Early exposure to dogs might curb schizophrenia risk, Maryland researchers say
Man's best friend indeed.
- There is a growing understanding in the medical community of how important the immune system is for our mental health.
- Much of the risk for mental illness is due to heritability, but a large portion of that risk is also due to the environment.
- Since children are often exposed to pet dogs at a young age, it could be that their presence affects developing children's immune systems; new research on over a 1,000 study participants suggests that this may indeed be the case.
Scientists estimate that roughly 80 percent of an individual's risk for schizophrenia is attributable to heredity. Unfortunately, there is virtually nothing that can be done to reduce this risk; it's innate. The remaining 20 percent of risk, however, arises from environmental factors.
There are a few ways that we can reduce this risk. We can, for instance, ensure that mothers experience as little stress as possible during pregnancy and that they get adequate nutrition. We can protect children from abuse and trauma and discourage drug use. Now, new research out of Maryland suggests we can also keep a dog in the house.
The immune system and mental health
Many mental illnesses like schizophrenia have an environmental component. There's a developing understanding in the scientific community that mental illness and the immune system are linked. For example, research has shown that victims of childhood abuse are more susceptible to immune disorders and that chronic inflammation plays a role in diseases like depression.
Since pets are often introduced to young, developing children, studying the effect of their exposure on later mental illness rates is a reasonable avenue of research. Cats and dogs can change our environment and our immune systems by introducing allergens, viruses, and bacteria; by changing the home's microbiome; and — not least of all — by relieving stress and changing our brain chemistry as a result.
The researchers in this study therefore recruited a population of 1,371 men and women of varying ages, ethnicities, places of birth, and parental levels of education (as a means of measuring socioeconomic status). Of these, 396 had schizophrenia, 381 had bipolar disorder, and 594 served as controls. Then, these individuals were asked whether they had a pet dog or cat during their first 12 years of life.
Comparing pet ownership and the rates of the two mental illnesses, the researchers discovered that being exposed to a dog before the age of 13 had a huge effect on whether or not that person would later develop schizophrenia. Dog ownership cut the risk down by a staggering 25 percent.
"The largest apparent protective effect was found for children who had a household pet dog at birth or were first exposed after birth but before age 3," said lead author Robert Yolken in a statement.
"There are several plausible explanations for this possible 'protective' effect from contact with dogs," he added. "Perhaps something in the canine microbiome that gets passed to humans and bolsters the immune system against or subdues a genetic predisposition to schizophrenia."
Unfortunately for cat lovers, there was no similar impact from cat ownership on mental illness rates.
"However," said Yolken, "we did find a slightly increased risk of developing both disorders for those who were first in contact with cats between the ages of 9 and 12. This indicates that the time of exposure may be critical to whether or not it alters the risk."
Aside from this slight increase in risk from cats during this specific age range, neither pet appeared to have any effect on bipolar disease.
A major impact
The reason why this effect might exist wasn't made clear during this study — only that a link between dog ownership and schizophrenia exists. Considering that this protective effect was strongest when the very young (0–3) were exposed to dogs, it could very well be the case that exposure to dogs had some benefit for the children's developing immune systems.
But the study has its limitations, and other, unaccounted for variables could be causing this result. For example, dog ownership is more common in affluent families. Even though the study accounted for socioeconomic status through some indirect metrics (specifically, place of birth and parental level of education), it could still be the case that affluent, at-risk children are protected from the kinds of stressors that could trigger schizophrenia in addition to owning a dog.
However, if further research confirms this finding, it could have a major implications for 25,000 people every year — that's one quarter of the annual schizophrenia diagnoses in the U.S. Whether it's because of their microbiomes or their sunny personalities, man's best friend appears to be doing more for our mental state than we might assume.
- Wired that way: genes do shape behaviours but it's complicated ... ›
- How non-industrial cultures view mental illness - Big Think ›
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
Dominique Crenn, the only female chef in America with three Michelin stars, joins Big Think Live.
Having been exposed to mavericks in the French culinary world at a young age, three-star Michelin chef Dominique Crenn made it her mission to cook in a way that is not only delicious and elegant, but also expressive, memorable, and true to her experience.
Controversial physics theory says reality around us behaves like a computer neural network.
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- The theory claims that natural selection produces both atoms and "observers".
Vanchurin interview:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="539759cbfd8fcd5b6ebf14a3b597b3f9"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/bmyRy2-UhEE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Vanchurin on “Hidden Phenomena”:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="18886ffd5e5840bb19d4494212f88d82"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/2NDVdNwsHCo?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>Vitaly Vanchurin speaking at the 6th International FQXi Conference, "Mind Matters: Intelligence and Agency in the Physical World." The Foundational Questions...
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