Posts Tagged ‘testosterone’

To investigate whether the differences in how men and women navigate are related to our sex or to cultural conditioning, researchers in Norway measured male and female brain activity while volunteers tried to find their way through a virtual reality maze.

Wearing 3D goggles and using a joystick to make their way through an artificial environment, the participants (18 males and 18 females) had their brain functions continuously recorded by an fMRI scanner as they carried out virtual navigation tasks.

In line with previous findings, the men performed better, using shortcuts, orienting themselves more using cardinal directions, and solving 50 percent more tasks than the women in the study.

“Men’s sense of direction was more effective,” said Carl Pintzka, a neuroscientist at the Norwegian University of Science and Technology (NTNU). “They quite simply got to their destination faster.”

One of the reasons for this is because of the difference in how men and women use their brains when we’re finding our way around. According to the researchers, men use the hippocampus more, whereas women place greater reliance on their brains’ frontal areas.

“That’s in sync with the fact that the hippocampus is necessary to make use of cardinal directions,” said Pintzka. “[M]en usually go in the general direction where [their destination is] located. Women usually orient themselves along a route to get there.”

Generally, the cardinal approach is more efficient, as it depends less on where you start.

But women’s brains make them better at finding objects locally, the researchers say. “In ancient times, men were hunters and women were gatherers. Therefore, our brains probably evolved differently,” said Pintzka. “In simple terms, women are faster at finding things in the house, and men are faster at finding the house.”

What was most remarkable about the study was what happened when the researchers gave women a drop of testosterone to see how it affected their ability to navigate the virtual maze. In a separate experiment, 21 women received a drop of testosterone under their tongues, while 21 got a placebo.

The researchers found that the women receiving testosterone showed improved knowledge of the layout of the maze, and relied on their hippocampus more to find their way around. Having said that, these hormone-derived benefits didn’t enable them to solve more maze tasks in the exercise.

It’s worth bearing in mind that the study used a fairly small sample size in both of the experiments carried out, so the findings need to be read in light of that. Nonetheless, the scientists believe their paper, which is published in Behavioural Brain Research, will help us to better understand the different ways male and female brains work, which could assist in the fight against diseases such as Alzheimer’s.

“Almost all brain-related diseases are different in men and women, either in the number of affected individuals or in severity,” said Pintzka. “Therefore, something is likely protecting or harming people of one sex. Since we know that twice as many women as men are diagnosed with Alzheimer’s disease, there might be something related to sex hormones that is harmful.”

http://www.sciencealert.com/women-can-navigate-better-when-given-testosterone-study-finds

Thanks to Dr. Enrique Leira for bringing this to the It’s Interesting community.

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The antechinus is a small, shrewlike marsupial indigenous to Australia and New Guinea. These animals are best known for their odd practice of having sex until it kills them, but what else does their mating behavior entail?

There are currently 15 known species of antechinus (animals in the Antechinus genus) living in the forests and woodlands of Australia and New Guinea, five of which were discovered since 2012, said Andrew Baker, a mammal ecologist at the Queensland University of Technology in Australia and leader of the group that made the discoveries.

Generally speaking, antechinus are loners that stick to themselves until the breeding season nears.

Antechinus breed during the Australian winter, when their food — small vertebrates and invertebrates — is scarce. This timing ensures their babies will be born in the spring, when food is bountiful.

Interestingly, males stop producing sperm before the mating season begins.

It’s not clear how sexually mature males and females find mates, but Baker suspects scent, and pheromones, are involved. And as with many other species, males likely roam longer and wider in search of sex, he said.

Baker also suspects that male-male fighting is probably common among antechinuses. “They have surging testosterone levels that tend to make them very aggressive,” Baker said.

Antechinus don’t bother wasting time with wooing mates or engaging in courtship rituals. Instead, they prefer to get down to business immediately.

In fact, a male has no issue with resorting to ambush mating, during which he will catch hold of a female from behind and mate with her while grabbing the scruff of her neck with his forepaws and biting her neck.

It’s not uncommon to find females with tufts of fur around the neck area missing, Baker said, adding that females are fine with the rough ambush as long as they have an opportunity to mate with other males afterward.

Both male and female antechinus are promiscuous, and will try to mate with numerous partners throughout the breeding period. However, to increase their chances of fathering offspring, males will mate with females for as long as possible.

Scientists have documented antechinus copulation events lasting for 10, 12 and even 14 hours. “That’s intermittent thrusting between just one male and one female,” Baker said. When not thrusting, the male will guard the female, keeping her from getting away (and looking for other mates) and other males from getting to her.

Anetchinus will mate continuously for the entire breeding period, which lasts, on average, about two weeks. This activity takes a toll on the male’s body.

The sustained high levels of testosterone stop the production of cortisol from being turned off, allowing males to burn more sugar, Baker said. “It frees them from the need to feed as often, but the downside is that cortisol in sustained levels is poisonous,” he said.

Over time, the males will start to behave erratically, bleed internally, lose fur, develop sores and ulcers that don’t heal, become blind, and develop high parasite loads as their immune system shuts down. “They are like a blank slate for every parasite and disease going around,” Baker said.

It’s rare for a male to survive the breeding period.

Females, on the other hand, may die of exhaustion after weaning their litter, which have multiple paternities. Less than 50 percent of females make it to their second breeding season, and only a very small percentage make it to their third, Baker said.

http://www.livescience.com/51371-animal-sex-antechinus.html


World Cup soccer players with higher facial-width-to-height ratios are more likely to commit fouls, score goals and make assists, according to a study by a researcher at the University of Colorado Boulder.

The structure of a soccer player’s face can predict his performance on the field—including his likelihood of scoring goals, making assists and committing fouls—according to a study led by a researcher at the University of Colorado Boulder.

The scientists studied the facial-width-to-height ratio (FHWR) of about 1,000 players from 32 countries who competed in the 2010 World Cup. The results, published in the journal Adaptive Human Behavior and Physiology, showed that midfielders, who play both offense and defense, and forwards, who lead the offense, with higher FWHRs were more likely to commit fouls. Forwards with higher FWHRs also were more likely to score goals or make assists.

“Previous research into facial structure of athletes has been primarily in the United States and Canada,” said Keith Welker, a postdoctoral researcher in CU-Boulder Department of Psychology and Neuroscience and the lead author of the paper. “No one had really looked at how facial-width-to-height ratio is associated with athletic performance by comparing people from across the world.”

FWHR is the distance between the cheekbones divided by the distance between the mid-brow and the upper lip. Past studies have shown that a high FWHR is associated with more aggressive behavior, with both positive and negative results. For example, high FWHR correlates with greater antisocial and unethical behavior, but it also correlates with greater success among CEOs and achievement drive among U.S. presidents. However, some previous research has failed to find a correlation between FWHR and aggressive behavior in certain populations.

The new study adds weight to the argument that FWHR does correlate with aggression. Welker and his colleagues chose to look at the 2010 World Cup because of the quality and quantity of the data available. “There are a lot of athletic data out there,” Welker said. “We were exploring contexts to look at aggressive behavior and found that the World Cup, which quantifies goals, fouls and assists, provides a multinational way of addressing whether facial structure produces this aggressive behavior and performance.”

Scientists have several ideas about how FWHR might be associated with aggression. One possibility is that it’s related to testosterone exposure earlier in life. Testosterone during puberty can affect a variety of physical traits, including bone density, muscle growth and cranial shape, Welker said.

Co-authors of the study were Stefan Goetz, Shyneth Galicia and Jordan Liphardt of Wayne State University in Michigan and Justin Carré of Nipissing University in Ontario, Canada. –

See more at: http://www.colorado.edu/news/releases/2014/11/11/facial-structure-predicts-goals-fouls-among-world-cup-soccer-players#sthash.mAvOP9oO.dpuf

Last year, newly published letters written by Nobel prize winner Heinrich Böll appeared to confirm that Nazi troops took crystal methamphetamines in order to stay awake and motivated, despite the desperate conditions they faced on the front line.

Now, new research has revealed that Adolf Hitler was himself a regular user of the drug, now a Class A, prized among addicts for its feeling of euphoria but feared for its mental destructiveness.

According to a 47-page wartime dossier compiled by American Military Intelligence, the Fuhrer was a famous hypochondriac and took over 74 different medications, including methamphetamines.

It claims that Hitler took the drug before his final meeting with Italian fascist leader Mussolini in July of 1943, during which he apparently ranted non-stop for two hours.

Hitler eased the pain of his final days in his bunker with nine injections of a drug called Vitamultin, too, which contained among its ingredients meth-amphetamine.

The dossier – which is the subject of a new documentary Hitler’s Hidden Drug Habit – goes on to claim that the Fuhrer became addicted to drugs after seeking the medical advice of Berlin-based Dr Morell in 1936.

He was initially prescribed a drug called Mutaflor in order to relieve the pain of his stomach cramps.

He was then prescribed Brom-Nervacit, a barbiturate, Eukodal, a morphine-based sedative, bulls’ semen to boost his testosterone, stimulants Coramine and Cardiazol, and Pervitin, an ‘alertness pill’ made with crystal meth-amphetamine.

His reliance on medication became costly, and by the end of 1943, Hitler was dependant on a mentally debilitating cocktail of uppers and downers.

“Morell was a quack and a fraud and a snake oil salesman,” Bill Panagopoulos, an American collector who discovered the dossier, said.

“He should not have been practising medicine anywhere outside a veterinary clinic.”

“Some [of the drugs] were innocuous, some not so innocuous, some poisonous. Did he develop a dependence on any of these drugs? Which of these drugs, if any, were addictive? And did he become addicted to them? I’d be interested to know what the combination of these medications would do to someone who’s otherwise in good health.”

http://www.independent.co.uk/news/people/hitler-was-a-regular-user-of-crystal-meth-american-military-intelligence-dossier-reveals-9789711.html