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