Chapter 6. Evolution of the Brain and Behavior
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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
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.
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
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
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 NPR.org’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
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.
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
By Cristy Gelling Lemur species that live in large groups can tell when to steal food from a competitor in a lab experiment, researchers report June 26 in PLOS ONE. The finding supports the idea that brainpower in primates evolved to fit their complex social lives. Because the sneakier lemurs don't have bigger brains than less sneaky ones living in smaller groups, researchers suggest that social smarts don’t always depend on brain size. Much of the evidence for sociality’s role in the evolution of intelligence comes from indirect measures such as brain size, says study coauthor Evan MacLean of Duke University. But brain size does not always correspond to brainpower, so MacLean uses behavioral tests. He and his colleagues tested the social intelligence of six species of lemur, primates from Madagascar distantly related to monkeys and apes. Each of the species lives in social groups ranging from families of just three, mongoose lemurs’ preferred posse, to gangs of about 16, a typical size for a group of ring-tailed lemurs. The researchers trained lemurs to view humans as competitors for food, then presented the animals with a choice between pilfering treats from one of two people: one facing the animals or another with his or her back turned. Species that live in small groups reached for the food under a competitor’s nose as often as they did behind people’s backs. But the ring-tailed lemurs were much more likely to choose the unguarded food. © Society for Science & the Public 2000 - 2013
Sid Perkins Sporting feats such as baseball's 100-mile-per-hour fastball are made possible by a suite of anatomical features that appeared in our hominin ancestors about 2 million years ago, a video study of college athletes suggests. And this ability to throw projectiles may have been crucial for human hunting, which in turn may have had a vital role in our evolution. “Throwing projectiles probably enabled our ancestors to effectively and safely kill big game,” says Neil Roach, a biological anthropologist at George Washington University in Washington DC, who led the work. Eating more calorie-rich meat and fat would have helped early hominins' brains and bodies to grow, enabling our ancestors to expand into new regions of the world, he suggests. The study is published today in Nature1. Although some primates occasionally throw objects, and with a fair degree of accuracy, only humans can routinely hurl projectiles with both speed and accuracy, says Roach. Adult male chimpanzees can throw objects at speeds of around 30 kilometres per hour, but even a 12-year-old human can pitch a baseball three times faster than that, he notes. In fact, the quickest motion that the human body produces — rotation of the humerus, the long bone in the upper arm, at a rate that is briefly equivalent to 25 full rotations in a single second — occurs while a person is throwing a projectile. © 2013 Nature Publishing Group,
By Susan Milius After 17 years underground, throngs of ruby-eyed cicadas clawed up through the soil this year to partake in a once-in-a-lifetime, synchronized mating frenzy. Except it wasn’t one big insect orgy: It was three. The insects that unearthed themselves to breed in 2013 belong to three distinct species. You need only flip them over to see some differences, written in the varieties of their orange markings. You can hear the differences too, says Chris Simon of the University of Connecticut in Storrs. The tymbals on either side of a male’s abdomen vibrate to make the racket for which cicadas are famous. A chorus of courting Magicicada cassini males sounds like an electric carving knife revving up. M. septendecula coughs out a series of rasps. And M. septendecim serenades with the whistling drone of a B-movie spaceship. The various thrums and buzzings may mingle in the same neighborhood, but the last time ancestors of these species mated with each other was almost 4 million years ago, Simon says. That’s the conclusion of the most detailed genetic studies yet of periodical cicada evolutionary history, which Simon and colleagues published in April in the Proceedings of the National Academy of Sciences. With DNA plus episodic field observations, the scientists are getting an idea about the odd family tree of periodical cicadas, how the insects synchronize their life cycles and why they breed side-by-side with others unsuitable for mating. © Society for Science & the Public 2000 - 2013
by Andrew Porterfield Honey bees may have only a fraction of our neurons—just under a million versus our tens of billions—but our brains aren't so different. Take sidedness. The human brain is divided into right and left sides—our right brain controls the left side of our body and vice versa. New research reveals that something similar happens in bees. When scientists removed the right or left antenna of honey bees, those insects with intact right antennae more quickly recognized bees from the same hive, stuck out their tongues (showing willingness to feed), and fended off invaders. Bees with just their left antennae took longer to recognize bees, didn't want to feed, and mistook familiar bees for foreign ones. This suggests, the team concludes today in Scientific Reports, that bee brains have a sidedness just like ours do. The researchers also think that right antennae might control other bee behavior, like their sophisticated, mysterious "waggle dance" to indicate food. But there's no buzz for the left-antennaed. © 2010 American Association for the Advancement of Science
Traci Watson When it comes to friendship it may be quantity, not quality, that matters — at least for Barbary macaques in a crisis. Scientists have long known that sociable humans live longer than their solitary peers, but is the same true for animals? A harsh natural experiment may offer some answers. It also raises intriguing questions about the type of social ties that matter. Endangered Barbary macaques (Macaca sylvanus) in the mountains of Morocco are accustomed to cold, but the 2008–09 winter was devastatingly hard for them. Snow covered the ground for almost four months instead of the usual one, and the monkeys, which eat seeds and grasses on the ground, began to starve. Richard McFarland, a behavioural ecologist at the University of the Witwatersrand in Johannesburg, South Africa, and his colleagues were studying the animals as part of a wider project on the monkeys' social lives launched in January 2008. When they went looking for the macaques in January 2009, they found corpses, says McFarland. Of the 47 adults in two troops that the team studied, only 17 survived, making for a 64% mortality rate, McFarland and his colleague Bonaventura Majolo of the University of Lincoln, UK, report today in Biology Letters1. Analysis showed that the more friends a monkey had, the more likely it was to have survived. Individuals with whom a monkey had exchanged grooming or had had bodily contact with at least once during observation sessions were deemed as social contacts. Perhaps the animals with more buddies had more partners with whom to huddle against the cold, the researchers suggest. Monkeys with large social networks may also have been able to look for food with fewer interruptions from hostile group members. © 2013 Nature Publishing Group
By Melissa Hogenboom Science reporter, BBC News The social brain theory - that animals in large social groups have bigger brains - has now been supported by a computer model. For animals in smaller social groups, the cost of having a large brain outweighs the benefits. Scientists used a simulation modelling technique to confirm that large social groups are only possible through sophisticated communication. The study is published in Proceedings of the Royal Society B. The human brain is a very costly organ which consumes a lot of energy. Animals that live in small social groups could therefore be at a disadvantage if they had large brains taking up processing power that could better be used elsewhere. A team at Oxford University has now looked at the cognitive demands of making social decisions using a method called agent-based modelling, which models simplified representations of reality. As expected, they found that more complex social decisions take up more 'brain' power. The cognitive complexity of language evolved as social groups became larger and more complex, said lead author of the study Tamas David-Barrett from the University of Oxford. He explained that a group of five is an ideal number to coordinate an event such as a hunt, but as the group size increases, the coordination involved would become increasingly complex. BBC © 2013
Did that prairie dog just call you fat? Quite possibly. On The Current Friday, biologist Con Slobodchikoff described how he learned to understand what prairie dogs are saying to one another and discovered how eloquent they can be. Slobodchikoff, a professor emeritus at North Arizona University, told Erica Johnson, guest host of The Current, that he started studying prairie dog language 30 years ago after scientists reported that other ground squirrels had different alarm calls to warn each other of flying predators such as hawks and eagles, versus predators on the ground, such as coyotes or badgers. Prairie dogs, he said, were ideal animals to study because they are social animals that live in small co-operative groups within a larger colony, or "town" and they never leave their colony or territory, where they have built an elaborate underground complex of tunnels and burrows. In order to figure out what the prairie dogs were saying, Slobodchikoff and his colleagues trapped them and painted them with fur dye to identify each one. Then they recorded the animals' calls in the presence of different predators. They found that the animals make distinctive calls that can distinguish between a wide variety of animals, including coyotes, domestic dogs and humans. The patterns are so distinct, Slobodchikoff said, that human visitors that he brings to a prairie dog colony can typically learn them within two hours. But then Slobodchikoff noticed that the animals made slightly different calls when different individuals of the same species went by. © CBC 2013
by Traci Watson For the male dark fishing spider, the price of love is death. New research shows that the male Dolomedes tenebrosus (right) expires just after the height of passion, despite no visible assault by his partner. Scientists collected the common U.S. arachnids (see image) in Nebraska parks and did a little matchmaking. In 25 observed matings, after the male stuffed his sperm into the female's body using his antennalike pedipalp, he immediately went limp and his legs curled underneath him, researchers report online today in Biology Letters. By counting the pulse rate in the spiders' abdomens, researchers measured the heartbeat of motionless males and confirmed that they do indeed die. As if death weren't sacrifice enough, the scientists found that lovemaking also disfigures the male. In most spiders, part of the male's pedipalp swells to deliver sperm before shrinking to normal size. In D. tenebrosus, the pedipalp remains enormously enlarged and presumably useless even after the deed is done. Evolutionary theory predicts male monogamy—such as that shown by the dark fishing spider—when females are larger than males. Smaller animals are more likely to survive to mating age than big ones, the thinking goes, making larger females scarcer than smaller males. And that means males must settle for just one inamorata. True to theory, the female dark fishing spider, whose outstretched legs span a human's palm, outweighs her man 14-to-1. © 2010 American Association for the Advancement of Science
By Felicity Muth Pigs are one of the top animals consumed across the world. According to the US Census Bureau, in 2010, around one hundred million metric tons of pork were consumed that year, with 10% of this being in the US (although it does seem that overall meat consumption is declining). With so many of us eating pork, you might think we’d know a bit more about these animals. A lot of people are surprised to hear about some of the cognitive abilities of the average pig. While it’s problematic to call an animal ‘intelligent’ or not, as this is a term is ill-defined and too often related to human cognition, pigs have shown us that they have a number of cognitive abilities tested across many different types of test. They have good learning and memory in many contexts (both short- and long-term), including episodic memory (memory for past events in their life), the ability to differentiate between familiar and unfamiliar pigs, and an inclination to explore novel objects. In addition to these behavioural feats, the pig brain is well-developed. For example, the volume of the prefrontal cortex is around 24% of the total neocortex and 10% of the total brain volume, comparable to primates including humans. I’m not sure why, despite this research, pigs have a reputation for being ‘stupid’. Similar to the ‘three-second memory’ myth with fish, I wonder if it’s perpetuated to make people not feel bad about eating these animals, or the conditions under which they are often reared. © 2013 Scientific American
by Tia Ghose, LiveScience Ape and human infants at comparable stages of development use similar gestures, such as pointing or lifting their arms to be picked up, new research suggests. Chimpanzee, bonobo and human babies rely mainly on gestures at about a year old, and gradually develop symbolic language (words, for human babies; and signs, for apes) as they get older. The findings suggest that “gesture plays an important role in the evolution of language, because it preceded language use across the species," said study co-author Kristen Gillespie-Lynch, a developmental psychologist at the College of Staten Island in New York. The idea that language arose from gesture and a primitive sign language has a long history. French philosopher Étienne Bonnot de Condillac proposed the idea in 1746, and other scientists have noted that walking on two legs, which frees up the hands for gesturing, occurred earlier in human evolution than changes to the vocal tract that enabled speaking. But although apes in captivity can learn some language by learning from humans, in the wild, they don't gesture nearly as much as human infants, making it difficult to tease out commonalities in language development that have biological versus environmental roots. © 2013 Discovery Communications, LLC
Sid Perkins The near-complete fossil of a tiny creature unearthed in China in 2002 has bolstered the idea that the anthropoid group of primates — whose modern-day members include monkeys, apes and humans — had appeared by at least 55 million years ago. The fossil primate does not belong to that lineage, however: it is thought to be the earliest-discovered ancestor of small tree-dwelling primates called tarsiers, showing that even at this early time, the tarsier and anthropoid groups had split apart. The slender-limbed, long-tailed primate, described today in Nature1, was about the size of today’s pygmy mouse lemur and would have weighed between 20 and 30 grams, the researchers estimate. The mammal sports an odd blend of features, with its skull, teeth and limb bones having proportions resembling those of tarsiers, but its heel and foot bones more like anthropoids. “This mosaic of features hasn’t been seen before in any living or fossil primate,” says study author Christopher Beard, a palaeontologist at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. By analysing almost 1,200 morphological aspects of the fossil and comparing them to those of 156 other extant and extinct mammals, the team put the ancient primate near the base of the tarsier family tree. The creature is dubbed Archicebus achilles, in which the genus name Archicebus roughly translates as 'original long-tailed monkey', while the species name achilles is a wry nod to the primate's anthropoid-like heel bone. © 2013 Nature Publishing Group
Link ID: 18240 - Posted: 06.06.2013
By Susan Milius After death, male guppies can keep on siring offspring because females store sperm for so long. As a result, a living male in a stream in Trinidad can end up competing with long-gone fish from his grandfather’s generation. At its most posthumously successful, stored ghost sperm sired about one in four of the offspring among wild guppies released into a stream, evolutionary biologist Andrés López-Sepulcre of École Normale Supérieure in Paris and his colleagues report June 5 in Proceedings of the Royal Society B. Biologists have long known that female Poecilia reticulata guppies store sperm. The cells clump in little pockets in a female’s ovarian cavity and feed on sugars released by ovarian tissue. Storage in itself isn’t unusual, López-Sepulcre says. Some crabs, turtles, lizards, bats and other creatures preserve sperm for later use. Posthumous reproduction by stored sperm also isn’t unheard of. “The fun part of our study,” López-Sepulcre says, “is that you have males who are alive and males who are dead competing with each other.” Researchers deployed guppies in several streams as part of a study on evolutionary change. Every month researchers catch, check and release as many fish as possible to track deaths and births. They also genetically analyze parenthood of the fish. Female guppies give live birth to broods of two to about 10 youngsters, with not all sired by the same male. Females live about 15 months; males about three. © Society for Science & the Public 2000 - 2013
By Rachel Ehrenberg The salad days of human evolution saw a dietary shift toward grasses and probably grass-fed animals, analyses of more than 100 fossilized teeth from eight species of ancient hominids indicate. “These changes in diet have been predicted,” says paleoanthropologist Richard Klein of Stanford University. “But it’s very nice to have some data, and these data support it very strongly.” Changes in the size and shape of jaws and teeth in both ancient hominids and their ape relatives point to changes in diet. The new study adds to these lines of anatomical evidence chemical analyses that look at different forms of carbon in the fossilized teeth. The ratio of two types of carbon in tooth enamel reflects diet, says geochemist Thure Cerling of the University of Utah, who spent weeks in a vault in the National Museum of Kenya collecting milligram-sized samples of tooth enamel for the analyses. Grasses, grasslike sedges and many other plants in hot, arid environments have evolved a trick that helps prevent water loss. The metabolic adjustment results in taking up more of a heavier form of carbon, known as carbon-13, than most trees and shrubs do. The tooth studies, which cover more than 3 million years and include specimens from southern, eastern and central Africa, found greater quantities of this heavier carbon in hominids that are closer to humans on the evolutionary tree. This pattern suggests that, compared with humans’ more ancient relatives, recent ones were eating more grass or more grass-feeding animals, like zebras. The analyses appear June 3 in the Proceedings of the National Academy of Sciences. © Society for Science & the Public 2000 - 2013