Dog walks in Melbourne and the Golden retriever neoteny
Firstly yes the dogs are having fun and they are testing their limits, but the reason that it becomes so easy between these two puppies is that while they each would try and play with any other puppy or most other dogs they thought would allow them - they are of similar breeds. Both in the sporting AKC category and all breeds involved in their ancestry are retrievers, particularly of the bird variety. Having this common interest means that the brain is wired similar for how to retrieve / and play and they both have relatively soft jaws so their puppy mouthing is exceptionally soft and well measured.
You will find that almost all puppies will play with all breeds of dogs, but as dogs age, they have a tendency to try and mostly play with their own type of breed, or dog group category unless they are socialised a lot more than average.
This is part of growing up, but mostly a safety thing. If as an adult you make a major play challenge to an insecure dog, you risk being bitten. If you make a play challenge to a social dog, it will still often become serious as no dog takes its pack position lightly and they will typically assume a dominant or submissive posture in the play.
neoteny = retention of juvenile features in the adult dog.Whether you know this or not, it is a major feature of why dogs have been allowed to partner with man for so long and become one of our favourite companion or domestic animals.
No other species, cat included, goes for so many walks or visits to non dog things with humans than dogs do. They are no longer just protection or working animals, they are mostly our friends in modern society, our partners our true trusted companions.
One of the main reasons that this became possible was that the big bad wolf, the large carnivore predator animal was clever enough to understand that if it partnered with humans it could get food and shelter on a regular basis. Sure it would have to give up some fun pack times, but its safety would be a lot more assured, as well as the safety of the species. Plus for some reason dogs seem to genuinely love humans.
So back to Oddie and the golden retriever playing on our dog walk. What you are witnessing here is also one of the main reasons that domestic dogs have prospered so well in modern human times. Their ability to be cute as puppies, and for adult dogs to be cute while playing as adults, has meant that their neoteny appeals to many more humans than a fierce independent wolf ever could.
Even if you could fully train and trust an adult wolf, they wouldn't always have that cuteness factor that us humans find so damn irresistible. The one that keeps dogs in our houses long after they have grown out of that puppy stage. Puppy wolves quickly grow out of the unlimited cute easy play stage and become rivals. Canine dogs don't grow out of this (except for a few very independent breeds that dont even like dog packs that much) and dogs that are not socialised regularly.
Hence why puppy play and neoteny is not just fun for humans to watch, but vital to a dogs survival as an individual and as a species ! May puppies play forever !