Lionel Penrose

Lionel Sharples Penrose (11 June 1898 – 12 May 1972) was an English psychiatrist, medical geneticist, paediatrician, mathematician and chess theorist, who carried out pioneering work on the genetics of intellectual disability. Penrose was initially the Galton professor of eugenics (1945–1963) at University College London, before having his title changed to professor of human genetics (1963–1965) at his request. He was later emeritus professor. At Cambridge, he gained a first class degree in moral sciences before leaving for Vienna for a year, to study at the psychological department at the University of Vienna.

Career Penrose undertook research into schizophrenia, designing tests of intelligence that were non-verbal in nature that are still in use. He was one of the earliest investigators of phenylketonuria in the 1930s.

From 1939 to 1945 he was director of psychiatric research at the Ontario Hospital, lecturer in psychiatry at Western University, and medical statistician to the province. Penrose was a central figure in British medical genetics following World War II. From 1945 to 1965, he worked as Galton Professor at the Galton Laboratory at University College London. The first title of his chair was "Professor of Eugenics" (1945–1963), then he had it changed to "Professor of Human Genetics" (1963–1965). According to his successor, Professor Harry Harris, Penrose "never liked the name 'eugenics', because it seemed to him to be too much associated with uninformed and dangerous policies of racial purification." Harris also reported the "long delay" in changing this name was due to "legal problems" associated with the original donation from Francis Galton and described how Penrose simply ignored the "eugenics" element of his job title.

Penrose, a member of the Society of Friends (Quakers), was a lead figure in the Medical Association for the Prevention of War in the 1950s.

Penrose developed the Penrose method, a method for apportioning seats in a global assembly based on the square root of each nation's population. Such a voting system is based on the idea that the voting power of any voter (measured by the Penrose–Banzhaf index) decreases with the size of the voting body as one over its square root. See also Penrose square root law.

Penrose was particularly interested in different facets of biology, for example fingerprints, demography, and cytogenetics, which were a result of his research into the etiology of intellectual disability, especially Down syndrome. He did intensive research on the latter, communicating the results of his investigations in 1963 and winning the Joseph P. Kennedy Jr. Foundation Award for his contributions to the understanding of the causes of intellectual disability.

Family

Lionel Penrose's father was James Doyle Penrose. His mother, Elisabeth Josephine, was daughter of Alexander Peckover, 1st Baron Peckover; his brother was Sir Roland Penrose, both British artists. He married Margaret Leathes in 1928 and they had four children:

Oliver Penrose, born 1929, physicist; Sir Roger Penrose, born 1931, mathematical physicist and mathematician (with whom Lionel co-authored papers on the Penrose triangle); and who shared the 2020 Nobel Prize in Physics; Jonathan Penrose, (1933–2021), chess grandmaster and psychologist; Shirley Hodgson, born 1945, geneticist.

After Penrose's death, Margaret married the mathematician Max Newman (1897–1984). She died in 1989.