Final answer:
Guinea pigs were domesticated in South America, particularly in the Andes region, around 5,000 B.C.
Step-by-step explanation:
Guinea pigs were domesticated in the region of South America. They originated in the Andes and have been a significant source of food and cultural importance in regions specifically like today's Peru and Bolivia. This domestication process dates back to around 5,000 B.C., making guinea pigs one of the earliest animals to be domesticated in the New World.