Single dose of psilocybin may create lasting personality change
September 29, 2011
A single high dose of the hallucinogen psilocybin, the active ingredient in so-called “magic mushrooms,” was enough to bring about a measureable personality change lasting at least a year in nearly 60 percent of the 51 participants in a new study, according to the Johns Hopkins researchers who conducted it.
Lasting change was found in the part of the personality known as openness, which includes traits related to imagination, aesthetics, feelings, abstract ideas and general broad-mindedness. Changes in these traits, measured on a widely used and scientifically validated personality inventory, were larger in magnitude than changes typically observed in healthy adults over decades of life experiences, the scientists say. Researchers in the field say that after the age of 30, personality doesn’t usually change significantly.
“Normally, if anything, openness tends to decrease as people get older,” says study leader Roland R. Griffiths, a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
The research, approved by Johns Hopkins’ Institutional Review Board, was funded in part by the National Institute on Drug Abuse and published in the Journal of Psychopharmacology.
The study participants completed two to five eight-hour drug sessions, with consecutive sessions separated by at least three weeks. Participants were informed they would receive a “moderate or high dose” of psilocybin during one of their drug sessions, but neither they nor the session monitors knew when.
During each session, participants were encouraged to lie down on a couch, use an eye mask to block external visual distraction, wear headphones through which music was played and focus their attention on their inner experiences.
Personality was assessed at screening, one to two months after each drug session and approximately 14 months after the last drug session. Griffiths says he believes the personality changes found in this study are likely permanent since they were sustained for over a year by many.
Nearly all of the participants in the new study considered themselves spiritually active (participating regularly in religious services, prayer or meditation). More than half had postgraduate degrees. The sessions with the otherwise illegal hallucinogen were closely monitored and volunteers were considered to be psychologically healthy
“We don’t know whether the findings can be generalized to the larger population,” Griffiths says.
As a word of caution, Griffiths also notes that some of the study participants reported strong fear or anxiety for a portion of their daylong psilocybin sessions, although none reported any lingering harmful effects. He cautions, however, that if hallucinogens are used in less well supervised settings, the possible fear or anxiety responses could lead to harmful behaviors.
Griffiths says lasting personality change is rarely looked at as a function of a single discrete experience in the laboratory. In the study, the change occurred specifically in those volunteers who had undergone a “mystical experience,” as validated on a questionnaire developed by early hallucinogen researchers and refined by Griffiths for use at Hopkins. He defines “mystical experience” as among other things, “a sense of interconnectedness with all people and things accompanied by a sense of sacredness and reverence.”
Personality was measured on a widely used and scientifically validated personality inventory, which covers openness and the other four broad domains that psychologists consider the makeup of personality: neuroticism, extroversion, agreeableness and conscientiousness. Only openness changed during the course of the study.
Griffiths says he believes psilocybin may have therapeutic uses. He is currently studying whether the hallucinogen has a use in helping cancer patients handle the depression and anxiety that comes along with a diagnosis, and whether it can help longtime cigarette smokers overcome their addiction.
“There may be applications for this we can’t even imagine at this point,” he says. “It certainly deserves to be systematically studied.”
Along with the National Institute on Drug Abuse, this study was funded by the Council on Spiritual Practices, Heffter Research Institute and the Betsy Gordon Foundation.
Other Hopkins authors of the research include Matthew W. Johnson, Ph.D, and Katherine A. MacLean, Ph.D.
Johns Hopkins Medicine
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Glow-in-the-dark millipede says ‘stay away’
September 26, 2011
As night falls in certain mountain regions in California, a strange breed of creepy crawlies emerges from the soil: Millipedes that glow in the dark. The reason behind the glowing secret has stumped biologists until now.
Paul Marek, a research associate in the UA’s Department of Entomology and Center for Insect Science, and his team now provide the first evidence gained from field experiments of bioluminescence being used as a warning signal. They discovered that the nightly glow of millipedes belonging to the genus Motyxia helps the multi-legged invertebrates avoid attacks by predators.
The findings will be published in the Sept. 27 print edition of the journal Current Biology.
Biologists have discovered and described more than 12,000 species of millipedes, but the vast majority remains undiscovered and is thought to number around 100,000.
Just like all other millipedes, Motyxia are vegetarians, feeding mostly on decaying plant material, but in the course of adapting to a lifestyle primarily underground, they lost the ability to see.
“They spend the day burrowed beneath the soil and leaf material, but even though they are blind, they somehow sense when night falls, and come to the surface to forage and mate and to go about their millipede business,” said Marek, who conducted this work under the NIH Postdoctoral Excellence in Research and Training program in the labs of Wendy Moore, an assistant professor of entomology and curator of the University of Arizona Insect Collection and Dan Papaj, a professor of ecology and evolutionary biology at the University of Arizona.
“When they are disturbed, they ooze toxic cyanide and other foul-tasting chemicals from small pores running along the sides of their bodies as a defense mechanism,” Marek explained. “Some millipede species that are active during the day display bright warning colors to announce their defenses to predators, but because Motyxia are out when it’s dark, we hypothesized they use their greenish glow in place of a warning coloration.”
Known as bioluminescence, the ability to glow in the dark is remarkably widespread in the animal kingdom. The most commonly known examples include fireflies, glowworms – which are in fact beetles – and animals inhabiting the pitch-black darkness of the deep oceans.
In some of those examples, bioluminescence is thought to help attract mates, send messages back and forth among members of the same species, or attract prey like in the case of the deep-sea angler fish, which dangles a glowing lure in front of its gaping mouth. Any small fish or other animal following the beacon’s glow is gulped up as it approaches the invisible predator hiding in the darkness.
Marek and his coworkers hypothesized by using bioluminescence as a warning signal, luminescent millipedes would be attacked less than non-luminescent ones.
To test this hypothesis, Charity Hall, Marek’s wife and a metalsmith, made a bronze cast of a millipede, which the team used to create molds to cast 300 fake millipedes in clay. Half of those they painted with an artificial, long-lasting glow-in-the-dark paint.
For the field experiment, the group took their clay millipede collection to Giant Sequoia National Monument in California, where they set them on the ground along a transect line, spaced five meters (16 feet) apart. Glowing and non-glowing individuals were distributed in random order to avoid sampling bias.
They then set out to collect real millipedes in the same general area.
“Motyxia are extremely common out there,” Marek said. “If you sit there in a moonless night, the ground will look like the starry night sky up above, from all those millipedes glowing in the dark.”
The live millipedes were divided into two groups: One was covered with paint to conceal their natural glow, the other was left untreated. Just like with the clay models, the real millipedes were distributed along a different transect line, with glowing and non-glowing animals in random order.
“To make sure they wouldn’t walk out of the experiment, we used a fly-fishing knot gently tied around their back segments to tether them to the ground,” Marek explained.
The next morning, the researchers went to collect the live and clay millipedes and assess the results.
“It was just – carnage,” Marek said. “We were really surprised at the predation rate on these millipedes. Overall, about one-third of them – both real and fake – had been attacked.”
Four times as many non-glowing millipedes showed evidence of attacks compared to their glowing peers. Similarly, in the clay group, non-luminescent models were attacked twice as often than those that emitted the glow.
To learn more about what kinds of predators had nibbled on – or devoured – the study subjects, Marek took the clay models and the remains of the real millipedes to the rodent collection at the California Academy of Sciences and matched the strike marks with the teeth in rodent skulls. Combining those data with observations at the study site, the team concluded that the grasshopper mouse (Onychomys torridus) is one of the millipedes’ most likely predators.
“Remarkably, most of the predation marks were localized to the head, even in the clay models,” Marek said. “So somehow those predators were able to tell the head from the tail end and go for the head first, which is a behavior typically seen in vertebrate predators.”
To get a better idea of how the ability to glow in the dark evolved in millipedes, the team sequenced selected gene regions and estimated their evolutionary history to pinpoint the origin of bioluminescence in millipedes. Interestingly, a few of the species in the glowing genus Motyxia can switch their glow on and off. Marek and his co-workers measured glowing intensity of species in the genus using darkroom photography and traced the results on an evolutionary tree. They determined that the ability to glow evolved only once in millipedes and is restricted to a set of closely related species, all in the genus Motyxia.
“There are only three places on the planet where you can see glow-in-the-dark millipedes,” Marek said. “The Santa Monica Mountains, the Tehachapi Mountains and the southern Sierra Nevada Mountains, all of which are in California.”
The precise biochemical mechanism by which the millipedes achieve this feat is up for future research.
“For now, all that we know is they use a different mechanism than fireflies or glowworms,” said Marek, “which use an enzymatic reaction. The millipedes have a photoprotein that is similar to the Green Fluorescent Protein of the jellyfish Aequorea victoria. It is thought to be activated by calcium and energy-rich compounds in the cell to create the glow.”
The co-authors of the paper, Bioluminescent aposematism in millipedes, are Daniel Papaj, a professor in the UA’s department of ecology and evolutionary biology, Justin Yeager, a doctoral student at Tulane University, Sergio Molina, who is in the biology department at Pima Community College in Tucson, Ariz., and Wendy Moore, an assistant professor in the UA’s department of entomology and curator of the University of Arizona Insect Collection.
This research was supported by a National Institutes of Health Training Grant to the Center for Insect Science at UA (2 K12 GM000708) and a National Science Foundation Phylogenetic Systematics grant to Paul Marek in the department of entomology (DEB-1119179).
Contact: Daniel Stolte
stolte@email.arizona.edu
520-626-4402
University of Arizona
Do women’s voices really allow men to detect ovulation?
September 22, 2011
The voice can reveal a lot about a person – their sex, their age, how they are feeling – and recent studies have even suggested that women’s voices might also contain cues that men can read about how close they are to ovulation. A new study, however, published today in the journal PLoS ONE, challenges the view that women broadcast reproductive information in their voice.
Previous studies in this area have typically relied on the comparison of voices recorded in just two phases in the cycle: high conception risk vs. low conception risk. This new work, on the other hand, looked at variation in the voice throughout the entire menstrual cycle – a crucial step to evaluate the potential information contained in any observed voice changes.
Their results showed that the overall variation in women’s vocal quality throughout the whole cycle precludes unequivocal identification of the period with the highest conception risk. Specifically, while they found that the women studied spoke with the highest tone (suggested by previous studies to be associated with attractiveness) just prior to ovulation, the tone rose again to levels indistinguishable from pre-ovulation shortly after ovulation, making it a very poor mating clue. Furthermore, they found that the men studied showed only a very slight preference for pre-ovulation voices relative to voices recorded during ovulation.
The authors conclude that women’s voices do not provide reliable information about the timing of ovulation, confirming the view that information about reproductive state is ‘leaked’ rather than broadcast. In an interesting further finding, the study found that women’s voice were harsher and more irregular during menstruation, providing scientific data to explain why female opera singers may be granted ‘grace days’ during menstruation.
The international collaborative study was led by Prof Julia Fischer (German Primate Centre), Dr Stuart Semple (Roehampton University, London) and Dr Ofer Amir (Tel-Aviv University).
Citation: Citation: Fischer J, Semple S, Fickenscher G, Jurgens R, Kruse E, et al. (2011) Do Women’s Voices Provide Cues of the Likelihood of Ovulation? The Importance of Sampling Regime. PLoS ONE 6(9): e24490. doi:10.1371/journal.pone.0024490
Funding: The authors have no support or funding to report.
Competing Interests: The authors have declared that no competing interests exist.
http://dx.plos.org/10.1371/journal.pone.0024490
Shake hands with the invisible man – researcher identifies genetic defect that leaves some without fingerprints
September 19, 2011
Like DNA, fingerprints are unique to each person or set of identical twins. That makes them a valuable identification tool for everything from crime detection to international travel. But what happens when the tips of our fingers are missing those distinctive patterns of ridges?
It’s not the premise for a science fiction movie, but a real-life condition known as adermatoglyphia. It’s also known as “Immigration Delay Disease,” because affected individuals experience difficulty in passing through security or checkpoints where fingerprint identification is required. Now Prof. Eli Sprecher from Tel Aviv University’s Sackler Faculty of Medicine and the Tel Aviv Sourasky Medical Center has identified the genetic mutation responsible for this unusual condition.
Though adermatoglyphia itself is extremely rare, defects that stem from any one genetic mutation give researchers unique insights into the most complex biological phenomena, such as the consequences of lacking a single protein.
The findings have been published in the American Journal of Human Genetics.
Baffling border control
“Immigration Delay Disease” came to the attention of the medical community when it did just that – delay the attempts of one Swiss woman to cross the border into the United States, which requires that non-citizens be fingerprinted upon entry. Border control personnel were mystified when the woman informed them that she was unable to comply.
Though an exceptionally rare condition – only four documented families are known to suffer from the disease worldwide – Prof. Sprecher was inspired to delve deeper into the causes of the condition, which, in addition to causing an absence of fingerprints, also leads to a reduction in the number of sweat glands. Abnormal fingerprints can also be a warning sign of more severe disorders.
Scientists know that fingerprints are fully formed 24 weeks after fertilization, and do not change throughout our lives. But “the factors underlying the formation and pattern of fingerprints during embryonic development are largely unknown,” says Prof. Sprecher. He adds that it isn’t only fingertips that have patterned skin – palms, toes, and the soles of the feet also feature these ridges, called dermatoglyphs.
To determine the cause of this rare condition, the researchers did a genetic analysis of the Swiss family, nine of whom have no fingerprints. They compared the genes of those with adermatoglyphia and those without to identify where the genetic alteration lies. They discovered that a skin-specific version of the gene SMARCAD1 has a regulating factor on fingerprint development. The group that presented with adermatoglyphia, Prof. Sprecher explains, were found to have decreased levels of the short skin-specific version of the gene.
An inconvenience, but little more
Now that this gene has been identified, researchers will be able to further investigate how SMARCAD1 regulates fingerprint development. While adermatoglyphia may be intriguing, and can certainly be problematic for border security, it’s also non-threatening. Despite the minor issue of the hand’s inability to produce sweat, says Prof. Sprecher, those affected do not otherwise suffer.
This research was carried out in collaboration with Dr. Janna Nousbeck of the Tel Aviv Sourasky Medical Center and Prof. Peter Itin of the University Hospital at Basel, Switzerland.
American Friends of Tel Aviv University (www.aftau.org) supports Israel’s leading, most comprehensive and most sought-after center of higher learning. Independently ranked 94th among the world’s top universities for the impact of its research, TAU’s innovations and discoveries are cited more often by the global scientific community than all but 10 other universities.
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Contact: George Hunka
ghunka@aftau.org
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American Friends of Tel Aviv University
Self-delusion is a winning survival strategy, study suggests
September 14, 2011
Harboring a mistakenly inflated belief that we can easily meet challenges or win conflicts is actually good for us, a new study suggests.
Researchers have shown for the first time that overconfidence actually beats accurate assessments in a wide variety of situations, be it sport, business or even war.
However, this bold approach also risks wreaking ever-greater havoc. The authors cite the 2008 financial crash and the 2003 Iraq war as just two examples of when extreme overconfidence backfired.
A team from the University of Edinburgh and the University of California, San Diego used a mathematical model to simulate the effects of overconfidence over generations. It pitted overconfident, accurate, and underconfident strategies against each other.
A paper published in Nature today shows that overconfidence frequently brings rewards, as long as spoils of conflict are sufficiently large compared with the costs of competing for them. In contrast, people with unbiased, accurate perceptions usually fare worse.
The implications are that, over a long period of time the evolutionary principal of natural selection is likely to have favoured a bias towards overconfidence. Therefore people with the mentality of someone like boxer Mohammad Ali would have left more descendents than those with the mindset of film maker Woody Allen.
The evolutionary model also showed that overconfidence becomes greatest in the face of high levels of uncertainty and risk. When we face unfamiliar enemies or new technologies, overconfidence becomes an even better strategy.
Dr Dominic Johnson, reader in Politics and International Relations at the University: “The model shows that overconfidence can plausibly evolve in wide range of environments, as well as the situations in which it will fail. The question now is how to channel human overconfidence so we can exploit its benefits while avoiding occasional disasters.”
Contact: Edd McCracken
Edd.McCracken@ed.ac.uk
44-131-651-4400
University of Edinburgh
Groundbreaking DNA tests could trap deer poachers
September 9, 2011
Poachers could be tracked down through tests for human DNA on deer remains, according to research led by scientists at the University of Strathclyde.
Identifying deer poachers can be problematic, as the crimes are often committed in remote areas and are not discovered until some time after the event. Poachers’ practice of disassembling a carcass also often means that little physical evidence, and consequently little human DNA, is left behind.
However, researchers at Strathclyde and Jim Govan, a Forensic Scientist with the Scottish Police Services Authority, have devised a method which could pick up low levels of DNA and identify poachers. The chances of the DNA profiles it picked up being randomly found within the population would be less than one in a billion.
The study is thought to be the first time that human DNA profiles have been obtained successfully from an animal carcass and the potential for using this process on other animals is currently being investigated.
Scottish Minister for Environment and Climate Change, Stewart Stevenson said: “I welcome this development which demonstrates Scotland is at the forefront of the application of this cutting-edge science. The ability to test for the remains of human DNA on animal carcasses, gives law enforcers more tools to protect our wildlife from criminal activity. I look forward to hearing more about how this development can be used practically in tackling the illegal activity of deer poaching.”
Dr Shanan Tobe, a Research Fellow in the Centre for Forensic Science in Strathclyde’s Department of Pure and Applied Chemistry, conducted the research. He said: “Poaching can be extremely difficult to investigate and prosecute owing to the nature of the evidence available. There are particular problems with deer poaching because deer can be legally hunted in season and identifying deer alone would not show whether or not they had been killed in the course of poaching.
“Our research has picked up DNA at very low levels and could be a significant breakthrough in wildlife crime. It could not only help to catch existing poachers but could also act as a deterrent to others.”
The researchers obtained samples from the legs of 10 deer which had been legally culled and examined them for matches for DNA provided by volunteers who had taken part in the cull. The tests yielded results that could be matched back to the volunteer hunter. The method has potential to be used on other evidence in wildlife crime, such as feathers, eggs, snares or traps.
More than half of the funding for the research came from PAW (Partnership for Action Against Wildlife Crime) Scotland which was managed by Scottish Natural Heritage. With the remaining funds coming from the Deer Commission for Scotland (now part of SNH), the British Association for Shooting & Conservation and the British Deer Society.
All deer samples used in the study were obtained from deer as part of an annual cull. No animals were harmed for the purpose of the research.
The research paper, Recovery of human DNA profiles from poached deer remains: A feasibility study, has been published in the journal Science and Justice and is available online (doi:10.1016/j.scijus.2011.06.002).
Contact: Media and Corporate Communications
corporatecomms@strath.ac.uk
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University of Strathclyde
Our galaxy might hold thousands of ticking ‘time bombs’
September 6, 2011
In the Hollywood blockbuster “Speed,” a bomb on a bus is rigged to blow up if the bus slows down below 50 miles per hour. The premise – slow down and you explode – makes for a great action movie plot, and also happens to have a cosmic equivalent.
New research shows that some old stars might be held up by their rapid spins, and when they slow down, they explode as supernovae. Thousands of these “time bombs” could be scattered throughout our Galaxy.
“We haven’t found one of these ‘time bomb’ stars yet in the Milky Way, but this research suggests that we’ve been looking for the wrong signs. Our work points to a new way of searching for supernova precursors,” said astrophysicist Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics (CfA).
The specific type of stellar explosion Di Stefano and her colleagues studied is called a Type Ia supernova. It occurs when an old, compact star known as a white dwarf destabilizes.
A white dwarf is a stellar remnant that has ceased nuclear fusion. It typically can weigh up to 1.4 times as much as our Sun – a figure called the Chandrasekhar mass after the astronomer who first calculated it. Any heavier, and gravity overwhelms the forces supporting the white dwarf, compacting it and igniting runaway nuclear fusion that blows the star apart.
There are two possible ways for a white dwarf to exceed the Chandrasekhar mass and explode as a Type Ia supernova. It can accrete gas from a donor star, or two white dwarfs can collide. Most astronomers favor the first scenario as the more likely explanation. But we would expect to see certain signs if the theory is correct, and we don’t for most Type Ia supernovae.
For example, we should detect small amounts of hydrogen and helium gas near the explosion, but we don’t. That gas would come from matter that wasn’t accreted by the white dwarf, or from the disruption of the companion star in the explosion. Astronomers also have looked for the donor star after the supernova faded from sight, without success.
Di Stefano and her colleagues suggest that white dwarf spin might solve this puzzle. A spin-up/spin-down process would introduce a long delay between the time of accretion and the explosion. As a white dwarf gains mass, it also gains angular momentum, which speeds up its spin. If the white dwarf rotates fast enough, its spin can help support it, allowing it to cross the 1.4-solar-mass barrier and become a super-Chandrasekhar-mass star.
Once accretion stops, the white dwarf will gradually slow down. Eventually, the spin isn’t enough to counteract gravity, leading to a Type Ia supernova.
“Our work is new because we show that spin-up and spin-down of the white dwarf have important consequences. Astronomers therefore must take angular momentum of accreting white dwarfs seriously, even though it’s very difficult science,” explained Di Stefano.
The spin-down process could produce a time delay of up to a billion years between the end of accretion and the supernova explosion. This would allow the companion star to age and evolve into a second white dwarf, and any surrounding material to dissipate.
In our Galaxy, scientists estimate that there are three Type Ia supernovae every thousand years. If a typical super-Chandrasekhar-mass white dwarf takes millions of years to spin down and explode, then calculations suggest that there should be dozens of pre-explosion systems within a few thousand light-years of Earth.
Those supernova precursors will be difficult to detect. However, upcoming wide-field surveys conducted at facilities like Pan-STARRS and the Large Synoptic Survey Telescope should be able to spot them.
“We don’t know of any super-Chandrasekhar-mass white dwarfs in the Milky Way yet, but we’re looking forward to hunting them out,” said co-author Rasmus Voss of Radboud University Nijmegen, The Netherlands.
Contact: Christine Pulliam
cpulliam@cfa.harvard.edu
617-495-7463
Harvard-Smithsonian Center for Astrophysics
Perception of facial expressions differs across cultures
September 1, 2011
Facial expressions have been called the “universal language of emotion,” but people from different cultures perceive happy, sad or angry facial expressions in unique ways, according to new research published by the American Psychological Association.
“By conducting this study, we hoped to show that people from different cultures think about facial expressions in different ways,” said lead researcher Rachael E. Jack, PhD, of the University of Glasgow. “East Asians and Western Caucasians differ in terms of the features they think constitute an angry face or a happy face.”
The study, which was part of Jack’s doctoral thesis, was published online in APA’s Journal of Experimental Psychology: General. Jack is a post-doctoral research assistant, and the study was co-authored by Philippe Schyns, PhD, director of the Institute of Neuroscience and Psychology at the University of Glasgow, and Roberto Caldara, PhD, a psychology professor at the University of Fribourg in Switzerland.
Some prior research has supported the notion that facial expressions are a hard-wired human behavior with evolutionary origins, so facial expressions wouldn’t differ across cultures. But this study challenges that theory and used statistical image processing techniques to examine how study participants perceived facial expressions through their own mental representations.
“A mental representation of a facial expression is the image we see in our ‘mind’s eye’ when we think about what a fearful or happy face looks like,” Jack said. “Mental representations are shaped by our past experiences and help us know what to expect when we are interpreting facial expressions.”
Fifteen Chinese people and 15 Caucasians living in Glasgow took part in the study. They viewed emotion-neutral faces that were randomly altered on a computer screen and then categorized the facial expressions as happy, sad, surprised, fearful, disgusted or angry. The responses allowed researchers to identify the expressive facial features that participants associated with each emotion.
The study found that the Chinese participants relied on the eyes more to represent facial expressions, while Western Caucasians relied on the eyebrows and mouth. Those cultural distinctions could lead to missed cues or misinterpreted signals about emotions during cross-cultural communications, the study reported.
“Our findings highlight the importance of understanding cultural differences in communication, which is particularly relevant in our increasingly connected world,” Jack said. “We hope that our work will facilitate clearer channels of communication between diverse cultures and help promote the understanding of cultural differences within society.”
The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States and is the world’s largest association of psychologists. APA’s membership includes more than 154,000 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting health, education and human welfare.
Article: “Internal Representations Reveal Cultural Diversity in Expectations of Facial Expressions of Emotion,” Rachael E. Jack, Roberto Caldara and Philippe G. Schyns, PhDs; University of Glasgow; Journal of Experimental Psychology: General; Vol. 141, No. 1.
Full text of the article is available from the APA Public Affairs Office and at: http://www.apa.org/pubs/journals/releases/xge-facial-expressions.pdf.
Dr. Jack can be contacted at Rachael.Jack@glasgow.ac.uk or 011 44 (0)7801 374 251.
Contact: APA Public Affairs
public.affairs@apa.org
202-336-5700
American Psychological Association
Tasmanian tiger’s jaw was too small to attack sheep, study shows
September 1, 2011
Australia’s iconic thylacine, or Tasmanian tiger, was hunted to death in the early Twentieth century for allegedly killing sheep; however, a new study published in the Zoological Society of London’s Journal of Zoology has found that the tiger had such weak jaws that its prey was probably no larger than a possum.
“Our research has shown that its rather feeble jaw restricted it to catching smaller, more agile prey,” said lead author Marie Attard, of the University of New South Wales Computational Biomechanics Research Group. “That’s an unusual trait for a large predator like that, considering its substantial 30 kg body mass and carnivorous diet. As for its supposed ability to take prey as large as sheep, our findings suggest that its reputation was at best overblown.
“While there is still much debate about its diet and feeding behaviour, this new insight suggests that its inability to kill large prey may have hastened it on the road to extinction.”
Thylacines were top predators that once ranged across Australia and New Guinea but were found only in Tasmania by the time of European settlement. The resulting loss of habitat and prey, and a bounty paid to hunters to kill them, have been blamed for the demise of this carnivorous marsupial.
Despite its obvious decline, it did not receive official protection from the Tasmanian Government until two months before the last known individual died at Hobart Zoo on 7th September, 1936.
Using advanced computer modelling techniques, the UNSW research team were able to simulate various predatory behaviours, including biting, tearing and pulling, to predict patterns of stress in the skull of a thylacine and those of Australasia’s two largest remaining marsupial carnivores, the Tasmanian devil and the spotted-tailed quoll.
The thylacine’s skull was highly stressed compared to those of its close living relatives in response to simulations of struggling prey and bites using their jaw muscles.
“By comparing the skull performance of the extinct thylacine with those of closely related, living species we can predict the likely body size of its prey,” says the director of the Computational Biomechanics Research Group, Dr Stephen Wroe. “We can be pretty sure that thylacines were competing with other marsupial carnivores to prey on smaller mammals, such as bandicoots, wallabies and possums.
“Especially among large predators, the more specialised a species becomes the more vulnerable is it to extinction. Just a small disturbance to the ecosystem, such as those resulting from the way European settlers altered the land, may have been enough to tip this delicately poised species over the edge.”
Contact: Ben Norman
Lifesciencenews@wiley.com
44-012-437-70375
Wiley-Blackwell
A planet made of diamond
August 25, 2011
The discovery has been made by an international research team, led by Professor Matthew Bailes of Swinburne University of Technology in Melbourne, Australia, and is reported in the journal Science.
The researchers, from The University of Manchester as well as institutions in Australia, Germany, Italy, and the USA, first detected an unusual star called a pulsar using the Parkes radio telescope of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) and followed up their discovery with the Lovell radio telescope, based at Jodrell Bank Observatory in Cheshire, and one of the Keck telescopes in Hawaii.
Pulsars are small spinning stars about 20 km in diameter – the size of a small city – that emit a beam of radio waves. As the star spins and the radio beam sweeps repeatedly over Earth, radio telescopes detect a regular pattern of radio pulses.
For the newly discovered pulsar, known as PSR J1719-1438, the astronomers noticed that the arrival times of the pulses were systematically modulated. They concluded that this was due to the gravitational pull of a small companion planet, orbiting the pulsar in a binary system.
The pulsar and its planet are part of the Milky Way’s plane of stars and lie 4,000 light-years away in the constellation of Serpens (the Snake). The system is about an eighth of the way towards the Galactic Centre from the Earth.
The modulations in the radio pulses tell astronomers a number of things about the planet.
First, it orbits the pulsar in just two hours and ten minutes, and the distance between the two objects is 600,000 km – a little less than the radius of our Sun.
Second, the companion must be small, less than 60,000 km (that’s about five times the Earth’s diameter). The planet is so close to the pulsar that, if it were any bigger, it would be ripped apart by the pulsar’s gravity.
But despite its small size, the planet has slightly more mass than Jupiter.
“This high density of the planet provides a clue to its origin”, said Professor Bailes.
The team thinks that the ‘diamond planet’ is all that remains of a once-massive star, most of whose matter was siphoned off towards the pulsar.
Pulsar J1719-1438 is a very fast-spinning pulsar – what’s called a millisecond pulsar. Amazingly, it rotates more than 10,000 times per minute, has a mass of about 1.4 times that of our Sun but is only 20 km in diameter. About 70 per cent of millisecond pulsars have companions of some kind.
Astronomers think it is the companion that, in its star form, transforms an old, dead pulsar into a millisecond pulsar by transferring matter and spinning it up to a very high speed. The result is a fast-spinning millisecond pulsar with a shrunken companion – most often a so-called white dwarf.
“We know of a few other systems, called ultra-compact low-mass X-ray binaries, that are likely to be evolving according to the scenario above and may likely represent the progenitors of a pulsar like J1719-1438″ said team member Dr Andrea Possenti, Director at INAF-Osservatorio Astronomico di Cagliari.
But pulsar J1719-1438 and its companion are so close together that the companion can only be a very stripped-down white dwarf, one that has lost its outer layers and over 99.9 per cent of its original mass.
“This remnant is likely to be largely carbon and oxygen, because a star made of lighter elements like hydrogen and helium would be too big to fit the measured orbiting times,” said Dr Michael Keith (CSIRO), one of the research team members.
The density means that this material is certain to be crystalline: that is, a large part of the star may be similar to a diamond.
“The ultimate fate of the binary is determined by the mass and orbital period of the donor star at the time of mass transfer. The rarity of millisecond pulsars with planet-mass companions means that producing such ‘exotic planets’ is the exception rather than the rule, and requires special circumstances,” said Dr Benjamin Stappers from The University of Manchester.
The team found pulsar J1719-1438 among almost 200,000 Gigabytes of data using special codes on supercomputers at Swinburne University of Technology in Australia, The University of Manchester in the UK, and the INAF-Osservatorio Astronomico di Cagliari, Italy.
The discovery was made during a systematic search for pulsars over the whole sky that also involves the 100 metre Effelsberg radio telescope of the Max-Planck-Institute for Radioastronomy (MPIfR) in Germany. “This is the largest and most sensitive survey of this type ever conducted. We expected to find exciting things, and it is great to see it happening. There is more to come!” said Professor Michael Kramer, Director at the MPIfR.
Professor Matthew Bailes leads the ‘Dynamic Universe’ theme in a new wide-field astronomy initiative, the Centre of Excellence for All-sky Astrophysics (CAASTRO).
The discovery of the new binary system is of special significance for him and fellow team member Professor Andrew Lyne, from The University of Manchester, who jointly ignited the whole pulsar-planet field in 1991 with what proved to an erroneous claim of the first extra-solar planet. The next year though the first extra-solar planetary system was discovered around the pulsar PSR B1257+12.