Chapter 6. Evolution of the Brain and Behavior
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// by Richard Farrell Conventional thinking has long held that pelvic bones in whales and dolphins, evolutionary throwbacks to ancestors that once walked on land, are vestigial and will disappear millions of years from now. But researchers from University of Southern California and the Natural History Museum of Los Angeles County (NHM) have upended that assumption. The scientists argue in a paper just published in the journal Evolution that cetacean (whale and dolphin) pelvic bones certainly do have a purpose and that they're specifically targeted, by selection, for mating. The muscles that control a cetacean's penis are attached to the creature's pelvic bones. Matthew Dean, assistant professor at the USC Dornsife College of Letters, Arts and Sciences, and Jim Dines, collections manager of mammalogy at NHM, wanted to find out if pelvic bones could be evolutionarily advantageous by impacting the overall amount of control an individual creature has with its penis. The pair spent four years examining whale and dolphin pelvic bones, using a 3D laser scanner to study the shape and size of the samples in extreme detail. Then they gathered as much data as they could find -- reaching back to whaler days -- on whale testis size relative to body mass. The testis data was important because in nature, species in "promiscuous," competitive mating environments (where females mate with multiple males) develop larger testes, relative to their body mass, in order to outdo the competition. © 2014 Discovery Communications, LLC.
Ewen Callaway Caffeine's buzz is so nice it evolved twice. The coffee genome has now been published, and it reveals that the coffee plant makes caffeine using a different set of genes from those found in tea, cacao and other perk-you-up plants. Coffee plants are grown across some 11 million hectares of land, with more than two billion cups of the beverage drunk every day. It is brewed from the fermented, roasted and ground berries of Coffea canephora and Coffea arabica, known as robusta and arabica, respectively. An international team of scientists has now identified more than 25,000 protein-making genes in the robusta coffee genome. The species accounts for about one-third of the coffee produced, much of it for instant-coffee brands such as Nescafe. Arabica contains less caffeine, but its lower acidity and bitterness make it more flavourful to many coffee drinkers. However, the robusta species was selected for sequencing because its genome is simpler than arabica’s. Caffeine evolved long before sleep-deprived humans became addicted to it, probably to defend the coffee plant against predators and for other benefits. For example, coffee leaves contain the highest levels of caffeine of any part of the plant, and when they fall on the soil they stop other plants from growing nearby. “Caffeine also habituates pollinators and makes them want to come back for more, which is what it does to us, too,” says Victor Albert, a genome scientist at the University of Buffalo in New York, who co-led the sequencing effort. The results were published on 4 September in Science1. © 2014 Nature Publishing Group
by Sandrine Ceurstemont Screening an instructional monkey movie in a forest reveals that marmosets do not only learn from family members: they also copy on-screen strangers. It is the first time such a video has been used for investigations in the wild. Tina Gunhold at the University of Vienna, Austria, and her colleagues filmed a common marmoset retrieving a treat from a plastic device. They then took the device to the Atlantic Forest near Aldeia in Pernambuco, Brazil, and showed the movie to wild marmosets there. Although monkeys are known to learn from others in their social group, especially when they are youngMovie Camera, little is known about their ability to learn from monkeys that do not belong to the same group. Marmosets are territorial, so the presence of an outsider – even a virtual one on a screen – could provoke an attack. "We didn't know if wild marmosets would be frightened of the video box but actually they were all attracted to it," says Gunhold. Compared to monkeys shown a static image of the stranger, video-watching marmosets were more likely to manipulate the device, typically copying the technique shown (see video). Young monkeys spent more time near the video box than older family members, suggesting that they found the movie more engaging – although as soon as one monkey mastered the task, it was impossible to tell whether the others were learning from the video or from their relative. "We think it's a combination of both," says Gunhold. © Copyright Reed Business Information Ltd.
By Kate Wong In 1871 Charles Darwin surmised that humans were evolutionarily closer to the African apes than to any other species alive. The recent sequencing of the gorilla, chimpanzee and bonobo genomes confirms that supposition and provides a clearer view of how we are connected: chimps and bonobos in particular take pride of place as our nearest living relatives, sharing approximately 99 percent of our DNA, with gorillas trailing at 98 percent. Yet that tiny portion of unshared DNA makes a world of difference: it gives us, for instance, our bipedal stance and the ability to plan missions to Mars. Scientists do not yet know how most of the DNA that is uniquely ours affects gene function. But they can conduct whole-genome analyses—with intriguing results. For example, comparing the 33 percent of our genome that codes for proteins with our relatives' genomes reveals that although the sum total of our genetic differences is small, the individual differences pervade the genome, affecting each of our chromosomes in numerous ways. © 2014 Scientific American
By Jonathan Webb Science reporter, BBC News Monkeys at the top and bottom of the social pecking order have physically different brains, research has found. A particular network of brain areas was bigger in dominant animals, while other regions were bigger in subordinates. The study suggests that primate brains, including ours, can be specialised for life at either end of the hierarchy. The differences might reflect inherited tendencies toward leading or following, or the brain adapting to an animal's role in life - or a little of both. Neuroscientists made the discovery, which appears in the journal Plos Biology, by comparing brain scans from 25 macaque monkeys that were already "on file" as part of ongoing research at the University of Oxford. "We were also looking at learning and memory and decision-making, and the changes that are going on in your brain when you're doing those things," explained Dr MaryAnn Noonan, the study's first author. The decision to look at the animals' social status produced an unexpectedly clear result, Dr Noonan said. "It was surprising. All our monkeys were of different ages and different genders - but with fMRI (functional magnetic resonance imaging) you can control for all of that. And we were consistently seeing these same networks coming out." BBC © 2014
|By Madhuvanthi Kannan We humans assume we are the smartest of all creations. In a world with over 8.7 million species, only we have the ability to understand the inner workings of our body while also unraveling the mysteries of the universe. We are the geniuses, the philosophers, the artists, the poets and savants. We amuse at a dog playing ball, a dolphin jumping rings, or a monkey imitating man because we think of these as remarkable acts for animals that, we presume, aren’t smart as us. But what is smart? Is it just about having ideas, or being good at language and math? Scientists have shown, time and again, that many animals have an extraordinary intellect. Unlike an average human brain that can barely recall a vivid scene from the last hour, chimps have a photographic memory and can memorize patterns they see in the blink of an eye. Sea lions and elephants can remember faces from decades ago. Animals also have a unique sense perception. Sniffer dogs can detect the first signs of colon cancer by the scents of patients, while doctors flounder in early diagnosis. So the point is animals are smart too. But that’s not the upsetting realization. What happens when, for just once, a chimp or a dog challenges man to one of their feats? Well, for one, a precarious face-off – like the one Matt Reeves conceived in the Planet of the Apes – would seem a tad less unlikely than we thought. In a recent study by psychologists Colin Camerer and Tetsuro Matsuzawa, chimps and humans played a strategy game – and unexpectedly, the chimps outplayed the humans. Chimps are a scientist’s favorite model to understand human brain and behavior. Chimp and human DNAs overlap by a whopping 99 percent, which makes us closer to chimps than horses to zebras. Yet at some point, we evolved differently. Our behavior and personalities, molded to some extent by our distinct societies, are strikingly different from that of our fellow primates. Chimps are aggressive and status-hungry within their hierarchical societies, knit around a dominant alpha male. We are, perhaps, a little less so. So the question arises whether competitive behavior is hard-wired in them. © 2014 Scientific American
By Virginia Morell Figaro, a Goffin’s cockatoo (Cacatua goffini) housed at a research lab in Austria, stunned scientists a few years ago when he began spontaneously making stick tools from the wooden beams of his aviary. The Indonesian parrots are not known to use tools in the wild, yet Figaro confidently employed his sticks to rake in nuts outside his wire enclosure. Wondering if Figaro’s fellow cockatoos could learn by watching his methods, scientists set up experiments for a dozen of them. One group watched as Figaro used a stick to reach a nut placed inside an acrylic box with a wire-mesh front panel; others saw “ghost demonstrators”—magnets that were hidden beneath a table and that the researchers controlled—displace the treats. Each bird was then placed in front of the box, with a stick just like Figaro’s lying nearby. The group of three males and three females that had watched Figaro also picked up the sticks, and made some efforts reminiscent of his actions. But only those three males, such as the one in the photo above, became proficient with the tool and successfully retrieved the nuts, the scientists report online today in the Proceedings of the Royal Society B. None of the females did so; nor did any of the birds, male or female, in the ghost demonstrator group. Because the latter group failed entirely, the study shows that the birds need living teachers, the scientists say. Intriguingly, the clever observers developed a better technique than Figaro’s for getting the treat. Thus, the cockatoos weren’t copying his exact actions, but emulating them—a distinction that implies some degree of creativity. Two of the successful cockatoos were later given a chance to make a tool of their own. One did so immediately (as in the video above), and the other succeeded after watching Figaro. It may be that by learning to use a tool, the birds are stimulated to make tools of their own, the scientists say. © 2014 American Association for the Advancement of Science.
Keyword: Learning & Memory
Link ID: 20027 - Posted: 09.03.2014
By Virginia Morell A dog’s bark may sound like nothing but noise, but it encodes important information. In 2005, scientists showed that people can tell whether a dog is lonely, happy, or aggressive just by listening to his bark. Now, the same group has shown that dogs themselves distinguish between the barks of pooches they’re familiar with and the barks of strangers and respond differently to each. The team tested pet dogs’ reactions to barks by playing back recorded barks of a familiar and unfamiliar dog. The recordings were made in two different settings: when the pooch was alone, and when he was barking at a stranger at his home’s fence. When the test dogs heard a strange dog barking, they stayed closer to and for a longer period of time at their home’s gate than when they heard the bark of a familiar dog. But when they heard an unknown and lonely dog barking, they stayed close to their house and away from the gate, the team reports this month in Applied Animal Behaviour Science. They also moved closer toward their house when they heard a familiar dog’s barks, and they barked more often in response to a strange dog barking. Dogs, the scientists conclude from this first study of pet dogs barking in their natural environment (their owners’ homes), do indeed pay attention to and glean detailed information from their fellows’ barks. © 2014 American Association for the Advancement of Science
By Michael Balter Humans are generally highly cooperative and often impressively altruistic, quicker than any other animal species to help out strangers in need. A new study suggests that our lineage got that way by adopting so-called cooperative breeding: the caring for infants not just by the mother, but also by other members of the family and sometimes even unrelated adults. In addition to helping us get along with others, the advance led to the development of language and complex civilizations, the authors say. Cooperative breeding is not unique to humans. Up to 10% of birds are cooperative breeders, as are meerkats and New World monkeys such as tamarins and marmosets. But our closest primate relatives, great apes such as chimpanzees, are not cooperative breeders. Because the human and chimpanzee lineages split between 5 million and 7 million years ago, and humans are the only apes that engage in cooperative breeding, researchers have puzzled over how this helping behavior might have evolved all over again on the human line. In the late 1990s, Sarah Blaffer Hrdy, now an anthropologist emeritus at the University of California, Davis, proposed the cooperative breeding hypothesis. According to her model, early in their evolution humans added cooperative breeding behaviors to their already existing advanced ape cognition, leading to a powerful combination of smarts and sociality that fueled even bigger brains, the evolution of language, and unprecedented levels of cooperation. Soon after Hrdy’s proposal, anthropologists Carel van Schaik and Judith Burkart of the University of Zurich in Switzerland began to test some of these ideas, demonstrating that cooperatively breeding primates like marmosets engaged in seemingly altruistic behavior by helping other marmosets get food with no immediate reward to themselves. © 2014 American Association for the Advancement of Science.
By Priyanka Pulla Humans are late bloomers when compared with other primates—they spend almost twice as long in childhood and adolescence as chimps, gibbons, or macaques do. But why? One widely accepted but hard-to-test theory is that children’s brains consume so much energy that they divert glucose from the rest of the body, slowing growth. Now, a clever study of glucose uptake and body growth in children confirms this “expensive tissue” hypothesis. Previous studies have shown that our brains guzzle between 44% and 87% of the total energy consumed by our resting bodies during infancy and childhood. Could that be why we take so long to grow up? One way to find out is with more precise studies of brain metabolism throughout childhood, but those studies don’t exist yet. However, a new study published online today in the Proceedings of the National Academy of Sciences (PNAS) spliced together three older data sets to provide a test of this hypothesis. First, the researchers used a 1987 study of PET scans of 36 people between infancy and 30 years of age to estimate age trends in glucose uptake by three major sections of the brain. Then, to calculate how uptake varied for the entire brain, they combined that data with the brain volumes and ages of 400 individuals between 4.5 years of age and adulthood, gathered from a National Institutes of Health study and others. Finally, to link age and brain glucose uptake to body size, they used an age series of brain and body weights of 1000 individuals from birth to adulthood, gathered in 1978. © 2014 American Association for the Advancement of Science.
By Meeri Kim From ultrasonic bat chirps to eerie whale songs, the animal kingdom is a noisy place. While some sounds might have meaning — typically something like “I'm a male, aren't I great?” — no other creatures have a true language except for us. Or do they? A new study on animal calls has found that the patterns of barks, whistles, and clicks from seven different species appear to be more complex than previously thought. The researchers used mathematical tests to see how well the sequences of sounds fit to models ranging in complexity. In fact, five species including the killer whale and free-tailed bat had communication behaviors that were definitively more language-like than random. The study was published online Wednesday in the Proceedings of the Royal Society B. “We're still a very, very long way from understanding this transition from animal communication to human language, and it's a huge mystery at the moment,” said study author and zoologist Arik Kershenbaum, who did the work at the National Institute for Mathematical and Biological Synthesis. “These types of mathematical analyses can give us some clues.” While the most complicated mathematical models come closer to our own speech patterns, the simple models — called Markov processes — are more random and have been historically thought to fit animal calls. “A Markov process is where you have a sequence of numbers or letters or notes, and the probability of any particular note depends only on the few notes that have come before,” said Kershenbaum. So the next note could depend on the last two or 10 notes before it, but there is a defined window of history that can be used to predict what happens next. “What makes human language special is that there's no finite limit as to what comes next,” he said.
By Jane C. Hu Last week, people around the world mourned the death of beloved actor and comedian Robin Williams. According to the Gorilla Foundation in Woodside, California, we were not the only primates mourning. A press release from the foundation announced that Koko the gorilla—the main subject of its research on ape language ability, capable in sign language and a celebrity in her own right—“was quiet and looked very thoughtful” when she heard about Williams’ death, and later became “somber” as the news sank in. Williams, described in the press release as one of Koko’s “closest friends,” spent an afternoon with the gorilla in 2001. The foundation released a video showing the two laughing and tickling one another. At one point, Koko lifts up Williams’ shirt to touch his bare chest. In another scene, Koko steals Williams’ glasses and wears them around her trailer. These clips resonated with people. In the days after Williams’ death, the video amassed more than 3 million views. Many viewers were charmed and touched to learn that a gorilla forged a bond with a celebrity in just an afternoon and, 13 years later, not only remembered him and understood the finality of his death, but grieved. The foundation hailed the relationship as a triumph over “interspecies boundaries,” and the story was covered in outlets from BuzzFeed to the New York Post to Slate. The story is a prime example of selective interpretation, a critique that has plagued ape language research since its first experiments. Was Koko really mourning Robin Williams? How much are we projecting ourselves onto her and what are we reading into her behaviors? Animals perceive the emotions of the humans around them, and the anecdotes in the release could easily be evidence that Koko was responding to the sadness she sensed in her human caregivers. © 2014 The Slate Group LLC.
|By Jason G. Goldman When you do not know the answer to a question, say, a crossword puzzle hint, you realize your shortcomings and devise a strategy for finding the missing information. The ability to identify the state of your knowledge—thinking about thinking—is known as metacognition. It is hard to tell whether other animals are also capable of metacognition because we cannot ask them; studies of primates and birds have not yet been able to rule out simpler explanations for this complex process. Scientists know, however, that some animals, such as western scrub jays, can plan for the future. Western scrub jays, corvids native to western North America, are a favorite of cognitive scientists because they are not “stuck in time”—that is, they are able to remember past events and are known to cache their food in anticipation of hunger, according to psychologist Arii Watanabe of the University of Cambridge. But the question remained: Are they aware that they are planning? Watanabe devised a way to test them. He let five birds watch two researchers hide food, in this case a wax worm. The first researcher could hide the food in any of four cups lined up in front of him. The second had three covered cups, so he could place the food only in the open one. The trick was that the researchers hid their food at the same time, forcing the birds to choose which one to watch. If the jays were capable of metacognition, Watanabe surmised, the birds should realize that they could easily find the second researcher's food. The wax worm had to be in the singular open cup. They should instead prefer keeping their eyes on the setup with four open cups because witnessing where that food went would prove more useful in the future. And that is exactly what happened: the jays spent more time watching the first researcher. The results appeared in the July issue of the journal © 2014 Scientific American,
by Sarah Zielinski PRINCETON, N.J. — Learning can be a quick shortcut for figuring out how to do something on your own. The ability to learn from watching another individual — called social learning — is something that hasn’t been documented in many species outside of primates and birds. But now a lizard can be added to the list of critters that can learn from one another. Young eastern water skinks were able to learn by watching older lizards, Martin Whiting of Macquarie University in Sydney reported August 10 at the Animal Behavior Society meeting at Princeton University. The eastern water skink, which reaches a length of about 30 centimeters, can be found near streams and waterways in eastern Australia. The lizards live up to eight years, and while they don’t live in groups, they often see each other in the wild. That could provide an opportunity for learning from each other. Whiting and his colleagues worked with 18 mature (older than 5 years) and 18 young (1.5 to 2 years) male skinks in the lab. The lizards were placed in bins with a barrier in the middle that was either opaque or transparent. In the first of two experiments, the skinks were given a yellow-lidded container with a mealworm inside. They had to learn to open the lid to get the food. In that task, skinks that could see a demonstrator through a transparent barrier were no better at opening the lid than those who had to figure it out on their own. After watching a demonstrator lizard (top row), the skink in the other half of the tub was supposed to have learned that a mealworm was beneath the blue lid. The skink in the middle arena, however, failed the task when he opened the white lid first.D.W.A. Noble et al/Biology Letters 2014 © Society for Science & the Public 2000 - 2013.
by Philippa Skett It's the strangest sweet tooth in the world. Birds lost the ability to taste sugars, but nectar-feeding hummingbirds re-evolved the capacity by repurposing receptors used to taste savoury food. To differentiate between tastes, receptors on the surface of taste buds on the tongue, known as T1Rs, bind to molecules in certain foods, triggering a neurological response. In vertebrates such as humans, a pair of these receptors – T1R2 and T1R3 – work together to deliver the sweet kick we experience from sugar. But Maude Baldwin at Harvard University and her colleagues found that birds don't have the genes that code for T1R2. They are found in lizards, though, suggesting that they were lost at some point during the evolution of birds or the dinosaurs they evolved from. But hummingbirds clearly can detect sugar: not only do they regularly sup on nectar, taste tests show they prefer sweet tasting foods over blander options. Now Baldwin and her team have worked out why: another pair of receptors – T1R1 and T1R3 – work together to detect sugar. Other vertebrates use T1R1 to taste savoury foods. It seems that in hummingbirds the proteins on the surface of the two receptors have been modified so that they respond to sugars instead. © Copyright Reed Business Information Ltd.
By CARL ZIMMER Your body is home to about 100 trillion bacteria and other microbes, collectively known as your microbiome. Naturalists first became aware of our invisible lodgers in the 1600s, but it wasn’t until the past few years that we’ve become really familiar with them. This recent research has given the microbiome a cuddly kind of fame. We’ve come to appreciate how beneficial our microbes are — breaking down our food, fighting off infections and nurturing our immune system. It’s a lovely, invisible garden we should be tending for our own well-being. But in the journal Bioessays, a team of scientists has raised a creepier possibility. Perhaps our menagerie of germs is also influencing our behavior in order to advance its own evolutionary success — giving us cravings for certain foods, for example. “One of the ways we started thinking about this was in a crime-novel perspective,” said Carlo C. Maley, an evolutionary biologist at the University of California, San Francisco, and a co-author of the new paper. “What are the means, motives and opportunity for the microbes to manipulate us? They have all three.” The idea that a simple organism could control a complex animal may sound like science fiction. In fact, there are many well-documented examples of parasites controlling their hosts. Some species of fungi, for example, infiltrate the brains of ants and coax them to climb plants and clamp onto the underside of leaves. The fungi then sprout out of the ants and send spores showering onto uninfected ants below. How parasites control their hosts remains mysterious. But it looks as if they release molecules that directly or indirectly can influence their brains. © 2014 The New York Times Company
by Bethany Brookshire When a laboratory mouse and a house mouse come nose to nose for the first time, each one is encountering something it has never seen before. They are both Mus musculus. But the wild mouse is facing a larger, fatter, calmer and less aggressive version of itself that’s the result of brother-to-sister inbreeding for generations, resulting in mice that are almost completely genetically identical. Laboratory mice are incredibly valuable tools for research into diseases from Alzheimer’s to Zellweger syndrome. Scientists have a deep understanding of lab mouse DNA, and can use that knowledge to study how specific genes may control certain behaviors and underlie disease. But with all the inbreeding comes some traits that, while desirable in a lab mouse, may not reflect the behavior of an animal in the wild. So for some questions, and some behaviors, scientists might need something a bit wilder. A new study takes lab mice back to their roots and along the way uncovers a new gene function. Lea Chalfin and colleagues at the Weizmann Institute of Science in Rohovot, Israel, bred laboratory mice with wild mice for 10 generations. The result was a mouse with wild mouse genes and wild mouse behavior — with a few important lab mouse genes mixed in. The technique allows scientists to place specific mutations in a wild mouse. The results have interesting implications for studying the mouse species, and might provide some new ways to study human disease as well. Chalfin and her colleagues were especially interested in behaviors linked to female aggression. © Society for Science & the Public 2000 - 2013
By Victoria Gill Science reporter, BBC News Scientists in Brazil have managed to eavesdrop on underwater "turtle talk". Their recordings have revealed that, in the nesting season, river turtles appear to exchange information vocally - communicating with each other using at least six different sounds. This included chatter recorded between females and hatchlings. The researchers say this is the first record of parental care in turtles. It shows they could be vulnerable to the effects of noise pollution, they warn. The results, published recently in the Journal Herpetologica, include recordings of the strange turtle talk. They reveal that the animals may lead much more socially complex lives than previously thought. The team, including researchers from the Wildlife Conservation Society (WCS) and the National Institute of Amazonian Research carried out their study on the Rio Trombetas in the Amazon between 2009 and 2011. They used microphones and underwater hydrophones to record more than 250 individual sounds from the animals. The scientists then analysed these vocalisations and divided them into six different types, correlating each category with a specific behaviour. Dr Camila Ferrara, of the WCS Brazil programme, told BBC News: "The [exact] meanings aren't clear... but we think they're exchanging information. "We think sound helps the animals to synchronise their activities in the nesting season," she said. The noises the animals made were subtly different depending on their behaviour. For example, there was a specific sound when adults were migrating through the river, and another when they gathered in front of nesting beaches. There was a different sound again made by adults when they were waiting on the beaches for the arrival of their hatchlings. BBC © 2014
By Victoria Gill Science reporter, BBC News Very mobile ears help many animals direct their attention to the rustle of a possible predator. But a study in horses suggests they also pay close attention to the direction another's ears are pointing in order to work out what they are thinking. Researchers from the University of Sussex say these swivelling ears have become a useful communication tool. Their findings are published in the journal Current Biology. The research team studies animal behaviour to build up a picture of how communication and social skills evolved. "We're interested in how [they] communicate," said lead researcher Jennifer Wathan. "And being sensitive to what another individual is thinking is a fundamental skill from which other [more complex] skills develop." Ms Wathan and her colleague Prof Karen McComb set up a behavioural experiment where 72 individual horses had to use visual cues from another horse in order to choose where to feed. They led each horse to a point where it had to select one of two buckets. On a wall behind this decision-making spot was a life-sized photograph of a horse's head facing either to left or right. In some of the trials, the horses ears or eyes were covered. Horse images used in a study of horse communication The ears have it: Horses in the test followed the gaze of another horse, and the direction its ears pointed If the ears and eyes of the horse in the picture were visible, the horses being tested would choose the bucket towards which its gaze - and its ears - were directed. If the horse in the picture had either its eyes or its ears covered, the horse being tested would just choose a feed bucket at random. Like many mammals that are hunted by predators, horses can rotate their ears through almost 180 degrees - but Ms Wathan said that in our "human-centric" view of the world, we had overlooked the importance of these very mobile ears in animal communication. BBC © 2014
Nishad Karim African penguins communicate feelings such as hunger, anger and loneliness through six distinctive vocal calls, according to scientists who have observed the birds' behaviour in captivity. The calls of the "jackass" penguin were identified by researchers at the University of Turin, Italy. Four are exclusive to adults and two are exclusive to juveniles and chicks. The study, led by Dr Livio Favaro, found that adult penguins produce distinctive short calls to express their isolation from groups or their mates, known as "contact" calls, or to show aggression during fights or confrontations, known as "agonistic" calls. They also observed an "ecstatic display song", sung by single birds during the mating season and the "mutual display song", a custom duet sung by nesting partners to each other. Juveniles and chicks produce calls relating to hunger. "There are two begging calls; the first one is where chicks utter 'begging peeps', short cheeps when they want food from adults, and the second one we've called 'begging moan', which is uttered by juveniles when they're out of the nest, but still need food from adults," said Favaro. The team made simultaneous video and audio recordings of 48 captive African penguins at the zoo Zoom Torino, over a 104 non-consecutive days. They then compared the audio recordings with the video footage of the birds' behaviour. Additional techniques, including visual inspection of spectrographs, produced statistical and quantifiable results. The research is published in the journal PLOS One. © 2014 Guardian News and Media Limited