The History of Dog Food

From a facebook post, edited.

Feed your dog good food, not dry food every meal. Even canned dog food is chopped up throwaway parts, fat, gristle.  A good meal for a dog is meat, brown rice and a vegetable. Milk and egg. They really like vegetables, especially cooked broccoli, carrots, sweet potato. You want to baby them? Put a little butter on the veggies.

 Don't forget the fat, gristle, and skin you throw "under the table". Dogs lived on that and other human garbage ever since they quit hunting as wolves.  At some point in history, a subset  of wolves, found it easier to live off the garbage of humans, a pretty messy bunch, who even then left offal, gristle, bones, and half eaten meals in their dumps which were the on the edges of their settlements on non-arable land.  These "follower" wolves lost the ability to hunt with a pack, and avoided humans by barking instead of howling.  They barked to alert the herd, no longer a pack, to intruders for mutual protection, but also alerted the smart, well-armed humans to dangerous intruders animal and human.  The follower wolves kept dangerous wild animals away from the dump and therefore the settlements, lived off of and cleaned up the human leftover food to the mutual benefit of both species.  In the beginning the follower wolves were still vicious wild animals, but learned to avoid the well-armed humans and were tolerated for their garbage collection and warning behaviors. 

 Hat tip to Jon Franklin for much of the above.   From there to The Wolf in the Parlor and under the table you will have to read his book of the same name.  Available at https://www.amazon.com/Wolf-Parlor-Came-Share-Brain/dp/0312662645 and elsewhere.
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 Animal food is the invention of the white flour industry to use the nutritious parts of the grain they throw "under the table."  

 In the late 19th century the big flour mills in the Midwest had a shelf life problem for their traditional whole grain flour.  The shelf life was too short to get the product to the population centers on the East Coast. Their solution was to separate the germ which was the spoilable part before final milling to create the standard American "White bread" flour.  

Once separated from the whole grain the germ spoils rapidly unless processed and the flour mills had trainloads of the stuff to get rid of.  Dumping was not an option as rotten grain germ is a smelly nuisance. Animal food processors and cereal producers had the ability to steam process the germ into stable pellets and flakes for later consumption and white flour became economical to produce. 

 An amusing industry sprung up arbitraging trainloads of short lived germ as they went from the mills to the germ processors.  Neither the mills nor the germ users could afford an interruption in the supply chain, but of course wanted the best price at their end of the chain.  The arbitrage involved the timing of the trains.  Guess right and the processors bought high, guess really wrong and you had a trainload of garbage to clean up.