We know humans get jealous, but do our dogs?
A new study is among the first to prove "man's best friend" wants to be our only friend.
Researchers at the University of California San Diego monitored dozens of dogs in their homes.
They had their owners ignore them -- and actively play with a "fake dog"... or a jack-o-lantern pail.
The owners also read a book.
They found the dogs were two times more likely to push or touch the owner when they were playing with the "fake dog".
That indicates the dog was trying to break up the connection the owner had with a potential rival.