One aspect of development during adolescence is puberty. Puberty is accompanied by hormonal changes, body growth, sexual maturation, and motor development. There are individual and group differences for when adolescents go through these changes. For example, the average age of menarche in the United States is around 12 to 13 years of age, but in Africa the average range for menarche is about 14 to 17 years old.
What do you think contributes to the difference in when girls begin their menarche between the United States and Africa, or other countries?