Feh.
I’d go as far as saying that some breeds have as much intelligence as a 2-yr old child.
I’d be willing to say my dogs have more intelligence than my Congresswomen and Senators!
We will tell our Maltese-yorkie-poo to go get the ball, and she will run into another room and locate it and bring it back.
That’s intelligence beyond even six months.
Then the two inherited Chihuahuas from my wife’s family aren’t intelligent enough to let us know they have to use the restroom. So, it depends on the breed.
Without a doubt. My dogs actually have a list of known words as long as my arm that must be spelled in front of them! The people that did this study need to find some smarter dogs. Sheesh ... 6 months?