Your Dog
If the smartest dogs are the Jack Russell Terrier and Scottish Border collie and the dumbest is the Afgan hound then what does that make your dog?
Well, we have a cross Alsation, that I would say was somewhere in the middle of these two, and we also have a Saluki (Egyptian Greyhound- as in the type of dog in the Egyptian pictures)
I would say that he is very intelligent, but seems to think that he is far superior to all other dogs!
Apparently the Saluki was highly worshipped and given as an expensive gift, years ago, and was classed as 'a gift from Allah', in some circles.
Hmm... I had a Belgian Shepherd (extremely smart) and before that, a poodle (pretty smart dogs, too) but at the moment, I've got Rusty, a 1 year old mixed-breed.
He's not as intelligent as the Belgian Shepherd, but equal to the poodle. I honestly think though, that even among the "dumber" breeds, training accounts for 90% of a dog's ability to understand what you want from them (a.k.a. canine intelligence).
The smartest dog (Jack Russell?) left untrained and unsupervised, could seem like the village idiot, next to a well-trained mutt, in my experience.