humm, looks like that article bounce around the subject a lot and finally says little to nothing...
however!
"In the case of dogs versus cats we also have a problem, since each are specialized to do different things. Dogs are designed to be more efficient runners
while cats have better ability at manipulating things with their paws. Thus a test that involved pulling strings or operating levers would tend to favor a cat, while a test involving moving from place to place, where speed is a measure of performance, would favor a dog."
and we developed "smarter" because the opposite thumbs and the thus how we use these hands as tool and such, right?
https://youtube.com/watch?v=QrlTijuhVOA 