Chapter 6. Evolution of the Brain and Behavior

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.

Links 81 - 100 of 1527

by Laura Poppick, LiveScience Researchers have widely examined homosexual behavior in mammals and birds, but have addressed it less frequently in insects and spiders. To assess the range of evolutionary explanations for same-sex intercourse in the invertebrate world, a team of biologists from Tel Aviv University in Israel and the Swiss Federal Institute of Technology in Zurich, Switzerland examined roughly 100 existing studies on the topic and compiled the first comprehensive review of homosexuality in invertebrates. The review was published earlier this month in the journal Behavioral Ecology and Sociobiology. The team focused on male-male interactions to simplify the analysis, and found that most of these encounters occurred as accidents. Whereas larger animals have developed more complicated homosexual motivations — like maintaining alliances, which has been found in certain primate and seagull species — insects seem to mistakenly partake in it in a hasty attempt to secure mates. [Gay Animals: Alternate Lifestyles in the Wild] "They have evolved to mate quick and dirty," said study co-author Inon Scharf, an evolutionary ecologist at Tel Aviv University. "They grab every opportunity to mate that they have because, if they become slow, they may give up an opportunity to mate." In some cases, males carry around the scent of females they have just mated with, sending confusing signals to other perusing males. In other cases, males and females look so similar to one another that males cannot tell if a potential mate is a female until he mounts "her" and prepares for the act, Scharf said. © 2013 Discovery Communications, LLC.

Keyword: Sexual Behavior; Aggression
Link ID: 18518 - Posted: 08.17.2013

// by Jennifer Viegas Single parenting takes on new extremes for certain starfish that are hermaphrodites -- male and female at the same time and, in some cases, self-fertilizing. The species faces high risk of extinction, according to new research. The dire situation faced by the non-mating starfish, Parvulastra parvivipara and Parvulastra vivipara, helps to explain why so many organisms, including humans, have sex. Genetic diversity and the dispersal of youngsters support population growth. The plight of the starfish, documented in the latest issue of the journal Biology Letters, reveals how a life without sex but with self-fertilization could result in eventual oblivion. “There are quite a few reasons why these species are vulnerable,” senior author Michael Hart of Simon Fraser University’s Department of Biological Sciences told Discovery News. “The whole species could be wiped out.” Hart and his team studied the starfish, which are restricted to high intertidal pools of South Australia and Tasmania. These starfish also go by the nickname "sea cushions," since they look a bit more like a cushion than a star when viewed from the side. Most adult starfish of other species do reproduce via a separate male and female. Females usually produce eggs that males fertilize in the seawater. At that point, the fertilized eggs develop and grow before becoming little starfish that will attach themselves to the substrate and start the whole process over again. © 2013 Discovery Communications, LLC.

Keyword: Sexual Behavior; Aggression
Link ID: 18470 - Posted: 08.07.2013

By CARL ZIMMER “Monogamy is a problem,” said Dieter Lukas of the University of Cambridge in a telephone news conference this week. As Dr. Lukas explained to reporters, he and other biologists consider monogamy an evolutionary puzzle. In 9 percent of all mammal species, males and females will share a common territory for more than one breeding season, and in some cases bond for life. This is a problem — a scientific one — because male mammals could theoretically have more offspring by giving up on monogamy and mating with lots of females. In a new study, Dr. Lukas and his colleague Tim Clutton-Brock suggest that monogamy evolves when females spread out, making it hard for a male to travel around and fend off competing males. On the same day, Kit Opie of University College London and his colleagues published a similar study on primates, which are especially monogamous — males and females bond in over a quarter of primate species. The London scientists came to a different conclusion: that the threat of infanticide leads males to stick with only one female, protecting her from other males. Even with the scientific problem far from resolved, research like this inevitably turns us into narcissists. It’s all well and good to understand why the gray-handed night monkey became monogamous. But we want to know: What does this say about men and women? As with all things concerning the human heart, it’s complicated. © 2013 The New York Times Company

Keyword: Sexual Behavior; Aggression
Link ID: 18453 - Posted: 08.03.2013

By Melissa Hogenboom Science reporter, BBC News Several ancient dinosaurs evolved the brainpower needed for flight long before they could take to the skies, scientists say. Non-avian dinosaurs were found to have "bird brains", larger than that of Archaeopteryx, a 150 million-year-old bird-like dinosaur. Once regarded as a unique transition between dinosaurs and birds, scientists say Archaeopteryx has now lost its pivotal place. The study is published in Nature. A recent discovery in China which unveiled the earliest creature yet discovered on the evolutionary line to birds, also placed Archaeopteryx in less of a transitional evolutionary place. Bird brains tend to be more enlarged compared to their body size than reptiles, vital for providing the vision and coordination needed for flight. Scientists using high-resolution CT scans have now found that these "hyper-inflated" brains were present in many ancient dinosaurs, and had the neurological hardwiring needed to take to the skies. This included several bird-like oviraptorosaurs and the troodontids Zanabazar junior, which had larger brains relative to body size than that of Archaeopteryx. This latest work adds to previous studies which found the presence of feathers and wishbones on ancient dinosaurs. BBC © 2013

Keyword: Evolution
Link ID: 18439 - Posted: 08.01.2013

Andrew Curry In the 1970s, archaeologist Peter Bogucki was excavating a Stone Age site in the fertile plains of central Poland when he came across an assortment of odd artefacts. The people who had lived there around 7,000 years ago were among central Europe's first farmers, and they had left behind fragments of pottery dotted with tiny holes. It looked as though the coarse red clay had been baked while pierced with pieces of straw. Looking back through the archaeological literature, Bogucki found other examples of ancient perforated pottery. “They were so unusual — people would almost always include them in publications,” says Bogucki, now at Princeton University in New Jersey. He had seen something similar at a friend's house that was used for straining cheese, so he speculated that the pottery might be connected with cheese-making. But he had no way to test his idea. The mystery potsherds sat in storage until 2011, when Mélanie Roffet-Salque pulled them out and analysed fatty residues preserved in the clay. Roffet-Salque, a geochemist at the University of Bristol, UK, found signatures of abundant milk fats — evidence that the early farmers had used the pottery as sieves to separate fatty milk solids from liquid whey. That makes the Polish relics the oldest known evidence of cheese-making in the world1. © 2013 Nature Publishing Group

Keyword: Evolution; Aggression
Link ID: 18438 - Posted: 08.01.2013

By CARL ZIMMER The golden lion tamarin, a one-pound primate that lives in Brazil, is a stunningly monogamous creature. A male will typically pair with a female and they will stay close for the rest of their lives, mating only with each other and then working together to care for their young. To biologists, this deeply monogamous way of life — found in 9 percent of mammal species — is puzzling. A seemingly better evolutionary strategy for male mammals would be to spend their time looking for other females with which to mate. “Monogamy is a problem,” said Dieter Lukas of the University of Cambridge in a telephone news conference on Monday. “Why should the male keep to one female?” The evolution of monogamy has inspired many different ideas. “These hypotheses have been suggested for the past 40 years, and there’s been no resolution of the debate,” said Kit Opie of the University College London in an interview. On Monday, Dr. Opie and Dr. Lukas each published a large-scale study of monogamy that they hoped would resolve the debate. But they ended up coming to opposing conclusions, which means the debate over monogamy continues. Dr. Lukas, co-author of a paper in the journal Science with Tim Clutton-Brock of Cambridge, looked at 2,545 species of mammals, tracing their mating evolution from their common ancestor some 170 million years ago. The scientists found that mammals shifted from solitary living to monogamy 61 times over their evolution. They then searched for any factors that these mammals had in common. They concluded that monogamy evolves when females become hostile with one another and live in ranges that do not overlap. When females live this way, they set up so much distance between one another that a single male cannot prevent other males from mating with them. Staying close to one female became a better strategy. Once males began doing so, they sometimes evolved to provide care to their offspring as well. © 2013 The New York Times Company

Keyword: Sexual Behavior; Aggression
Link ID: 18429 - Posted: 07.30.2013

By JAMES GORMAN Should some of the most social, intelligent and charismatic animals on the planet be kept in captivity by human beings? That is a question asked more frequently than ever by both scientists and animal welfare advocates, sometimes about close human cousins like chimpanzees and other great apes, but also about another animal that is remarkable for its intelligence and complex social organization — the killer whale, or orca. Killer whales, found in all the world’s oceans, were once as despised as wolves. But in the last half century these elegant black-and-white predators — a threat to seals and other prey as they cruise the oceans, but often friendly to humans in the wild — have joined the pantheon of adored wildlife, along with the familiar polar bears, elephants and lions. With life spans that approach those of humans, orcas have strong family bonds, elaborate vocal communication and cooperative hunting strategies. And their beauty and power, combined with a willingness to work with humans, have made them legendary performers at marine parks since they were first captured and exhibited in the 1960s. They are no longer taken from the wild as young to be raised and trained, but are bred in captivity in the United States for public display at marine parks. Some scientists and activists have argued for years against keeping them in artificial enclosures and training them for exhibition. They argue for more natural settings, like enclosed sea pens, as well as an end to captive breeding and to the orcas’ use in what opponents call entertainment and marine parks call education. Now the issue has been raised with new intensity in the documentary film “Blackfish” and the book “Death at SeaWorld,” by David Kirby, just released in paperback. © 2013 The New York Times Company

Keyword: Aggression; Aggression
Link ID: 18427 - Posted: 07.30.2013

John Hawks Humans are known for sporting big brains. On average, the size of primates' brains is nearly double what is expected for mammals of the same body size. Across nearly seven million years, the human brain has tripled in size, with most of this growth occurring in the past two million years. Determining brain changes over time is tricky. We have no ancient brains to weigh on a scale. We can, however, measure the inside of ancient skulls, and a few rare fossils have preserved natural casts of the interior of skulls. Both approaches to looking at early skulls give us evidence about the volumes of ancient brains and some details about the relative sizes of major cerebral areas. For the first two thirds of our history, the size of our ancestors' brains was within the range of those of other apes living today. The species of the famous Lucy fossil, Australopithecus afarensis, had skulls with internal volumes of between 400 and 550 milliliters, whereas chimpanzee skulls hold around 400 ml and gorillas between 500 and 700 ml. During this time, Australopithecine brains started to show subtle changes in structure and shape as compared with apes. For instance, the neocortex had begun to expand, reorganizing its functions away from visual processing toward other regions of the brain. The final third of our evolution saw nearly all the action in brain size. Homo habilis, the first of our genus Homo who appeared 1.9 million years ago, saw a modest hop in brain size, including an expansion of a language-connected part of the frontal lobe called Broca's area. The first fossil skulls of Homo erectus, 1.8 million years ago, had brains averaging a bit larger than 600 ml. © 2013 Scientific American

Keyword: Evolution; Aggression
Link ID: 18418 - Posted: 07.29.2013

By DAVID CRARY, AP National Writer NEW YORK (AP) — There's extensive evidence that pigs are as smart and sociable as dogs. Yet one species is afforded affection and respect; the other faces mass slaughter en route to becoming bacon, ham and pork chops. Seeking to capitalize on that discrepancy, animal-welfare advocates are launching a campaign called The Someone Project that aims to highlight research depicting pigs, chickens, cows and other farm animals as more intelligent and emotionally complex than commonly believed. The hope is that more people might view these animals with the same empathy that they view dogs, cats, elephants, great apes and dolphins. "When you ask people why they eat chickens but not cats, the only thing they can come up with is that they sense cats and dogs are more cognitively sophisticated that then species we eat — and we know this isn't true," said Bruce Friedrich of Farm Sanctuary, the animal-protection and vegan-advocacy organization that is coordinating the new project. "What it boils down to is people don't know farm animals the way they know dogs or cats," Friedrich said. "We're a nation of animal lovers, and yet the animals we encounter most frequently are the animals we pay people to kill so we can eat them." The lead scientist for the project is Lori Marino, a lecturer in psychology at Emory University who has conducted extensive research on the intelligence of whales, dolphins and primates. She plans to review existing scientific literature on farm animals' intelligence, identify areas warranting new research, and prepare reports on her findings that would be circulated worldwide via social media, videos and her personal attendance at scientific conferences. © 2013 Hearst Communications Inc.

Keyword: Intelligence; Aggression
Link ID: 18417 - Posted: 07.29.2013

By Michelle Warwicker BBC Nature Individual wild wolves can be recognised by just their howls with 100% accuracy, a study has shown. The team from Nottingham Trent University, UK, developed a computer program to analyse the vocal signatures of eastern grey wolves. Wolves roam huge home ranges, making it difficult for conservationists to track them visually. But the technology could provide a way for experts to monitor individual wolves by sound alone. "Wolves howl a lot in the wild," said PhD student Holly Root-Gutteridge, who led the research. "Now we can be sure... exactly which wolf it is that's howling." The team's findings are published in the journal Bioacoustics. Wolves use their distinctive calls to protect territory from rivals and to call to other pack members. "They enjoy it as a group activity," said Ms Root-Gutteridge, "When you get a chorus howl going they all join in." The team's computer program is unique because it analyses both volume (or amplitude) and pitch (or frequency) of wolf howls, whereas previously scientists had only examined the animals' pitch. "Think of [pitch] as the note the wolf is singing," explained Ms Root-Gutteridge. "What we've added now is the amplitude - or volume - which is basically how loud it's singing at different times." "It's a bit like language: If you put the stress in different places you form a different sound." BBC © 2013

Keyword: Language; Aggression
Link ID: 18401 - Posted: 07.23.2013

By Rebecca Morelle Science reporter, BBC World Service Scientists have found further evidence that dolphins call each other by "name". Research has revealed that the marine mammals use a unique whistle to identify each other. A team from the University of St Andrews in Scotland found that when the animals hear their own call played back to them, they respond. The study is published in the Proceedings of the National Academy of Sciences. Dr Vincent Janik, from the university's Sea Mammal Research Unit, said: "(Dolphins) live in this three-dimensional environment, offshore without any kind of landmarks and they need to stay together as a group. "These animals live in an environment where they need a very efficient system to stay in touch." It had been-long suspected that dolphins use distinctive whistles in much the same way that humans use names. Previous research found that these calls were used frequently, and dolphins in the same groups were able to learn and copy the unusual sounds. But this is the first time that the animals response to being addressed by their "name" has been studied. To investigate, researchers recorded a group of wild bottlenose dolphins, capturing each animal's signature sound. BBC © 2013

Keyword: Language; Aggression
Link ID: 18400 - Posted: 07.23.2013

by Virginia Morell The next time your dog digs a hole in the backyard after watching you garden, don't punish him. He's just imitating you. A new study reveals that our canine pals are capable of copying our behavior as long as 10 minutes after it's happened. The ability is considered mentally demanding and, until this discovery, something that only humans and apes were known to do. Scientists first discovered that dogs are excellent at imitating their owners in 2006. Or at least, one dog had the talent: Philip, a 4-year-old Belgian Tervuren working with József Topál, a behavioral ethologist at the Hungarian Academy of Sciences in Budapest. Topál adapted the method (called "Do as I do") that Keith and Catherine Hayes developed in the 1950s for teaching an infant chimpanzee to copy their actions. Philip was already a trained assistant dog for his disabled owner and readily followed Topál's commands. First, Topál told him to stay, and then commanded "Do as I do." The researcher then performed a simple action, such as jumping in place, barking, putting an object in a box, or carrying it to Philip's owner. Next, Topál ordered, "Do it!", and Philip responded by matching the scientist's actions. The experiment was designed to explore dog's imitative abilities, not to measure how long Philip's memory lasted; but his owner used Philip's skill to teach him how to do new, useful behaviors, such as fetching objects or putting things away. Despite Philip's abilities, "nobody really cared, or saw that it could be useful for investigating how dogs learn or see their world," says Ádám Miklósi, a behavioral ethologist at Eötvös Loránd University in Budapest who was part of Topál's team. And in 2009, another team concluded that dogs were only able to correctly imitate if there was no more than a 5-second delay between watching the action and repeating it. With such a short retention span, dogs' vaunted imitation skills seemed useless. © 2010 American Association for the Advancement of Science

Keyword: Learning & Memory; Aggression
Link ID: 18399 - Posted: 07.23.2013

by Virginia Morell A single cue—the taste of a madeleine, a small cake, dipped in lime tea—was all Marcel Proust needed to be transported down memory lane. He had what scientists term an autobiographical memory of the events, a type of memory that many researchers consider unique to humans. Now, a new study argues that at least two species of great apes, chimpanzees and orangutans, have a similar ability; in zoo experiments, the animals drew on 3-year-old memories to solve a problem. Their findings are the first report of such a long-lasting memory in nonhuman animals. The work supports the idea that autobiographical memory may have evolved as a problem-solving aid, but researchers caution that the type of memory system the apes used remains an open question. Elephants can remember, they say, but many scientists think that animals have a very different kind of memory than our own. Many can recall details about their environment and routes they've traveled. But having explicit autobiographical memories of things "I" did, or remembering events that occurred in the past, or imagining those in the future—so-called mental time travel—are considered by many psychologists to be uniquely human skills. Until recently, scientists argued that animals are stuck in time, meaning that they have no sense of the past or future and that they aren't able to recall specific events from their lives—that is, they don't have episodic memories, the what-where-when of an event that happened. © 2010 American Association for the Advancement of Science

Keyword: Learning & Memory; Aggression
Link ID: 18395 - Posted: 07.20.2013

by Jennifer Viegas The memory of dogs is more human-like than previously thought, allowing our furry pals to copy our actions, even after delays. The discovery, outlined in the latest issue of Animal Cognition, means that dogs possess what’s known as “declarative memory,” which refers to memories which can be consciously recalled, such as facts or knowledge. Humans, of course, have this ability, as anyone playing a trivia game demonstrates. But it had never fully been scientifically proven in dogs before, although dog owners and canine aficionados have likely witnessed the skill first-hand for years. Claudia Fugazza and Adám Miklósi of Eötvös Loránd University in Hungary conducted the study. A LOT of dog studies happen in Hungary, where people really love their pooches and some of the world’s leading canine researchers live. The team investigated if dogs could defer imitation, which in this case meant copying what their owners were doing. Eight adult pet dogs were trained using the “Do As I Do” method. (Fugazza is a leading expert on this training method for dogs.) The tasks included copying their owners walking around a bucket and ringing a bell. Can dogs then successfully replicate what they learned after a 10 or so minute distracting break? The owner, Valentina, got her dog Adila to pay attention to her. She then demonstrated an activity, like ringing a bell with her hand. © 2013 Discovery Communications, LLC

Keyword: Learning & Memory; Aggression
Link ID: 18386 - Posted: 07.18.2013

The idea that dogs only see the world in black, white and shades of gray is a common misconception. What’s true, though, is that like most mammals, dogs only have two types of color receptors (commonly called “cones”) in their eyes, unlike humans, who have three. Each of these cones is sensitive to a different wavelength (i.e. color) of light. By detecting different quantities of each wavelength and combining them, our three cones can transmit various signals for all the hues of the color wheel, the same way the three primary colors can be mixed in different amounts to do the same. But because they only have two cones, dogs’ ability to see color is indeed quite limited compared to ours (a rough comparison would be the vision of humans with red-green colorblindness, since they, too, only have two cones). Whereas a human with full color vision sees red, orange, yellow, green, blue and violet along the spectrum of visible light, a dog sees grayish brown, dark yellow, light yellow, grayish yellow, light blue and dark blue, respectively—essentially, different combinations of the same two colors, yellow and blue: Consequently, researchers have long believed that dogs seldom rely on colors to discriminate between objects, instead looking solely at items’ darkness or brightness to do so. But a new experiment indicates that this idea, too, is a misconception. As described in a paper published yesterday in the Proceedings of the Royal Society B, a team of Russian researchers recently found that, at least among a small group of eight dogs, the animals were much more likely to recognize a piece of paper by its color than its brightness level—suggesting that your dog might be aware of some of the colors of everyday objects after all.

Keyword: Vision; Aggression
Link ID: 18385 - Posted: 07.18.2013

By NICHOLAS BAKALAR There are many dying languages in the world. But at least one has recently been born, created by children living in a remote village in northern Australia. Carmel O’Shannessy, a linguist at the University of Michigan, has been studying the young people’s speech for more than a decade and has concluded that they speak neither a dialect nor the mixture of languages called a creole, but a new language with unique grammatical rules. The language, called Warlpiri rampaku, or Light Warlpiri, is spoken only by people under 35 in Lajamanu, an isolated village of about 700 people in Australia’s Northern Territory. In all, about 350 people speak the language as their native tongue. Dr. O’Shannessy has published several studies of Light Warlpiri, the most recent in the June issue of Language. “Many of the first speakers of this language are still alive,” said Mary Laughren, a research fellow in linguistics at the University of Queensland in Australia, who was not involved in the studies. One reason Dr. O’Shannessy’s research is so significant, she said, “is that she has been able to record and document a ‘new’ language in the very early period of its existence.” Everyone in Lajamanu also speaks “strong” Warlpiri, an aboriginal language unrelated to English and shared with about 4,000 people in several Australian villages. Many also speak Kriol, an English-based creole developed in the late 19th century and widely spoken in northern Australia among aboriginal people of many different native languages. Lajamanu parents are happy to have their children learn English in school for use in the wider world, but eager to preserve Warlpiri as the language of their culture. There is an elementary school in Lajamanu, but most children go to boarding school in Darwin for secondary education. The language there is English. But they continue to speak Light Warlpiri among themselves. © 2013 The New York Times Company

Keyword: Language; Aggression
Link ID: 18376 - Posted: 07.15.2013

Josh Howgego Thresher sharks can use their lengthy tail fins to swat sardines from shoals, researchers have found by taking underwater footage. Such tactical use of the tail fin during hunting — which was previously observed only in mammals such as dolphins and killer whales1 — might indicate that sharks are more intelligent than scientists thought. Pelagic thresher sharks (Alopias pelagicus) are nocturnal and notoriously shy. Researchers have long suspected that the shark uses its tail — which makes up half of its body length — to stun its prey, but the behaviour has not been documented before under natural conditions2. Simon Oliver, lead investigator of the Thresher Shark Research and Conservation Project, and his colleagues studied the sharks off the coast of Cebu, an island in the Philippines. Oliver, who is based at the University of Liverpool, UK, has been watching the animals during the day since 2005, but he hadn’t seen the sharks hunting until some divers saw it happening and phoned him. “Immediately I dropped everything and went to investigate,” he says. The sharks hunt by first lunging into a school of fish, priming their tails as they move in. They then swipe the tail in a trebuchet-like motion through an arc of 180o in just one-third of a second — fast enough to both physically hit the fish and to create a stunning shock wave (see image below). Each strike can take out up to seven sardines, so Oliver thinks it is probably the most energy-efficient way for the animals to hunt. The team published the results today in PLOS ONE3. © 2013 Nature Publishing Group

Keyword: Intelligence; Aggression
Link ID: 18367 - Posted: 07.11.2013

By Kate Wong In the July issue of Scientific American, anthropologist Barbara King of The College of William & Mary makes the case that animals ranging from ducks to dolphins may grieve when a relative or close companion dies. In so doing she departs from a long-standing tradition among animal behaviorists of assiduously avoiding projecting human emotions onto other animals. Not all animal responses to death qualify as mourning, however. King is careful to establish criteria for grief, noting that “researchers may strongly suspect grief only when certain conditions are met: First, two (or more) animals choose to spend time together beyond survival-oriented behaviors such as foraging or mating. Second, when one animal dies, the survivor alters his or her normal behavioral routine—perhaps reducing the amount of time devoted to eating or sleeping, adopting a body posture or facial expression indicative of depression or agitation, or generally failing to thrive.” Here King describes two recent, well-publicized examples of animal reactions to death that illustrate the challenges of interpreting such behaviors: “Occasionally the pull of anthropomorphism may overwhelm scientists’ normal caution in reporting animal responses to death. When Teresa Iglesias of the University of California at Davis and her colleagues published a paper in Animal Behaviour last year entitled ‘Western scrub jay funerals: cacophonous aggregations in response to dead conspecifics,’ the news media responded enthusiastically to the notion of a bird funeral. Yet nothing like a caretaking ritual around jay bodies actually had been observed. From a series of experiments, the scientists had discovered that scrub jays respond by vocalizing upon sighting the bodies of dead companions; they seem to be communicating information to their flock mates about potential risks in the environment. Iglesias told me last year, for my post about her paper at’s 13.7 blog, that ‘funeral’ is an apt term ‘only to the extent that it is an animal paying attention to another dead animal’ (and excluding behaviors such as scavenging). Any of the animal examples discussed in this article would, on this definition, quality as a ‘funeral,’ a too-generous application of the term.” © 2013 Scientific American

Keyword: Emotions; Aggression
Link ID: 18364 - Posted: 07.09.2013

by Debora MacKenzie Starfish use the light-sensitive organs at the tips of their arms to form images, helping the animals find their way home if they stray from the reef. We have known about the sensors that starfish have at the ends of their arms for 200 years, but no one knew whether they are real eyes that form images or simply structures that detect changes in light intensity. We finally have an answer: they appear to act as real eyes. The discovery is another blow to creationist arguments that something as complex as a human eye could never evolve from simpler structures. The blue sea star (Linckia laevigata), which is widely sold as dried souvenirs, lives on shallow rock reefs in the Indian and Pacific oceans. It can detect light, preferring to come out at night to graze on algae. The light sensitivity has recently been found to be due to pigments called opsins, expressed in cells close to the animal's nerve net. What has not been clear, says Anders Garm at the University of Copenhagen in Denmark, is whether these cells simply tell the starfish about ambient light levels, as happens in more primitive light-sensitive animals, or whether they actually form spatial images. © Copyright Reed Business Information Ltd.

Keyword: Vision; Aggression
Link ID: 18357 - Posted: 07.08.2013

By TIM REQUARTH and MEEHAN CRIST Babies learn to speak months after they begin to understand language. As they are learning to talk, they babble, repeating the same syllable (“da-da-da”) or combining syllables into a string (“da-do-da-do”). But when babies babble, what are they actually doing? And why does it take them so long to begin speaking? Insights into these mysteries of human language acquisition are now coming from a surprising source: songbirds. Researchers who focus on infant language and those who specialize in birdsong have teamed up in a new study suggesting that learning the transitions between syllables — from “da” to “do” and “do” to “da” — is the crucial bottleneck between babbling and speaking. “We’ve discovered a previously unidentified component of vocal development,” said the lead author, Dina Lipkind, a psychology researcher at Hunter College in Manhattan. “What we’re showing is that babbling is not only to learn sounds, but also to learn transitions between sounds.” The results provide insight into language acquisition and may eventually help shed light on human speech disorders. “Every time you find out something fundamental about the way development works, you gain purchase on what happens when children are at risk for disorder,” said D. Kimbrough Oller, a language researcher at the University of Memphis, who was not involved in the study. At first, however, the scientists behind these findings weren’t studying human infants at all. They were studying birds. “When I got into this, I never believed we were going to learn about human speech,” said Ofer Tchernichovski, a birdsong researcher at Hunter and the senior author of the study, published online on May 29 in the journal Nature. © 2013 The New York Times Company

Keyword: Language; Aggression
Link ID: 18332 - Posted: 07.01.2013