Final answer:
Lactose intolerance is a condition where individuals cannot digest lactose, the sugar found in milk, due to an insufficient production of the enzyme lactase. The ability to digest lactose varies around the world, with lactose tolerance being more common among Europeans and less common among Asians.
Step-by-step explanation:
Lactose intolerance is a condition where individuals cannot digest lactose, the sugar found in milk, due to an insufficient production of the enzyme lactase. This genetic defect results in symptoms such as bloating, cramps, and diarrhea after consuming milk or dairy products. The ability to digest lactose varies around the world, with lactose tolerance being more common among Europeans and less common among Asians. This variation in lactose tolerance is thought to be influenced by both genetic and evolutionary factors.