| In the future someone may decide to write a follow-up to Carl Sagan's classic book on human intelligence, theories of evolution and dinosaurs. If that occurs I hope someone would be able to explain what terrible thing occured generations ago to the earliest dog ancestors. I have this theory that some evil beast/bird in biege made some sort of high pitched noise (which could not be heard by man, or those who preceded man). This noise struck fear into the heart of every "pre-dog" alive, and may have been passed down through generations of canines.
At this point all that remains is some kind of distant memory inside the limbic region of dogs. Every dog I have every known responds to the sound of a UPS truck with the same catastrophic panic as a four year who finds a mean teenage cousin dressed up as a dracula/death clown in his closet.
That is to say:
AAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHH!
Whatever sound these trucks create, unheard by human ears, makes sane dogs crazy and crazy dogs bonkers.
What is it about those trucks? | 
