I definitely agree that we got ahead as a species by by increased cooperation. I'm not convinced that individually we are smarter. Average brain sizes have been decreasing since the paleolithic.
Equally the choice test offered to the foxes is not much of a guide to intelligence, it is more a guide to the ability to know what humans are testing you on. Same goes for Hare's test. It just shows dogs are bred to react to human cues.
What is equally interesting is that while we were domesticating wolves, they were domesticating us. We have been bred to react to dog cues. The next time some puppy does the big eye thing and you melt, that's why.
You will not convince me that dogs are smarter than wolves... I've seen too many dopey labradors!
None of is is to denigrate either of our species - we are a magic team in a world of surprising stories of interspecies cooperation.