How Dogs Evolved Into 'Our Best Friends'

Dogs have aided humans for thousands of years. Man's best friend has provided protection, companionship and hunting assistance since the days of the earliest human settlements.

But how and when dogs evolved from wolves is a matter of debate. Naturalist Mark Derr says there are two main schools of thought: Some researchers believe that humans domesticated wolves who were scrounging around their villages for trash. Others think that humans were taking care of wolves from the time they were puppies — until enough puppies were tamed and they somehow then evolved into dogs.   More