Actually, dogs have been living with us for 40 000 years or more, according to recent descoveries. They are scavengers, and evolved from early grey wolves which were way more inclined to scavenge than wolves are now. Dogs, having lived with humans, would get whatever humans threw for them, as well as what they could find for themselves. their digestive system has not evolved from being a carnivores, however they have evolved enough to not need Taurine in their diets, the way thet true carnivores (like cats) do. They have changed enough to be able to survive on a vegitarian diet (though it's definately NOT what's best for them), and though they they certainly don't NEED them, veggies, fruit and herbs do have vitamins and minerals that are definately benificial, and they can use and absorb these if they're cooked or pureed (in the case of veggies, fruit doesn't need it). How many poor farmers and peasants in history would share much of the meat they could barely afford, what would dogs have ate then? They were certainly kept by these people for their usefulness, but would have eaten the cerials, potatoes and other cheaper veggies and grains that farmers would have fed their families on, with the odd rodent or small animal they managed to catch or scavenge for themselves. Dogs would not have survived if they didn't adapt to being able to eat, absorb and thrive of diets consisteing of mainly veggies, starches and grains. So although they do not specifically NEED them, it's truly benificial for them to get them.