Douglas Scott Falconer was born on 10 March 1913 in Old Meldrum, Aberdeenshire, and attended school in Edinburgh. While at the Edinburgh Academy, he first encountered science and found he had an aptitude for physics and chemistry. Biology was not taught, so Falconer developed his knowledge from his personal reading of works like Wells and Huxley's 'Science of Life' (1931), and, later some early genetics texts.
After leaving school, Falconer contracted tuberculosis, and spent five years recuperating. He spent much of this time teaching himself about botany and continuing his reading in genetics and biology.
In 1936, at the age of 23, Falconer began at St Andrew's University to read Zoology, and gained class medals in all subjects save chemistry. D'Arcy Wentworth Thompson was one of his lecturers, and he was so impressed with Falconer that he recommended he be awarded a degree without taking an examination. Falconer did ultimately sit an exam, and gained his degree with first-class honours.
Having been passed over for military service for health reasons, Falconer gained a scholarship to attend Cambridge University in 1940, and began to study for a doctorate under James Gray. His thesis topic was on the agricultural pest the wireworm, and formed part of Grey's research for the war effort. Falconer was instructed by his examiners to rewrite his thesis, and this hard lesson instilled in him the commitment to clarity of writing and expression for which he became well known.
After leaving Cambridge, Falconer became a temporary lecturer in Zoology at Queen Margaret College, University of London, where he also taught a course on genetics. In 1945 he was approached by the Agricultural Research Council who were looking to form a body of scientists to staff the Genetics Section of the newly formed Animal Breeding and Genetics Research Organisation (ABGRO) in Edinburgh. Before taking up this appointment, Falconer went to work wth R.A. Fisher to further develop his genetics knowledge. Here he worked on the mouse, specifically on the location of mutant genes and the inheritance of milk yield. This work laid the foundations for Falconer's later work on the mouse, gene mapping and the quantitative study of traits controlled by single or many genes.
In 1947, Falconer moved up to Edinburgh to take up his appointment at ABGRO, housed within the University's Institute of Animal Genetics. Here Falconer found himself surrounded with an energetic group of notable scientists who between them covered the entire field of genetics research at that time. Falconer was tasked with conducting quantitative research which would lead to the improvement of livestock and food production, an important national priority following the war. Laboratory animals such as mice, rabbits and Drosophila were used as cost-effective models to test theories of what might be achieved with livestock breeding. Falconer carried out various selection experiments for different traits (for example, body weight), and examined the impact of different environments on selection.
Falconer also conducted much important work on the genetics of the mouse, about which relatively little was known at this time. In 1952 he discovered the first sex-linked mutation in the mouse. Falconer's mouse mutants were used to produce the first workable linkage maps, which his colleague Toby Carter used to estimate the length of the genetics map of the mouse - an estimate which was found to be nearly accurate when proof was finally achieved through genome sequencing in 2002.
Another important area of Falconer's research was on human genetics; specifically on the inheritance of liability to disease. Falconer used the measurement of incidence of a disease in a population and in groups of known relatives to estimate the inheritance of liability.
In addition to his research, Falconer taught in all four years of the University of Edinburgh's undergraduate Biology course, and designed a three-year course on quantitative genetics. These lectures gave rise to the textbook for which he is best known, 'Introduction to Quantitative Genetics'. This was first published in 1960 and ran through a further four editions and numerous translations. It remains a standard textbook on the subject.
In 1957 Falconer was appointed deputy director of the ARC Unit of Animal Genetics (formerly the Genetics Section of ABGRO). In 1968 he took over from C.H. Waddington as the director and transferred to a personal chair in the University's genetics department. He became head of department in 1969, a post he held until 1977, when John Fincham became Buchanan Chair of Animal Genetics. Falconer officially retired in 1980 when the ARC Unit was closed down, although he continued to write and research in the department for many years.
Among Falconer's many awards and honours were a Sc.D. from the University of Cambridge in 1969, election as a Fellow of the Royal Society of Edinburgh in 1972, and as a Fellow of the Royal Society of London in 1973.
Douglas Falconer married fellow Cambridge student Margaret Duke in 1942, and they had two sons. He died on 23 February 2004.