Nashville, TN, – Preliminary new research discussed today at the American College of Neuropsychopharmacology's Annual Meeting finds that oxytocin, when administered using intravenous fluid and nasal technology may have significant positive effects on adult autism patients. The study, funded by the Seaver Foundation, examined the effects of oxytocin on repetitive behaviors and aspects of social cognition in adults with autism. Investigators Eric Hollander, MD and Jennifer Bartz, PhD presented results of both intravenous and intranasal administration of oxytocin in high-functioning adult autism patients and discussed the implications of this research for the treatment of autism. Dr. Hollander is Chairman of Psychiatry and at the Mt. Sinai School of Medicine in New York, NY and Director of the Seaver and New York Autism Center of Excellence, one of eight NIH-funded (STAART) centers devoted to the study of autism. Dr. Bartz is a Post Doctoral Fellow at the Seaver Center at the Mt., Sinai School of Medicine. "Studies with animals have found that oxytocin plays a role in a variety of behaviors, including parent-child and adult-to-adult pair bonding, social memory, social cognition, anxiety reduction and repetitive behaviors," explained Dr. Bartz. "However," adds Dr. Hollander, "we have only recently considered that administration of oxytocin can have behavioral effects. Autism is a particularly ripe neuropsychiatric disorder for studying this approach because it presents with the types of symptoms that have been found to be associated with the oxytocin system."

Keyword: Autism; Hormones & Behavior
Link ID: 9696 - Posted: 06.24.2010

Results of a new genetic study bring scientists one step closer to understanding why some smokers become addicted to nicotine, the primary reinforcing component of tobacco. The research, funded by the National Institute on Drug Abuse, part of the National Institutes of Health, represents the most powerful and extensive evidence to date of genetic risk factors for tobacco addiction. The study not only completed the first scan of the human genome to identify genes not previously associated with nicotine dependence (or addiction), it also focused on genetic variants in previously suspected gene families. The research results will appear December 1 in the online issue of the Journal of Human Molecular Genetics. “This genome wide association scan is an important step in a large-scale genetic examination of nicotine addiction,” says Dr. Elias A. Zerhouni, Director of the NIH. “As more genomic variations are discovered that are associated with substance abuse, including smoking, we will be better able to understand how to prevent and treat human addictive disorders.” Smoking behaviors, including the onset of smoking, smoking persistence (current smoking versus past smoking), and nicotine addiction, cluster in families. Studies of twins indicate that this clustering partly reflects genetic factors. To identify those genes that could potentially contribute to nicotine dependence scientists combined a comprehensive genome-wide scan with a more traditional approach that focuses on a limited number of candidate genes, using unrelated nicotine-dependent smokers as cases and unrelated non-dependent smokers as controls. A candidate gene has one or more variant forms, which, according to current scientific evidence, appear to be linked to a genetic disease. “When two teenage friends experiment with smoking at the same age, one can become addicted and the other might not,” says NIDA Director Dr. Nora D. Volkow. “We want to know why. This systematic survey of the genome coupled with the ongoing identification of variants in candidate genes brings us closer to understanding what factors increase a person’s risk of transitioning from experimentation to nicotine addiction.”

Keyword: Drug Abuse; Genes & Behavior
Link ID: 9695 - Posted: 06.24.2010

Worker bees, wasps, and ants are often considered neuter. But in many species they are females with ovaries, who although unable to mate, can lay unfertilized eggs which turn into males if reared. For some species, such as bumble bees, this is the source of many of the males in the species. But in others, like the honeybee, workers "police" each other – killing eggs laid by workers or confronting egg-laying workers. In 1964 the English biologist William Hamilton put forward his "relatedness hypothesis", a major landmark in kin selection theory. His hypothesis was that worker bees, wasps and ants do not reproduce because most workers are half sisters. Instead the workers favor the queen's male progeny, since she has mated with multiple males, ensuring variation in the species. According to this theory, a species where the mother queen mates with multiple males would have more worker policing. This theory is widespread and in animal behavior textbooks. However, Hamilton's relatedness hypothesis was challenged in 2004 by researchers from the University of Lausanne, Switzerland. They compared 50 species and found no evidence that multiple mating by the queen correlated with reduced rearing of workers' sons or greater worker reproductive policing. Were the textbooks wrong" A new study appearing in the current issue of The American Naturalist strongly supports Hamilton's original theory. Tom Wenseleers and Francis Ratnieks (University of Sheffield) compared 90 species and found that workers' sons are reared 100 times less in species with a queen mated to multiple males.

Keyword: Sexual Behavior; Evolution
Link ID: 9694 - Posted: 06.24.2010

Catherine Brahic It is well-established that some birds are able to modulate their songs to adapt to different environments. In 2004, for instance, researchers showed that individual nightingales made their songs very much louder so they could be heard over urban noise (see Urban nightingales' songs are illegally loud). Now, researchers have shown this adaptation is happening on a population level, as well in cities around Europe. Hans Slabbekoorn and Ardie den Boer-Visser, at Leiden University in the Netherlands, recorded and compared great tits (Parus major) singing in 10 European cities and in nearby forests. They found that in all the cities, songs were sung faster and in higher pitches than in nearby forests. (Listen to recordings from Brussels and the nearby Rivière forest.) Slabbekoorn says the differences between the urban and rural songs are "remarkably" consistent across all the sites surveyed. The researchers say this is explained by the fact that urban noise pollution, most of which comes from traffic, tends to be at a lower pitch. This drowns out low-pitched birdsong notes. In contrast, noise in natural environments is not biased towards one end of the frequency spectrum. (Listen to an isolated song, the same song in a noisy urban setting, and in a forest setting.) © Copyright Reed Business Information Ltd

Keyword: Language
Link ID: 9693 - Posted: 06.24.2010

There are biological brain differences that mark out psychopaths from other people, according to scientists. Psychopaths showed less activity in brain areas involved in assessing the emotion of facial expressions, the British Journal of Psychiatry reports. In particular, they were far less responsive to fearful faces than healthy volunteers. The Institute of Psychiatry, Kings College London team say this might partly explain psychopathic behaviour. Criminal psychopaths are people with aggressive and anti-social personalities who lack emotional empathy. They can commit hideous crimes, such as rape or murder, yet show no signs of remorse or guilt. It has been suggested that people with psychopathic disorders lack empathy because they have defects in processing facial and vocal expressions of distress, such as fear and sadness, in others. Professor Declan Murphy and colleagues set out to test this using a scan that shows up brain activity. They showed six psychopaths and nine healthy volunteers pictures of faces showing different emotions. Both groups had increased activity in brain areas involved in processing facial expressions in response to happy faces compared with neutral faces, but this increase was smaller among the psychopaths. By contrast, when processing fearful faces compared with neutral faces, the healthy volunteers showed increased activation and the psychopaths decreased activation in these brain regions. (C)BBC

Keyword: Aggression; Emotions
Link ID: 9692 - Posted: 12.04.2006

By JOHN LANCHESTER Popular science books have a set form, which in its way is as strict as the sonnet. They begin with some personal history of how the author became interested in a subject, move on to an explanation of the generally agreed science of the subject, and then describe the specific angle taken by the author on the subject’s remaining mysteries. Add a judicious sprinkling of personal history throughout, and voilà, the formula covers everything from quantum physics to geology to evolution. Luca Turin’s engaging new book follows this form, but doesn’t feel at all like something we’ve read before — which is a tribute both to its subject and to its author. “The Secret of Scent” is about one of the great mysteries in science, one that is not just under our noses (like all the best mysteries), but actually inside the nose. That mystery is smell, and specifically the way the brain interprets molecules as smells. No two molecules, however similar their chemical structure, smell identical. Why not? As Turin asks, “What is this chemical alphabet that our noses read so effortlessly from birth?” Science thinks that it has answered this question, and that the answer has to do with the shape of a molecule: the geometric arrangement of its atoms determines its smell. Turin disagrees. He thinks smell is determined by something else; but to rush too quickly to his hypothesis would be to miss the fun of “The Secret of Scent,” most of which lies in the incidental details of the journey and in Turin’s sharply expressed opinions about more or less everything — Moscow in the ’80s, peer review in science, the modern university system and why biologists “were never the pick of the intellectual crop. I should know — I’m one of them.” Copyright 2006 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 9691 - Posted: 06.24.2010

by Michael Chorost Review by Jackie Leach Scully, Ph.D. First things first. The subtitle is wrong. This book is not about a journey back to the world of normal hearing. What it is about is the process of learning how to "hear" in a completely novel way, as you have to when damaged organic structures are replaced by electronic ones: when, in fact, you become a sensory cyborg. Michael Chorost was hearing impaired from childhood, but at the age of 36 a viral infection reduced his residual hearing to almost zero. With his hearing aids no longer adequate for the life he had built, he elected to have a cochlear implant. A CI is a complex device that converts soundwaves into electrical impulses (like a conventional hearing aid) and then into computer code to trigger the auditory nerves directly via a microelectrode array implanted in the cochlea. In the first chapter, Chorost outlines his position starkly: he is worried not just about whether the implant will work (and thus allow him to go back to something like his former life), but what it will be like, experientially, to become part-computer. The implant "really is a computer. It's cold, angular and digital, yet it's going to be embedded in my flesh, which is warm, squishy and wet...The computer would decide what I heard and how I heard it...It would be the sole mediator between the auditory world and myself. Since I would hear nothing but what its software allowed, the computer's control over my hearing would be complete." (p. 8) In the following chapters Chorost describes the surgery, his physical recovery, the activation of the implant (when he is switched on), and the tortuous process of learning -- often this means observing his brain learning -- how to hear again. © CenterSite, LLC, 1995-2006

Keyword: Hearing
Link ID: 9690 - Posted: 06.24.2010

By PATRICIA LEIGH BROWN OAKLAND, Calif— Until recently, many children who did not conform to gender norms in their clothing or behavior and identified intensely with the opposite sex were steered to psychoanalysis or behavior modification. But as advocates gain ground for what they call gender-identity rights, evidenced most recently by New York City’s decision to let people alter the sex listed on their birth certificates, a major change is taking place among schools and families. Children as young as 5 who display predispositions to dress like the opposite sex are being supported by a growing number of young parents, educators and mental health professionals. Doctors, some of them from the top pediatric hospitals, have begun to advise families to let these children be “who they are” to foster a sense of security and self-esteem. They are motivated, in part, by the high incidence of depression, suicidal feelings and self-mutilation that has been common in past generations of transgender children. Legal trends suggest that schools are now required to respect parents’ decisions. “First we became sensitive to two mommies and two daddies,” said Reynaldo Almeida, the director of the Aurora School, a progressive private school in Oakland. “Now it’s kids who come to school who aren’t gender typical.” Copyright 2006 The New York Times Company

Keyword: Sexual Behavior
Link ID: 9689 - Posted: 06.24.2010

Thomas H. Maugh II, Los Angeles Times Cancer chemotherapy can severely damage the brain, killing crucial brain cells and causing key parts of the brain to shrink, according to two studies released this week. The new findings add to a growing body of evidence suggesting that the phenomenon of "chemobrain" -- the mental fuzziness, memory loss and cognitive impairment often reported by cancer patients but often dismissed by oncologists -- is a serious problem. "Those of us on the front lines have known this for a long time, but now we have some neuropathological evidence that what we are seeing involves an anatomic change," said Dr. Stewart Fleishman, director of cancer supportive services at Beth Israel Medical Center and St. Luke's-Roosevelt Hospital Center in New York. The new studies should help convince physicians who are skeptical about the phenomenon, said Fleishman, who was not involved in the research. Because chemotherapy is such a crucial component of cancer treatment and cannot be abandoned, scientists are calling for increased research on shielding the brain from its toxic effects and developing more-selective cancer drugs. ©2006 San Francisco Chronicle

Keyword: Learning & Memory; Neurotoxins
Link ID: 9688 - Posted: 06.24.2010

BETHESDA, Md -- Inhibiting glucocorticoid, a type of steroid, can prevent skin abnormalities induced by psychological stress, according to a new study from the December issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. The new study also shows how psychological stress induces skin abnormalities that could initiate or worsen skin disorders such as psoriasis and atopic dermatitis. Previous research has shown that psychological stress increases glucocorticoid production. In addition, it is well recognized that psychological stress adversely affects many skin disorders, including psoriasis and atopic dermatitis. "In this study, we showed that the increase in glucocorticoids induced by psychological stress induces abnormalities in skin structure and function, which could exacerbate skin diseases," Feingold explained. This provides a link for understanding how psychological stress can adversely affect skin disorders. Blocking the production or action of glucocorticoids prevented the skin abnormalities induced by psychological stress. The skin is the body's largest organ and plays a crucial role in providing a barrier between the environment and the internal organs. It protects us from harmful microorganisms, ultraviolet light, toxic chemicals, and more. However, its most important function is providing a permeability barrier that prevents us from drying out. We are approximately 65 percent water and we are able to survive and function in dry environments because the skin forms a permeability barrier that prevents the loss of water.

Keyword: Stress; Hormones & Behavior
Link ID: 9687 - Posted: 12.02.2006

Roxanne Khamsi What you speak may influence what you hear, a new study shows. People perceive different patterns in the same sound sequences depending on their native tongue, researchers have found. The short, first note of “Greensleeves” may sound naturally elegant to those who sing the tune. But this type of “pick-up note”, as it is known to musicians, sounds awkward to the ear of a native Japanese speaker, according to researchers. And they can explain why: people's preference for longer or shorter notes at the beginning of a musical phrase apparently depends on their native tongue. Scientists already know that human hearing naturally group sounds together. A listener might, for example, hear identical clicks from a watch as “tick-tock; tick-tock” and so on, hearing an emphasis on the first click – even though all the clicks are identical. Another may hear “tock-tick, tock-tick” with the emphasis on the second click rather than the first. Aniruddh Patel of the Neurosciences Institute in San Diego, California, US, and colleagues wanted to know how people from different cultures group non-identical sounds. They recruited a group of 100 volunteers, half of whom were American and the other half Japanese. The volunteers listened to sequences of alternating long and short or loud and soft tones (audio clips in wav format). © Copyright Reed Business Information Ltd.

Keyword: Language; Hearing
Link ID: 9686 - Posted: 06.24.2010

Roxanne Khamsi Silencing the genes that produce prion proteins can dramatically slow the progression of mad cow disease, suggests a new study in mice. Researchers say that the approach might one day work to treat human prion illnesses, such as variant Creutzfeldt Jakob Disease (vCJD). People can contract vCJD after eating meat contaminated with mad cow disease. Though the illness is extremely rare, it can lead to schizophrenia-like psychosis and typically causes death within a year of diagnosis. While doctors can prescribe drugs to temporarily treat some of the symptoms of prion disease, which include seizures, they still have no way to stop the progression of the illness. Alexander Pfeifer at the University of Bonn in Germany, and colleagues, explored the possibility of fighting prion disease in mice using a method of gene silencing known as RNA interference (RNAi). This method exploits messenger RNA (mRNA) sequences in the cell, which are responsible producing proteins by using the animal’s genetic code as an instruction list. RNAi relies on molecules that bind to mRNA sequences in the cell, thereby preventing the production of specific proteins. © Copyright Reed Business Information Ltd

Keyword: Prions
Link ID: 9685 - Posted: 06.24.2010

A new study analyzing the economic implications of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) concludes that the older (first generation) antipsychotic medication perphenazine was less expensive and no less effective than the newer (second generation) medications used in the trial during initial treatment, suggesting that older antipsychotics still have a role in treating schizophrenia. The study, published in the American Journal of Psychiatry on December 1, 2006, was funded by the National Institutes of Health's National Institute of Mental Health (NIMH). The $42.6 million CATIE trial aimed to help doctors and the 2.4 million Americans who suffer from chronic schizophrenia tailor treatments to individual needs. It is the first study to directly compare several second generation antipsychotic medications and a representative first generation antipsychotic medication. More than 90 percent of antipsychotic prescriptions are written for second generation medications, despite the fact they are more expensive than the first generation agents used to treat schizophrenia. The majority of clinicians have traditionally believed that the newer antipsychotics are more effective and better tolerated than older agents, and many experts argued that these advantages justified the difference in cost. Robert Rosenheck, M.D., of Yale University, and colleagues analyzed costs and quality-of-life factors associated with each of the five medications used in Phase 1 of the CATIE trial—olanzapine, quietapine, risperidone, ziprasidone, and perphenazine. They found that total monthly health costs, a figure that includes both average medication costs and inpatient and outpatient costs, were up to 30 percent lower for those taking the perphenazine than for those taking the second generation medications. In addition, the researchers found no statistically significant difference in overall effectiveness between perphenazine and the second generation antipsychotics, with regard to symptom relief and side effect burden.

Keyword: Schizophrenia
Link ID: 9684 - Posted: 06.24.2010

By Kelli Whitlock Burton Three widely used chemotherapy drugs can cause permanent damage to healthy brain cells, a new animal study suggests. The work could explain a range of cognitive problems collectively called "chemobrain," which may leave as many as 80% of all cancer patients with memory loss, confusion, and an inability to concentrate. "This offers a physiological basis to something that some of us have been concerned about for a long time," says Patricia Duffner, a pediatric oncologist at the University of Buffalo School of Medicine in New York who was not affiliated with the study. Scientists at the University of Rochester in New York examined the neural impact of three chemotherapeutic drugs: cisplatin, often used to treat breast, lung, and colon cancer; carmustine, used to treat brain tumors; and cytarabine, a treatment for leukemia and some lymphomas. The drugs caused widespread brain cell death in human cancer cell cultures and in live mice, even when administered at low levels, the researchers found. In cell cultures, the dosage needed to kill 40% to 80% of the cancer cells also killed 70% to 100% of healthy brain cells, the team reports in the today's issue of the Journal of Biology. And in live animals that received chemotherapy in doses that mimic those used in people, the numbers of dividing cells continued to drop for weeks after chemotherapy stopped. Particularly vulnerable were neurons in the hippocampus, an important memory center, and oligodendrocytes—cells that make a compound called myelin, which insulates neurons to allow electrical impulses to travel quickly across the brain. © 2006 American Association for the Advancement of Science.

Keyword: Learning & Memory; Glia
Link ID: 9683 - Posted: 06.24.2010

By Noreen Parks It seems the harder scientists listen to animals, the more they end up eavesdropping on their conversations. Take butterflyfishes—flamboyantly colored, hand-sized denizens of coral reefs, known for their monogamy, gregariousness, and fierce territoriality. New research, reported Wednesday at the joint meeting of the Acoustical Society of America and Acoustical Society of Japan, shows that butterflyfishes make a variety of sounds to communicate among themselves. The fish may have evolved unique anatomy to enhance their use of sound, the researchers say. All fish have internal "ears," air-filled swim bladders sensitive to sound waves, and "lateral line" sense organs that detect motion in surrounding water. However, only in one genus of butterflyfishes are these body parts connected—a discovery made some years ago. Scientists have speculated that the unusual anatomical arrangement is involved in sound perception, but no one knew what role, if any, sound plays in butterflyfish lives. To find out, marine biologist Tim Tricas of the University of Hawaii, Manoa, and colleagues dove to a Hawaii reef and located several pairs of banded butterflyfish (Chaetodon multicinctus) observed maintaining feeding territories. In multiple experiments, the researchers placed one pair in a glass bottle and positioned the bottle inside another pair's territory for up to 40 minutes. The results, recorded by a video camera and underwater microphone, revealed territory defenders aggressively charging the intruders, while making rapid, sound-generating moves, such as flicking and erecting their fins, "jumping," and turning. In response, the bottled fish grunted repeatedly. Only paired fish grunted—not single individuals—so Tricas suspects grunts are distress signals to mates. © 2006 American Association for the Advancement of Science.

Keyword: Animal Communication
Link ID: 9682 - Posted: 06.24.2010

Jennifer Viegas, Discovery News — Termites are known to send underground SOS signals to each other by banging their heads against tunnel walls, and now scientists have filmed them in the act. The high-speed video, which captured the frantic behavior at 10,000 frames per second, reveals that some termite species are faster head bangers than others. With each hit, the Formosan subterranean termite raises its head about 1 millimeter off the ground before slamming it into tunnel walls at a rate of about 100-200 millimeters per second. A termite native to New Orleans is even faster, with head bangs at around 400 millimeters per second. Their heads bounce and rebound off the walls like a rhythmic drum roll. The researchers suggest the rattling noise — audible sometimes even to people — could help locate infestations. "If a house is very infested with termites, you might be able to hear them head-banging (without special equipment), especially if you removed an infested board or crushed their galleries or part of their carton nest," said Tom Fink, who will present his findings on the head-banging behavior Saturday at the Acoustical Society of America Meeting in Honolulu, Hawaii. © 2006 Discovery Communications Inc.

Keyword: Animal Communication
Link ID: 9681 - Posted: 06.24.2010

Guanfacine, a medication commonly prescribed to alleviate symptoms of post-traumatic stress disorder, is no more effective than a placebo, according to a study led by researchers at the San Francisco VA Medical Center. “There was no benefit at all, and there were several adverse side effects,” says lead author Thomas Neylan, MD, medical director of the PTSD treatment program at SFVAMC. “People with symptoms of PTSD should probably stay away from this drug and others of its type.” The study appears in the December 1, 2006 issue of the American Journal of Psychiatry. Guanfacine belongs to a class of medications known as alpha-2 agonists, which lower the brain’s supply of the neurotransmitter norepinephrine. Neurotransmitters are chemicals that transmit electrical signals between nerve cells. They are responsible for many aspects of behavior. “Norepinephrine is released in the brain during states of excited arousal, and PTSD is associated with that state – patients startle easily, have trouble sleeping, and are hypervigilant and anxious,” explains Neylan, who is also an associate professor of psychiatry at the University of California, San Francisco. Guanfacine and clonidine, another alpha-2 agonist, are commonly prescribed for PTSD symptoms. “There are at least 20 peer-reviewed articles published in the field of PTSD that recommend drugs which lower norepinephrine,” Neylan says. “However, ours was the first randomized, controlled study of alpha-2 agonists for symptoms of PTSD.”

Keyword: Stress
Link ID: 9680 - Posted: 06.24.2010

Emma Marris Women are more attuned to the subtle non-verbal communication made by the direction of a colleague's gaze, according to new research. Almost like a reflex, people will follow a person's gaze and look towards what the other person is looking at. This phenomenon, known as 'gaze cuing', is deeply entrenched in human behaviour. "We do it without effort, very quickly, and that's quite amazing," says Michael Platt, a neurobiologist at Duke University in Durham, North Carolina. "We do it from the first hours of being born." Previous work has indicated that women seem to be more adept at this than men. And now research shows that they're even more attuned to the gaze of others when they are familiar faces. Thirty-two volunteers were shown images of people looking one way or another, followed by a picture of a box on one side or another of the face. Subjects were to press a button to indicate which side the box was on, and researchers measured whether they were faster at doing so when the direction of the gaze and the box was the same rather than different. Some of the faces in the experiment were of colleagues of the subjects, to see whether familiarity with the person doing the gazing would enhance the effect. A brief flash of a unfamiliar face showed that the direction of gaze only improved the speed of identifying the box's location by about 9 milliseconds for volunteers of both genders. But when the researchers looked specifically at the 17 volunteers who came from within the Duke neurobiology department, they found women's scores improved by 26 milliseconds, and men's by 12. ©2006 Nature Publishing Group

Keyword: Sexual Behavior; Vision
Link ID: 9679 - Posted: 06.24.2010

Alison Abbott There are many good reasons to believe that we all have our own unique smell. Dogs, for example — as pets or police sniffers — seem to be able to distinguish individuals by their smell. And the mother-baby bond is cemented by their own distinctive odours. Now a large and systematic study led by Dustin Penn from the Konrad Lorenz Institute for Ethology in Vienna, Austria, has provided stronger support for the notion that your smell might distinguish you from others — maybe even as much as your face. The researchers further suggest that profiles of individual odours may also fall into two groups according to gender — men more commonly have some smelly compounds, women more commonly others. The researchers took samples of armpit sweat, urine and spit from 197 adults. Each subject was sampled five times over a ten-week collecting period. They extracted thousands of volatile chemicals from the samples — the type of compound most likely to have an odour — and identified them by chromatography and mass spectrometry. ©2006 Nature Publishing Group

Keyword: Chemical Senses (Smell & Taste)
Link ID: 9678 - Posted: 06.24.2010

Debora MacKenzie The more fertile a male red deer is, the more likely he is to sire a son, researchers show. It is the first study to demonstrate that male mammals can influence the gender of their offspring through sperm quality. Red deer stags go to spectacular lengths to mate, defending harems of females and fighting off competitors. Now scientists have discovered that those who win at the rut have more sons, to carry on their fathers’ winning ways. The losers at the rut play it safe with daughters. Or they try to – how much the females influence this remains unclear. It has long been theorised that males who are most successful at mating would produce more sons – to inherit their fathers’ brilliant plumage or big antlers – than daughters. Sons produce more offspring than daughters can. While this has been shown for blue tits (see It's the healthy bird that fathers more sons), where the egg determines the sex of the offspring, it has never been shown for mammals, where sperm do. Montserrat Gomendio and colleagues at the National Museum of Natural Sciences in Madrid, Spain, have now demonstrated this in red deer. The team collected testes from stags hunted during the rutting season, and assessed their sperm quality. Then they inseminated well-fed females. “We were very surprised to see a large difference in fertility,” Gomendio told New Scientist. The proportion of females a stag could make pregnant (the stags' fertility) ranged from 24% to 70%. © Copyright Reed Business Information Ltd

Keyword: Sexual Behavior; Evolution
Link ID: 9677 - Posted: 06.24.2010