Voluntary acts of kindness and positive outward gestures without thought of reward are two of the more redeeming aspects of human society, but to what extent do these prosocial behaviours exist in other animals?

A new study by researchers in Austria suggests that dogs are prosocial among their own kind too, with an experiment involving the voluntary offering of food between the animals showing that dogs also understand the concept of giving.

"Dogs and their nearest relatives, the wolves, exhibit social and cooperative behaviour, so there are grounds to assume that these animals also behave prosocially toward conspecifics," said Friederike Range, an ethologist at the Messerli Research Institute. "Additionally, over thousands of years of domestication, dogs were selected for special social skills."

But measuring prosocial behaviour in dogs isn't easy, says Range, because they're so very social with humans. It can be difficult to tell between seemingly prosocial acts and behaviours that could actually just be the dog obediently reacting to cues and unintended communications from researchers.

So to take people out of the equation as much as possible, Range and his colleagues conducted an experiment where two dogs were set up by themselves in cages side by side. One of the dogs, called the donor dog, had the ability to extend one of two trays toward a receiver dog, using its mouth to pull on a string.

One of these trays contained a treat, while the other was empty. The dogs had been trained over weeks to understand how the tray-pulling system worked, and the donor dog in each instance knew that it would receive nothing itself if it gave the treat to its fellow canine (other than the pleasure perhaps of knowing it had done a kindness to its counterpart).

The researchers found that dogs, in the absence of any ulterior motive, do indeed exhibit prosocial behaviour, by voluntarily giving food to other dogs. But, having said that, they can be accused of preferential treatment.

"Dogs truly behave prosocially toward other dogs. That had never been experimentally demonstrated before," said Range. "What we also found was that the degree of familiarity among the dogs further influenced this behaviour. Prosocial behaviour was exhibited less frequently toward unfamiliar dogs than toward familiar ones."

In other words, dogs look out for their friends more than they do random strangers, but the same could be said of our own prosocial behaviour. Humans have the capacity for kindness, but we demonstrate it more frequently with those with which we are more familiar.

The findings are reported in Scientific Reports, but now that we know dogs are prosocial, that of course means there are other puzzles for the researchers to solve. Why do dogs act this way? Is it a result of domestication, their cognitive complexity, or has it been shaped by the species' reliance on cooperative activities, such as foraging together? As dog lovers, we can't wait to hear the answers.