This is a little complex, but I think you’ll get it. Not all genes are equal. Some are a recipe for something like a muscle or an enzyme that helps you digest food. Others control how things develop from embryos. When these key regulatory genes give different signals, or switch on or off at different times, it makes big differences in how things turn out.

We are much more different from chimps than dogs are different from wolves. We share about 98-99% of our genes with chimps. That doesn’t mean we’re 98% chimp. It just means that we got most of our genes from the same ancestor, but some key genes are different. These genes make us very different.

Dogs have genes that make them keep some of the traits that wolves only have as cubs. They stay more playful and less aggressive. They accept humans as pack leaders. Humans started engineering wolves into dogs thousands of years ago. Some people think it happened when humans took wolf cubs and used them to help hunt and guard. They kept and took care of the ones that they liked and got rid of the ones they didn’t. Wolves with genes that made them get along with humans lived and reproduced more than wolves that didn’t. Others think it started by wolves scavenging on our trash (which was bones and food we didn’t want). Wolves who were too scared to get close to humans missed out. The ones who weren’t scared were more likely to survive and reproduce, passing on their genes.

Whichever story is true, it starts off like any story of natural selection. Each individual has their own set of genes that are different from everyone else’s (unless they have an identical twin, for example). This variation is the “raw material” of selection. It is caused by random mutations in DNA.

A researcher did an experiment where he selected for dog-like behavior in foxes. By selectively breeding ones that were less afraid of humans, he got foxes who really weren’t afraid at all. They probably had different genes that made them less afraid. After more generations, more of these genes were brought together in the same animals, so now they act like dogs.

With dogs, it is always possible that a new mutation or combination of genes will result in a dog that is not the friendly companion we expect. It doesn’t necessarily mean that a wolf gene was triggered though. What happens more often is that dogs who could have been good family pets are mistreated, making them very aggressive. Wolves are not usually aggressive to their own pack members in the wild. They have to cooperate to kill big prey, raise pups, and guard their territory. They can be very aggressive toward other wolves that try to enter their territory, though.

You may want to study animal behavior. Here’s a site on dog evolution that you may enjoy: click here

Good question. Dogs are social animals and live in social groups the same way that humans do, so that probably has something to do with it. How the first humans that had dogs came to have said dogs is something I'm not sure we'll ever know. Dogs are descended from wolves, that much we do know, so the first dogs were a lot more wolf-like than the dogs that we know now.

Scientists used to think that people tamed wolves - maybe they rescued some baby wolves that had lost their mother. Now some people think that the wolves 'tamed' us - they saw our warm fires and ate our foody garbage and decided it was a good idea to stay near us. Gradually the wolves evolved into the dogs we know today, as people kept the 'wolf-dogs' they liked and didn't keep the others.