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Discovery of organ explains koalas’ super-bass notes

Throat structure explains why male mating calls are bizarrely deeper than expected for the animal’s size. Male koalas produce a deep-pitched sound thanks in part to special folds that span an opening between their nasal and oral cavities. For such diminutive animals, male koalas have an uncannily deep voice. The pitch of their bellowing mating call is 20 times lower than would be anticipated for their size, and more like something you would hear from an elephant, for instance. Benjamin Charlton, a biologist at the University of Sussex in Brighton, UK, wanted to know what gave these marsupial Barry Whites their rumbling bass voice. “The first time I heard a koala bellow, I was genuinely amazed that an animal this small could produce such a sound,” he says. In 2011, he was part of a team that discovered that koalas have a descended larynx (which holds the vocal cords) — something found only in humans and certain species of deer. This makes their vocal tract longer than expected and helps to produce unusually resonant calls. But the koala’s laryngeal vocal cords are too small to produce the extremely low fundamental frequencies of the mating bellows, so Charlton and his colleagues, together with Roland Frey at the Leibniz Institute for Zoo and Wildlife Research in Berlin, dissected ten male koalas (Phascolarctos cinereus) to take a closer look.

Focusing on the koala’s throat and soft palate, they found a set of much larger folds that had never been described before, spanning an opening between the nasal and oral cavities of the pharynx — the upper part of the throat behind the mouth and nose but above the larynx. These ‘velar’ vocal folds are the right size to produce the low frequencies of koala bellows, and Charlton and his team were able to reproduce the sounds by using a pump to suck air through the pharynx and larynx of dead koalas — mimicking the bellows that live koalas make when they inhale. This marks the first time that an organ specialized for sound production other than the larynx has been found in a terrestrial mammal, says Charlton. The only other similar example is in toothed whales, which have phonic lips that generate clicks used for echolocation. It may seem odd that the koala structure, described today in Current Biology, has only now been discovered, but Charlton thinks that previous investigators may simply not have considered its potential role in sound production in this species.

He now plans to examine female koalas, as well as other marsupials that produce disproportionately low bellows, to see whether the feature is unique to male koalas. Velar folds have not been documented in any other mammals, so could have been overlooked in the same way. But Charlton thinks that “it seems likely that this remarkable adaptation evolved independently in the koala.” Karen Black, an evolutionary biologist at the University of New South Wales in Sydney, Australia, says that it is not surprising that koalas have a unique anatomy for sound production. The low-frequency bellows allow koalas to communicate over long distances in their open forest habitats, she says. She notes that they also have extremely large auditory bony structures called bullae in their middle ear, which could be an adaptation for picking up low-frequency sounds. William Ellis, a wildlife ecologist at the University of Queensland in Brisbane, Australia, who collaborated to the 2011 study, thinks that the low-pitched bellow could be an evolutionary adaptation. Because the bellow is an accurate, if exaggerated, indicator of size, it may help smaller males to avoid fights with bigger rivals, he says. But he is sure that there is more to learn about the behaviour. “For an animal that spends so much of its time resting, the bellow is perhaps the most interesting thing the koala regularly does,” he says. “Yet we are only just figuring it out.”

Nature
January 7, 2014

Original web page at Nature

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The origin of the turtle shell: Mystery solved

A team of researchers from Japan has finally solved the riddle of the origin of the turtle shell. By observing the development of different animal species and confirming their results with fossil analysis and genomic data, researchers from the RIKEN Center for Developmental Biology show that the shell on the turtle’s back derives only from its ancestors’ ribcage and not from a combination of internal and external bone structures as is often thought. Their study is published today in the journal Nature Communications. The skeleton of vertebrates has evolved throughout history from two different structures, called the endo- and exoskeleton. In the human skeleton, the backbone and bones of the limbs evolved from the endoskeleton, whereas most of the skull elements derive from the exoskeleton. Fish scales and the alligator’s bony skin nodules are other examples of exoskeletons. The origin of the shell on the turtle’s back, or carapace, was unclear until now because it comprises parts of obvious endoskeletal origin and others that look more like the exoskeleton of alligators and fish. The outer part of the turtle carapace was thought to have derived from exoskeletal bones, while the internal part has been shown to originate from ribs and vertebrae and to be connected to the internal skeleton of the animal. However, no direct evidence has been obtained to show that the bony structures developing outside the ribcage in turtles derived from the exoskeleton.

To investigate whether the turtle carapace evolved with any contribution from its ancestors’ exoskeleton, Dr. Tatsuya Hirasawa and his team carefully observed developing embryos of Chinese soft-shell turtles, chickens and alligators. In their analysis, they compared the development of the turtle carapace, the chick’s ribs and the alligator’s bony skin nodules. The researchers found that the major part of the turtle’s carapace is made from hypertrophied ribs and vertebrae and therefore derives solely from endoskeletal tissue. This finding was confirmed by the observation of fossils of the ancient turtle Odontochelys and the ancient reptile Sinosaurosphargis, that both exhibit shells of endoskeletal origin. Odontochelys has a rigid shell instead of a flexible ribcage. And Sinosaurosphargis possesses an endoskeletal shell similar to the turtle’s under, and separate from, a layer of exoskeletal bones. Taken together these results show that the turtle carapace has evolved independently from the exoskeleton. This scenario is also consistent with the recent phylogenetic analyses based on genomic data that have placed turtles in the same group as birds, crocodiles and marine reptiles like Sinosaurophargis, contradicting recent studies based solely on fossil record. “Recently, genomic analyses had given us evidence that turtles evolved from reptiles closely related to alligators and dinosaurs, not from primitive reptiles as once thought. Our findings match the evolutionary history revealed by the genomic analyses, and we are about to unravel the mystery of when and how the turtle shell evolved,” explains Dr. Tatsuya Hirasawa who led the research. “Our aim is to one day understand it as well as we understand the evolution of birds from dinosaurs,” he concludes.

Science Daily
July 23, 2013

Original web page at Science Daily

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Whole human brain mapped in 3D

Ten-year ‘BigBrain’ effort yields 10-trillion-byte atlas of fine-scale cerebral anatomy. Researchers used a special tool called a microtome cut a human brain preserved in paraffin wax into 20-micrometre thick slivers and map its anatomical structure with high resolution. An international group of neuroscientists has sliced, imaged and analysed the brain of a 65-year-old woman to create the most detailed map yet of a human brain in its entirety. The atlas, called ‘BigBrain’, shows the organization of neurons with microscopic precision, which could help to clarify or even redefine the structure of brain regions obtained from decades-old anatomical studies. “The quality of those maps is analogous to what cartographers of the Earth offered as their best versions back in the seventeenth century,” says David Van Essen, a neurobiologist at Washington University in St. Louis, Missouri, who was not involved in the study. He says that the new and improved set of anatomical guideposts could allow researchers to merge different types of data — such as gene expression, neuroanatomy and neural activity — more precisely onto specific regions of the brain.

The brain is comprised of a heterogeneous network of neurons of different sizes and with shapes that vary from triangular to round, packed more or less tightly in different areas. BigBrain reveals variations in neuronal distribution in the layers of the cerebral cortex and across brain regions — differences that are thought to relate to distinct functional units. The atlas was compiled from 7,400 brain slices, each thinner than a human hair. Imaging the sections by microscope took a combined 1,000 hours and generated 10 trillion bytes of data. Supercomputers in Canada and Germany churned away for years reconstructing a three-dimensional volume from the images, and correcting for tears and wrinkles in individual sheets of tissue. The researchers describe their results recently in Science, and will make the full data set publicly available online. It shows the brain at a resolution of 20 micrometres — 50 times higher than the typical 1 millimetre resolution of atlases based on whole-brain scans. “This completely changes the game in terms of our ability to discriminate very fine structural and physiological properties of the human brain,” said study co-author Alan Evans, a neurologist at the Montreal Neurological Institute at McGill University in Canada, at a press conference on 19 June.

“Their quality really looks very high,” says Christof Koch, chief scientific officer at the Allen Institute for Brain Science in Seattle, Washington. The Allen Institute maintains its own human brain atlas, which provides structural data at slightly lower resolution than that of the latest study but includes extensive annotations and maps of gene expression. BigBrain is part of the Human Brain Project, a 10-year, €1-billion European initiative to create a supercomputer simulation of the human brain. Detailed knowledge of neuronal clustering could help to set realistic parameters for the simulation, says lead author Katrin Amunts, a neuroscientist at the Heinrich Heine University Dusseldorf in Germany. Although the atlas shows data from only one person’s brain, it is an important starting point for interpreting data from other brains in the future, adds Van Essen, who compares BigBrain to the sequencing of the first human genome. “Getting a really accurate map in one individual is, I think, very valuable,” he says. The atlas will serve as a reference with which other data sets can be aligned, and the BigBrain team plans to work with the Allen Brain Institute to link information from their two databases. Since the BigBrain effort began in 2003, technology has advanced to enable researchers to scan human brain sections at a resolution of one micrometre. But completing another atlas at such a high resolution would create about 20,000 trillion bytes of data — more than the most advanced computers today could process efficiently, says Amunts. The technology is continuing to grow rapidly,” says Sean Hill, executive director of the International Neuroinformatics Coordinating Facility in Stockholm. But he notes that the problem of data management and processing will require more resources and attention as neuroscience shifts towards big data sets. “This is an example of something that is only going to increase in frequency,” says Hill. Amunts says that the team is already working on mapping “brain number 2”.

Nature
July 9, 2013

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Fish otoliths point to climate impacts

The earbones, or ‘otoliths’, help fish to detect movement and to orient themselves in the water. Otoliths set down annual growth rings that can be measured and counted to estimate the age and growth rates of fish. “Otoliths can form the basis of new techniques for modelling fish growth, productivity and distribution in future environments,” said Dr John Morrongiello of CSIRO’s Wealth from Oceans Flagship, lead author of a paper published online in Nature Climate Change November 28. “They are widely used to support fishery stock assessments, and are beginning to be used to measure and predict ecological responses to ocean warming and climate change. “Any change identified in growth and age maturity, especially of commercially-important species, clearly has implications for forecasting future stock states and the sustainable management of fisheries.” “Millions of otoliths are archived in research laboratories and museums worldwide, and many fish species live for decades and some, such as orange roughy, live for up to 150 years. “Their otoliths record variations in growth rates that reflect environmental conditions. Longer-lived fish and older samples take us back as far as the 1800s.”

Science Daily
December 11, 2012

Original web page at Science Daily

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Elephants walk on the world’s biggest platform shoes

Even though an elephant’s leg looks like a solid column, it actually stands on tip-toe like a horse or a dog. Its heel rests on a large pad of fat that gives it a flat-footed appearance. The pad hides a sixth toe — a backward-pointing strut that evolved from one of their sesamoids, a set of small tendon-anchoring bones in the animal’s ankle. This extra digit, between 5 and 10 centimetres long, had been dismissed as an irrelevant piece of cartilage. Almost 300 years after it was first described, John Hutchinson at the Royal Veterinary College in London confirmed that it is a true bone that supports the squishy back of the elephant’s foot. The ones on the hindfeet even seem to have joints. The study is published in Science. Some moles and frogs have similar extra digits, and the giant panda has adapted the same sesamoid bone into a bamboo-grasping ‘thumb’. “The elephant’s toe is basically a panda’s thumb, with the same connections and everything,” says Hutchinson. “It’s a repeated theme in evolution. You turn one of your sesamoids into a functional finger instead of evolving a new one.”

The sixth toe was first described in the eighteenth century, but it has been largely ignored. “People forgot that this thing was even there and it only came up in specialist papers on elephant anatomy,” says Hutchinson. This was partly because live elephants are difficult to study. They react poorly to anaesthesia, and their feet are impervious to X-rays and ultrasound at safe intensities. Dissecting cadavers is the only real option. “Fortunately, I have the dubious distinction of having perhaps the world’s largest collection of frozen elephant feet,” says Hutchinson, who has long-standing relationships with several zoos. They send him the feet of elephants that have died or been euthanized, so that he can establish the cause of death, which is often related to foot problems in captive elephants. He now has more than 60 stored in various freezers. Hutchinson thinks that researchers who dissected elephants in the past missed the sixth toe because it is so deeply embedded in the fat pad. “There are all these weird fibres and compartments, muscles and tendons weaving their way through, and this structure in the middle of it all,” says Hutchinson. “Unless you really cut through carefully and think about the anatomy, it might seem like an odd piece of cartilage.” This is why the extra digit never appears in museum specimens — curators usually throw it away.

Hutchinson and his team studied the toe using computer tomography (CT), electron microscopy, dissection and histology over a period of three years. Hutchinson found that the extra digit initially develops as rods of cartilage that slowly transform into bone, years after the rest of the bones of the foot have become ossified. By loading the feet with weights inside a CT scanner, they showed that the sixth toe acts as a strut that stiffens the back of the fat pad. It helps the pad to support the elephant’s weight without collapsing down too far. This also explains why the toe gets stronger as the animals gets older and heavier. “It helps us get our heads around the fact that this quite delicate foot is hidden within this great, hulking beast,” says Victoria Herridge, who studies elephant anatomy and evolution at University College London, and was not involved in the study. Fossils suggest that the earliest ancestors of elephants had flat feet, with no sixth toes, and their ankles rested on the ground. As the animals evolved into giants, they adopted a tip-toe stance that straightened their legs and better supported their weight. During this change in their posture, one of their sesamoid bones was co-opted into a load-sharing strut.

But Gerald Weissengruber at the University of Veterinary Medicine Vienna says that the paper has “fundamental flaws”. He says that it is unclear if the sixth toe is a sesamoid bone at all, because it has no obvious muscles attached to it as do the panda’s thumb or a human sesamoid. Weissengruber also points out that Hutchinson mainly looked at captive elephants, which are known to suffer from foot and bone disorders. Disease could have turned cartilage in their foot into bone, and the ‘joint’ in the back toe might just be a fracture. A similar thing often happens to the cartilage in horse’s hoofs. Hutchinson acknowledges the problem. “We don’t know how much of the ossification is normal and how much is pathological,” he says. “It would be nice to look at wild elephants.”

Nature
January 10, 2012

Original web page at Nature

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Koalas’ bellows boast about size

Koalas have a well-earned reputation for being dopey. Sleeping 19 hours out of every 24, and feeding for 3 of the remaining 5 hours, there doesn’t seem to be much time for anything else in their lethargic lifestyle: that is until the mating season. Then the males begin bellowing. Benjamin Charlton from the University of Vienna, Austria, explains that they probably bellow to attract females and to intimidate other males. But what messages could these rumbling bellows communicate about their senders? Intrigued by the marsupial’s strange sound, biologists decided to find out what messages the koalas’ bellows may send and discovered that they are boasting about their size. The largest koalas produce deeper resonances than smaller males, and even the smallest males produce resonances that make them sound larger than a bison, which are 100 times their size. Charlton and an international team of collaborators publish their discovery that the koalas are boasting about their size in the Journal of Experimental Biology.

According to Charlton, they could be telling nearby listeners about their size. He explains that there was a possibility that koalas may be one of the few animals that have a descended larynx, which makes the vocal tract longer. Also, because all pipes — including vocal tracts — have frequencies where the air inside them vibrates naturally and amplifies sound, larger animals with longer vocal tracts produce lower resonances, giving their voices a more baritone quality. So, the longer vocal tracts of the largest koalas should produce deeper resonances to tell the listening koala audience just how big they are. Intrigued, Charlton, Tecumseh Fitch and their colleagues decided to find out whether male koalas have descended larynxes. Teaming up with Allan McKinnon at Moggill Koala Hospital and Gary Cowin and William Ellis at the University of Queensland, Australia, Charlton investigated the anatomy of the marsupial’s vocal tract. Using MRI and post-mortem studies, the team found that the koala’s larynx had descended to the level of the 3rd and 4th cervical vertebrae, instead of being high in the throat. They were also surprised to find that the muscle that attaches the larynx to the sternum was anchored very deep in the thorax and they suggest that it could be involved in pulling the larynx even further down into the chest cavity.

But what effect does the koala’s deeply descended larynx have on the acoustics of their bellows? Traveling to the Lone Pine Koala Sanctuary, home to 140 koalas, Charlton patiently recorded their rumbling bellows. He also measured the animals’ head sizes, with the help of Jacqui Brumm and Karen Nilsson, as skull size is a good proxy for body size. Back in the lab, Charlton analyzed the bellows’ spectra and found that the largest males always had lower resonances than the smaller animals. More surprisingly, when Charlton calculated the koala’s vocal tract length based on their acoustics, he was astonished to find that the koalas were able to make themselves sound as if they had 50-cm-long vocal tracts, nearly the entire length of the animal. In fact, the diminutive animals sound even larger than bison. Charlton suspects that koalas use the resonances of the oral and nasal tracts simultaneously to sound much larger than they are. So, koala males are able to communicate their size, with the largest animals producing the richest baritone bellows. Charlton also suspects that the males’ boastful bellows could have driven the evolution of their descended larynxes. ‘Individuals that could elongate their vocal tracts by lowering the larynx may have gained advantages during sexual competition by sounding larger, and this would drive the evolution of laryngeal descent,’ he says.

Science Daily
October 18, 2011

Original web page at Science Daily

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Bizarre reptile challenges notion of crocodiles as ‘living fossils’

We all know that crocodiles are reptiles with long snouts, conical teeth, strong jaws and long tails. But according to researchers at Stony Brook University in New York, we don’t know what we thought we knew. Rather, some crocodiles possessed a dazzling array of adaptations that resulted in unique and sometimes bizarre anatomy, including blunt, pug-nosed snouts, pudgy bodies and short tails. These anatomical adaptations of the incredibly diverse group of reptiles called notosuchian crocodyliforms are brilliantly illuminated in a new Memoir of the Society of Vertebrate Paleontology. This massive, richly illustrated volume, edited by Drs. David W. Krause and Nathan J. Kley of Stony Brook, clearly dispels the notion that crocodiles are static, unchanging “living fossils.” The volume, which gives an account of fossil crocodyliform anatomy, is set for publication on December 8, 2010.

The epitome of crocodyliform anomaly is represented by Simosuchus clarki, which lived in Madagascar at the end of the “Age of Dinosaurs” (about 66 million years ago). First described preliminarily in 2000 from a well-preserved skull and partial skeleton, Simosuchus shattered the crocodyliform mold with its blunt snout, leaf-shaped teeth, and short, tank-like body covered in a suit of bony armor. “ Simosuchus is easily the most bizarre crocodyliform ever found,” declared Dr. Christopher Brochu, a leading expert on fossil crocodiles from the University of Iowa. Over the next decade, expeditions to Madagascar recovered more skulls and skeletons, now representing nearly every bone of Simosuchus. A reconstruction of this uncommonly complete fossil reptile and an interpretation of its place in the crocodile evolutionary tree became the subject of the new volume. “The completeness and preservation of the specimens demanded detailed treatment,” said Krause, Distinguished Service Professor in the Department of Anatomical Sciences at Stony Brook University. “It just seemed unconscionable to not document such fantastic fossil material of this unique animal.”

Brochu, who did not participate in the research, said that “very few crocodilians – even those alive today – have been subjected to this level of analysis. This reference sets a new standard for analyses of extinct crocodyliforms and is going to used for decades.” A separate chapter of the monograph is devoted to each of the major parts of the animal – skull, backbone, limbs, and armor. “The skull and lower jaw in particular are preserved almost completely,” said Kley, assistant professor in the Department of Anatomical Sciences at Stony Brook University. “This, combined with high-resolution CT scans of the most exquisitely preserved specimen, has allowed us to describe the structure of the head skeleton – both externally and internally – in exceptional detail, including even the pathways of the tiniest nerves and blood vessels.” But while it is easy to lose one-self in the details of these incredible fossils, one of the most amazing features is the overall shape of the animal. Two feet long, pudgy, with a blunt snout and the shortest tail of any known crocodyliform, Simosuchus was not equipped to snatch unsuspecting animal prey from the water’s edge as many modern crocodiles do.

“Simosuchus lived on land, and its crouched posture and wide body probably meant it was not very agile or fast,” said Joseph Sertich, a Ph.D. student in the Department of Anatomical Sciences at Stony Brook who participated in the research. In addition, its short, under-slung jaw and weak, leaf-shaped teeth show that it probably munched on a diet of plants. While the idea of a gentle, vegetarian crocodile is unusual to us today, the new memoir makes it easy to imagine Simosuchus ambling through its semi-arid grassland habitat, pausing to nip at plants and crouching low to hide from predators like the meat-eating dinosaur Majungasaurus. The paleontologists also found evidence that pointed to the evolutionary origin of Simosuchus. “Interestingly, an analysis of evolutionary relationships suggests Simosuchus’ closest relative lived much earlier, in Egypt,” said Sertich.

Science Daily
December 21, 2010

Original web page at Science Daily

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Blue whale-sized mouthfuls make foraging super efficient

How much can a blue whale eat in a single mouthful and how much energy do they burn while foraging? These are the questions that Bob Shadwick from the University of British Columbia, Canada, and his colleagues have asked. They discovered that blue whales can swallow almost 2,000,000kJ (almost 480,000kcalories) in a single mouthful of krill, and eat 90 times as much energy as they burn during a dive. Diving blue whales can dive for anything up to 15 minutes. However, Bob Shadwick from the University of British Columbia, Canada, explains that blue whales may be able to dive for longer, because of the colossal oxygen supplies they could carry in their blood and muscles, so why don’t they? ‘The theory was that what they are doing under water must use a lot of energy,’ says Shadwick. Explaining that the whales feed by lunging repeatedly through deep shoals of krill, engulfing their own body weight in water before filtering out the nutritious crustaceans, Shadwick says, ‘It was thought that the huge drag effect when they feed and reaccelerate this gigantic body must be the cost’. However, measuring the energetics of blue whale lunges at depth seemed almost impossible until Shadwick and his student Jeremy Goldbogen got chatting to John Hildebrand, John Calambokidis, Erin Oleson and Greg Schorr who were skilfully attaching hydrophones, pressure sensors and two-axis accelerometers to the elusive animals. Shadwick and Goldbogen realised that they could use Calambokidis’s measurements to calculate the energetic cost of blue whale lunges. They publish their discovery that blue whales swallow almost 2,000,000kJ (almost 480,000kcalories) in a mouthful of krill, and take in 90 times as much energy as they burn during a single dive in The Journal of Experimental Biology.

Analysing the behaviour of each whale, Goldbogen saw that dives lasted between 3.1 and 15.2 minutes and a whale could lunge as many as 6 times during a single dive. Having found previously that he could correlate the acoustic noise of the water swishing past the hydrophone with the speed at which a whale was moving, Goldbogen calculated the blue whales’ speeds as they lunged repeatedly during each dive. Next the team had to calculate the forces exerted on the whales as they accelerated their colossal mouthful of water. Noticing that the whales’ mouths inflated almost like a parachute as they engulfed the krill, Goldbogen tracked down parachute aerodynamics expert Jean Potvin to help them build a mathematical model to calculate the forces acting on the whales as they lunged. With Potvin on the team, they were able to calculate that the whales used between 3226 kJ of energy during each lunge. But how did this compare with the amount of energy that the whales could extract from each gigantic mouthful of krill?

Goldbogen estimated the volume of the whales’ mouths by searching the whaling literature for morphological data and teamed up with paleontologist Nick Pyenson to measure the size of blue whale jaw bones in several natural history museums. He also obtained krill density values from the literature — which are probably on the low side. Then he calculated the volume of water and amount of krill that a whale could engulf and found that the whales could consume anything from 34,776kJ up to an unprecedented 1,912,680kJ from a single mouthful of krill, providing as much as 240 times as much energy as the animals used in a single lunge. And when the team calculated the amount of energy that a whale could take on board during a dive, they found that each foraging dive could provide 90 times as much energy as they used. Shadwick admits that he was initially surprised that the whales’ foraging dives were so efficient. ‘We went over the numbers a lot,’ he remembers, but then he and Goldbogen realised that the whales’ immense efficiency makes sense. ‘The key to this is the size factor because they can engulf such a large volume with so much food in it that it really pays off,’ says Shadwick.

Science Daily
December 21, 2010

Original web page at Science Daily

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Dogs have bigger brains than cats because they are more sociable

Over millions of years dogs have developed bigger brains than cats because highly social species of mammals need more brain power than solitary animals, according to a study by Oxford University. For the first time researchers have attempted to chart the evolutionary history of the brain across different groups of mammals over 60 million years. They have discovered that there are huge variations in how the brains of different groups of mammals have evolved over that time. They also suggest that there is a link between the sociality of mammals and the size of their brains relative to body size, according to a study published in the PNAS journal. The research team analysed available data on the brain size and body size of more than 500 species of living and fossilised mammals. It found that the brains of monkeys grew the most over time, followed by horses, dolphins, camels and dogs. The study shows that groups of mammals with relatively bigger brains tend to live in stable social groups. The brains of more solitary mammals, such as cats, deer and rhino, grew much more slowly during the same period.

Previous research which has looked at why certain groups of living mammals have bigger brains has relied on studies of distantly-related living mammals. It was widely believed that the growth rate of the brain relative to body size followed a general trend across all groups of mammals. However, this study by Dr Susanne Shultz and Professor Robin Dunbar, from Oxford University’s Institute of Cognitive and Evolutionary Anthropology (ICEA), overturns this view. They find that there is wide variation in patterns of brain growth across different groups of mammals and they have discovered that not all mammal groups have larger brains, suggesting that social animals needed to think more. Lead author Dr Susanne Shultz, a Royal Society Dorothy Hodgkin Fellow at ICEA, said: ‘This study overturns the long-held belief that brain size has increased across all mammals. Instead, groups of highly social species have undergone much more rapid increases than more solitary species. This suggests that the cooperation and coordination needed for group living can be challenging and over time some mammals have evolved larger brains to be able to cope with the demands of socialising.’

Co-author and Director of ICEA Professor Robin Dunbar said: ‘For the first time, it has been possible to provide a genuine evolutionary time depth to the study of brain evolution. It is interesting to see that even animals that have contact with humans, like cats, have much smaller brains than dogs and horses because of their lack of sociality.’ The research team used available data of the measurements of brain size and body size of each group of living mammals and compared them with similar data for the fossilised remains of mammals of the same lineage. They examined the growth rates of the brain size relative to body size to see if there were any changes in the proportions over time. The growth rates of each mammal group were compared with other mammal groups to see what patterns emerged.

Science Daily
December 7, 2010

Original web page at Science Daily

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The bigger the animal, the stiffer the ‘shoes’: Carnivores’ feet ‘tuned’ to their body size

If a Tiger’s feet were built the same way as a mongoose’s feet, they’d have to be about the size of a hippo’s feet to support the big cat’s weight. But they’re not. For decades, researchers have been looking at how different-sized legs and feet are put together across the four-legged animal kingdom, but until now they overlooked the “shoes,” those soft pads on the bottom of the foot that bear the brunt of the animal’s walking and running. New research from scientists in Taiwan and at Duke University has found that the mechanical properties of the pads vary in predictable fashion as animals get larger. In short, bigger critters need stiffer shoes.

Kai-Jung Chi, an assistant professor of physics at National Chung Hsing University in Taiwan ran a series of carefully calibrated “compressive tests” on the footpads of carnivores that have that extra toe halfway up the foreleg, including dogs, wolves, domestic cats, leopards and hyenas. She was measuring the relative stiffness of the pads across species — how much they deformed under a given amount of compression. “People hadn’t looked at pads,” said co-author V. Louise Roth, an associate professor of biology and evolutionary anthropology who was Chi’s thesis adviser at Duke. “They’ve been looking at the bones and muscles, but not that soft tissue.” Whether running, walking or standing still, the bulk of the animal’s weight is borne on that pillowy clover-shaped pad behind the four toes, the metapodial-phalangeal pad, or m-p pad for short. It’s made from pockets of fatty tissue hemmed in by baffles of collagen. Chi carefully dissected these pads whole from the feet of deceased animals (none of which were euthanized for this study), so that they could be put in the strain meter by themselves without any surrounding structures.

Laid out on a graph, Chi’s analysis of 47 carnivore species shows that the area of their m-p pads doesn’t increase at the same rate as the body sizes. But the stiffness of pads does increase with size, and that’s what keeps the larger animal’s feet from being unwieldy. The mass of the animal increases cubically with its greater size, but the feet don’t scale up the same way. “A mouse and an elephant are made with the same ingredients,” Roth said. “So how do you do that?” Earlier research had found that the stresses on the long bones of the limbs stay fairly consistent over the range of sizes, in part because of changes in posture that distribute the stresses of walking differently, Roth said. But that clearly wasn’t enough by itself. The researchers also found that larger animals have a pronounced difference in stiffness between the pads on the forelimbs and the pads on the hind limbs. Bigger animals have relatively softer pads on their rear feet, whereas in smaller animals the front and rear are about the same stiffness. Chi thinks the softer pads on the rear of the bigger animals may help them recover some energy from each step, and provide a bit more boost to their propulsion. (Think of the way a large predator folds up its forelimbs and launches itself with its hind legs.) “It is as if the foot pads’ stiffness is tuned to enhance how the animal moves and how strength is maintained in its bones,” Roth said. The research appeared February 23 in the Journal of the Royal Society, Interface.

Science Daily
March 23, 2010

Original web page at Science Daily

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Natural ‘magnetometer’ in upper beak of birds?

Iron containing short nerve branches in the upper beak of birds may serve as a magnetometer to measure the vector of the Earth magnetic field (intensity and inclination) and not only as a magnetic compass, which shows the direction of the magnetic field lines. Several years ago, the Frankfurt neurobiologists Dr. Gerta Fleissner and her husband Prof. Dr. Günther Fleissner discovered these structures in homing pigeons and have, in close cooperation with the experimental physicist Dr. Gerald Falkenberg (DESY Hamburg), characterized the essential iron oxides. After we had shown the system of dendrites with distinct subcellular iron-containing compartments in homing pigeons, immediately the question was posed whether similar dendritic systems may be found in other bird species, too,” as Gerta Fleissner, the principal investigator, comments. Meanwhile they could describe similar candidate structures in the beaks of various avian species. X-Ray-fluorescence measurements at DESY demonstrated that the iron oxides within these nervous dendrites are identical. These findings were published few days ago in the high-ranking interdisciplinary online journal PLoS One.

More than about 500 dendrites in the periphery encode the magnetic field information, which is composed in the central nervous system to a magnetic map. It obviously does not matter, whether birds use this magnetic map for their long distance orientation or do not — the equipment can be found in migratory birds, like robin and garden warbler, and well as in domestic chicken. “This finding is astonishing, as the birds studied have a different life styles and must fulfil diverse orientational tasks: Homing pigeons, trained to return from different release sites to their homeloft, short-distance migrants like robins, long-distance migratory birds like garden warblers and also extreme residents like domestic chicken,” explains Gerta Fleissner. In order to provide convincing evidence, several thousand comparative measurements were performed. The beak tissue was studied under the microscope to identify iron-containing hot spots as a basis for consecutive physicochemical analyses. At the Hamburg Synchrotron Strahlungslabor at DESY the distribution and quantity of various elements was topographically mapped by a high resolution X-ray device. “Here, the beak tissue can be investigated without destruction by histological procedures concerning the site and detailed nature of magnetic iron compounds within the dendrites,” Gerta Fleissner explains and she emphasizes that the cooperation with the experimental physicist Gerald Falkenberg as project leader at DESY was essential for this scientific breakthrough.

Specialized iron compounds in the dendrites locally amplify the Earth magnetic field and thus induce a primary receptor potential. Most probably each of these more than 500 dendrites encodes only one direction of the magnetic field. These manifold data are processed to the brain of the bird and here — recomposed — serve as a basis for a magnetic map, which facilitates the spatial orientation. Whether this magnetic map is consulted, strongly depends on the avian species and its current motivation to do so: migratory birds, for example, show magnetic orientation only during their migratory restlessness, as could be shown in multiple behavioural experiments by Prof. Wolfgang Wiltschko, who has discovered magnetic field guided navigation in birds. The cooperation with his research team has suggested that magnetic compass and magnetic map sense are based on different mechanisms and are localized at different sites: The magnetic compass resides in the eye, the magnetometer for the magnetic map lies in the beak. “The now published results clearly help to falsify the old myths concerning iron-based magnetoreception via randomly distributed sites everywhere in the organism, like blood, brain or skull. They rather deliver a sound concept how to identify magnetoreceptive systems in various organisms,” Günther Fleissner happily reports. These clear and well-reproducible data may be used as a basis for further experimental projects that might elucidate the manifold unknown steps between magnetic field perception and its use as a navigational cue.

Science Daily
March 23, 2010

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Tendons shape bones during embryonic development

In all vertebrates, including humans, bones, muscles and tendons work together to give the skeleton its characteristic balance of stability and movement. Now, new research uncovers a previously unrecognized interaction between tendons, which connect muscles to bones, and the developing embryonic skeleton. This study, published in the December 15th issue of the journal Developmental Cell, demonstrates that tendons drive the development of specific bone features that are needed for a strong skeletal system. “Our skeleton with its bones, joints, and muscle attachments serves us so well in our daily lives that we hardly pay attention to this extraordinary system,” says senior study author, Dr. Elazar Zelzer from the Weizmann Institute of Science in Rehovot, Israel. “Although previous research has uncovered mechanisms that contribute to the development and growth of each issue composing this complex and wonderfully adaptable organ system, specific interactions between bones, muscles and tendons that drive the ordered assembly of the musculoskeletal system are not fully understood.”

Dr. Zelzer and colleagues were interested in uncovering how “bone ridges” form. Bone ridges are knobby, thickened areas of bone that can be found wherever tendons are attached. These reinforced sections of bone are important anchoring points for connecting bones to muscles, and strong attachment at these sites enables the skeleton to cope with mechanical stresses exerted by the muscles. While studying mouse embryos, the researchers discovered that tendons control the formation their own bone ridges through a two-stage process. First, tendons initiate outgrowth of the bone ridge by secreting a protein (BMP4) that promotes bone formation. Then, during the second stage, muscle activity helps to promote further bone growth and set the final size of the bone ridge. Taken together, the results demonstrate that tendons are needed for bone ridge patterning. “These findings provide a new perspective on the regulation of skeletogenesis in the context of the musculoskeletal system and shed light on a specific mechanism that underlies the assembly of this system,” concludes Dr. Zelzer.

Science Daily
January 12, 2010

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How accurate is patient’s anatomical knowledge: A cross-sectional, questionnaire study of six patient groups and general public sample

Older studies have shown that patients often do not understand the terms used by doctors and many do not even have a rudimentary understanding of anatomy. The present study was designed to investigate the levels of anatomical knowledge of different patient groups and the general public in order to see whether this has improved over time and whether patients with a specific organ pathology (e.g. liver disease) have a relatively better understanding of the location of that organ. Level of anatomical knowledge was assessed on a multiple-choice questionnaire, in a sample of 722 participants, comprising approximately 100 patients in each of 6 different diagnostic groups and 133 in the general population, using a between-groups, cross-sectional design. Comparisons of relative accuracy of anatomical knowledge between the present and earlier results, and across the clinical and general public groups were evaluated using Chi square tests. Associations with age and education were assessed with the Pearson correlation test and one-way analysis of variance, respectively.

Across groups knowledge of the location of body organs was poor and has not significantly improved since an earlier equivalent study over 30 years ago (chi2=0.04, df=1, ns). Diagnostic groups did not differ in their overall scores but those with liver disease and diabetes were more accurate regarding the location of their respective affected organs (chi2=18.10, p<0.001, df=1; chi2=10.75, p<0.01, df=1). Age was significantly negatively correlated (r = -0.084, p=0.025) and education was positively correlated with anatomical knowledge (F = 12.94, p = 0.000). Although there was no overall gender difference, women were significantly better at identifying organs on female body outlines. Many patients and general public do not know the location of key body organs, even those in which their medical problem is located, which could have important consequences for doctor-patient communication. These results indicate that healthcare professionals still need to take care in providing organ specific information to patients and should not assume that patients have this information, even for those organs in which their medical problem is located. BioMed Central June 30, 2009

Original web page at Biomed Central

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Dinosaur’s digits show how birds got wings

Birds are generally considered to be the living descendants of dinosaurs, yet differences between bird wings and dinosaur hands have long left palaeontologists struggling to explain how birds would have evolved from their dinosaur ancestors. Birds’ wings are thought to form from the fusion of the second, third and fourth digits on their hands as the embryo develops. Theropods, the predominantly carnivorous dinosaurs that included tyrannosaurids such as Tyrannosaurus rex and dromaeosaurids such as Velociraptor mongoliensis, also only had three long fingers. But palaeontologists had thought that these were the first, second and third digits because in early theropod fossils, such as that of Dilophosaurus, these three fingers were elongated, with a seemingly semi-vestigial fourth digit and a nearly absent fifth.

Based on this species, it looked very much like theropod dinosaurs lost their fifth digit early on then, around the time of Dilophosaurus, started to lose their fourth digit too. But this evolutionary explanation left researchers wondering how birds’ wings could have developed from digits 2, 3 and 4. The prevailing explanation was that theropods lost their fourth and fifth digits, then birds lost their first digits and regrew their fourth digits. Now, a team led by Xing Xu from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and James Clark from The George Washington University in Washington DC is proposing a simpler answer based on a new dinosaur species found in Jurassic rocks formed 156 million to 161 million years ago in the Junggar Basin in western China.

Limusaurus has a vestigial first finger. The species, a ceratosaur named Limusaurus inextricabilis, is a beaked and herbivorous early theropod with two remarkable characteristics: a reduced first digit and a metacarpal (lower finger bone) at the base of the second digit that matches those found at the base of the first digits in tyrannosaurids and dromaeosaurids. These two features suggest that the first digits in late theropods are in fact the second digits, the researchers report today in Nature. We believe that late theropod dinosaurs “had digits 2, 3 and 4, but that these have long been misidentified as digits 1, 2 and 3”, says Xu. On the basis of this evidence, the team argue that early theropods lost their first and fifth digits once and that these digits remained lost in late theropods, an explanation that vastly simplifies the current convoluted evolutionary story. “When birds are considered to have digits 2, 3 and 4 it is far simpler for most theropods to have 2, 3 and 4 as well,” says Clark.

This fossil “can be viewed as a kind of ‘missing link’ that shows an intermediate digital morphology between living birds and more primitive theropods”, says Paul Barrett, a palaeontologist at the Natural History Museum in London. However, some researchers are concerned about how the new fossil is being interpreted. “A lot of the arguments depend on bird wings being formed from the second, third and fourth digits and it is possible that they are not,” explains evolutionary geneticist Günter Wagner from Yale University. During development, digits are identified by what embryonic tissue forms them, where they grow and what genes shape them as they grow. If the tissue that forms the second digit is bombarded by genes telling it to form in the shape of a first digit, it will appear to be a first digit – but growing in the location where a second digit normally forms. And experimental evidence suggests this is happening inside modern bird wings, Wagner says.

“The ceratosaur fossil may be showing us a species in the midst of a digit identity shift, but whether the digits that we see in later theropods are the actual second, third and fourth digits or the first, second and third digits in the second, third and fourth positions, altered by gene bombardment to look like the second, third and fourth digits, is difficult to determine,” he says. It is also possible that the ceratosaur does not play a part in the larger evolutionary story and evolved its unusual hands in response to a lifestyle that, because it was beaked and herbivorous rather than toothed and carnivorous, was quite different from that of other theropods. “I think it far more likely that this new animal just has an oddly reduced hand,” says Kevin Padian, an palaeontologist at the University of California, Berkeley. “It is equally reasonable that we are just dealing with another odd possibility of evolution,” he says.

Nature
June 30, 2009

Original web page at Nature

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Why wind turbines can mean death for bats

Power-generating wind turbines have long been recognized as a potentially life-threatening hazard for birds. But at most wind facilities, bats actually die in much greater numbers. Now, researchers reporting in Current Biology, a Cell Press journal, on August 26th think they know why. Ninety percent of the bats they examined after death showed signs of internal hemorrhaging consistent with trauma from the sudden drop in air pressure (a condition known as barotrauma) at turbine blades. Only about half of the bats showed any evidence of direct contact with the blades. “Because bats can detect objects with echolocation, they seldom collide with man-made structures,” said Erin Baerwald of the University of Calgary in Canada. “An atmospheric-pressure drop at wind-turbine blades is an undetectable—and potentially unforeseeable—hazard for bats, thus partially explaining the large number of bat fatalities at these specific structures. “Given that bats are more susceptible to barotrauma than birds, and that bat fatalities at wind turbines far outnumber bird fatalities at most sites, wildlife fatalities at wind turbines are now a bat issue, not a bird issue.”

The respiratory systems of bats and birds differ in important ways, in terms of both their structure and their function. Bats’ lungs, like those of other mammals, are balloon-like, with two-way airflow ending in thin flexible sacs surrounded by capillaries, the researchers explained. When outside pressure drops, those sacs can over-expand, bursting the capillaries around them. Bird lungs, on the other hand, are more rigid and tube-like, with one-way circular airflow passing over and around capillaries. That rigid system can more easily withstand sudden drops in air pressure. The majority of bats killed at wind turbines are migratory bats that roost in trees, including hoary bats, eastern red bats, and silver-haired bats. While little is known about their population sizes, the researchers said, those deaths could have far-reaching consequences.

Bats typically live for many years, in some cases reaching ages of 30 or more. Most also have just one or two pups at a time, and not necessarily every year. “Slow reproductive rates can limit a population’s ability to recover from crashes and thereby increase the risk of endangerment or extinction,” said Robert Barclay, also at the University of Calgary, noting that migrating animals tend to be more vulnerable as it is. All three species of migratory bats killed by wind turbines fly at night, eating thousands of insects—including many crop pests—per day as they go. Therefore, bat losses in one area could have very real effects on ecosystems miles away, along the bats’ migration routes. Baerwald said there is no obvious way to reduce the pressure drop at wind turbines without severely limiting their use. Because bats are more active when wind speeds are low, one strategy may be to increase the speed at which turbine blades begin to rotate during the bats’ fall migration period.

Science Daily
September 2, 2008

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Ancient Komodo dragon has space-age skull

The fearsome Komodo dragon is the world’s largest living lizard and can take very large animal prey: now a new international study has revealed how it can be such an efficient killing machine despite having a wimpy bite and a featherweight skull. They note that the dragon — inhabiting the central Indonesian islands of Komodo, Rinca, Flores, Gili Motang and Gili Dasami — shares the feeding and dental characteristics of extinct dinosaurs, sharks and sabre-toothed cats. Scientists Karen Moreno and Stephen Wroe from the University of New South Wales have used a computer-based technique called Finite Element Analysis (FEA) to test the bite force and feeding mechanics of the predator. Their findings are to be published in the latest issue of the Journal of Anatomy. Normally used in the analysis of trains, planes and cars, the technique allowed the team to “reverse engineer” nature’s design to assess the mechanical forces that a Komodo skull can handle. “The Komodo has a featherweight, space-frame skull and bites like a wimp,” according to Wroe, “but a combination of very clever engineering, and wickedly sharp teeth, allow it to do serious damage to even buffalo-sized prey.

“The Komodo displays a unique hold and pull-feeding technique,” says Dr Wroe. “Its delicate skull differs greatly from most living terrestrial large prey specialists, but it’s a precision instrument, beautifully optimised to make the most of its natural cranial and dental properties. “Unlike most modern predators, Varanus komodoensis applies minimal input from the jaw muscles when killing and butchering prey. But it compensates using a series of actions controlled by its postcranial muscles. A particularly interesting feature of the skull’s performance is that it reveals considerably lower overall stress when these additional forces driven by the neck are added to those of the jaw-closing muscles. “This remarkable reduction in stress in response to additional force is facilitated partly by the shape of the bones, but also by the way bone of different strengths are arranged within the skull.” The Komodo dragon grows to an average length of two to three metres and weighing around 70 kilograms. The reptile’s unusual size is attributed to island gigantism, since there are no other carnivorous mammals to fill the niche on the islands where they live. As a result of their size, these lizards are apex predators, dominating the ecosystems in which they live. Although Komodo dragons eat mostly carrion, they will also hunt and ambush prey including invertebrates, birds, and mammals. Its saliva is frequently blood-tinged, because its teeth are almost completely covered by gingival tissue that is naturally lacerated during feeding. Discovered by Western scientists in 1910, the Komodo dragon’s large size and fearsome reputation makes it a popular zoo exhibit. In the wild its total population is estimated at 4,000-5,000: its range has contracted due to human activities and it is listed as vulnerable by the IUCN.

Science Daily
April 29, 2008

Original web page at Science Daily

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Reconstructing the biology of extinct species: A new approach

An international research team has documented the link between the way an animal moves and the dimensions of an important part of its organ of balance, the three semicircular canals of the inner ear on each side of the skull. “We have shown that there is a fundamental adaptive mechanism linking a species’ locomotion with the sensory systems that process information about its environment,” says Alan Walker, Evan Pugh Professor of Anthropology and Biology at Penn State University, one of the team’s leaders. The researchers studied 91 separate primate species, including all taxonomic families. The study also included 119 additional species, most of which are mammals ranging in size from mouse to elephant, that habitually move in diverse ways in varied environments.

The project is the first large-scale study to document the relationship of the dimensions of the semicircular canals to locomotion. These structures are filled with a fluid, which moves within the canals when the animal moves. The fluid’s movement is sensed by special cells that send signals to the brain, triggering the neck and eye muscles to reflexively keep the visual image stable. The basic hypothesis of the project was that the organ of balance — which helps stabilize an animal’s gaze and coordinate its movements as it travels through the environment — should be irrevocably linked to the type of locomotion produced by its limbs. “If an animal evolves a new way of moving about the world, its organ of balance must evolve accordingly,” Walker explains. From the visual information, the animal tracks its position relative to stationary objects such as tree trunks, branches, rocks or cliffs, or the ground. Having a stable image of the environment is especially crucial for acrobatic animals that leap, glide, or fly.

To make the discovery, the scientists scanned skull samples of each species, measuring the size of each semicircular canal and calculating the radius of curvature. Most of the specimens were scanned at the Center for Quantitative Imaging at Penn State on the OMNI-X high-resolution x-ray CT scanner, which can resolve features approximately 1/100 the size of those detected by medical CT scanners. In addition, experienced field workers used personal knowledge or film of animals in the wild to classify species into one of six locomotor categories ranging from very slow and deliberate to fast and agile. The scientists then compared the canal size of each species to its category of movement. The results revealed a highly significant statistical relationship between the radius of curvature of the semicircular canals and the species’ habitual way of moving. More acrobatic species consistently have semicircular canals with a larger radius of curvature than do slower-moving ones. For example, a small, fast-moving leaper like a bushbaby has semicircular canals that are relatively and absolutely much bigger than those of the similar-sized, slow-moving loris.

However, because larger animals have absolutely larger canals, the analysis had to take body size into account. The research revealed that this functional tie between the semicircular canals and locomotor pattern is evident both within the primates alone and within the entire mammalian sample. “How an animal moves is a basic adaptation,” says Walker, an expert in primate locomotion. “Now we have a way to reconstruct how extinct species moved that is completely independent of analysis of the limb structure. For the first time, we can test our previous conclusions using a new source of information.”

Science Daily
July 10, 2007

Original web page at Science Daily

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The sperm of several rodent species have scythe-shaped heads, which help them attach to other sperm

You don’t have to be a complete organism to take part in Darwinian evolution: Even sperm engage in the survival of the fittest. A new study indicates that the sperm of certain rodent species have evolved hook-shaped heads, apparently to beat each other to the egg. Sperm with better hooks are able to attach to more of their brethren, allowing them to form fast-moving chains that leave their rivals behind. For years, biologists have puzzled at the strange shape of rodent sperm. As opposed to the sperm of most other mammals, which have paddle-shaped heads, the sperm heads of many rat and mouse species are curved like scythes. About 10 years ago, scientists studying the European woodmouse discovered that these hooks allow groups of up to 100 sperm to attach to each other, and that these “sperm trains” moved faster than sperm swimming alone.

Curious if there were any evolutionary forces at play, evolutionary biologist Simone Immler of the University of Sheffield in the United Kingdom and colleagues studied the sperm of 37 rodent species, including the Norway rat and the house mouse. As in the European woodmouse, the team found that–in most of the species studied–sperm hooked into an entourage moved faster than loners did. What’s more, species with larger testes–and thus greater quantities of sperm per ejaculate–tended to have sperm with sharper hooks. That may be because more sperm equals more competition between sperm to reach the egg, the team speculates in the 24 January issue of Public Library of Science ONE. Because each sperm has a slightly different genetic make-up, those who reach the egg first pass their superior hooks to the next generation. “It’s a really interesting study,” says Rhonda Snook, an evolutionary biologist of the University of Sheffield, who was not affiliated with the paper. The findings address the long-held question about the unique shape of rodent sperm, she says, as well as the role competition has played in hook formation.

ScienceNow
February 6, 2007

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Scientists crack rhino horn riddle

Rhinoceros horns have long been objects of mythological beliefs. Some cultures prize them for their supposed magical or medicinal qualities. Others have used them as dagger handles or good luck charms. But new research at Ohio University removes some of the mystique by explaining how the horn gets its distinctive curve and sharply pointed tip. Scientists have discovered new details about the structural materials that form the horn and the role those materials play in the development of the horn’s characteristic shape. The horns of most animals have a bony core covered by a thin sheath of keratin, the same substance as hair and nails. Rhino horns are unique, however, because they are composed entirely of keratin. Scientists had been puzzled by the difference, but the Ohio University study now has revealed an interesting clue: dark patches running through the center of the horns.

The team examined the heads of rhinos that died of natural causes and were donated by The Wilds in Cumberland, Ohio, and the Phoenix Zoo. Researchers conducted CT scans on the horns at O’Bleness Memorial Hospital in Athens and found dense mineral deposits made of calcium and melanin in the middle. The calcium deposits make the horn core harder and stronger, and the melanin protects the core from breakdown by the sun’s UV rays, the scientists report. The softer outer portion of the horn weakens with sun exposure and is worn into its distinctive shape through horn clashing and by being rubbed on the ground and vegetation. The structure of the rhino horns is similar to a pencil’s tough lead core and weaker wood periphery, which allows the horns to be honed to a sharp point. The study also ends speculation that the horn was simply a clump of modified hair. “The horns most closely resemble the structure of horses’ hoofs, turtle beaks and cockatoo bills. This might be related to the strength of these materials, although more research is needed in this area,” said Tobin Hieronymus, a doctoral student in biological sciences and lead author on the study.

The study also found that the melanin and calcium patches appear in yearly growth surges but the effects of temperature, diet and stress on the growth are still unknown. The results of the horn growth study may be of interest to conservation groups whose goal is to strengthen rhino populations and reduce the poaching of horn for the black market. “Ultimately, we think our findings will help dispel some of the folk wisdom attached to the horn. The more we can learn about the horn, the better we can understand and manage rhino populations in the wild and in captivity,” said Lawrence Witmer, a professor of anatomy in Ohio University’s College of Osteopathic Medicine and director of the project.

Science Daily
December 5, 2006

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Evolutionary oddity : Erectile tissue helps flamingos eat

Flamingos are known for their peculiar feeding behavior. While standing in shallow water, they bend their necks, tilt their bills upside down in the water and swish their heads from side-to-side. Their large tongue acts like a piston, sucking water into the front of the bill and then pushing it out the sides. Fringed plates on the tongue trap algae and crustaceans in the circulating water. “The flamingos’ feeding habits have captured people’s curiosity for ages, but that wasn’t the original focus of our research,” said Casey Holliday, who recently earned a doctorate in biological sciences from Ohio University and served as lead author on the study. “We were investigating the evolution of jaw muscles in lizards, birds and dinosaurs. By sheer luck we discovered something new about flamingos.”

To get a detailed look at the flamingo’s jaw muscle structure, the researchers injected a colored barium/latex mixture into the blood vessels of a bird that had died and was donated by the Brevard Zoo in Florida. A 3-D view of the bird’s head was created using a new computed tomography (CT) scanning technique developed by the Ohio University team that highlights blood vessel anatomy. The researchers noticed large oval masses of erectile tissue located on the floor of the mouth on either side of the tongue. “No one ever anticipated finding something like this, and now we’re scratching our heads trying to understand the role these tissues play,” said Lawrence Witmer, a professor of anatomy in Ohio University’s College of Osteopathic Medicine who directed the study.

The researchers know that when the erectile tissues fill with blood, they stiffen, strengthening and supporting the floor of the mouth. “We suspect this stabilizes the mouth and tongue and helps with the peculiar way that flamingos eat,” he said. “It’s an important new piece of the puzzle of flamingo feeding—frankly, a piece we hadn’t known was missing!”
Source: The Anatomical Record

Science Daily
November 21, 2006

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Fingerprints may illuminate life in the womb

Fingerprints may provide important clues about life in the womb, and may even become useful as predictors of disease risk. US researchers, in Atlanta and New York, have now shown that differences in fingerprints between the thumb and little finger are associated with likelihood of developing diabetes later in life. A person’s fingerprints are set for life by around the 19th week of gestation, roughly halfway through a normal pregnancy. Most organs, including the pancreas, are also formed by that time. Henry Kahn at the Centers for Disease Control and Prevention in Atlanta and colleagues decided to look at quantitative differences in ridges between the first and last fingertips – the thumb and pinkie.

The team speculated that any disturbances during their formation might also say something about the state of the pancreas, and possibly the likelihood of a person developing diabetes as they age. Diabetes results from the failure of the pancreas to produce insulin, or enough insulin, which the body needs to help it take up glucose. The researchers studied 569 Dutch people, some of whom were in the womb during the Dutch famine of 1944 and 1945, dubbed the “hunger winter”. Kahn and his team tested the volunteers’ glucose tolerance – a measure which is abnormally high in people with diabetes – and also counted the number of ridges on their thumbs and little fingers by rolling the inked digits onto paper.

Fingerprint ridges are counted in a specific way – prints with a large whorl often have a higher ridge count. The researchers found that people with normal glucose tolerance had an average difference of 6.4 ridges between the two digits, whereas people with diabetes had a much higher “ridge count gradient”, at about 8.3. “The field needs a way to assess how the human fetus was doing before the end of pregnancy,” says Kahn, who reported the findings at a meeting on Developmental Origins of Health and Disease in Toronto, Canada in October. “This is a tool that could give us a glimpse at the early fetus. It’s accessible and it’s cheap.” He believes the some of the signalling factors which influence organ growth may also affect formation of the fingertips, giving an insight into conditions in the womb.

The team also analysed the data according to the month of conception and found that there was a seasonal effect: normal and diabetic participants conceived in late winter had lower ridge count differences between them compared with those conceived in late summer. But the seasonal pattern was wiped out in people exposed to the famine, they found . This suggests that environmental factors must play a role. “Was it the food? Maternal stress hormones?” Kahn asks. “I think there’s probably something in this,” says John Manning, a psychologist at the University of Central Lancashire in Preston, UK, who studies finger-length ratios. “There’s a lot of information in the fingers, in terms of what happens prenatally. We don’t know what kinds of conditions control them.” He agrees with Kahn that signalling factors, such as a group of proteins known as “sonic hedgehog”, may be involved, but he also suspects a role for hormones.

New Scientist
December 20, 2005

Original web page at New Scientist