Good stuff. I don't disagree. No doubt generational exposure and adaptation to environment can strengthen organism.
My point was only speaking to animal physiology versus plant physiology and the bioavailability of intake (i.e. what each is best suited for in an ideal or less than ideal environment).
You are what you are and what nature intended regardless of adaptational changes (in my opinion). Adaptation merely allows for survival in less than ideal world but at a cost. Those that have adapted to bad environment have also sacrificed somewhere/somehow. The organism still must recognize what it is best suited for and the habitats that make it flourish best.
In regards to humans and water, I personally do not believe we were intended to drink much water in its lone state. If you look at similar specie (primates, gorillas), they don't drink much. They get hydration primarily from plants because these sources have broken down (chelated) vital nutrients to yet another level accessible to animal phisiology (Bacteria --> Plant --> Animal).
This excessive need for water in current day is a result of excess civilization, industrialization, and commercialization, and the toll its taken on our bodies. Just my opinions.