MAN CHANGE. DOG,NO.
In today's day and age it seems like the propensity for dogs to act 'aggressive' or in aggressive manors is increasing. Or is it? Shelters are more full now then they've ever been with biting, destructive neuroticism and other problematic dogs.
There are so many dogs in kennels that contracted companies come in with garbage trucks; throw 10-15 mutts in an airtight gas dumpster, gas them like vermin and then drive away after collecting their much needed pay. Maybe it isn't so much that dogs are changing...maybe we are. Two hundred years ago we did'nt even have zip codes. Some other things that weren't around were computers, doorbells, Las Vegas, NASA, nuclear weapons, credit cards, big box stores, plastic surgery and...Starbucks... to name a few.
Lets face it, modern technology is awesome and with everything we have available, at such expedience, its safe to say human lives are becoming easier and easier. Faster and faster. expendable and expendable. With a cushy way of living sometimes comes softness. Lets take a trip back just sixty years ago, When world wars were in their prevalence.
The first polaroid camera was invented, 45" records and the Volkswagon bug arrived. Men smoked drank and fought, for real. Women could dance and knew 100 recipes off the top of their heads. They could hem a skirt, cook a roasted chicken while ironing and taking care of 9 kids with a two inch ash on the end of their Lucky Strike. And they sure as hell didnt care what you thought about them- their confidence only took a back seat for the family they cared for.
Sixty years ago you didn't see dogs in strollers, car seats and baby pouches. Nor did they wear crew sport neon jogging apparel. No one knew what gooberlicious peanut butter dentastix were. There was no need for anti-stress wraps, coats and superficial accessories. No one knew what wee wee pads, treat bags or plastic clickers were. Sixty years ago you needed: one bowl, one leash, one collar.
Emotional burdens and superfluous judgement was a lot lower then it is today. People were oak, and could give two shits what you thought of them or their personal business. What you see today is a fear in people. A fear of reacting and conducting oneself in order to get a desired result. A fear of direction. A fear of judgement. A fear of being cocksure and brassy.
So I don't think dogs have changed. I think people have changed. Today we are at a constant rate of evolution. Dogs on the other hand are far far away from discovering technology. And as such, remain very much the same as they were 20,000 years ago. It will always be hard to change the behavior of any organism, no matter what the species, if one fails to see things on their level and communicate accordingly.
An animal who pees on car tires, licks his anus and eats poop isn't going to understand that just because 'he's mommy's special angel' he shouldn't bite somebody, jump up with poopy paws, or growl when you try to take his precious snuggle toy.
No species will ever be able to fully understand its own species. As the more enlightened navigator of cognitive abilities it is important for us to remember what the world is now; to quote philosopher Jiddu Krishnamurti ,with all its misery, conflict, destructive brutality, aggression and so on. Man is still as he was. Is still brutal, violent, aggressive, acquisitive, competitive. As is dog.
Societies, morals, laws and formalities will come and go, but rest assured; The code of survival will remain the same for our dogs as well as us for many millenniums to come. Do not be afraid of progressing to the level of a dog in order to better understand him. I say progressing in better terms as opposed to regressing.
Human is very far from the top of the totem pole by natures standards, from which we judge all other life forms as being beneath us. As brilliant minded as we may be at inventing things to make our lives easier, in the natural world we are small, hairless, weak, slow maturing, extremely dis-evolutionized mammals. Many of us incapable of surviving without modern novilties.
Never be afraid of a gut instinct, of simplicity, of thinking so basic as a dog would, that it almost can feel vividly astute. When you look at your dog laying on the floor over there, do not look at him as something less, but instead something entirely different, on the same level.