Science

I have been obsessed with dog science since 2006 or so when a good friend worked for Dr Bonnie Bergin and I spent a couple days at her facility. Bergin was a grade school teacher before she moved on to training assistance dogs for mobility and hearing impaired humans. She destroyed "alpha dog" theory and beat training methods that were based on that idea.

Bergin is the one who got me into hand signals and sign language. Bergin trains 120 verbal requests and 90 hand signals by 8 months of age using very positive methods and emotional connection, not intimidation.

Bergin specifically focused on helping people with physical challenges live independent lives as she saw while on vacation in Mexico IIRC. Eg. peddlers with donkeys. She knew that she needed dogs which were smart enough to be helpful yet not so actively inquisitive as to be bored or self-entertaining if they need to lie beside a wheelchair for extended periods of time. She began breeding dogs for that combination and now uses a cross that is American Lab x English Golden Retriever. She was keen to avoid some of the common physical issues in these breeds such as hip dysplasia. She got all kinds of grants and support. Bought a former grade school and has operated the only accredited college of canine studies for many years now.

https://www.berginu.edu/meet-dr-bergin.html

My view and experience is that different dogs show their intelligence in different ways depending on their temperament and physicality. Border collies and poodles are famously good with language. Huskies are uncanny in their ability to speak words but every dog and very "breed" has a unique way of expressing their intelligence. IOW some aren't less intelligent just because they aren't keyed into audible human language. I tried not to tell strangers that my dogs were deaf because the dog can feel pity and that isn't positive or warranted. They mostly did not miss anything by being deaf. If anything, they were more focused. And I prefer sign language even with hearing dogs because it is clearer to them.

Dog science has been red hot over the last two decades in part because so little real science had been done before. Much of conventional wisdom about dogs is/was wrong.