Humans and dogs have lived side-by-side for centuries, and new research has given us even more insight into the feelings of man's best friend .

Researchers at Kyoto University's department of psychology in Japan have worked out that dogs - as well as some species of monkey - have an almost human-like sense of morality.

During a series of experiments, they found that our canine chums were less likely to interact with anyone they perceive as acting rudely or unfairly.

The Japanese team set up three experiments and documented their findings in the journal Neuroscience & Biobehavioral Reviews .