An excellent post on the very smart science blog Pharyngula adds an intriguing possibility to the argument about which are smarter - cats or dogs?
Pharyngula explains in sometimes brain-frazzling detail how the domestic cat's lack of interest in sweets and candy is defined by its genes. A mangled mutation of a taste receptor gene that normally registers the effect of sugary tastes has effectively left the gene dead and unable to function. Basically, your kitty can't experience sweets in the same way we humans do for instance, so they generally give them a wide berth. He also suggests this has happened through evolution and is common to other members of the cat family, like lions and tigers.
Now this makes me wonder whether this is proof that cats are smarter than dogs, at least when it comes to evolving successfully. Sweets, and in particular, chocolate can be highly dangerous to animals. The large doses of toxic theobromine in dark and baking chocolates can send the canine system in particular into overdrive, causing increased urination, over-excitement, muscle tremors, increased heart rate and - in the worst case scenario - fatal cardiac attacks. Yet what happens when you lob a tasty-looking chunk of chocolate in a dog's direction? Yep, the concept of death by chocolate is completely alien to it. Instead it, er, wolfs the stuff down much like its much more resilient ancient ancestor probably would. So why haven't dogs - like cats - learned any better? Given the way we've tinkered with almost every aspect of their physiognomy in the name of selective breeding, should we take some of the blame?