| Smidlee said:
Continuely standing straight up also has it's disadvantage just like a sub continuely using active sonar. Thus other animals can easily see you before you see them. |
that's a pretty useless counter-example, because subs can get attacked from a great distance once they are spotted, while early humans in the "look over grass" theory would be up against feline predators (the natural predators of the savanna), which are known to only melee, so if those are spotted outside your area of danger they become useless even if they manage to spot you from out of your vision
and these predators easily give up on attacks if the chances of succeeding are bad (if they are spotted early), for burning calories or (even worse) be up against harsh defense which could lead to injuries or broken bones/legs (certain death) is stupid
