Chapter 6. Evolution of the Brain and Behavior

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// by Richard Farrell Bonobos have a capacity to do something human infants have been shown to do: use a single sound whose meaning varies based on context, a form of "flexible" communication previously thought specific to humans. The finding was made by researchers from the University of Birmingham and the University of Neuchatel, in a paper just published in the journal Peer J. The newly identified bonobo call is a short, high-pitched "peep," made with a closed mouth. The scientists studied the call's acoustic structure and observed that it did not change between what they termed "neutral" and "positive" circumstances (for example, between activities such as feeding or resting), suggesting that other bonobos receiving the call would need to weigh contextual information to discern its meaning. Human babies do something similarly flexible, using sounds called protophones -- different from highly specific sounds such as crying or laughter -- that are made independent of how they are feeling emotionally. The appearance of this capability in the first year of life is "a critical step in the development of vocal language and may have been a critical step in the evolution of human language," an earlier study on infant vocalization noted. The find challenges the idea that calls from primates such as bonobos -- which, along with chimpanzees, are our closest relatives -- are strictly matched with specific contexts and emotions, whether those sounds are territorial barks or shrieks of alarm. © 2015 Discovery Communications, LLC.

Keyword: Language; Evolution
Link ID: 21265 - Posted: 08.05.2015

By Michael Balter Have you ever wondered why you say “The boy is playing Frisbee with his dog” instead of “The boy dog his is Frisbee playing with”? You may be trying to give your brain a break, according to a new study. An analysis of 37 widely varying tongues finds that, despite the apparent great differences among them, they share what might be a universal feature of human language: All of them have evolved to make communication as efficient as possible. Earth is a veritable Tower of Babel: Up to 7000 languages are still spoken across the globe, belonging to roughly 150 language families. And they vary widely in the way they put sentences together. For example, the three major building blocks of a sentence, subject (S), verb (V), and object (O), can come in three different orders. English and French are SVO languages, whereas German and Japanese are SOV languages; a much smaller number, such as Arabic and Hebrew, use the VSO order. (No well-documented languages start sentences or clauses with the object, although some linguists have jokingly suggested that Klingon might do so.) Yet despite these different ways of structuring sentences, previous studies of a limited number of languages have shown that they tend to limit the distance between words that depend on each other for their meaning. Such “dependency” is key if sentences are to make sense. For example, in the sentence “Jane threw out the trash,” the word “Jane” is dependent on “threw”—it modifies the verb by telling us who was doing the throwing, just as we need “trash” to know what was thrown, and “out” to know where the trash went. Although “threw” and “trash” are three words away from each other, we can still understand the sentence easily. © 2015 American Association for the Advancement of Science.

Keyword: Language; Evolution
Link ID: 21263 - Posted: 08.04.2015

By Andrea Alfano Forget the insult “fathead.” We may actually owe our extraordinary smarts to the fat in our brain. A study published in Neuron in February revealed that the variety of fat molecules found in the human neocortex, the brain region responsible for advanced cognitive functions such as language, evolved at an exceptionally fast rate after the human-ape split. The researchers analyzed the concentrations of 5,713 different lipids, or fat molecules and their derivatives, present in samples of brain, kidney and muscle tissues taken from humans, chimpanzees, macaques and mice. Lipids have a variety of critical functions in all cells, including their role as the primary component of a cell's membrane. They are particularly important in the brain because they enable electrical signal transmission among neurons. Yet until this study, it was unknown whether the lipids in the human brain differed significantly from lipids in other mammals. The team discovered that the levels of various lipids found in human brain samples, especially from the neocortex, stood out. Humans and chimps diverged from their common ancestor around the same time, according to much evolutionary evidence. Because the two species have had about the same amount of time to rack up changes to their lipid profiles, the investigators expected them to have roughly the same number of species-specific lipid concentrations, explains computational biologist and study leader Kasia Bozek of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Indeed, lipid changes in the cerebellum, a primitive part of the brain similar in all vertebrates, were comparable between humans and chimps. But the human neocortex has accumulated about three times more lipid changes than the chimpanzee cortex has since we split from our common ancestor. © 2015 Scientific American

Keyword: Evolution
Link ID: 21260 - Posted: 08.04.2015

Kill, Fido! Docile ants become aggressive guard dogs after a secret signal from their caterpillar overlord. The idea turns on its head the assumption that the two species exchange favours in an even-handed relationship. The caterpillars of the Japanese oakblue butterfly (Narathura japonica) grow up wrapped inside leaves on oak trees. To protect themselves against predators like spiders and wasps, they attract ant bodyguards, Pristomyrmex punctatus, with an offering of sugar droplets. The relationships was thought to be a fair exchange of services in which both parties benefit. But Masaru Hojo from Kobe University in Japan noticed something peculiar: the caterpillars were always attended by the same ant individuals. “It also seemed that the ants never moved away or returned to their nests,” he says. They seemed to abandon searching for food, and were just standing around guarding the caterpillar. Intrigued, Hojo and his colleagues conducted lab experiments in which they allowed some ants to interact with the caterpillars and feed on the secretions, and kept others separate. Ants that ate the caterpillar’s secretions remained close to the caterpillar. They didn’t return to their nest. And whenever the caterpillar everted its tentacles – flipped them so they turned inside out – the ants moved around rapidly, acting aggressively. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Drug Abuse
Link ID: 21244 - Posted: 08.01.2015

Ewen Callaway Our ancestors were not a picky bunch. Overwhelming genetic evidence shows that Homo sapiens had sex with Neander­thals, Denisovans and other archaic relatives. Now researchers are using large genomics studies to unravel the decidedly mixed contributions that these ancient romps made to human biology — from the ability of H. sapiens to cope with environments outside Africa, to the tendency of modern humans to get asthma, skin diseases and maybe even depression. The proportion of the human genome that comes from archaic relatives is small. The genomes of most Europeans and Asians are 2–4% Neanderthal1, with Denisovan DNA making up about 5% of the genomes of Mela­nesians2 and Aboriginal Australians3. DNA slivers from other distant relatives probably pepper a variety of human genomes4. But these sequences may have had an outsize effect on human biology. In some cases, they are very different from the corresponding H. sapiens DNA, notes population geneticist David Reich of Harvard Medical School in Boston, Massachusetts — which makes it more likely that they could introduce useful traits. “Even though it’s only a couple or a few per cent of ancestry, that ancestry was sufficiently distant that it punched above its weight,” he says. Last year, Reich co-led one of two teams that catalogued the Neanderthal DNA living on in modern-day humans5, 6. The studies hinted that Neanderthal versions of some genes may have helped Eurasians to reduce heat loss or grow thicker hair. But the evidence that these genes were beneficial was fairly weak. To get a better handle on how Neanderthal DNA shapes human biology, Corinne Simonti and Tony Capra, evolutionary geneticists at Vanderbilt University in Nashville, Tennessee, turned to genome-wide association studies (GWAS) that had already compared thousands of DNA variants in people with and without a certain disease or condition. © 2015 Nature Publishing Group,

Keyword: Evolution
Link ID: 21240 - Posted: 07.30.2015

Alison Abbott Neuroscientists have identified an area of the brain that might give the human mind its unique abilities, including language. The area lit up in human, but not monkey, brains when they were presented with different types of abstract information. The idea that integrating abstract information drives many of the human brain's unique abilities has been around for decades. But a paper published1 in Current Biology, which directly compares activity in human and macaque monkey brains as they listen to simple auditory patterns, provides the first physical evidence that a specific area for such integration may exist in humans. Other studies that compare monkeys and humans have revealed differences in the brain’s anatomy, for example, but not differences that could explain where humans’ abstract abilities come from, say neuroscientists. “This gives us a powerful clue about what is special about our minds,” says psychologist Gary Marcus at New York University. “Nothing is more important than understanding how we got to be how we are.” A team of researchers headed by Stanislas Dehaene at the INSERM Cognitive Neuroimaging Unit at Gif-sur-Yvette near Paris, looked at changing patterns of activation in the brain as untrained monkeys and human adults listened to a simple sequence of tones, for example three identical tones followed by a different tone (like the famous four-note opening of Beethoven’s fifth symphony: da-da-da-DAH). The researchers played several different sequences with this structure — known as AAAB — and other sequences to the subjects while they lay in a functional magnetic resonance imaging (fMRI) scanner. The fMRI technique picks up changes in blood flow in the brain that correlate with regional brain activity. © 2015 Nature Publishing Group,

Keyword: Attention; Evolution
Link ID: 21220 - Posted: 07.25.2015

THERE’S more to semen than sperm. In many animals, seminal fluid alters both the bodies and sometimes even the behaviour of females. Human semen, too, triggers changes in the uterus, and might have wider effects on women, aimed at just one goal. “It’s all about maximising the chances of the male reproducing,” says Sarah Robertson of the University of Adelaide in Australia. The effects are most striking in fruit flies: seminal fluid can make the females eat more, lay more eggs and be less receptive to other males. Now a team led by Tracey Chapman at the University of East Anglia in Norwich, UK, has found that male fruit flies selectively alter the chemical make-up of their seminal fluid. In the presence of rivals, the males produce more seminal proteins. “It came as a real surprise,” says Chapman. “It’s a sophisticated response to the social and sexual situation.” Some of their findings were presented at the Society for Molecular Biology and Evolution conference in Vienna, Austria, last week, including their discovery that one of these proteins is a “master regulator” of genes. Females exposed to it show a wide range of changes in gene expression. Chapman thinks this kind of seminal signalling is widespread in the animal world. The semen of people, pigs and mice affects the female reproductive tract, and the question is whether it can also produce behavioural responses in female mammals similar to those seen in fruit flies. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 21209 - Posted: 07.23.2015

Ewen Callaway A mysterious group of humans crossed the Bering land bridge from Siberia into the Americas thousands of years ago, genetic analyses reveal. Modern-day signatures of this ‘ghost population’ survive in people who live deep in the Brazilian Amazon, but the two research teams who have made the discovery have different ideas about when and how these migrants reached the Americas1, 2. "This is an unexpected finding," says Jennifer Raff, an anthropological geneticist at the University of Texas at Austin who was not involved in either study. "It’s honestly one of the most exciting results we’ve seen in a while." North and South America were the last continents that humans settled. Previous studies of DNA from modern and ancient Native Americans suggest that the trek was made at least 15,000 years ago (although the timing is not clear-cut) by a single group dubbed the ‘First Americans’, who crossed the Bering land bridge linking Asia and North America. “The simplest hypothesis would be that a single population penetrated the ice sheets and gave rise to most of the Americans,” says David Reich, a population geneticist at Harvard Medical School in Boston, Massachusetts. In 2012, his team found evidence for a single founding migration in the genomes from members of 52 Native American groups3. So Reich was flabbergasted when a colleague called Pontus Skoglund mentioned during a conference last year that he had found signs of a second ancient migration to the Americas lurking in the DNA of contemporary Native Amazonians. Reich wasted no time in verifying the discovery. “During the session afterward, he passed his laptop over the crowd, and he had corroborated the results,” says Skoglund, who is now a researcher in Reich’s lab. © 2015 Nature Publishing Group

Keyword: Genes & Behavior
Link ID: 21201 - Posted: 07.22.2015

Carl Zimmer An ant colony is an insect fortress: When enemies invade, soldier ants quickly detect the incursion and rip their foes apart with their oversize mandibles. But some invaders manage to slip in with ease, none more mystifyingly than the ant nest beetle. Adult beetles stride into an ant colony in search of a mate, without being harassed. They lay eggs, from which larva hatch. As far as scientists can tell, workers feed the young beetles as if they were ants. When the beetles grow into adults, the ants swarm around them, grooming their bodies. In exchange for this hospitality, the beetles sink their jaws into ant larvae and freshly moulted adults in order to drink their body fluids. “They’re like vampire beetles wandering in the ant nests,” said Andrea Di Giulio, an entomologist at Roma Tre University in Rome. Dr. Di Giulio and his colleagues have now uncovered a remarkable trick that the beetles use to fool their hosts. It turns out they can perform uncanny impressions, mimicking a range of ant calls. Dr. Di Giulio and his colleagues study a species of ant nest beetle called Paussus favieri, which lives in the Atlas Mountains of Morocco, where it infiltrates the nests of Moroccan ants, known as Pheidole pallidula. Like many ant species, Pheidole pallidula makes noises by rubbing its legs against ridges on its body. The meanings of these signals vary from species to species; leaf-cutting ants summon bodyguards for the march back to the nest; in other species, a queen trills to her workers to attend to her. Scientists have found that Pheidole pallidula ants make three distinct sounds, each produced by a different caste: soldiers, workers and the queen. © 2015 The New York Times Company

Keyword: Evolution; Language
Link ID: 21193 - Posted: 07.20.2015

by Stephen Buchmann Flowers, bugs and bees: Stephen Buchmann wanted to study them all when he was a kid. "I never grew out of my bug-and-dinosaur phase," he tells NPR's Arun Rath. "You know, since about the third grade, I decided I wanted to chase insects, especially bees." These days, he's living that dream. As a pollination ecologist, he's now taking a particular interest in how flowers attract insects. In his new book, The Reason for Flowers, he looks at more than just the biology of flowers — he dives into the ways they've laid down roots in human history and culture, too. On the real 'reason for flowers' The reason for flowers is actually one word: sex. So, flowers are literally living scented billboards that are advertising for sexual favors, whether those are from bees, flies, beetles, butterflies or us, because quite frankly most of the flowers in the world have gotten us to do their bidding. But that's only the first stage because flowers, if they're lucky, turn into fruits, and those fruits and seeds feed the world. On the raucous secret lives of beetles One of my favorite memories is roaming the Napa foothills as a UC Davis grad student. And I would go to the wineries, of course, and in between I would find western spice bush, which is this marvelous flower that kind of smells like a blend between a cabernet and rotten fruit. And when you find those flowers and open them up, you discover literally dozens of beetles in there, mating, defecating, pollinating — having a grand time. © 2015 NPR

Keyword: Sexual Behavior; Evolution
Link ID: 21192 - Posted: 07.20.2015

Tina Hesman Saey The Earth has rhythm. Every 24 hours, the planet pirouettes on its axis, bathing its surface alternately in sunlight and darkness. Organisms from algae to people have evolved to keep time with the planet’s light/dark beat. They do so using the world’s most important timekeepers: daily, or circadian, clocks that allow organisms to schedule their days so as not to be caught off guard by sunrise and sunset. A master clock in the human brain appears to synchronize sleep and wake with light. But there are more. Circadian clocks tick in nearly every cell in the body. “There’s a clock in the liver. There’s a clock in the adipose [fat] tissue. There’s a clock in the spleen,” says Barbara Helm, a chronobiologist at the University of Glasgow in Scotland. Those clocks set sleep patterns and meal times. They govern the flow of hormones and regulate the body’s response to sugar and many other important biological processes (SN: 4/10/10, p. 22). Having timekeepers offers such an evolutionary advantage that species have developed them again and again throughout history, many scientists say. But as common and important as circadian clocks have become, exactly why such timepieces arose in the first place has been a deep and abiding mystery. Many scientists favor the view that multiple organisms independently evolved their own circadian clocks, each reinventing its own wheel. Creatures probably did this to protect their fragile DNA from the sun’s damaging ultraviolet rays. But a small group of researchers think otherwise. They say there had to be one mother clock from which all others came. That clock evolved to shield the cell from oxygen damage or perhaps provide other, unknown advantages. © Society for Science & the Public 2000 - 2015

Keyword: Biological Rhythms; Evolution
Link ID: 21171 - Posted: 07.15.2015

By Michael Balter The human hand is a marvel of dexterity. It can thread a needle, coax intricate melodies from the keys of a piano, and create lasting works of art with a pen or a paintbrush. Many scientists have assumed that our hands evolved their distinctive proportions over millions of years of recent evolution. But a new study suggests a radically different conclusion: Some aspects of the human hand are actually anatomically primitive—more so even than that of many other apes, including our evolutionary cousin the chimpanzee. The findings have important implications for the origins of human toolmaking, as well as for what the ancestor of both humans and chimps might have looked like. Humans and chimps diverged from a common ancestor perhaps about 7 million years ago, and their hands now look very different. We have a relatively long thumb and shorter fingers, which allows us to touch our thumbs to any point along our fingers and thus easily grasp objects. Chimps, on the other hand, have much longer fingers and shorter thumbs, perfect for swinging in trees but much less handy for precision grasping. For decades the dominant view among researchers was that the common ancestor of chimps and humans had chimplike hands, and that the human hand changed in response to the pressures of natural selection to make us better toolmakers. But recently some researchers have begun to challenge the idea that the human hand fundamentally changed its proportions after the evolutionary split with chimps. The earliest humanmade stone tools are thought to date back 3.3 million years, but new evidence has emerged that some of the earliest members of the human line—such as the 4.4-million-year-old Ardipithecus ramidus (“Ardi”)—had hands that resembled those of modern humans rather than chimps, even though it did not make tools. © 2015 American Association for the Advancement of Science

Keyword: Evolution
Link ID: 21170 - Posted: 07.15.2015

by Bob Holmes Bonobos can be just as handy as chimpanzees. In fact, bonobos' tool-using abilities look a lot like those of early humans, suggesting that observing them could teach anthropologists about how our own ancestors evolved such skills. Until now, bonobos have been more renowned for their free and easy sex lives than their abilities with tools. They have never been seen to forage using tools in the wild, although only a handful of wild populations have been studied because of political instability in the Democratic Republic of the Congo, where they live. As for those in captivity, Itai Roffman of Haifa University in Israel and his colleagues previously observed one captive bonobo, called Kanzi, using stone tools to crack a log and extract food. However, it was possible that Kanzi was a lone genius, raised by humans and taught sign language, as well as once being shown how to use tools. To find out if other captive bonobos shared Kanzi's aptitude, Roffman's team looked to animals at a zoo in Germany and a bonobo sanctuary in Iowa. The team gave them a series of problems that required tools to solve – for example, showing the bonobos that food was buried under rocks, then leaving a tray of potential aids such as sticks and antlers nearby. Two of eight zoo animals and four of seven in the sanctuary made use of the tools – in some cases almost immediately. The bonobos used sticks, rocks and antlers to dig, and also used long sticks as levers to move larger rocks out of the way (see video above). Some used different tools in sequence. © Copyright Reed Business Information Ltd

Keyword: Evolution
Link ID: 21147 - Posted: 07.08.2015

By Sabrina Imbler To our knowledge, there’s no correlation between a man’s singing ability and his care and attentiveness as a father. But any Pavarotti among the nightingales will serenade his mate while she sits on her eggs. And after they hatch he will visit the nest about 16 times each hour to feed their offspring. Because, among nightingales at least, the best singers also make the best fathers. So finds a study in the journal BMC Evolutionary Biology. [Conny Bartsch, Michael Weiss and Silke Kipper, Multiple song features are related to paternal effort in common nightingales] Some 80 percent of birds practice biparental care, meaning both the male and female rear their offspring together. So it’s crucial for a female bird to pick as a mate the most promising father—both genetically and behaviorally. Female birds look for signs of fitness that range from the flamboyant plumage of the peacock to the bizarre dances of birds of paradise. And for nightingales, it’s the most elaborate song that apparently wins the day. The average male has some 180 tunes in his repertoire. These avian Sinatras vocalize highly variable song types including buzzes, whistles and trills. And such virtuoso singing seems to signal the female that this is a guy she can count on. That is, when it’s time to help raise the kids, he’s not a flight risk. © 2015 Scientific American

Keyword: Sexual Behavior; Evolution
Link ID: 21140 - Posted: 07.07.2015

By Adrian Cho Whether they're from humans, whales, or elephants, the brains of many mammals are covered with elaborate folds. Now, a new study shows that the degree of this folding follows a simple mathematical relationship—called a scaling law—that also explains the crumpling of paper. That observation suggests that the myriad forms of mammalian brains arise not from subtle developmental processes that vary from species to species, but rather from the same simple physical process. In biology, it rare to find a mathematical relationship that so tightly fits all the data, say Georg Striedter, a neuroscientist at the University of California, Irvine. "They've captured something," he says. Still, Striedter argues that the scaling law describes a pattern among fully developed brains and doesn't explain how the folding in a developing brain happens. The folding in the mammalian brain serves to increase the total area of the cortex, the outer layer of gray matter where the neurons reside. Not all mammals have folded cortices. For example, mice and rats have smooth-surfaced brains and are "lissencephalic." In contrast, primates, whales, dogs, and cats have folded brains and are "gyrencephalic." For decades, scientists have struggled to relate the amount of folding in a species' brain to some other characteristic. For example, although animals with tiny brains tend to have smooth ones, there is no clean relationship between the amount of folding—measured by the ratio of the total area of the cortex to the exposed outer surface of the brain—and brain mass. Make a plot of folding versus brain mass for various species and the data points fall all over and not on a unified curve. Similarly, there is no clean relationship between the amount of folding and the number of neurons, the total area of the cortex, or the thickness of the cortex. © 2015 American Association for the Advancement of Science

Keyword: Development of the Brain; Evolution
Link ID: 21133 - Posted: 07.04.2015

Henry Nicholls Andy Russell had entered the lecture hall late and stood at the back, listening to the close of a talk by Marta Manser, an evolutionary biologist at the University of Zurich who works on animal communication. Manser was explaining some basic concepts in linguistics to her audience, how humans use meaningless sounds or “phonemes” to generate a vast dictionary of meaningful words. In English, for instance, just 40 different phonemes can be resampled into a rich vocabulary of some 200,000 words. But, explained Manser, this linguistic trick of reorganising the meaningless to create new meaning had not been demonstrated in any non-human animal. This was back in 2012. Russell’s “Holy shit, man” excitement was because he was pretty sure he had evidence for phoneme structuring in the chestnut-crowned babbler, a bird he’s been studying in the semi-arid deserts of south-east Australia for almost a decade. After the talk, Russell (a behavioural ecologist at the University of Exeter) travelled to Zurich to present his evidence to Manser’s colleague Simon Townsend, whose research explores the links between animal communication systems and human language. The fruits of their collaboration are published today in PLoS Biology. One of Russell’s students Jodie Crane had been recording the calls of the chestnut-crowned babbler for her PhD. The PLoS Biology paper focuses on two of these calls, which appear to be made up of two identical elements, just arranged in a different way. © 2015 Guardian News and Media Limited

Keyword: Language; Evolution
Link ID: 21110 - Posted: 06.30.2015

Sharon Darwish Bottlenose dolphins have an average brain mass of 1.6 kg, slightly greater than that of humans, and about four times the size of chimpanzee brains. Although you couldn’t really imagine a dolphin writing poetry, dolphins demonstrate high levels of intelligence and social behaviour. For example, they display mirror self-recognition, as well as an understanding of symbol-based communication systems. Research into the differing brain sizes and intellectual capabilities within the animal kingdom is fascinating. Why have some species evolved to be more intelligent than others? Does brain size affect cognitive ability? Some studies say yes, but some insist otherwise. It really depends which species we are talking about. In humans, for example, larger brains do not indicate higher intelligence – otherwise Einstein, who had an average-sized brain, may have not been quite as successful in his career. (Yes, that link was to a 23-pager on the analysis of Einstein’s brain. It makes for great bedtime reading.) Most neuroscientists now believe that it is the structure of the brain on a cellular and molecular level that determines its computational capacity. Within certain animal species however, a larger brain offers evolutionary advantage. For example, large-brained female guppies are better survivors and demonstrate greater cognitive strengths than their smaller-brained counterparts. © 2015 Guardian News and Media Limited

Keyword: Development of the Brain; Genes & Behavior
Link ID: 21102 - Posted: 06.27.2015

By Sarah Lewin Evolutionary biologists have long wondered why the eardrum—the membrane that relays sound waves to the inner ear—looks in humans and other mammals remarkably like the one in reptiles and birds. Did the membrane and therefore the ability to hear in these groups evolve from a common ancestor? Or did the auditory systems evolve independently to perform the same function, a phenomenon called convergent evolution? A recent set of experiments performed at the University of Tokyo and the RIKEN Evolutionary Morphology Laboratory in Japan resolves the issue. When the scientists genetically inhibited lower jaw development in both fetal mice and chickens, the mice formed neither eardrums nor ear canals. In contrast, the birds grew two upper jaws, from which two sets of eardrums and ear canals sprouted. The results, published in Nature Communications, confirm that the middle ear grows out of the lower jaw in mammals but emerges from the upper jaw in birds—all supporting the hypothesis that the similar anatomy evolved independently in mammals and in reptiles and birds. (Scientific American is part of Springer Nature.) Fossils of auditory bones had supported this conclusion as well, but eardrums do not fossilize and so could not be examined directly. © 2015 Scientific American

Keyword: Hearing; Evolution
Link ID: 21098 - Posted: 06.27.2015

By Michael Balter For much of the time dinosaurs were lording over the land, sleek marine reptiles called ichthyosaurs were the masters of the sea. The dolphinlike predators had enormous eyes for hunting and grew as long as 20 meters. But paleontologists have long been baffled by their brain structure, because most fossil specimens have been squished flat by marine sediments. One rare exception—discovered in the 1800s in southern England’s Bristol Channel—is a spectacularly preserved, 180-million-year-old ichthyosaur named Hauffiopteryx. Now, using computerized tomography (CT) scanning, researchers have created a 3D digital reconstruction of Hauffiopteryx’s skull, making a “ghost image” of its brain known as a digital endocast (above). The team, which reported its findings online earlier this month in Palaeontology, found that the brain’s optic lobes were particularly large; so were the cerebellum, which controls motor functions, and the olfactory region, where odors are processed. Taken together, the team concludes these features show ichthyosaurs were highly mobile predators with a keen sense of sight and smell. © 2015 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 21097 - Posted: 06.27.2015

By Sarah C. P. Williams Parrots, like the one in the video above, are masters of mimicry, able to repeat hundreds of unique sounds, including human phrases, with uncanny accuracy. Now, scientists say they have pinpointed the neurons that turn these birds into copycats. The discovery could not only illuminate the origins of bird-speak, but might shed light on how new areas of the brain arise during evolution. Parrots, songbirds, and hummingbirds—which can all chirp different dialects, pick up new songs, and mimic sound—all have a “song nuclei” in their brain: a group of interconnected neurons that synchronizes singing and learning. But the exact boundaries of that region are fuzzy; some researchers define it as larger or smaller than others do, depending on what criteria they use to outline the area. And differences between the song nuclei of parrots—which can better imitate complex sounds—and other birds are hard to pinpoint. Neurobiologist Erich Jarvis of Duke University in Durham, North Carolina, was studying the activation of PVALB—a gene that had been previously found in songbirds—within the brains of parrots when he noticed something strange. Stained sections of deceased parrot brains revealed that the gene was turned on at distinct levels within two distinct areas of what he thought was the song nuclei of the birds’ brains. Sometimes, the gene was activated in a spherical central core of the nuclei. But other times, it was only active in an outer shell of cells surrounding that core. When he and collaborators looked more closely, they found that the inner core and the outer shell—like the chocolate and surrounding candy shell of an M&M—varied in many more ways as well.

Keyword: Language; Evolution
Link ID: 21091 - Posted: 06.25.2015