How could Neville NOT know they were intelligent?
Ending aside, this is what really bugged me.
They set traps, had trained attack dogs, moved stuff around and had an obviously planned ambush....... it goes on and on....... yet he never cottened on to this? To me this is what really spoiled the film. The book and the previous film versions all openly acknowledged they has a brain. It was Nevill's thought process and methodology that was the point.