Why did 40% of the human population evolve to tolerate lactose

Answer 1

It is believed that the ability to tolerate lactose evolved in some populations due to the domestication of dairy animals such as cows, goats, and sheep. Consuming milk and dairy products provided an additional source of nutrients and calories for early humans, especially in times of scarcity. Over time, individuals with a genetic mutation that allowed them to digest lactose beyond infancy had a survival advantage and were more likely to pass on their genes to future generations. This led to the spread of lactose tolerance in populations that traditionally practiced dairy farming or consumed dairy products regularly.