One has to wonder if quietly observing animals from cover led to the discovery of new plant food sources as well. Wholeheartedly agree about water supply, most of the human population still lives within about 700 feet of sealevel.
Sure, it makes sense that animals would not eat poisonous plants. I’ve noticed my dog occasionally chews on certain plants, while pointedly ignoring the surrounding grasses.
As a prepper & forager, I’ve tried the plants my dog likes, and found them delicious, often having medicinal value.
The rule being, approach with caution, in small quantities.