The domestic dog (Canis lupus familiaris or Canis familiaris) is a domesticated canid which has been selectively bred for millennia for various behaviors, sensory capabilities, and physical attributes. 

Although initially thought to have originated as a manmade variant of an extant canid species (variously supposed as being the dhole, golden jackal, or gray wolf), extensive genetic studies undertaken during the 2010s indicate that dogs diverged from an extinct wolf-like canid in Eurasia 40,000 years ago. Being the oldest domesticated animal, their long association with people has allowed dogs to be uniquely attuned to human behavior, as well as thrive on a starch-rich diet which would be inadequate for other canid species. 

Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are a source of meat.
How long has the domestic dog been bred?
Do dogs perform a lot of roles for people?
What's an example of one?
How about another example?
Do dogs get along with law enforcement?
What about with the military?
Are they better friends to women or men, according to their nickname?
Can you eat a dog, according to some cultures?
When were extensive genetic studies conducted?
How long ago did the dog diverge from a wolf-like ancestor?
Where?
Is the dog the oldest domesticated animal?
Would they be able to thrive by eating stuff like pasta, potatoes, and other starchy foods?
Would such foods be good for other canid species?
What does a dog do to handicapped invididuals?
How many attributes have dogs been bred for?
Are dogs actually related to the golden jackal or gray wolf?
Can a dog pull a load like a sleigh?
Have dogs had any impact on human society?
How many roles do dogs perform for people?
for millennia
has been selectively bred for millennia
yes
Dogs perform many roles for people
hunting
 such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals.
herding
such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals
yes
assisting police and military,
yes
assisting police and military,
men
nickname "man's best friend"
yes
In some cultures, however, dogs are a source of meat.
during the 2010s
 extensive genetic studies undertaken during the 2010s
40,000 years ago
extinct wolf-like canid in Eurasia 40,000 years ago
Eurasia
indicate that dogs diverged from an extinct wolf-like canid in Eurasia 40,000 years ago.
yes
 Being the oldest domesticated animal
yes
as well as thrive on a starch-rich diet which would be inadequate for other canid species. 
no
which would be inadequate for other canid species. 
aid them
 aiding handicapped individuals
various
 various behaviors, sensory capabilities, and physical attributes.
no
(variously supposed as being the dhole, golden jackal, or gray wolf),
yes
 pulling loads
yes
This impact on human society
Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals
Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals