New research suggests that owning a pet may not, as some previous studies have suggested, actually help people stay youthful and healthy as they age, but pet ownership may inform the treatment of social disorders.A new study asserts that the underlying chemistry in the bond between dogs as compared to the lack thereof between humans and wolves might explain things like schizophrenia and autism.A separate study maintains, though, that growing old with a dog won't increase the longevity of life.
"We think that the genetic information for social behavior is very similar in dogs and humans.There is kind of a common genetic architecture or social behavior that humans have tapped into and that has led to the most suitable dogs being chosen for domestication," according to Per Jensen, a Swedish researcher and professor at Linköping University.He runs the GENEWELL project, a fairly well known, EU-funded study of how animal physiology regulates stress responses.Parts of the project focusing on dogs have honed in on oxytocin, which is the chemical commonly referred to as the love hormone.
Experts generally understand oxytocin to strengthen the bonds between humans and animals. "Oxytocin is an extremely strong mediator of the dog-human bond," Jensen explains. "People have looked at the effects of oxytocin levels on both physical contact and eye contact and there's no doubt that oxytocin is a really important player in maintaining and establishing the cooperation and the contact between dog and owner."
They studied how the hormone operates by spraying either saltwater or oxytocin on the noses of dogs.When dogs received oxytocin, they generally responded to challenges that were too difficult by immediately turning to their owners in search of help.They asked for help more quickly than those who only got saltwater, yet scientists also observed variability in the time it would take oxytocin dogs to seek help.Oxytocin attaches to receptors in the brain, but any dog can produce any one of several different types of oxytocin receptors, which is genetically determined.
The team realized that dogs of a particular type of receptor all responded uniformly strongly to the oxytocin.Other studies have conducted similar tests on wolves, and the wolves never turned to humans for help to complete a task.With this in mind, the team got wolf DNA samples and found the same oxytocin receptors in wolves that are in dogs, which means that some wolves — those with the receptor that correlates with the strongest response—can actually have the same response with enough oxytocin.This led to the finding that wolves can actually be domesticated this way.
"My theory was that for pro-social behavior, you need both systems to interact.The oxytocin system depends on the dopamine system," Diana Prata said.She's a researcher in Lisbon, Portugal at the Instituto de Medicina Molecular, and she was also the lead researcher on the study. "There was some evidence in animal studies where they promote affiliative (relationship-building) behavior with oxytocin, but then, when they (the researchers) blocked the dopamine system, that social behavior was decreased.We are trying to also demonstrate that the two systems interact in humans."
UK researchers published the other findings of the lack of effect pet ownership on longevity of life in the British Medical Journal.The study involved 8,700 elder participants in England, a third of whom own pets.Research examined whether ownership affected 11 of the most common biomarkers for aging, which included memory and cognitive function, grip strength, walking speed, lung function and any blood-based indicators of inflammation in the lungs.
Dog ownership actually correlated with slower walking speeds for only a few meters in comparison to non-owners.Similarly, it also correlated with taking longer to rise from a chair.Many other markers were tested as well and not just with dogs.Cat owners were also tested, and they were found to fail leg raise tests more than those in other pet ownership categories. "The companionship of creatures great and small seems to confer essentially no relation with standard physical and psychological biomarkers of aging," according to the study's conclusions.
Richard Watt, epidemiologist at University College, London, found these conclusions to be "a surprise, a real surprise." Watt spearheaded the study, and he says, "There's some evidence that there is a protective effect. "As a pet owner, I can see the benefit of walking dogs, the emotional companionship a dog provides, as well as the interaction with other pet owners while out and about." Even though it appeared as though pathways were clear, "our results did not confirm our hypothesis (that pets) are a protective factor" in the aging process.
These findings diverge drastically from countless previous studies that focused to varying degrees on the alleged health benefits associated with pet ownership.Swedish researchers, in fact, just recently published a study in November in which they found that dog owners showed a measurably lesser susceptibility to death by CVD (cardiovascular disease) throughout their 12-year follow-up.