I just ran across this while down the rabbit hole (ie searching a topic for an hour or so). It's 3 yrs old, but a good read.
I have really scoff and gag at the money-grubbing push of breed specific dog food. They are pure hype and greed. However, it's interesting to know that non-agricultural vs agricultural societies resulted in dogs having different abilities to use starch . I am not sure how significant that is for diet, but I'm sure one day they'll find out. (I do know some breeds have diet needs .. like Dalmatians predisposition to forming crystals).
http://www.futurity.org/dogs-evolved-people-started-farming/
This is very interesting. Thanks for sharing!
I love genetics and DNA. 
I had learned all the 30 yrs or more of wolf/dog theories, only to have them squashed by DNA. Learn new things.. I'm good with that.
http://www.sciencemag.org/news/2017/04/where-did-your-dog-come-new-tree-breeds-may-hold-answer
On wolves btw... our current wolves are not the ancient wolves dogs came from:
Wolves provide no clarity. Grey wolves used to live across the entire Northern Hemisphere, so they could have potentially been domesticated anywhere within that vast range (although North America is certainly out). What’s more, genetic studies tell us that no living group of wolves is more closely related to dogs than any other, which means that the wolves that originally gave rise to dogs are now extinct. Sequencing living wolves and dogs will never truly reveal their shrouded past; it’d be, as Larson says, like trying to solve a crime when the culprit isn’t even on the list of suspects.<<
https://www.theatlantic.com/science/archive/2016/06/the-origin-of-dogs/484976/
