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
Institute for the Study of Human Knowledge Institute for the Study of Human Knowledge The Institute for the Study of Human Knowledge (ISHK) is a non-profit educational charity and publisher established in 1969 by the noted and award-winning psychologist and writer Robert E. Ornstein and based in Los Altos, California, in the USA. Its watchword is "public education: health and human nature information." Robert Ornstein, psychologist, writer and professor at Stanford University, founded and chairs ISHK. He has published over 25 books on the mind and won over a dozen awards from organizations over the years, including the American Psychological Association and the United Nations Educational, Scientific