I agree with all that. But I know the argument (playing devil's advocate here) then, might go like this... theory: But dogs evolved with humans for a very long time (not so long on a whole evolutionary scale, but pretty long) and when humans went from hunter/gatherer to agriculturists, settling in one place, dogs ate what humans ate and that was inclusive of carbohydrates. That is why dogs are able to metabolize grain all right. Not as well as we do, of course, but they seem to be able to break it down somewhat anyhow...not that it's necessarily good for them. Many wild dogs also scavenge from the edges of human villages... those proto dogs that are thought to be our dogs' ancestors are not feral, but domestic in the sense that they're descendants of the self-domesticated dogs that evolved from wolves... those that have been seen off the coast of Africa on an Pemba Island, for instance.
Wolves probably broke into a few groups, some of which were tamer and could tolerate close proximity to humans, where usually, with the exception of captive wolves, wolves can not eat in the presence of humans. This group or groups (different locations and types of wolves throughout the world likely) got tamer and tamer and as a result, this caused physical changes because the brain's pituitary changed with this peace loving way they were adapting... and put out more happy hormones. There is a direct link from this to smaller brain size, skull, teeth, floppy ears, unusual coat color and other such physical changes. They look more like puppies. And domesticated animals are thought to be neotenic versions of their more adult-like counterparts. Ie: We are more juvenile as adults than Chimpanzees are as adults. Dogs, as adults are more playful than adult wolves. This was all discovered as many of you might already know, during a wild fox study done by Dmitri Belyaev, a Russian scientist. The foxes that were more docile were bred. This was the only criteria for breeding....tameness. After a few generations, the foxes started developing curly tails, white in the fur, smaller teeth, jaws, skulls etc. And they were ONLY selected for docility. In social animals, tolerance pays off. They survive better and evolve when they are more tolerant and can work in numbers better. So, with these tamer wolves, evolving to become domesticated dogs after probably another or more than just one other domestication event, they also started eating what humans were eating, which included grains and some vegetables, along with some meat and bones.
I don't think 100 years, since the approximate beginning of kibble is much time for too much evolution to take place, so no, I don't think kibble is a natural food for dogs. But I question whether some carbs might be a natural food for dogs because domestic dogs' evolutionary niche is with humans, not a total hunting of prey. Now, of course, humans hunted and ate meat when they could get it, no doubt. So, naturally, the dogs that hung around ate that too. But once humans started growing grain, some researchers think that their dogs must have eaten that too. It certainly may be that it's not a necessary nutritional need or an item that makes their digestion work better. But do we really know for sure what is natural for a dog?
However, it appears that around 10,000 BC when humans started their agriculture and the hunting and gathering lessened, they also became less healthy. Archaeology evidence shows when grain was introduced, tooth decay and arthritis set in. People died younger if I recall what I read a long time ago. So, grain may indeed be the very devil himself.
I think if a dog is doing fine on their diet long term as well as the immediate condition, then that must be just fine. But I had dogs on kibble and they were healthy. My child hood dogs lived to be 18 and 15 and they were not toy breeds. We didn't even feed premium dog food. It was Purina and Gravy Train. Those dogs had loads of stamina. My Bruno use to go with my horse and me on loooooong all day trail rides. He was none the worse for wear. I had a GSD too who also, all day long went riding with us....hard running, lots of it. He was beautiful and healthy. I wonder if commercial dog food has declined in quality significantly since those days.
I'm feeding raw because I too, have seen the benefits right before my eyes. My gut (oy, bad choice of a word) tells me that what carnivores (besides Pandas) eat out in the woods is probably pretty natural. I don't trust commercial dog food companies anymore. I don't know what they put in that stuff. I believe it's dwindled over the years in quality. They don't care about my dogs like I do. They are in it to make money. And making money involves being frugal with it. So that is what they do. I am not terribly frugal when it comes to my dogs. Also, it makes sense to me that fresh, unprocessed food is healthier. It is for us and it is for dogs. They're getting lots of meat and that's what dogs need. I don't think commercial food has enough meat in it and not the best quality. So, yep...that pretty much sums it up for me as to why I feed them this way. I do see some problems with their poop but not all the time. Sometimes it's just too hard or too much mucus which makes me think colitis. Then I make an adjustment and it's all good for a few days until again, something isn't quite right. But over all, I'd say my dogs are doing well. Jose` especially...lots of really noticeable differences with that boy.
I don't think anyone knows for sure what is natural for a dog. What is natural after all? Is it what wild dogs hunt and eat in the woods or is it what almost domesticated dogs ate when living on the outskirts of human settlements as they became tamer and tamer? Are they really unsuited for a diet inclusive of some carbs? I wish I could get in a time machine and go back through time and see first hand what did those wolves eat as they were becoming domesticated. Did they get some flat bread or some berries, whatever else humans were eating? Or just an old rabbit that either they caught or a human caught for them? The human would have had to have had a good day hunting. But again, just because they might eat something doesn't mean it's good for them, right?