It has been known for some time that house mice (Mus musculus) produce ultrasonic vocalizations (USVs) during courtship but it has generally been assumed that these are no more than squeaks. However, recent spectrographic analyses have revealed that USVs are complex and show features of song. Although the vocalizations are inaudible to human ears, when playbacks of recorded songs are slowed down their similarity to bird song becomes striking. Frauke Hoffmann, Kerstin Musolf and Dustin Penn of the University of Veterinary Medicine, Vienna's Konrad Lorenz Institute of Ethology aimed to learn what type of information is contained in males' songs for the discerning ear of the female mouse to detect. Their initial studies, the first to study song in wild mice, confirmed that males emit songs when they encounter a females' scent and that females are attracted to males' songs. Additionally, the scientists discovered that females are able to distinguish siblings from unrelated males by their songs – even though they had previously never heard their brothers sing.

In their recent studies, Penn's group recorded and analysed the courtship calls of wild-caught male house mice for the first time, using digital audio software to examine parameters such as duration, pitch and frequency. They found that males' songs contain "signatures" or "fingerprints" that differ from one individual to another. Moreover, they confirmed that the songs of siblings are very similar to one another compared to the songs of unrelated males, which helps explains how females can distinguish unrelated males. This finding could potentially lead us to understand how female mice avoid inbreeding.

Interestingly, in some species of birds the males with the most complex songs appear to be most successful at attracting females. Further studies are needed to determine whether the complexity of male mouse vocalizations has an effect on females that is similar to that of "sexy syllables" in birds.

The vocalizations of wild house mice differ significantly from those of inbred strains of laboratory mice. Wild male mice produce more syllables within high frequency ranges than laboratory mice, a result that is consistent with other studies that find genetic effects on mouse song. "It seems as though house mice might provide a new model organism for the study of song in animals," says Dustin Penn. "Who would have thought that?"

Max Planck researchers reveal the structure of the cellular protein degradation machinery

Mate competition by males over females is common in many animal species. During mating season male testosterone levels rise, resulting in an increase in aggressive behavior and masculine features. Male bonobos, however, invest much more into friendly relationships with females. Elevated testosterone and aggression levels would collide with this increased tendency towards forming pair-relationships.

Bonobos are among the closest living relatives of humans. Like other great apes they live in groups made up of several males and females. Contrary to other ape species however, male bonobos do not, in general, outrank female individuals and do not dominate them in mating contexts. This constellation suggests that the selection for typically masculine behavioral patterns like aggression, dominance and intrasexual competition are met with antagonistic forces: On one hand it is advantageous if a male outcompetes a fellow male. This, however, implies that there is increased aggression and an elevated level of testosterone in high-ranking males. On the other hand – as dominance relations between the sexes are rather balanced in bonobos – it is likely that males benefit from having friendly pair-relationships with female individuals. Studies with birds and rodents show that a tendency towards forming pair-relationships correlates with lower male aggression rates and testosterone levels.

In a current study, Martin Surbeck, Gottfried Hohmann, Tobias Deschner and colleagues of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, found that in wild bonobos high-ranking males were more aggressive and their mating success was higher when compared to lower-ranking males. Contrary to other species in which males compete fiercely over access to females, there was no correlation between dominance status or aggression with testosterone levels. In addition, the researchers found that high-ranking males invested more often than lower-ranking group members into friendly relationships with females. This suggests that these friendly relationships between the sexes are associated with lower male testosterone levels.

"Our study suggests that in bonobos – as in in humans – intersexual friendships result in hormonal patterns that we know from species in which male individuals are actively participating in raising their young and in which the two sexes enter lasting pair-relationships", says Martin Surbeck.

Dogs pick up not only on the words we say but also on our intent to communicate with them, according to a report published online in the Cell Press journal Current Biology on January 5. The findings might help to explain why so many people treat their furry friends like their children; dogs' receptivity to human communication is surprisingly similar to the receptivity of very young children, the researchers say. "Increasing evidence supports the notion that humans and dogs share some social skills, with dogs' social-cognitive functioning resembling that of a 6-month to 2-year-old child in many respects," said József Topál of the Hungarian Academy of Sciences. "The utilization of ostensive cues is one of these features: dogs, as well as human infants, are sensitive to cues that signal communicative intent." Those cues include verbal addressing and eye contact, he explained. Whether or not dogs rely on similar pathways in the brain for processing those cues isn't yet clear.

Topál's team presented dogs with video recordings of a person turning toward one of two identical plastic pots while an eye tracker captured information on the dogs' reactions. In one condition, the person first looked straight at the dog, addressing it in a high-pitched voice with "Hi dog!" In the second condition, the person gave only a low-pitched "Hi dog" while avoiding eye contact.

The data show that the dogs were more likely to follow along and look at the pot when the person first expressed an intention to communicate. "Our findings reveal that dogs are receptive to human communication in a manner that was previously attributed only to human infants," Topál said. As is often the case in research, the results will undoubtedly confirm what many dog owners and trainers already know, the researchers say. Notably, however, it is the first study to use eye-tracking techniques to study dogs' social skills. "By following the eye movements of dogs, we are able to get a firsthand look at how their minds are actually working," Topál said. "We think that the use of this new eye-tracking technology has many potential surprises in store."

New Caledonian crows have, in the past, distinguished themselves with their advanced tool using abilities. A team of researchers from the University of Auckland and the University of Cambridge have now shown these crows can learn to use new types of tools. When confronted with the Aesop's fable paradigm, which requires stones to be dropped into a water-filled tube to bring floating food within reach, the crows quickly learned to use stones as tools. They then preferred to drop into the tube large rocks rather than small rocks, and heavy objects over light objects (which floated on the surface of the water and so were ineffective).

Further experiments showed that the crows' performances were not based on simple learning, which suggests that the crows had some understanding of how the task actually worked. The authors, therefore, concluded that these crows have cognitive mechanisms beyond simple associative learning that are capable of processing causal information about novel tool types.


For more insight into the intelligence of crows, watch A Murder of Crows (~50 min.) at pbs.org.

Rats free trapped companions, even when given choice of chocolate instead

The first evidence of empathy-driven helping behavior in rodents has been observed in laboratory rats that repeatedly free companions from a restraint, according to a new study by University of Chicago neuroscientists. The observation, published in Science, places the origin of pro-social helping behavior earlier in the evolutionary tree than previously thought. Though empathetic behavior has been observed anecdotally in non-human primates and other wild species, the concept had not previously been observed in rodents in a laboratory setting. "This is the first evidence of helping behavior triggered by empathy in rats," said Jean Decety, PhD, Irving B. Harris Professor of Psychology and Psychiatry at the University of Chicago. "There are a lot of ideas in the literature showing that empathy is not unique to humans, and it has been well demonstrated in apes, but in rodents it was not very clear. We put together in one series of experiments evidence of helping behavior based on empathy in rodents, and that's really the first time it's been seen."

The study demonstrates the deep evolutionary roots of empathy-driven behavior, said Jeffrey Mogil, the E.P. Taylor Professor in Pain Studies at McGill University, who has studied emotional contagion of pain in mice. "On its face, this is more than empathy, this is pro-social behavior," said Mogil, who was not involved in the study. "It's more than has been shown before by a long shot, and that's very impressive, especially since there's no advanced technology here."

The experiments, designed by psychology graduate student and first author Inbal Ben-Ami Bartal with co-authors Decety and Peggy Mason, placed two rats that normally share a cage into a special test arena. One rat was held in a restrainer device — a closed tube with a door that can be nudged open from the outside. The second rat roamed free in the cage around the restrainer, able to see and hear the trapped cagemate but not required to take action. The researchers observed that the free rat acted more agitated when its cagemate was restrained, compared to its activity when the rat was placed in a cage with an empty restrainer. This response offered evidence of an "emotional contagion," a frequently observed phenomenon in humans and animals in which a subject shares in the fear, distress or even pain suffered by another subject.

While emotional contagion is the simplest form of empathy, the rats' subsequent actions clearly comprised active helping behavior, a far more complex expression of empathy. After several daily restraint sessions, the free rat learned how to open the restrainer door and free its cagemate. Though slow to act at first, once the rat discovered the ability to free its companion, it would take action almost immediately upon placement in the test arena. "We are not training these rats in any way," Bartal said. "These rats are learning because they are motivated by something internal. We're not showing them how to open the door, they don't get any previous exposure on opening the door, and it's hard to open the door. But they keep trying and trying, and it eventually works."

To control for motivations other than empathy that would lead the rat to free its companion, the researchers conducted further experiments. When a stuffed toy rat was placed in the restrainer, the free rat did not open the door. When opening the restrainer door released his companion into a separate compartment, the free rat continued to nudge open the door, ruling out the reward of social interaction as motivation. The experiments left behavior motivated by empathy as the simplest explanation for the rats' behavior. "There was no other reason to take this action, except to terminate the distress of the trapped rats," Bartal said. "In the rat model world, seeing the same behavior repeated over and over basically means that this action is rewarding to the rat."

As a test of the power of this reward, another experiment was designed to give the free rats a choice: free their companion or feast on chocolate. Two restrainers were placed in the cage with the rat, one containing the cagemate, another containing a pile of chocolate chips. Though the free rat had the option of eating all the chocolate before freeing its companion, the rat was equally likely to open the restrainer containing the cagemate before opening the chocolate container. "That was very compelling," said Mason, PhD, Professor of Neurobiology. "It said to us that essentially helping their cagemate is on a par with chocolate. He can hog the entire chocolate stash if he wanted to, and he does not. We were shocked."

Now that this model of empathic behavior has been established, the researchers are carrying out additional experiments. Because not every rat learned to open the door and free its companion, studies can compare these individuals to look for the biological source of these behavioral differences. Early results suggested that females were more likely to become door openers than males, perhaps reflecting the important role of empathy in motherhood and providing another avenue for study. "This model of empathy and helping behavior opens the path for elucidating aspects of the underlying neurophysiological mechanisms that were not accessible until now." Bartal said.

The experiments also provide further evidence that empathy-driven helping behavior is not unique to humans – and suggest that Homo sapiens could learn a lesson from its rat cousins. "When we act without empathy we are acting against our biological inheritance," Mason said. "If humans would listen and act on their biological inheritance more often, we'd be better off."

Most of the linguistic functions in humans are controlled by the left cerebral hemisphere. A study of captive chimpanzees at the Yerkes National Primate Research Center (Atlanta, Georgia), reported in the January 2010 issue of Elsevier's Cortex, suggests that this "hemispheric lateralization" for language may have its evolutionary roots in the gestural communication of our common ancestors. A large majority of the chimpanzees in the study showed a significant bias towards right-handed gestures when communicating, which may reflect a similar dominance of the left hemisphere for communication in chimpanzees as that seen for language functions in humans.

A team of researchers, supervised by Prof. William D. Hopkins of Agnes Scott College (Decatur, Georgia), studied hand-use in 70 captive chimpanzees over a period of 10 months, recording a variety of communicative gestures specific to chimpanzees. These included 'arm threat', 'extend arm' or 'hand-slap' gestures produced in different social contexts, such as attention-getting interactions, shared excitation, threat, aggression, greeting, reconciliation or invitations for grooming or for play. The gestures were directed at the human observers, as well as toward other chimpanzees.

"The degree of predominance of the right hand for gestures is one of the most pronounced we have ever found in chimpanzees in comparison to other non-communicative manual actions. We already found such manual biases in this species for pointing gestures exclusively directed to humans. These additional data clearly showed that right-handedness for gestures is not specifically associated to interactions with humans, but generalizes to intraspecific communication", notes Prof. Hopkins.

The French co-authors, Dr. Adrien Meguerditchian and Prof. Jacques Vauclair, from the Aix-Marseille University (Aix-en-Provence, France), also point out that "this finding provides additional support to the idea that speech evolved initially from a gestural communicative system in our ancestors. Moreover, gestural communication in apes shares some key features with human language, such as intentionality, referential properties and flexibility of learning and use".

Border collies are brightest

Although you wouldn't want one to balance your checkbook, dogs can count. They can also understand more than 150 words and intentionally deceive other dogs and people to get treats, according to psychologist and leading canine researcher Stanley Coren, PhD, of the University of British Columbia. He spoke Saturday on the topic "How Dogs Think" at the American Psychological Association's 117th Annual Convention.

Coren, author of more than a half-dozen popular books on dogs and dog behavior, has reviewed numerous studies to conclude that dogs have the ability to solve complex problems and are more like humans and other higher primates than previously thought. "We all want insight into how our furry companions think, and we want to understand the silly, quirky and apparently irrational behaviors [that] Lassie or Rover demonstrate," Coren said in an interview. "Their stunning flashes of brilliance and creativity are reminders that they may not be Einsteins but are sure closer to humans than we thought."

According to several behavioral measures, Coren says dogs' mental abilities are close to a human child age 2 to 2.5 years. The intelligence of various types of dogs does differ and the dog's breed determines some of these differences, Coren says. "There are three types of dog intelligence: instinctive (what the dog is bred to do), adaptive (how well the dog learns from its environment to solve problems) and working and obedience (the equivalent of 'school learning')."

Data from 208 dog obedience judges from the United States and Canada showed the differences in working and obedience intelligence of dog breeds, according to Coren. "Border collies are number one; poodles are second, followed by German shepherds. Fourth on the list is golden retrievers; fifth, dobermans; sixth, Shetland sheepdogs; and finally, Labrador retrievers," said Coren.

As for language, the average dog can learn 165 words, including signals, and the "super dogs" (those in the top 20 percent of dog intelligence) can learn 250 words, Coren says. "The upper limit of dogs' ability to learn language is partly based on a study of a border collie named Rico who showed knowledge of 200 spoken words and demonstrated 'fast-track learning,' which scientists believed to be found only in humans and language learning apes," Coren said. Dogs can also count up to four or five, said Coren. And they have a basic understanding of arithmetic and will notice errors in simple computations, such as 1+1=1 or 1+1=3.

Four studies he examined looked how dogs solve spatial problems by modeling human or other dogs' behavior using a barrier type problem. Through observation, Coren said, dogs can learn the location of valued items (treats), better routes in the environment (the fastest way to a favorite chair), how to operate mechanisms (such as latches and simple machines) and the meaning of words and symbolic concepts (sometimes by simply listening to people speak and watching their actions). During play, dogs are capable of deliberately trying to deceive other dogs and people in order to get rewards, said Coren. "And they are nearly as successful in deceiving humans as humans are in deceiving dogs."

A Brown University-led research team has documented for the first time how bats land. The results are surprising: Not all bats land the same way. The findings, which appear in the Journal of Experimental Biology, could offer new insights into how the second-largest order of mammals evolved.

PROVIDENCE, R.I. [Brown University] — People have always been fascinated by bats, but the scope of that interest generally is limited to how bats fly and their bizarre habit of sleeping upside down. Until now, no one had studied how bats arrive at their daytime perches.

A Brown University-led research team is the first to document the landing approaches of three species of bats — two that live in caves and one that roosts in trees. What they found was surprising: Not all bats land the same way.

“Hanging upside down is what bats do,” said Daniel Riskin, a postdoctoral researcher in the Ecology and Evolutionary Biology department at Brown and lead author on a paper published in the Journal of Experimental Biology. “We've known this. But this is the first time anyone has measured how they land.”

Using sophisticated motion capture cameras in a special flight enclosure, the team filmed each species of bat as it swooped toward a latticed landing pad and landed on it. Cynopterus brachyotis, a tree-roosting bat common in tropical parts of southeast Asia, executed a half-backflip as it swooped upward to the landing site, landing as its hind legs and thumbs touched the pad simultaneously — a four-point landing, the group observed. The landing is hard, Riskin noted, with an impact force more than four times the species’ body weight.

The team then turned its attention to two cave-roosting species, Carollia perspicillata and Glossophaga soricina. These bats, common in Central and South America, approach their landing target with a vertical pitch and then, at the last instant, yaw to the left or to the right — executing a cartwheel of sorts — before grasping the landing pad with just their hind legs. The two-point landing is much gentler than the impact force exerted by the tree-roosting bats, the researchers observed; the cave-roosting bats have a landing impact force of just one-third of their body weight.

There are about 1,200 recognized bat species worldwide, so Riskin was cautious about not drawing any grand conclusions. Still, he said, the fact that the team has documented that bats land differently could open new insights into a species that makes up roughly one-fifth of all mammals on earth. “It's opening the door to how bats evolved,” Riskin said. “You can say that bats have been hanging upside down since they first evolved, and it has probably been one of the keys to their worldwide success.”

Other Brown researchers who worked on the paper include Sharon Swartz, associate professor of biology; Tatjana Hubel, a postdoctoral researcher; and Joseph Bahlman, a graduate student. John Ratcliffe, a biologist at the University of Southern Denmark, and Thomas Kunz, a biologist at Boston University, contributed to the paper.

Researchers have found what they say is some of the first unambiguous evidence that an animal other than humans can make spontaneous plans for future events. The report in the March 9th issue of Current Biology, a Cell Press publication, highlights a decade of observations in a zoo of a male chimpanzee calmly collecting stones and fashioning concrete discs that he would later use to hurl at zoo visitors.

"These observations convincingly show that our fellow apes do consider the future in a very complex way," said Mathias Osvath of Lund University. "It implies that they have a highly developed consciousness, including life-like mental simulations of potential events. They most probably have an 'inner world' like we have when reviewing past episodes of our lives or thinking of days to come. When wild chimps collect stones or go out to war, they probably plan this in advance. I would guess that they plan much of their everyday behavior."

While researchers have observed many ape behaviors that could involve planning both in the wild and in captivity, it generally hasn't been possible to judge whether they were really meeting a current or future need, he added. For instance, when a chimp breaks a twig for termite fishing or collects a stone for nut cracking, it can always be argued that they are motivated by immediate rather than future circumstances.

And that's what makes the newly described case so special, Osvath said. It is clear that the chimp's planning behavior is not based on a "current drive state." In contrast to the chimp's extreme agitation when throwing the stones, he was always calm when collecting or manufacturing his ammunition.

Osvath said he thinks wild chimps in general, as well as other animals, probably have the planning ability demonstrated by the individual described in the study. Indeed, experiments conducted recently with other captive chimpanzees have shown they are capable of making such plans. (Some have argued, however, that those findings could be the result of experimental artifacts.)

"I think that wild chimpanzees might be even better at planning as they probably rely on it for their daily survival," Osvath said. "The environment in a zoo is far less complex than in a forest. Zoo chimps never have to encounter the dangers in the forest or live through periods of scarce food. Planning would prove its value in 'real life' much more than in a zoo."

Chimpanzees recognize their pals by using some of the same brain regions that switch on when humans register a familiar face, according to a report published online on December 18th in Current Biology, a Cell Press publication. The study—the first to examine brain activity in chimpanzees after they attempt to match fellow chimps' faces—offers new insight into the origin of face recognition in humans, the researchers said.

"We can learn about human origins by studying our closest relatives," said Lisa Parr, a researcher at the Yerkes National Primate Research Center, Emory University. "We can discover what aspects of human cognition are really unique and which are present in other animals."

Earlier studies had shown that chimpanzees, like humans, are adept at recognizing their peers. "We knew [from behavioral studies] that chimps and humans process faces similarly," Parr said. "We wondered whether similar brain regions were responsible, and, for the most part, they seem to be."

In the study, the researchers examined brain activity (as reflected by blood sugar metabolism) in five chimpanzees by using Positron Emission Tomography (PET) scans. (Parr noted that the Yerkes National Primate Research Center is the only center of its kind to have on-site MRI, PET, and cyclotron facilities, making studies like Parr's possible.) The chimps were shown three faces, two of which were identical, while the third was of a different chimp. Subjects were then asked to indicate the faces that matched. In other trials, the chimpanzees did the same matching task with clip art images.

The imaging studies revealed significant face-selective activity in brain regions known to make up the distributed cortical face-processing network in humans. Further study showed distinct patches of activity in a region known as the fusiform gyrus—the primary site of face-selective activity in humans—when chimps observed faces.

The researchers concluded that the brain regions that are active during facial recognition may represent part of a distributed neural system for face processing in chimpanzees, like that proposed in humans, in which the initial visual analysis of faces activates regions in the occipital and temporal lobes of the cerebral cortex (a portion of the brain involved in memory, attention, and perceptual awareness) followed by additional processing in the fusiform gyrus and other regions.

Parr emphasized, however, that there have been decades of research on face processing in the human brain. As the first such study in chimpanzees, the new findings raise more questions than they can answer, and follow-up studies are underway.

Whispering bats are shrieking

Annemarie Surlykke from the University of Southern Denmark is fascinated by echolocation. She really wants to know how it works. Surlykke equates the ultrasound cries that bats use for echolocation with the beam of light from a torch: you won't see much with the light from a small bulb but you could see several hundred metres with a powerful beam. Surlykke explains that it's the same with echolocating bats. Some have big powerful calls for perception over a long range, while others are said to whisper; which puzzled Surlykke. How could 'whispering' bats echolocate with puny 70decibel cries that barely carry at all? Teaming up with her long time collaborator Elizabeth Kalko from the Smithsonian Tropical Research Institute and student Signe Brinkløv, Surlykke decided to measure the volume of a pair of whispering bat species' calls to find out how loud the whisperers are. They publish their discovery that whispering bats are really shrieking in The Journal of Experimental Biology on 12th December 2008 at http://jeb.biologists.org.

Travelling to the Smithsonian Research Institute's Barro Colorado Island in Panama, Surlykke decided to focus on two whispering members of the Phyllostomidae family: Artibeus jamaicensis and Macrophyllum macrophyllum. According to Surlykke, the Phyllostomidae family of bats are unique because of their remarkably diverse lifestyles and diets. Some feed on fast moving insects while others feast on fruit buried in trees, making them an ideal family to study to find out how echolocation works.

But measuring the volume of the bat's echolocation calls was extremely challenging. If Surlykke was going to get true volume measurements from hunting bats on the wing, she would have to be certain that the bats were facing head on and that she could measure their distance from the microphone that recorded the sound so that she could correct for the volume lost as the call travelled to the microphone. Setting up an array of four microphones, the team recorded 460 cries, which Surlykke eventually whittled down to 31 calls for M. macrophyllum and 19 for A. jamaicensis that she could use.

Correcting the volume measurements, Surlykke was delighted to find that far from whispering, the bats were shrieking. The tiny insectivore M. macrophyllum registered a top volume of 105decibel, while fruit feeding A. jamaicensis broke the record at 110decibel, a remarkable 100 times louder than a 70decibel bat whisper and almost twice as loud as A. jamaicensis.

Surlykke suspects that she can explain the differences in the animals' volumes by their different lifestyles. She explains that the relatively large A. jamaicensis feeds on fruit, which it probably locates through a combination of senses, including smell and short-range echolocation whispers. But the bats have to search over large areas to find fruiting trees, and Surlykke suspects that the bat uses its high volume, well-carrying shrieks for orientation in their complex forest environment.

However, tiny M. macrophyllum's lifestyle is completely different. They hunt for insects over water, scooping them up with their tail. Surlykke says that she suspected that M. macrophyllum would be louder because she couldn't see how the animals could locate moving insects with a low intensity echolocation call, but admits that she was amazed that they were so much louder and that they could also adjust the volume to match their prey.

Hundreds of thousands of Australians count snakes and spiders among their fears, and while scientists have previously assumed we possess an evolutionary predisposition to fear the unpopular animals, researchers at UQ's School of Psychology look to have proved otherwise. According to Dr Helena Purkis, the results of the UQ study could provide an unprecedented insight into just why the creepy creatures are so widely feared.

“Previous research shows we react differently to snakes and spiders than to other stimuli, such as flowers or mushrooms, or even other dangerous animals….or cars and guns, which are also much more dangerous,” Dr Purkis said. “[In the past, this] has been explained by saying that people are predisposed by evolution to fear certain things, such as snakes and spiders, that would have been dangerous to our ancestors. [However], people tend to be exposed to a lot of negative information regarding snakes and spiders, and we argue this makes them more likely to be associated with phobia.”

In the study, researchers compared the responses to stimuli of participants with no particular experience with snakes and spiders, to that of snake and spider experts.

“Previous research has argued that snakes and spiders attract preferential attention (they capture attention very quickly) and that during this early processing a negative (fear) response is generated… as an implicit and indexed subconscious [action],” Dr Purkis said. “We showed that although everyone preferentially attends to snakes or spiders in the environment as they are potentially dangerous, only inexperienced participants display a negative response.”

The study is the first to establish a clear difference between preferential attention and the accompanying emotional response: that is, that you can preferentially attend to something without a negative emotional response being elicited. Dr Purkis said the findings could significantly increase understanding about the basic cognitive and emotional processes involved in the acquisition and maintenance of fear.

“If we understand the relationship between preferential attention and emotion it will help us understand how a stimulus goes from being perceived as potentially dangerous, to eliciting an emotional response and to being associated with phobia,” she said. “[This] could give us some information about the way people need to deal with snakes and spiders in order to minimise negative emotional responses.”

UQ News Online

Some of the oldest tales and wisest mythology allude to the snake as a mischievous seducer, dangerous foe or powerful iconoclast; however, the legend surrounding this proverbial predator may not be based solely on fantasy. As scientists from the University of Virginia recently discovered, the common fear of snakes is most likely intrinsic.

Evolutionarily speaking, early humans who were capable of surviving the dangers of an uncivilized society adapted accordingly. And the same can be said of the common fear of certain animals, such as spiders and snakes: The ancestors of modern humans were either abnormally lucky or extraordinarily capable of detecting and deterring the threat of, for example, a poisonous snake.

Psychologists Vanessa LoBue and Judy DeLoache were able to show this phenomenon by examining the ability of adults and children to pinpoint snakes among other nonthreatening objects in pictures. “We wanted to know whether preschool children, who have much less experience with natural threats than adults, would detect the presence of snakes as quickly as their parents,” LoBue explained. “If there is an evolved tendency in humans for the rapid detection of snakes, it should appear in young children as well as their elders.”

Preschool children and their parents were shown nine color photographs on a computer screen and were asked to find either the single snake among eight flowers, frogs or caterpillars, or the single nonthreatening item among eight snakes. As the study surprisingly shows, parents and their children identified snakes more rapidly than they detected the other stimuli, despite the gap in age and experience.

The results, which appear in the March 2008 issue of Psychological Science, a journal of the Association for Psychological Science, may provide the first evidence of an adapted, visually-stimulated fear mechanism in humans.

When trying to understand someone's intentions, non-human primates expect others to act rationally by performing the most appropriate action allowed by the environment, according to a new study by researchers at Harvard University.

The findings appear in the Sept. 7 issue of the journal of Science. The work was led by Justin Wood, a graduate student in the Department of Psychology in the Faculty of Arts and Sciences at Harvard, with David Glynn, a research assistant, and Marc Hauser, professor of psychology at Harvard, along with Brenda Phillips of Boston University.

“A dominant view has been that non-human primates attend only to what actions 'look like' when trying to understand what others are thinking," says Wood. "In contrast, our research shows that non-human primates infer others' intentions in a much more sophisticated way. They expect other individuals to perform the most rational action that they can, given the environmental obstacles that they face."

The scientists studied the behavioral response of over 120 primates, including cotton-top tamarins, rhesus macaques and chimpanzees. These species represent each of the three major groups of primates: New World monkeys, Old World monkeys and apes. All three species were tested in the same way, and the results showed the same responses among the different types.

In the first experiment, the primates were presented with two potential food containers, and the experimenter either purposefully grasped one of the containers, or flopped their hand onto one of the containers in an accidental manner. For all three species, the primates sought the food container that was purposefully grasped a greater number of times than the container upon which the hand was flopped. This indicates that the primate inferred goal-oriented action on the part of the experimenter when he grasped the container, and was able to understand the difference between the goal-oriented and accidental behavior.

In the second experiment, the researchers asked if the primates infer others' goals under the expectation that other individuals will perform the most rational action allowed by the environmental obstacles. Again, the primates were presented with two potential food containers. In one scenario, an experimenter touched a container with his elbow when his hands were full, and in another scenario, touched a container with his elbow when his hands were empty. The primates looked for the food in the container indicated with the elbow more often when the experimenter's hands were full. The primates considered, just as a human being would, that if someone's hands are full then it is rational for them to use their elbow to indicate the container with food, whereas if their hands are empty it is not rational for them to use their elbow, because they could have used their unoccupied hand.

Developmental psychologists have long understood that young children are able to engage in this type of rational action perception, but scientists have not understood if this ability is unique to human beings, or shared with other animals. This study suggests that this ability evolved as long as 40 million years ago, with non-human primates.

“This study represents one of the broadest comparative studies of primate cognition, and the significance of the findings is reinforced by the fact that these results were consistent across three different species of primates,” says Wood. “The results have significant implications for understanding the evolution of the processes that allow us to make sense of other people's behavior.”

Fish use the threat of punishment to keep would-be jumpers in the mating queue firmly in line and the social order stable, a new study led by Australian marine scientists has found. Their discovery, which has implications for the whole animal kingdom including humans, has been hailed by some of the world’s leading biologists as a “must read” scientific paper and published in the Proceedings of the Royal Society of London Series B.

Studying small goby fish at Lizard Island on Australia’s Great Barrier Reef, Dr Marian Wong and colleagues from the ARC Centre of Excellence for Coral Reef Studies at James Cook University and, the Biological Station of Donana, Spain, have shown the threat of expulsion from the group acts as a powerful deterrent to keep subordinate fish from challenging those more dominant than themselves.

In fact the subordinate fish deliberately diet - or starve themselves - in order to remain smaller than their superiors and so present no threat that might lead to their being cast out, and perishing as a result. “Many animals have social queues in which the smaller members wait their turn before they can mate. We wanted to find out how they maintain stability in a situation where you’d expect there would be a lot of competition,” says Dr Wong. In the case of the gobies, only the top male and top female mate, and all the other females have to wait their turn in a queue based on their size – the fishy equivalent of the barnyard pecking order.

Dr Wong found that each fish has a size difference of about 5 per cent from the one above and the one below it in the queue. If the difference in size decreases below this threshold, a challenge is on as the junior fish tries to jump the mating queue – and the superior one responds by trying to drive it out of the group. Her fascinating discovery is that, in order to avoid constant fights and keep the social order stable, the fish seem to accept the threat of punishment – and adjust their own size in order to avoid presenting a challenge to the one above them, she says. “Social hierarchies are very stable in these fish and in practice challenges and expulsions are extremely rare – probably because expulsion from the group and the coral reef it occupies means almost certain death to the loser. “It is clear the fish accept the threat of punishment and co-operate as a way of maintaining their social order – and that’s not so very different to how humans and other animals behave.”

Dr Wong said that experimentally it has always proved extremely difficult to demonstrate how higher animals, such as apes, use punishment to control subordinates and discourage anti-social activity because of the difficulty in observing and interpreting their behaviour. In the case of the gobies the effect is much more apparent because they seek to maintain a particular size ratio relative to the fish above them in the queue, in order not to provoke a conflict. “The gobies have shed new light on our understanding of how social stability is maintained in animals,” she says. “While it not be accurate to draw a direct link between fish behaviour and specific human behaviour, it is clear there are general patterns of behaviour which apply to many higher life forms, ourselves included. These help us to understand why we do the things we do.”

Chimpanzees recognized when collaboration was necessary and chose the best collaborative partner
    
In the animal kingdom cooperation is crucial for survival. Predators hunt in prides and prey band together to protect themselves. Yet no other creature cooperates as successfully as we do. But where did this ability come from, and is it uniquely human? In a new study to be published in Science on 3 March 2006, Alicia Melis and co-authors from the Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany show that our close relatives, chimpanzees, are much better cooperators than we thought.

2 March 2006