Consider thirst. We have learned growing up that feeling "thirsty" is the first sign of dehydration. In other words, if you are afflicted by thirst then is is too late - your body is not saying "now's the time to drink water", its saying "you should have been drinking more water before".
Now consider hunger. Our understanding of hunger has been denatured if not destroyed by an indulgent culture and an unnatural environment, but we can all basically concede that feeling "hungry" indicates the need to consume food. However, it is not a sign of starvation. Contrary to the need to drink before becoming thirsty, there is no need to eat before we feel hungry. Indeed, it is actually hurtful to eat unless hungry.
So our body tells us when we need to eat, but it does not tell us when we need to drink. This is extremely curious when considering that we will die after about 40 days without food, but only 3 days without water.
Begging question: If water is so critical, then why doesn't our body tell us when we need it? Why does the body prioritize food instead of water?
My conclusion is this: eating our natural diet should satisfy both hunger and thirst. Our food should contain a lot of water so that eating is also hydrating. We have no way to percieve the need for water because our hunger should effectively take care of it.
After transitioning to the raw food diet, I noticed that my water consumption decreased dramatically. I no longer drank glasses of water at a time. I didn't wake up in the middle of the night or in the morning feeling extremely thirsty. I generally do not have any extra water with meals.
When we cook or bake foods, water is being removed. This, along with much other logic, tells us that cooking is not a natural way to consume food, and any food that requires cooking in order for consumption is not part of our natural diet. These types of foods include grains. We do not posses the salivary glands in order to eat grains in its unprocessed form. Imagine trying to swallow a mouthful of flour - you would choke on it! Even eating it in its cooked form, such as bread and pasta, requires a lot of extra water to go with it. Also, the inclusion of meat in our natural diet is not disproved by this logic alone, however raw meat is very risky and even more unhealthy for us to consume. Since we know that cooking meat is not natural, we can perhaps conclude that the consumption of raw meat would only occur naturally in cases of famine, as can be observed with chimpanzees.