When you take away the selective breeding done by humans, a number of these unique traits disappear. But feral dogs don't just become wolves again - their behaviors and even looks depend greatly on the ecological pressures that surround them. Our centuries of selective breeding have opened a wide variety of traits, both physical and behavioral, that may help a stray dog survive and breed.
A good example of what happens to dogs when people are taken out of the picture lies in Russia's capital city. Feral dogs have been running around Moscow for at least 150 years. These aren't just lost pets that band together - these dogs been on their own for awhile, and indeed, any poor, abandoned domesticated canine will meet an unfortunate fate at the hands of these territorial streetwalkers. Moscow's dogs have lost traits like spotted coloration, wagging tails and friendliness that distinguish domesticated dogs from wolves - but they haven't become them. The struggle to survive is tough for a stray, and only an estimated 3% ever breed. This strong selective pressure has led them to evolve into four distinct behavioral types, according to biologist Andrei Poyarkov who has studied the dogs for the past 30 years. There are guard dogs, who follow around security personnel, treating them as the alpha leaders of their packs. Others, called scavengers, have evolved completely different behaviors, preferring to roam the city for garbage instead of interacting with people. The most wolf-like dogs are referred to as wild dogs, and they hunt whatever they can find including cats and mice.
But the last group of Moscow's dogs is by far the most amazing. They are the beggars, for obvious reasons. In these packs, the alpha isn't the best hunter or strongest, it's the smartest. The most impressive beggars, however, get their own title: 'metro dogs'. They rely on scraps of food from the daily commuters who travel the public transportation system. To do so, the dogs have learned to navigate the subway. They know stops by name, and integrate a number of specific stations into their territories.
This dramatic shift from the survival of the fittest to the survival of the smartest has changed how Moscow's dogs interact with humans and with each other. Beggars are rarely hit by cars, as they have learned to cross the streets when people do. They've even been seen waiting for a green light when no pedestrians are crossing, suggesting that they have actually learned to recognize the green walking man image of the crosswalk signal.
via scienceblogs.com