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 the Father, in harmony, make up the perfect human being, according to Irenaeus (died around 202). The Greek Gnosis and some Christians had looked down on the human body as inferior. Irenaeus defends the body because it is the creation of God and a negative view would cast shadows both over God and his creation. The story of creation in the book Genesis (later quoted by Pope John Paul in his lectures on the body) shows, that the first human being, Adam, was indeed an image of God. Adam had supernatural life, immortality, super-natural sanctity and a closeness to God.