They've analysed the brain size of different groups of mammals as they’ve evolved over the past 60 million years, looking at the brain and body size of over 500 species of living and fossilised mammals. The brains of monkeys grew the most over time, followed by horses, dolphins, camels and dogs.  The intelligence of “a man’s best friend” has evolved at a greater rate than the less social cat over millions of years, scientists at Oxford University have claimed. Instead, groups of highly social species have undergone much more rapid increases than more solitary species. It was often thought that the feline pet was smarter than its canine counterpart because it needed less attention but researchers have discovered that cat’s brains are smaller because they are less social. They found that there was a link between the size of an animal’s brain in relation to the rest of its body and how socially active it was.
– The latest salvo in the battle regarding the relative intelligence of felines and dogs is bound to leave cat owners howling. Researchers are now claiming that dogs' intelligence has grown at faster rates historically than cats, spurred by canines' more social nature. They've discovered a historical link between the size of an animal’s brain in relation to the rest of its body and how socially active it has been. The study analyzed data on the brain and body size of more than 500 species and found the brains of monkeys grew the most over time, followed by horses, dolphins, camels and dogs, reports the Telegraph. The analysis revealed that groups of mammals with bigger brains tended to live in social groups, while brains of more isolated animals such as cats, deer, and rhinos tended to grow much more slowly. "It appears that interaction is good for the brain," says Oxford researcher Susanne Shultz. Findings "suggest that co-operation needed for group living can be challenging and over time some mammals have evolved larger brains to be able to cope.” Is the Telegraph buying its own story? Not quite. Columnist Pete Wedderburn debunks some of the science behind the study, arguing that dogs and cats are each intelligent in their own way—and possibly more intelligent than the humans who concocted the research.