What is the minimum age to learn to dive?

According to PADI standards, a child can start diving when he/she is 10 years old and can do its Junior PADI Open Water. According to other standards such as FFESSM, the limit is 16 years old. There are no studies proving that scuba diving is dangerous for a 10-year-old child. However, many agree on the fact that the lungs might not be developed enough to scuba dive or at least scuba dive too much during a couple of days in a row. Many agree that a 12-year-old child is at an appropriate age to start scuba diving, or a 10-year-old, depending on the morphology of the child.