Dogs are smarter than cats, say Oxford University researchers in the journal Proceedings of the National Academy of Sciences. All socially active species — including dogs, monkeys, dolphins, and horses — have developed larger brains over time than solitary ones like cats, deer, and rhinos. But does this really settle the long-running fight over the relative intelligence of cats and dogs? Here's a guide to the debate:

What did the study actually find?
The Oxford team looked at how 500 species, both living and fossilized, have evolved over about 60 million years. The ones that lived in social groups had much larger brains, relative to body size, than those species that tend toward self-sufficiency. "Dogs have always been regarded as the more social animals" while cats often go it alone, says lead researcher Susanna Shultz. That social interaction requires larger brains.

What about socializing builds brain power?
Shultz's team hypothesizes that the cooperation and coordination necessary to live as part of a group is more mentally challenging than making do on your own, and brains have evolved accordingly among different species.

Are cat partisans buying this?
Nope. "The domestic cat is highly intelligent thanks to its wild ancestry," says Beth Skillings, a veterinarian with Cats Protection. "Unlike dogs, they are smart enough to hunt alone and don't have to depend on others." Felines are also "very successful at subtly training their owners" by purring, meowing, "and sitting pitifully by their food bowl!"

Are there other studies to back up the Oxford team?
Yes. A 2009 study in the journal Animal Cognition similarly declared dogs smarter than cats, says Pete Wedderburn in The Daily Telegraph, based on a test in which cats and dogs pulled on strings to get a reward. "Dogs performed better," he says, but like the Oxford study, the string test doesn't "prove" that dogs are smarter. Dogs have bigger brains, but cats have 300 million neurons in their cortex ("the thinking part of the brain"), while dogs have 160 million.

What do neutral observers say?
When pet expert Steve Dale poses the cat-vs.-dog question to audiences at veterinary conferences, he says in The Daily Pilot, the votes are pretty evenly split: About "30 percent bark for dogs, and about 40 percent yowl for cats," while the rest say the species are the same. "Cats and dogs are smart in different ways," agrees Wedderburn, and both species are smarter than "the folk who issue press releases on behalf of researchers." 

Sources: Daily Telegraph (2, 3), Daily Mail, Daily Pilot, Laconia Citizen