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6 reasons dogs truly are man’s best friend
Research suggests dog ownership may improve heart health, decrease depression, and even help you live longer.
- Dogs have been man's best friend for at least the past 15,000 years.
- Science now shows that this symbiotic relationship has been as beneficial for humans as their canine companions.
- Benefits of dog ownership include familial ties, a reduce risk of schizophrenia, and improved cardiovascular health.
Under cover of darkness, a pack of ancient wolves slowly stalk the camps of our nomadic ancestors. But they are not on the prowl. These timid, congenial Canidaes have discovered they can scavenge human kills and midden piles for more reward, and far less risk, than the hunt.
Over successive generations, their offspring grow more docile and more dependent on their human benefactors. In time humans adopt these four-legged moochers, taking them into their service with the tacit agreement of better food and companionship. And so, the human-dog relationship was born.
That's one possibility at least. All that's generally agreed upon is that dogs became man's best friend as early as 15,000 years ago — though some fossil evidence suggests domestication as far back as 30,000 years. As science writer James Gorman points out, this means we loved our tail-wagging besties before inventing agriculture, language, or permanent homes and even before we domesticated cows, goats, and, of course, cats.
"As we became friends with them, they became friends with us, and we have a dependency that's charming," Bill Nye, science guy and lover of all good dogs, told us in a 2015 interview. "It's enriched both the dog lives and the human lives."
For humans, the perks of the dog-human relationship run much deeper than games of fetch or a handy excuse to go for a nice, long walk.
Dogs see us as family
Dogs see their people as family, and the feeling seems to be mutual.
It's not our imaginations or a poetic attempt to explain behavior through personification. Dogs do view their people as family.
Cognition scientists at Emory University placed dogs in an MRI machine and scanned their brains while presenting them with different odors. Some aromas were of food. Others were from other dogs. And some were from the dogs' human companions. The dogs' brains' reward centers lit up most when presented with the human scents, showing they prioritized human relationships.
These results bolstered other research that shows dogs act similarly to human sounds and that they are the only non-primates to run toward humans for protection and comfort.
Dogs reduce the risk of schizophrenia
A little girl meets Lothair and Molly, two certified therapy dogs, at U.S. Air Force Base Hospital Langley.
Dogs may be able to curb the risk of some mental diseases. That's the conclusion of research published in the peer-reviewed journal PLoS ONE, which found a link between dog ownership and a reduced risk of schizophrenia.
The researchers looked at 1,371 men and women across the socioeconomic spectrum. Roughly 400 participants suffered from schizophrenia, another 400 from bipolar disorder, and about 600 were controls. After a survey in which the participants were asked about pets, the researchers compared ownership with rates of mental illness.
They discovered that dog ownership before the age of 13 correlated with a 25 percent reduced risk of schizophrenia. Participants who owned dogs in the first years of life showed the largest protective effect.
"There are several plausible explanations for this possible 'protective' effect from contact with dogs," lead author Robert Yolken said in a statement. "Perhaps something in the canine microbiome that gets passed to humans and bolsters the immune system against or subdues a genetic predisposition to schizophrenia."
Sorry, ailurophiles. Cats did not show a similar link between ownership and a reduced risk of mental diseases.
Dogs are your heart's best friend, too
Regular walks with your dog is great exercise and boosts cardiovascular health.
The health benefits aren't just in the mind. Preliminary research published in Mayo Clinic Proceedings: Innovations, Quality & Outcomes suggests that pet ownership boosts heart health, especially if that pet is a dog.
Researchers evaluated roughly 1,800 participants using the American Heart Association's Life's Simple 7, seven life factors that people can improve to help achieve cardiovascular well-being. They then compared the health of pet owners with those who did not own pets and found a correlation between dog ownership and heart health. The researchers associated this salubrious effect with increased engagement and physical activity.
"In general, people who owned any pet were more likely to report more physical activity, better diet and blood sugar at an ideal level," Andrea Maugeri, a researcher with the International Clinical Research Center at St. Anne's University Hospital in Brno, said in a statement. "The greatest benefits from having a pet were for those who owned a dog, independent of their age, sex and education level."
Follow-up evaluations are scheduled until 2030.
Dogs make life better (and longer)
An older gentleman sits with his canine companion.
Better heart health means a better chance to live longer. That's according to a recent study and meta-analysis published in Circulation: Cardiovascular Quality and Outcomes.
The research found that dog owners who survived a heart attack were at a 33 percent reduced risk of early death compared to non-dog survivors. The same held true for stroke survivors (27 percent). Better still, dog ownership correlated with a 24 percent reduced risk of all-cause mortality, likely explained by an increase in physical activity and a decrease in depression and loneliness.
A study published in Scientific Reports corroborates a canine's life-giving, heart-healthy impact. The researchers reviewed the national registries for more than 3.4 million Swedes with no cardiovascular disease before 2001. Looking at the association between dog ownership and cardiovascular health, they found that single dog owners had a lowered risk of death, either due to cardiovascular disease (11 percent) or other causes (33 percent).
In a statement, lead junior author Mwenya Mubanga noted, "A very interesting finding in our study was that dog ownership was especially prominent as a protective factor in persons living alone, which is a group reported previously to be at higher risk of cardiovascular disease and death than those living in a multi-person household. Perhaps a dog may stand in as an important family member in the single households."
Dogs teach us ways to learn
Put simply, dogs are better at ignoring bad advice than their human peers. Research out of Yale University's Canine Cognition Center tasked dogs with retrieving treats from a puzzle. The researchers presented the steps to solve the puzzle but included many extraneous steps in the demonstration. When it was the dogs' turn, they nimbly skipped the unnecessary steps, thereby showing their ability to filter information effectively.
How did human children perform? Not so great. The children settled on pure imitation, regardless of whether a step proved useful in solving the puzzle.
"This tells us something really important about how humans learn relative to other animals," Big Think author Arpan Bhattacharyya wrote on the study. "We're really trusting of the information that we get from other individuals – even more trusting than dogs are.
"And what this means is we have to be really careful about the kinds of information we present ourselves with. We're not going to have the right filter for bad information, so we should stick to looking at information that's going to be positive, information that's going to be good."
Dogs teach us about ourselves
Dogs really do resemble their owners.
Dogs resemble their owners in more ways than floppy jowls or a perky gait. Dogs mirror their owners' personalities, and owners can use this information to better understand themselves.
Research published in the Journal of Research in Personality surveyed more than 1,600 dog owners, representing about 50 different breeds. They found that dog owners shaped their dogs' personalities. Extroverted owners rated their dogs as more active and playful, while the owners of more fearful dogs tended to exhibit more negative emotions. Similarly, more agreeable owners were guardians of less aggressive pets.
"We expected the dogs' personalities to be fairly stable because they don't have wild lifestyle changes humans do, but they actually change a lot. We uncovered similarities to their owners, the optimal time for training and even a time in their lives that they can get more aggressive toward other animals," lead author William Chopik said in a release.
Another study in Scientific Reports showed similar findings regarding stress. The researchers took hair and fur samples from owners and their dogs to measure both for the stress hormone cortisol. They found a correlation in long-term stress between the two.
More than simply good dogs
These are six ways that science has discovered dogs aid their interspecies partner. As genetic research advances, dogs may prove they are man's best friends in unforeseen ways. Scientists studying the canine genome have found a number of canine disorders that closely resemble those found in humans, including some cancers. Further study may provide a wealth of information that could help us solve our own genetic mysteries.
- Dog Owners Experience Reduced Risk for Cardiovascular Problems ... ›
- Dogs in the Workplace Mean Better Mental Health - Big Think ›
- Is Dog Man's Best Friend Because of Oxytocin? ›
Evolution proves to be just about as ingenious as Nikola Tesla
- For the first time, scientists developed 3D scans of shark intestines to learn how they digest what they eat.
- The scans reveal an intestinal structure that looks awfully familiar — it looks like a Tesla valve.
- The structure may allow sharks to better survive long breaks between feasts.
Considering how much sharks are feared by humans, it is a bit of a surprise that scientists don't know much about the predators. For example, until recently, sharks were thought to be solitary creatures searching the seas for food on their own. Now it appears that some sharks are quite social.
Another mystery is how these prehistoric swimming and eating machines digest food. Although scientists have made 2D sketches of captured sharks' digestive systems based on dissections, there is a limit to what can be learned in this way. Professor Adam Summers at University of Washington's Friday Harbor Labs says:
"Intestines are so complex, with so many overlapping layers, that dissection destroys the context and connectivity of the tissue. It would be like trying to understand what was reported in a newspaper by taking scissors to a rolled-up copy. The story just won't hang together."
Summers is co-author of a new study that has produced the first 3D scans of a shark's intestines, which turns out to have a strange, corkscrew structure. What's even more bizarre is that it resembles the amazing one-way valve designed by inventor Nikola Tesla in 1920. The research is published in the journal Proceedings of the Royal Society B.
What a 3D model reveals
Video: Pacific spiny dogfish intestine youtu.be
According to the study's lead author Samantha Leigh, "It's high time that some modern technology was used to look at these really amazing spiral intestines of sharks. We developed a new method to digitally scan these tissues and now can look at the soft tissues in such great detail without having to slice into them."
"CT scanning is one of the only ways to understand the shape of shark intestines in three dimensions," adds Summers. The researchers scanned the intestines of nearly three dozen different shark species.
It is believed that sharks go for extended periods — days or even weeks — between big meals. The scans reveal that food passes slowly through the intestine, affording sharks' digestive system the time to fully extract its nutrient value. The researchers hypothesize that such a slow digestive process may also require less energy.
It could be that this slow digestion is more susceptible to back flow given that the momentum of digested food through the tract must be minimal. Perhaps that is why sharks evolved something so similar to a Tesla valve.
What is Tesla's valve doing there?
Above, a Tesla valve. Below, a shark intestine.Credit: Samantha Leigh / California State University, Domi
Tesla's "valvular conduit," or what the world now calls a "Tesla valve," is a one-way valve with no moving parts. Its brilliance is based in fluid dynamics and only now coming to be fully appreciated. Essentially, a series of teardrop-shaped loops arranged along the length of the valve allow water to flow easily in one direction but not in the other. Modern tests reveal that at low flow rates, water can travel through the valve either way, but at high flow rates, the design kicks in. According to mathematician Leif Ristroph:
"Crucially, this turn-on comes with the generation of turbulent flows in the reverse direction, which 'plug' the pipe with vortices and disrupting currents. Moreover, the turbulence appears at far lower flow rates than have ever previously been observed for pipes of more standard shapes — up to 20 times lower speed than conventional turbulence in a cylindrical pipe or tube. This shows the power it has to control flows, which could be used in many applications."
A deeper dive
Summers suggests the scans are just the beginning. "The vast majority of shark species, and the majority of their physiology, are completely unknown," says Summers, adding that "every single natural history observation, internal visualization, and anatomical investigation shows us things we could not have guessed at."
To this end, the researchers plan to use 3D printing to produce models through which they can observe the behavior of different substances passing through them — after all, sharks typically eat fish, invertebrates, mammals, and seagrass. They also plan to explore with engineers ways in which the shark intestine design could be used industrially, perhaps for the treatment of wastewater or for filtering microplastics.
It could fairly be said, though, that Nikola Tesla was 100 years ahead of them.
The non-contact technique could someday be used to lift much heavier objects — maybe even humans.
- Since the 1980s, researchers have been using sound waves to move matter through a technique called acoustic trapping.
- Acoustic trapping devices move bits of matter by emitting strategically designed sound waves, which interact in such a way that the matter becomes "trapped" in areas of particular velocity and pressure.
- Acoustic and optical trapping devices are already used in various fields, including medicine, nanotechnology, and biological research.
Sound can have powerful effects on matter. After all, sound strikes our world in waves — vibrations of air molecules that bounce off of, get absorbed by, or pass through matter around us. Sound waves from a trained opera singer can shatter a wine glass. From a jet, they can collapse a stone wall. But sound can also be harnessed for delicate interactions with matter.
Since the 1980s, researchers have been using sound to move matter through a phenomenon called acoustic trapping. The method is based on the fact that sound waves produce an acoustic radiation force.
"When an acoustic wave interacts with a particle, it exerts both an oscillatory force and a much smaller steady-state 'radiation' force," wrote the American Physical Society. "This latter force is the one used for trapping and manipulation. Radiation forces are generated by the scattering of a traveling sound wave, or by energy gradients within the sound field."
When tiny particles encounter this radiation, they tend to be drawn toward regions of certain pressure and velocity within the sound field. Researchers can exploit this tendency by engineering sound waves that "trap" — or suspend — tiny particles in the air. Devices that do this are often called "acoustic tweezers."
Building a better tweezer
A study recently published in the Japanese Journal of Applied Physics describes how researchers created a new type of acoustic tweezer that was able to lift a small polystyrene ball into the air.
Tweezers of Sound: Acoustic Manipulation off a Reflective Surface youtu.be
It is not the first example of a successful "acoustic tweezer" device, but the new method is likely the first to overcome a common problem in acoustic trapping: sound waves bouncing off reflective surfaces, which disrupts acoustic traps.
To minimize the problems of reflectivity, the team behind the recent study configured ultrasonic transducers such that the sound waves that they produce overlap in a strategic way that is able to lift a small bit of polystyrene from a reflective surface. By changing how the transducers emit sound waves, the team can move the acoustic trap through space, which moves the bit of matter.
Move, but don't touch
So far, the device is only able to move millimeter-sized pieces of matter with varying degrees of success. "When we move a particle, it sometimes scatters away," the team noted. Still, improved acoustic trapping and other no-contact lifting technologies — like optical tweezers, commonly used in medicine — could prove useful in many future applications, including cell separation, nanotechnologies, and biological research.
Could future acoustic-trapping devices lift large and heavy objects, maybe even humans? It seems possible. In 2018, researchers from the University of Bristol managed to acoustically trap particles whose diameters were larger than the sound wavelength, which was a breakthrough because it surpassed "the classical Rayleigh scattering limit that has previously restricted stable acoustic particle trapping," the researchers wrote in their study.
In other words, the technique — which involved suspending matter in tornado-like acoustic traps — showed that it is possible to scale up acoustic trapping.
"Acoustic tractor beams have huge potential in many applications," Bruce Drinkwater, co-author of the 2018 study, said in a statement. "I'm particularly excited by the idea of contactless production lines where delicate objects are assembled without touching them."
Australian parrots have worked out how to open trash bins, and the trick is spreading across Sydney.
Dumpster-diving trash parrots
In a study about these smart birds just published in Science, researchers define animal culture as "population-specific behaviors acquired via social learning from knowledgeable individuals."
Co-lead author of the study Barbara Klump of the Max Planck Institute of Animal Behavior in Konstanz, Germany says, "[C]ompared to humans, there are few known examples of animals learning from each other. Demonstrating that food scavenging behavior is not due to genetics is a challenge."
An opportunity presented itself in a video that co-author Richard Major of the Australian Museum shared with Klump and the other co-authors. In the video, a sulphur-crested cockatoo used its beak to pull up the handle of a closed garbage bin — using its foot as a wedge — and then walked back the lid sufficiently to flip it open, exposing the bin's edible contents.
Major has been studying Cacatua galerita for 20 years and says, "Like many Australian birds, sulphur-crested cockatoos are loud and aggressive." The study describes them as a "large-brained, long-lived, and highly social parrot." Says Major, "They are also incredibly smart, persistent, and have adapted brilliantly to living with humans."(Research regarding some of the ways in which wild animals adapt to the presence of humans has already produced some fascinating results and is ongoing.)
Clever cockie opens bin - 01 youtu.be
The researchers became curious about how widespread this behavior might be and saw a research opportunity. After all, says John Martin, a researcher at Taronga Conservation Society, "Australian garbage bins have a uniform design across the country, and sulphur-crested cockatoos are common across the entire east coast."
Martin continues, "In 2018, we launched an online survey in various areas across Sydney and Australia with questions such as, 'What area are you from, have you seen this behavior before, and if so, when?'"
Word Gets Around
Credit: magspace/Adobe Stock
Although the cockatoos' maneuver was reported in only three suburbs before 2018, by the end of 2019, people in 44 areas reported observing the behavior. Clearly, more and more cockatoos were learning how to successfully dumpster dive.
As further proof, says Klump, "We observed that the birds do not open the garbage bins in the same way, but rather used different opening techniques in different suburbs, suggesting that the behavior is learned by observing others." One individual bird in north Sydney invented its own method, and the scientists saw it grow in popularity throughout the local population.
To track individual birds, the researchers marked 500 cockatoos with small red dots. Subsequent observations revealed that not all cockatoos are bin-openers. Only about 10 percent of them are, and they are mostly males. The other cockatoos apparently restrict their education to a different lesson: hang around with a bin-opener, and you will get supper.
Thanks to the surveys, the researchers consider the entire project to be a valuable citizen-science experiment. "By studying this behavior with the help of local residents, we are uncovering the unique and complex cultures of their neighborhood birds."
The few seconds of nuclear explosion opening shots in Godzilla alone required more than 6.5 times the entire budget of the monster movie they ended up in.