Dogs actually do have a language center in their brains. They process language just the same way we do, just not as well.
They do understand our words. This is not true of all domesticated animals (horses, for example, can only manage to distinguish a relatively small number of spoken commands…but boy do they know what you’re really saying).
They don’t understand “just your tone of voice” as a lot of people think.
As of 2016 the record vocabulary for a dog demonstrating understanding of words is over 1,000.
So if you give them a way to talk back, they’re going to use it.
The development of language skills is probably a side effect of domestication and of being kept in close contact with humans. A dog that was a better hunting partner would be kept and bred and over time they developed a better understanding of language.
In other words, dogs are pretty dang smart because we need them to understand us.
Tori