Lots of research has indicated that having a dog or a cat can help people live happier, healthier lives. But it’s been unclear whether there really is a cause-and-effect relationship between pet ownership and better physical and mental health. Now, new research indicates that the benefits of having a canine or feline companion are real and broad.

A team of psychologists from Miami University and St. Louis University conducted a series of studies aimed at trying to tease out the benefits of pet ownership.

“Although there is correlational evidence that pets may help individuals facing significant life stressors, little is known about the well-being benefits of patterns for everyday people,” they wrote in a paper published online this week by the Journal of Personality and Social Psychology.

In the first part of the research, 217 people answered detailed questionnaires online designed to determine whether pet owners tend to be different from people who do not own pets. The survey assessed variables such as depression, loneliness, self-esteem, illness, activity level and their relationships with other people. The researchers found that, in fact, there were lots of differences, with pet owners faring much better overall. For example, pet owners tended to be less lonely, have higher self-esteem, get more exercise, be more extroverted and were less fearful about getting close to other people.

In the second part of the research, the researchers studied 56 dog owners. In addition to filling out the same questionnaire used in the first part of the study, the researchers also gathered detailed information about how they related to their dogs, and to other people. The owners tended to get the most benefit from having a canine companion when their dogs “complemented rather than competed” with humans in their lives, the researchers found.

“In fact ... we repeatedly observed evidence that people who enjoyed greater benefits from their pets also were closer to other important people in their lives and received more support from them, not less,” the researchers wrote.

Dogs that were less fearful, more active and less aggressive toward people and other animals seemed to fulfill their owners’ needs the best, the researchers found.

In the last experiment, the researchers brought 97 undergraduates into the laboratory and asked them to write about a time when they felt socially excluded and then write about a favorite pet or a favorite friend. Writing about pets was just as effective as writing about a friend in terms of minimizing feelings of rejection, the researchers found.

“In summary, pets can serve as important sources of social support, providing many positive psychological and physical benefits for their owners,” the researchers wrote.