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Newborn dolphins go a month without sleep

Newborn dolphins and killer whales do not sleep for a whole month after birth, new research has revealed, and neither do their mothers, who stay awake to keep a close eye on their offspring. The feat of wakefulness is remarkable given that rats die if forcibly denied sleep. And in humans, as any new parent will tell you, sleep deprivation is an exquisite form of torture. The surprising sleeping patterns of captive killer whales – Orcinus orca – and bottlenose dolphins – Tursiops truncates – in the early months of life were observed by a team led by Jerome Siegel of the University of California at Los Angeles, US. Unlike all animals previously studied, which maximise rest and sleep after birth to optimise healthy growth and development, the cetaceans actively avoided shut-eye. “The idea that sleep is essential for development of the brain and body is certainly challenged,” says Siegel.

The patterns observed contrast with that seen in adult cetaceans, which normally “sleep” for 5 to 8 hours a day – either floating at the surface or lying on the bottom before rising periodically for air. But the newborn whales and dolphins were continually active, surfacing for air every 3 to 30 seconds. They also kept at least one eye open to track their mothers, who seemed to set the frenetic pace by always coursing ahead of their offspring. Siegel and his colleagues found that, over months, mothers and offspring gradually increased the amount of rest until it approached that of normal adults. And measurements of the stress hormone cortisol showed that levels were normal, so the animals were not apparently stressed by their insomnia.

The researchers suggest that for cetaceans, the ability to keep on the go after birth has several advantages. It makes it harder for predators to catch them because “in the water, there’s no safe place to curl up”, Siegel notes. It also keeps their body temperature up while their layer of insulating blubber builds up. The mystery, he says, is how the cetaceans seem to avoid the penalties of sleep deprivation seen in all other mammals. “It’s an extraordinary finding,” says Jim Horne, director of the Sleep Research Centre at the University of Loughborough, UK. “Normally, newly born mammals and their mothers stay asleep for as long as they can after birth.” Horne says that if it had been practically possible, measurement of brain activity would have provided better confirmation that the animals were awake than simply checking if they had at least one eye open. “You can’t be entirely sure that they’re actively awake all the time, not going into a drowsy, trance-like state,” he says. “But they are certainly showing extensive periods of wakefulness.” Horne says that humans sometimes fall asleep with their eyes open, so it is conceivable that nature allows the dolphins and whales to do the same.

New Scientist
July 19, 2005

Original web page at New Scientist

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Hummingbirds’ aerodynamics are midway between insects and other birds

An analysis shows air vortices at the tip of a hummingbird’s wings as it flies. “What led us to this study was the long-held view that hummingbirds fly like big insects,” says Douglas Warrick, of Oregon State University in Corvallis. Many experts had argued that hummingbirds’ skill at hovering, of which insects are the undisputed masters, means that the two groups may stay aloft in the same way: by generating lift from a wing’s upstroke as well as the down. This turns out to be only partially true.
Other birds get all of their lift from the downstroke, and insects manage to get equal lift from both up and down beats, but the hummingbird lies somewhere in between. It gets about 75% of its lift from the downstroke, and 25% from the upwards beat.

Warrick and his team investigated the birds’ performance by looking at the swirls of air left in their wake. To do this, they trained rufous hummingbirds (Selasphorus rufus) to hover in place while feeding from a syringe filled with sugar solution. Their wings are a marvellous result of the considerable demands imposed by sustained hovering flight.
They filled the air with a mist of microscopic olive-oil droplets, and shone a sheet of laser light in various orientations through the air around the birds to catch two-dimensional images of air currents. A couple of quick photographs taken a quarter-second apart caught the oil droplets in the act of swirling around a wing. Although hummingbirds do flap their wings up and down in relation to their body, they tend to hold their bodies upright so that their wings flap sideways in the air. To gain lift with each stroke the birds partially invert their wings, so that the aerofoil points in the right direction. Their flight looks a little like the arm and hand movements used by a swimmer when treading water, albeit it at a much faster pace.

Insects attain the same lift with both strokes because their wings actually turn inside out. A hummingbird, with wings of bone and feathers, isn’t quite so flexible. But the birds are still very efficient. “Their wings are a marvellous result of the considerable demands imposed by sustained hovering flight,” Warrick says. “Provided with enough food, they can hover indefinitely.” The researchers add that the hummingbird’s flapping bears a striking resemblance to that of large insects such as hawkmoths, an example of how evolution can produce similar engineering solutions in hugely distant animal groups.

Nature
July 5, 2005

Original web page at Nature

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Puppy love conquers community violence

A group of leading veterinarians says there’s clear evidence emerging that teaching people to look after their dogs and other companion animals can help reduce the incidence of violent crime and violence in communities.
Australian Veterinary Association (AVA) NSW President, Dr Mark Lawrie says more public funds are needed to continue the research and carry out education programs particularly through the Animal Management in Rural and Remote Indigenous Communities (AMRRIC) organisation. “Just as it has been conclusively shown that young people who are cruel to animals tend to grow up to be violent adults, the reverse can also be true. Young people who are taught to be kind to animals tend to be less violent adults. “In fact, recent international research found a group of 4th graders who were taught how to be kind to animals also had increased empathy towards humans.”

Dr Lawrie, who is also Secretary of AMRRIC, said AMRRIC was playing a role in helping geographically remote aboriginal communities better look after the health of their dogs by providing veterinarians who travel to communities to treat and operate on sick and suffering animals. “Until recently there has been a crisis in the health of dogs in many indigenous communities brought about by overpopulation and lack of resources to properly look after the animals. But we are now seeing reductions in dog populations in some communities that have asked for assistance from in one case, 400 dogs down to 75. “AMRRIC’s work is based on the belief that if you are able to look after the health of your dog or companion animal, you are more likely to look after your own health.

“From the work that has been done so far, it’s clear that education programs need to be developed and implemented with the assistance of these communities that will promote kindness to animals and people. “Family violence is a problem in all communities in Australia and around the world. But it’s also acknowledged now by indigenous leaders that many children are growing up in communities where violence has become a normal and ordinary part of life. “We believe that one way to combat this problem in remote indigenous communities is to promote animal health and welfare through education and link that to human health and welfare. We are calling for more such programs to be developed and implemented across society but in key areas with less access to services such as indigenous communities,” Dr Lawrie said.

E-mail address Bloglet
June 21, 2005

Original web page at WVA

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Australian dolphins learn to hunt with sponges stuck to their noses

Bottlenose dolphins are known to be smart, but a study of tool use has emphasized just how clever these mammals can be. Female dolphins in an Australian bay seem to be learning from their mothers how to stick marine sponges on their noses to help them hunt for fish, researchers say. “It is the first documented case of tool use in a marine mammal,” says Michael Krützen of the University of Zurich, Switzerland, who led the study into how the trick is passed from one generation to the next. Rather than being an inherited trait, the tool use is probably being learned by daughter dolphins from their mothers, the researchers report in the Proceedings of the National Academy of Sciences.

Sponge-using dolphins (Tursiops truncatus) were first described in 1997 in Shark Bay, 850 kilometres north of Perth, Australia. Since then, all dolphins known to use this tool have come from the same bay, and the vast majority have been female. Direct observations have been rare, but researchers think the dolphins use the marine sponges to disturb the sandy sea bottom in their search for prey, while protecting their beaks from abrasion.

The knack of learning to use tools from fellow creatures is thought to be very rare. Chimpanzees (Pan troglodytes) have been seen to use two stones to crack open nuts, for instance, and this is thought to be a culturally acquired trait. In other instances tool use seems to be inherited. New Caledonian crows (Corvus moneduloides), for example, use twigs to gain access to food in nooks and crannies of trees, and can do so without having been taught by another crow.

To see whether the dolphin behaviour was inherited, Krützen and his colleagues analysed DNA from 13 spongers, only one of which, Antoine, was male, and from 172 non-spongers. They found that most spongers shared similar mitochondrial DNA, which is genetic information passed down from the mother. This indicates that the spongers are probably all descended from a single “Sponging Eve”. The spongers also shared similar DNA from the nucleus, suggesting that Eve lived just a few generations ago. But not all the female dolphins with similar mitochondrial DNA use sponges. And when the researchers considered ten different means of genetic inheritance, considering that the sponging trait might be dominant, recessive, linked to the X-chromosome or not, they found no evidence that the trait was carried in DNA. “It’s highly unlikely that there is one or several genes that causes the animals to use tools,” says Krützen.

Andrew Whiten, a researcher who studies cultural tradition in chimpanzees at the University of St. Andrews, UK, says the work is very thorough. “Krützen and his colleagues have done a painstaking genetic analysis,” says Whiten. But he cautions that there is as yet no evidence that dolphins can pick up tool use by observation. Krützen points out that young dolphins spend up to four or five years with their mother, giving them lots of time to pick up the trick. “We know they are seeing it all the time,” says Janet Mann, a co-author of the study from Georgetown University in Washington DC. In general, dolphins are known to imitate each other very well, Krützen adds.

Mann says the males probably learn sponging from their mothers as well, but do not engage in it when older, perhaps because they are too busy pursuing fertile females to engage in complicated foraging. She hopes to catch the dolphins in the act of learning sponge use from their mothers soon. Krützen plans to study whether the sponge users have any advantage over non-spongers. A preliminary study of the fat content in dolphin blubber suggest that spongers get food that other animals do not, Krützen says.

Nature
June 21, 2005

Original web page at Nature

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Heroin addiction gene identified and blocked

Scientists have not only identified a critical gene involved in heroin addiction relapse, but they have also successfully blocked it, eliminating cravings for the drug. The study was conducted on heroin-addicted rats. But the researchers now think that, within a few years, better treatments will become available to human heroin users who cannot quit due to insidious cycles of relapse. “Many people try to stop taking heroin, but in a few months almost all of them go back to using the drug,” said Ivan Diamond, at the Ernest Gallo Clinic and Research Center in California, US, and one of the research team. David Shurtleff, director of the Division of Basic Neuroscience and Behavioral Research at the National Institute on Drug Abuse in Maryland, US, is encouraged by the research. “It will take creativity and additional research to translate this into usable therapies, but it does provide hope that we will be able to prevent compulsive drug seeking behaviour,” he told New Scientist.

Previous research has indicated that a section of the midbrain called the nucleus accumbens plays a central role in the “mental reward circuitry” of animals, such as rats and humans. This circuitry generates feelings of pleasure in response to drugs, as well as in response to other things, including food, sex and, in humans, work accomplishments. Drugs like heroin, however, seem to over-stimulate the normal reward process to the point where users value their next fix more highly than food, water and other essentials. In 2004, a study revealed that cocaine causes a gene in the nucleus accumbens, called AGS3, to rapidly encode masses of proteins that are involved in the cravings and pleasure associated with the drug.

Diamond and his team isolated AGS3 genes and proteins in nucleus accumbens cells taken from newborn baby rats. After cloning and studying the cells in the lab, the researchers determined that AGS3’s drug-related functions are most active in the inner nucleus accumbens core as opposed to its outer shell region. An AGS3 blocker was then created from a herpes virus. This temporarily binds to proteins within the reward circuit and blocks the cravings-pleasure cycle until the virus “washes out” of the body a few weeks later.

Heroin-addicted rats that were trained to give themselves the drug using a lever were injected with the AGS3 blocker into their nucleus accumbens after they had gone through a short period of withdrawal. A small dose of heroin then was administered to each rat. Normally even such a tiny “taste” of the drug leads to cravings for more, but the blocker prevented the addiction relapse by eliminating these desires. The treatment produced no other observed behavioural side effects.

Diamond told New Scientist that a related treatment could become available to humans within the next couple of years. His colleague Krista McFarland, at the Medical University of South Carolina, added that one of the challenges will be to find a safe method of administering the blocker to people.

Journal reference: Proceedings of the National Academy of Sciences

New Scientist
June 21, 2005

Original web page at New Scientist

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Animals forage with near-perfect efficiency

Animals have evolved a foraging behaviour that comes close what physicists calculate is the fastest way to find hidden objects, a new study reveals. Searching animals quickly move to the first location, then slowly search that small area, before quickly moving to another area and repeating the process.
That does not surprise biologists who have studied foraging and who say evolution should find the best strategy because it pays off in survival. The two-stage search process is an instinctive one evident when humans search for missing keys, for example, as well as when animals search for food. People search carefully around one location, then move quickly to another where they hope to find the missing object and search again.

That behaviour reflects the difficulty of spotting objects while moving quickly. Olivier Bénichou at the University of Paris 6 and colleagues modelled the process as if animals moved along a straight line, switching randomly between a “moving” phase – when they cannot find objects – and “searching” phases where they hunt while doing a slow, random walk. To find the optimum search method, the team calculated what pattern of switching between moving and searching states would find randomly placed objects in the shortest time.

“The typical durations of each phase vary a lot from species to species,” Bénichou and Raphaël Voituriez of the Curie Institute told New Scientist. For example, some large fish like tuna cruise continuously looking for prey, while ambush predators like rattlesnakes “sit-and-wait” for prey. But when they plotted animal data collected by biologists, they found a power-law relation predicted by their model – the faster animals switched between states, the more time they spent moving rather than searching. Such models are useful for relative comparisons, but are limited by their simplifying assumptions, says Howard Browman of the Institute of Marine Research in Storebø, Norway.

Other biologists agree foraging is a more complex process. “You can’t totally optimise searching for a randomly located object,” says John O’Brien at the University of North Carolina at Greensboro, US. Animals looking for lunch have to watch out that they do not end up as some other creature’s meal. For example, seed-eating birds look up as they hop around the ground. “We think they’re looking for overhead predators” before they stop and put their heads down to search for seeds, O’Brien told New Scientist.The key issue is the constraints which animals face, such as how fast they move, how well they see, and the distribution of their prey, which determine what can be optimised, he adds. Birds, for example, search more slowly if their prey is hard to spot because its colour matches the background.

New Scientist
June 7, 2005

Original web page at New Scientist

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How birds keep secrets in color

Songbirds are able to communicate with potential mates using plumage colors while remaining inconspicuous to avian predators, Swedish researchers suggest in PNAS this week. They do so by using colors that the larger birds are less able to discriminate from the background. Ultraviolet plumage coloration, which reflects light in the range of 355–380 nanometers, has long been known to serve as a secret communication channel in songbirds, exploiting a shortfall in the mammalian visual system. But it has not been clear how avian predators, which can see ultraviolet, are excluded. Ornithologists Olle Håstad, Jonas Victorsson, and Anders Ödeen, all based at Uppsala University, present evidence that small passerines such as the robin Erithacus rubecula, brambling Fringilla montifringilla, and golden oriole Oriolus oriolus exploit differences in the maximum sensitivities of their own visual systems and those of their potential bird predators.

Using retinal models for the songbird and predator visual systems, the researchers compared the reflectance of the head and chest plumage of 18 species of songbirds to that of their typical Swedish forest habitat. Against the appropriate background, the plumage was significantly more visible to the songbirds than predator birds, they report. “I’m really pleased to see this work published, because I always thought that the notion of UV signals being a private channel [of communication] never squared with the fact that avian predators of birds can see UV,” Innes Cuthill, professor of behavioral ecology at the University of Bristol, UK, told The Scientist. “This paper shows that, yes, there is potential mileage in the argument, because raptors aren’t as good at discriminating colors in the UV waveband as passerines,” he explained.

Evolutionary biologist David Harper, based at the University of Sussex, UK, agreed that the study “introduces an interesting idea that songbirds can communicate with each other without being conspicuous.” However, he also expressed concern over some aspects of the paper, particularly the lack of detail regarding the methodology and some of its assumptions. “This is one of those cases where we have to curse word limits,” he said. “Hopefully, future papers in less prestigious journals will be more enlightening.” Peter McGregor, a behavioral ecologist at Cornwall College Newquay, whose own research has centered on animal signalling, noted the “striking comparison with bioacoustics,” in particular the private “seeet call” (reference 1) of some bird species. But he also echoed Harper’s concerns. While studying sound is relatively straightforward, he told The Scientist, understanding color and the visual sense is much more challenging. For example, plumage signals are “omnidirectional and always on”, in addition to being subject to large variations in light regime throughout the course of the day, season, or year.

McGregor pointed to the study’s reliance on retinal models of both songbird and predator visual systems. Just looking at retinal pigments isn’t enough. “Retinas are hooked up to brains, and brains can do all sorts of flashy processing,” he said. In addition, there is a crucial distinction to make between what is signal and what is information; only the former is the result of selection. “Håstad et al. have found a correlation, not direct evidence of a private communication channel.” Ödeen admitted this is only the start, but emphasizes the nature of the differences between songbird and raptor/corvid visual systems. “We are looking at the tuning of maximum sensitivities. Raptors are sensitive some way into the UV [range], but their maximum sensitivity lies elsewhere,” he told The Scientist. “As the title of the paper suggests, songbirds are less conspicuous, not inconspicuous.”

Reference 1:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=726695&dopt=Abstract&holding=f1000

E-mail address The Scientist Daily
May 24, 2005

Original web page at The Scientist

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Practice doesn’t make perfect for duelling meerkats.

Vigorous play fighting as a pup does not improve a meerkat’s chances in important adult battles, dispelling the most popular theory to explain youthful brawls. As juveniles, many animals indulge in dangerous and energetically costly battles with litter-mates or other youngsters. Biologists have often assumed the rationale behind this play fighting is to develop the motor skills and coordination necessary for successful adult fights.

For meerkats the stakes are particularly high as only the dominant male-female pair in a colony gets to breed. The others are condemned to mere nest attendant duties. Lynda Sharpe at the University of Stellenbosch, South Africa, studied a population of wild meerkats in the southern Kalahari desert in South Africa from 1996 to 2002. She followed 18 pairs of same-sex litter-mates, recording the number, frequency and outcome of play fights and the individuals’ ultimate status within the group as an adult.

She found that young meerkats who played frequently were no more likely to win play fights, adult fights or become a member of the dominant pair. Furthermore, meerkats showed no sign of improvement with extra play sessions. Sharpe believes that while play fighting may not produce highly trained combatants it could have an important role in brain development.

New Scientist
May 10, 2005

Original web page at New Scientist

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Elephants do impressions

They say that elephants never forget. Now the creatures have shown that, when it comes to the fine art of vocal mimicry, they’re not averse to learning new tricks either. Researchers have recorded two African elephants (Loxodonta africana) that are adept mimics. One does a decent impression of an Asian elephant, and another is, remarkably, a dead ringer for a passing truck. The skilful impressions are far from the traditional grunts of an average African elephant.

The discovery adds elephants to a notably short roll call of animal mimics, which includes little more than humans, sea mammals, bats and birds. “The surprising thing is how few mammals show an ability to modulate their sounds,” says Peter Tyack of Woods Hole Oceanographic Institution in Massachusetts, who led the study. The two elephants in question are Mlaika, an adolescent female living in a semi-captive group in Kenya, and Calimero, an adult male who lived for 18 years with two Asian elephants at a Swiss zoo. Calimero, perhaps unsurprisingly, mimics the typical chirp noises of Asian elephants (Elephas maximus). “But Mlaika seemed to be making noises like a truck, of all things,” Tyack recalls.

He and his team analysed the sounds and found that their characteristics were definitely unlike those of sounds made by more conventional African elephants. The researchers present their results in this week’s Nature. Tyack and his team think Mlaika’s habit is due to her upbringing, which was within earshot of a road. Whatever the case, she has provided valuable insight into what elephants might be able to do with their voices. “Often it’s the odder examples, like a parrot talking, that first give us a hint at what’s going on,” he explains. “In both of these cases it seems that they were deprived of proper role models,” says elephant expert Katharine Payne of Cornell University in Ithaca, New York. It would be interesting to know whether they ever heard true African elephant calls in their youth, she adds.

Tyack suspects that elephants’ versatile vocal skills may help them recognize each other and therefore bond social groups together. He adds that other skilful vocalists, such as bats and dolphins, use sound for a range of social tasks including hunting and navigating. It’s a plausible idea, agrees Payne. Elephant societies are complex, and members frequently call over very long distances, even when there is no other elephant in sight.

Strong mimicking skills might even help the elephants to adopt family-specific calls, much as humans are identified by their family surnames, speculates Vincent Janik, who studies animal communication at the University of St Andrews, UK. “The next step is to look at family groups and see if they have a single call,” he says.

Nature
April 12, 2005

Original web page at Nature