researchers from CNRS and the Université de la Méditerranée have identified the pathogenic agents responsible for trench fever and typhus. Published in the journal PLoS ONE, this work reveals for the first time the presence of typhus in Europe at the start of the 18th century and lends weight to the hypothesis that this disease could have been imported into Europe by Spanish conquistadors returning from the Americas.

Between 1710 and 1712, while Louis XIV was waging a war with the north of Europe for the Spanish succession, the town of Douai in northern France was besieged on several occasions. In 1981, during building construction work, mass graves were discovered in the town. The skeletons brought to light were subjected to paleomicrobiology studies directed by Didier Raoult of the Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (CNRS/Université de la Méditerranée/IRD), in collaboration with researchers from the Laboratoire d'Anthropologie Bioculturelle de Marseille (CNRS/Université de la Méditerranée/EFS).

The manner in which the skeletons found in the mass graves were laid out and the absence of any bodily injuries caused by weapons point to an epidemic, possibly more lethal than the battles that took place during the siege of Douai in the early 18th century. Molecular biology analyses enabled the team to identify the pathogenic agent responsible for the epidemic. Using DNA extracted from dental pulp, the scientists identified the DNA of the bacteria responsible for trench fever (Bartonella quintana) and mostly typhus (Rickettsia prowazekii). This is the earliest demonstration of the presence in Europe of the typhus agent, an infectious disease transmitted by lice.

The same team of scientists had already revealed the presence of these pathogenic agents a century later in Napoleonic armies. The genotyping of Rickettsia prowazekii shows that it is the same bacterium that later became rife in Spain, thus supporting the hypothesis that typhus was imported into Europe by Spanish conquistadors at the start of the 18th century.

(Photo: © Communauté d'agglomération du Douaisis, direction de l'archéologie préventive)

CNRS

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