Final answer:
Precocious puberty in African American females is defined as puberty beginning before the age of 8 years. This includes the development of breasts and pubic hair and eventually leads to menarche, which typically occurs by the average age of 12.4 years in the United States.
Step-by-step explanation:
Precocious puberty in African American females is characterized by the onset of puberty before the age of 8 years. Puberty includes several milestones such as the development of breast tissue, the growth of public and axillary hair, and a noticeable growth spurt. Menarche, or the first menstrual period, is a significant event during puberty and in the United States occurs on average at 12.4 years but can normally range from 8 to 16 years. It is important to recognize that the onset of puberty can be influenced by a variety of factors, including nutrition, genetics, environment, and body fat levels.