It could be just a useful behavior that dogs learn from other dogs when domesticated, and it might be interesting to isolate a dog from other dogs and find out if he learns barking.
(It; could be; just a useful behavior that dogs learn from other dogs; T:when domesticated) (just a useful behavior; dogs learn; from other dogs; T:when domesticated) (he; learns; barking)
It just a useful behavior he
could be dogs learn learns
just a useful behavior that dogs learn from other dogs T:when domesticated
from other dogs T:when domesticated
barking