According to the American Society for the Prevention of Cruelty to Animals (ASPCA), an estimated 78 million dogs are owned as pets in the United States.
It is unclear when dogs were first domesticated, but a study published last year claims that, at least in Europe, dogs were tamed 20,000–40,000 years ago.
It is likely that humans and dogs have shared a special bond of friendship and mutual support ever since at least the Neolithic period — but why has this bond been so long-lasting?
Of course, these cousins of the wolves have historically been great at keeping us and our dwellings safe, guarding our houses, our cattle, and our various material goods. Throughout history, humans have also trained dogs to assist them with hunting, or they have bred numerous quirky-looking species for their cuteness or elegance.
However, dogs are also — and might have always been — truly valued companions, famed for their loyalty and seemingly constant willingness to put a smile on their owners' faces.
In this Spotlight, we outline the research that shows how our dogs make us happier, more resilient when facing stress, and physically healthier, to name but a few ways in which these much-loved quadrupeds support our well-being.
How dogs keep you in good health
Many studies have suggested that having dogs as pets is associated with better physical health, as reviews of the existing literature show. These findings persist.
Just last year, Medical News Today reported on a study that showed that owning a dog reduces a person's risk of premature death by up to a third.
Why is that? It is difficult to establish a causal relationship between owning a dog and enjoying better health.
However, the benefits may appear thanks to a series of factors related to lifestyle adjustments that people tend to make after they decide to adopt a canine friend.
The most prominent such lifestyle factor is physical activity. There is no way around it: if you own a dog, you have to commit to twice daily walks — and sometimes even more.
According to a paper published in The Journal of Physical Activity and Health, dog owners are more likely to walk for leisure purposes than both non-pet owners and people who own pet cats.
The results were based on studying a cohort of 41,514 participants from California, some of whom owned dogs, some of whom owned cats, and some of whom did not have any pets.
Moreover, several recent studies — including one from the University of Missouri in Columbia and another from Glasgow Caledonian University in the United Kingdom — found that adults aged 60 and over enjoy better health thanks to the "enforced" exercise they get by walking their dogs.
"Over the course of a week, this additional time spent walking may in itself be sufficient to meet [World Health Organization] recommendations of at least 150 minutes of moderate to vigorous physical activity."
Philippa Dall, Glasgow Caledonian University
Dogs can strengthen our health not just as we grow older, but also much, much earlier than that: before we are even born.
Research published last year suggests that children who were exposed to dogs while still in the womb — as their mothers spent time around dogs during pregnancy — had a lower risk of developing eczema in early childhood.
Also, children exposed to certain bacteria carried by dogs also experienced a reduction of asthma symptoms, the researchers noted.
'Dogs make people feel good'
Perhaps the most intuitive benefit of sharing your life and home with a canine friend is that dogs give you "feel-good vibes" almost instantly.
It is really difficult not to cheer up, even after a hard day's work, when you are greeted with — often vocal — enthusiasm by a friendly dog.
This, researchers explain, is due to the effect of the "love hormone" oxytocin.
"During the last decades," write the authors of a review that featured in Frontiers in Psychology, "animal assistance in therapy, education, and care has greatly increased."
When we interact with dogs, our oxytocin levels shoot up. Since this is the hormone largely responsible for social bonding, this hormonal "love injection" boosts our psychological well-being.
Previous studies analyzed in the review have revealed that dog owners have more positive social interactions, and that the presence of canine friends makes people more trusting...and also more deserving of trust.
Moreover, dogs appear to reduce symptoms of depression and render people more resilient to stress. That is why dogs are often used as therapy animals. As researcher Brian Hare, of Duke University in Durham, NC, noted in an interview for The Washington Post:
"Dogs make people feel good, and their only job is to help people in stressful situations feel better."
Researchers hypothesize that therapy dogs can improve the psychological well-being of children going through cancer therapy, as well as help individuals diagnosed with post-traumatic stress disorder (PTSD) deal with disruptive symptoms or even prevent the onset of PTSD episodes.
What clinical research in dogs can teach us
Our canine companions could also give us clues and open new avenues of research when it comes to clinical research concerning our own health problems.
Thus, learning more about dogs' gut microbiota and how they are affected by diet could help us understand how best to tackle our own eating habits.
Like humans, dogs can also develop some forms of cancer. Much like us, dogs can get brain tumors to similarly destructive effect, so learning which genes predispose our canine companions to gliomas may also be translated into cancer research for human patients.
Moreover, a contagious form of canine cancer could shed light into how forms of cancer found in humans have come to develop.
Dogs can also experience certain features characteristic of dementia, such as impaired problem-solving abilities.
Researchers explain that by understanding how cognitive tasks are affected in these quadrupeds, we may become better equipped to solve the riddle of dementia in the case of humans, too.
"Dogs," notes Dr. Rosalind Arden, of the London School of Economics and Political Science in the U.K., "are one of the few animals that reproduce many of the key features of dementia."
"[S]o," she goes on to add, "understanding their cognitive abilities could be valuable in helping us to understand the causes of this disorder in humans and possibly test treatments for it."
Dogs are not just incredibly loveable and often very funny friends whose antics fuel the Internet's store of memes continuously; their company also keeps us in good physical shape. Also, their health problems — sadly but endearingly — often mirror our own.
Most of all, however, we welcome them into our lives — and have done so since time immemorial — because they instantly bring us the sort of joy and calm that we would otherwise have to work hard to obtain.
Author Dean Koontz summarized this perfectly in his memoir of his own much-loved dog:
"One of the greatest gifts we receive from dogs is the tenderness they evoke in us. [...] By their delight in being with us, the reliable sunniness of their disposition, the joy they bring to playtime, the curiosity with which they embrace each new experience, dogs can melt cynicism, and sweeten the bitter heart."