Just a quick pointer to a really interesting talk on the modern dog and recent work on the genetics, dog diseases and evolution of man's best friend.
Go to NPR Science Friday to listen or download the podcast.
There is a link to an earlier talk on evolution of dogs which is also worth listening to. Genetic and fossil data suggest domestication of dogs began as early as 15,000 to 20,000 years ago.
Here's an intriguing question. Humans have controlled the evolution of dogs, but did the inclusion of dogs in the Pleistocene human social milieu influence human evolution? Nicholas Wade in his book Before the Dawn has suggested that dogs may have helped humans make the transition from foraging to settled societies. People who settle down in one place risk being attacked and dogs who attach themselves to a owner would have been sentries keeping guard.
Did that also reduce violence in general, make us less aggressive? Human skeletal morphology has changed a bit in the last 20,000 years or so. We have more gracile features - smaller and thinner skulls, smaller teeth than earlier humans. Some experts like primatologist Richard Wrangham believes that this gracilization could have occurred if aggression was less beneficial and evolution favored pedomorphic changes i.e. retention of juvenile features in adulthood. Adult aggressive traits would have then diminished over time.
Maybe dogs had something to do with this? If we outsourced violence or prevented it because of their presence.