Correct me if I'm wrong but Dogs are the best thing to ever happen in this world. 
Absolutely without a doubt! I love dogs. They are a member of the genus "canis" (canines), which forms part of the wolf like canines and they're the most widely abundant terrestrial carnivore!
I wonder how long they have been man's best friend?
That's a very good question, the dog was the first species to be domesticated and they have been selectively bred over a millenia for various behaviours, sensory capbilities and physical attributes. Truly a mans best friend!