Why is that human beings need to eat a variety of food to live, while dogs can be fed the same item and live?

I think dog food is a formula, with each bit of food containing the necessary nutritional elements to keep a dog going. Whether dogs are happy with this or not doesn't really matter since they usually don't have much choice. The same could be done for humans by combing the right proportion of the food groups into a single morsel of food and maybe some multi-vitamin elements.

Then take a bunch of those morsels and you have a bag of people food. Maybe the real difference is we humans have sophisticated palates. Not to mention the ability to shop and cook.Do you think your cave-man ancestors had a variety of foods each day?

No, they killed one saber-tooth tiger and fed off that for a month at a time. Maybe they had some berries on the side if they were lucky. You might find the Wikipedia entry for dog food helpful for more information: en.wikipedia.org/wiki/Dog_food.

First of all, we don't need much variety. We can convert anything in to energy, and that's what keeps us alive. Second, dog food isn't equivalent to, say, an orange, or steak.It has carbs, protein, and fat, and all of the nutrients the dog needs to stay healthy.

It'd be more equivalent to a blend of meat and bread with added vitamins. Humans could live off something like that with no issues at all.By comparison, eating a bowl of cereal will get you most of your vitamins, but you'll have almost no protein and fat, and you'll be missing out on things like omega 6 fatty acids, which you might not need in a large quantity, but are good for your long term health. While not directly related to this kind of question, if you really want to learn about food, I strongly recommend reading "The Omnivore's Dilemma" by Michael Pollan.

You'll find that probably 1/2 of what many people eat is essentially corn and soy. Not that much different from dog food, I don't think!

Technically, human beings don't need to eat a variety of foods. We could grind up everything that we need into Puppy Pellets, as well. We could probably even survive off of dog food.

We're just the pickier species.

Well for one dog food is designed to provide all the nutrition that a dog needs. In theory you could formulate a person food that would provide all of the nutrition a human needs... (Maybe we could call it soylent green) But We also have a more advanced brain and that brain craves stimulus. That is the reason most of us eat many different kinds of food.

There are those that subsist on a basically constant diet of things like fish and rice.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.