I found this little tidbit of information recently. Did you know that wolves, and other wild relatives of the domestic dog do not bark as adults? It’s true that they bark during their adolescence, but as they grow into adults, they no longer bark.
Domestic dogs, on the other hand, bark all throughout their lives, as we all know.
I have found various reasons for this, and they are all theories. Basically, man became friendly with wolves many thousands of years ago, and they of course befriended those that were less aggressive toward man, but still capable of warning man of any danger. Over time, man continued to choose wolves that were more playful, and that were capable of bonding with man.
These are considered adolescent traits, or puppy traits. And, since adolescent wolves do bark, over time they evolved into the playful, friendly, and barking dogs of today.