James Mourilyan Tanner, (1 August 1920 – 11 August 2010) was a British paediatric endocrinologist who was best known for his development of the Tanner scale, which measures the stages of sexual development during puberty. He was a professor emeritus of the Institute of Child Health at the University of London. Biography Tanner was born on 1 August 1920 in Camberley, Surrey, United Kingdom and was educated at Marlborough College and University College of the South West of England. His family travelled widely while he was a youth because his father, a soldier in the British Army, was stationed in various locations. Tanner was a top-ranked hurdler who might well have participated in the 1940 Summer Olympics which were to be held in London, but were cancelled after the outbreak of World War II. He decided to become a doctor and not follow his father into the military after his brother was killed early in the war. He attended St Mary's Hospital, London, under a scholarship in which he instructed fellow students in physical education. He went to the United States to complete his medical studies as part of a group of British students funded by a grant from the Rockefeller Foundation. He met his first wife, fellow physician Bernice Alture, while at the University of Pennsylvania School of Medicine and performed his internship at Johns Hopkins Hospital. Tanner oversaw a study initiated by the British government at an orphanage in Harpenden starting in 1948. While the study had originally been planned to study the effects of malnutrition on children, Tanner charted and photographed the growth of the children in the study over a period of several years, developing the Tanner Scale, which measures sexual maturation in adolescents based on characteristics that can be objectively measured, including size of the genitals and the quantity of pubic hair. The data gathered led to the development of the modern growth chart, used by paediatricians around the world to monitor the pattern of growth in children through adolescence, with separate curves measuring the growth trajectory for boys and girls identified as maturing early, normal or late. Based on his research, Tanner noted that 90% of an individual child's adult height is based on genetic factors, but that the environment is the key factor when thousands of children are studied. By studying the growth characteristics of large populations, Tanner concluded that community-wide data on