It happens automatic.It could been sleep walking
They roll on their belly to show that they are subordinate. When a dominant dog walks by, the subordinate dog will roll over to show that they don't want to fight, or that they are not going to...
MotherPreacherbossfathergrandparents
It was spread through business and trading.
They are spread by squirrels, rodents and birds who bury them in store in the ground then forget them.