Development of the human body used to approximately judge a child's age based on physical development. Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a boy. In response to the signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones, muscle, blood, skin, hair, breasts, and sex organs. Physical growth—height and weight—accelerates in the first half of puberty and is completed when an adult
Catholic theology of the body creation of God. God created the body like a work of art in his image. This creation reflects God’s intelligence. The human body is (eikon) somehow similar to God. To be completed as a mirror of him, is the task for every Christian. Unlike the human body, the soul is an image of God. The body cannot be an image of God, otherwise God would look like a human being with a human body. Only the soul can see God, but it is caught between the flesh and spirit. It constantly has to make a choice between the two. Origen