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).