John Thoday was one of Britain's most distinguished geneticists. Having, in the 1940s, made an important contribution to our understanding of how radiation affected chromosomes and induced mutations, he rose through the academic ranks at the University of Sheffield and founded its Department of Genetics in 1954.

He then switched his field of research from radiobiology to quantitative and evolutionary genetics, and helped to lay the foundations for our modern understanding of the genetic basis of many complex human diseases, such as heart disease, obesity and mental disease.

Appointed to the Arthur Balfour Professorship of Genetics at the University of Cambridge in 1959, he developed his initially tiny department into an internationally respected centre of research that made his discipline central to the teaching of biology in Cambridge.

John Marion Thoday was born in Chinley, Derbyshire, in 1916. He was the third son of the botanists Professor David Thoday, FRS, and Mary Gladys Thoday. His early years were spent in Cape Town, where his father had been Professor of Botany. When he was 6 the family moved to Bangor, on the appointment of his father to the chair of botany in the University of North Wales.

Much influenced by his father, Thoday was interested in botany from a young age, making a collection from a hybrid swarm of primula in Normandy when a schoolboy. He read botany at Bangor, graduating in 1939.

Thoday was stimulated by reading the revolutionary work on cytology by Cyril Darlington, which he learned first hand at a summer school at the John Innes Institute in 1938. He entered Trinity College, Cambridge, to study for a PhD in the Botany School in September 1939 under David Catcheside.

It was not a good time to start a PhD, and Thoday soon joined the RAF to work in aerial photographic intelligence. Posted to the Middle East in Cairo, then to Algiers and subsequently to Italy, he was commissioned as squadron leader in May 1944. He worked as a liaison officer on photographic intelligence, reporting to, among others, Enoch Powell.

Like many of his generation there were times when he gave the impression that these were the best years of his life, and 20 years later he would talk about his experiences in the Mediterranean and Middle East with enthusiasm.

He was demobbed at the end of 1945 and returned to his academic career. His first appointment, in 1946, was as a radiobiologist at the Mount Vernon Hospital and Radium Institute at Northwood. Radiobiology was, of course, a field in urgent need of development at the time, so little being known about the biological effects of radiation. The UK was lucky enough to have some very distinguished radiobiologists, three of whom, Douglas Lea, L. H. Gray and John Read, influenced Thoday greatly.

At Mount Vernon he studied the effects of radiation on chromosome breakage, and discovered the so-called 'oxygen effect', the fact that X-rays are much more effective in causing chromosome breakage in the presence of oxygen.

This was a significant achievement and revolutionised our understanding of the ways in which ionising radiations caused chromosome breakage and induced mutations.

In 1947 Thoday moved to Sheffield, as an assistant lecturer in cytogenetics in the Department of Botany. He achieved his PhD the following year. He then began to teach genetics to students of both botany and zoology.

Over the next decade he rose through the academic ranks in Sheffield, founding its Department of Genetics in 1954. He also changed his field of research dramatically, from radiobiology to quantitative and evolutionary genetics.

In 1953 he had published an important theoretical paper, Components of Fitness, which emphasised the importance of genetic variance for evolutionary potential.

Inspired by a review by Kenneth Mather, attention to which had been drawn by one of his first brilliant students, Ralph Riley, Thoday initiated an experimental programme using the fruit fly Drosophila to study genes mediating continuous variation.

Hitherto such genes, influencing such characteristicss as human height or crop yield, had been considered refractory to conventional genetic analysis: they were known as 'polygenes'.

Research by Thoday and his students in the decade from the mid-1950s overturned accepted opinion. Working with seemingly esoteric characters, such as the number of hairs on the side of a fly, Thoday and colleagues developed genetic methods to 'locate polygenes' on the genetic map. Esoteric these characters may well have been, but this work was seminal to developments, two decades later, in human genetics.

These new methods, grounded in those developed by Thoday, are now called quantitative trait locus (QTL) mapping, and are fundamental to our understanding of the genetic basis of many complex human diseases, such as heart disease, obesity and mental disease.

His highest research output occurred at a time of great productivity in genetics. It was a period when there was great innovation in the methods applied to research in genetics and allied disciplines. Thoday and a few others stood out because they were not merely genetical technicians but also philosophers of the subject as well as experimentalists. He was better able than most of his contemporaries to fit new findings into their broader biological contexts. In particular, he was deeply concerned with genetics of human society and with the genetical consequence both of the stratification of society and of its corollary, social mobility. Few at that time took such a total view of genetics.

Genetics in the UK was first established in Cambridge, with the work of William Bateson and his colleague Reginald Punnett. Punnett was the first holder of the Arthur Balfour Professorship of Genetics, established in honour of the politician in 1912. But it cannot be said that the study of genetics flourished under his leadership, which lasted until 1941 when the great statistician and geneticist R. A. Fisher succeeded him. Fisher achieved much but did not manage to establish the study of genetics as core in the biology curriculum.

On his retirement in 1960 the electors to the chair were faced with a problem. One obvious candidate, Guido Pontecorvo, turned them down; one not so obvious, Francis Crick, the electors, in particular C. D. Darlington, turned down. The electors were deadlocked. The statutes of the University of Cambridge, of course, allow for just such an eventuality: Statute D, XIV.20 (b)1 allows for the Chancellor of the University to appoint to a Chair. Apparently on the advice of Kenneth Mather, Lord Tedder, the Chancellor, appointed Thoday.

The Arthur Balfour endowment owned a house on Storey's Way that had been both the residence of the professor of genetics and the home of the department. Thoday negotiated the sale of this house to the newly established Churchill College and the move of the department to the old Vet. School on Milton Road - 'half way to Ely'. This site had obvious disadvantages: it was, by Cambridge standards, very remote from other departments in biology. Yet it had large grounds and outbuildings, suitable for experimental work with plants and animals, a productive orchard and a fine croquet lawn. It also had a local pub to which the entire department would retire for lunch to play darts (and heaven help anyone who bettered the professor) and drink beer.

Thoday's appointment in 1959 came at an opportune time. Change was in the air, in particular a radical reform in the teaching of biology. This was just the opportunity that genetics needed, and Thoday, with his experience of jointly teaching botanists and zoologists in Sheffield, immediately threw his energies into these reforms, which took effect in the mid-1960s. For the first time the teaching of genetics had its rightful place alongside zoology, botany and biochemistry in the first two years of the Natural Sciences Tripos.

At the time Thoday assumed the Chair of Genetics in Cambridge the department was minuscule. His great achievement over the next two decades was not only to make it central to the teaching of biology in Cambridge, but also to make it into a leading research department. To do this he made some interesting and difficult decisions.

The Medical Research Council's Laboratory of Molecular Biology (LMB) had outgrown its space in the Cavendish hut in the centre of town. Opposition from the Department of Biochemistry meant that no other space in town could be found for it, and Thoday offered space on Milton Road (which already housed another MRC institute, for nutritional research). In the event that was not to be, but it established good relations between Genetics and the LMB, who provided teaching in the extraordinarily exciting field of molecular biology for many years. This allowed Thoday to use his scarce resources in other fields. This he did, establishing a strong tradition that the department, unlike so many others in the UK, gave a very broad education in genetics, from molecular biology to population genetics, from cytology to human genetics.

The geographical isolation of the department on Milton Road was clearly a barrier to interdepartmental collaboration. Luckily, in 1975, the move of the Cavendish Laboratory to West Cambridge freed space on the central sites, and Thoday succeeded in moving the department to the centre in 1976. During this period he served the university as a member of the General Board, being an effective chair of its important Needs Committee. These obligations naturally made it more difficult for him to continue his own research, but he vicariously enjoyed and encouraged the work of his younger colleagues.

Thoday was elected to the Fellowship of the Royal Society in 1965 and was president of the Genetical Society from 1975 to 1977. A cheerful, ebullient man, he has left a mark on genetics and on the teaching of biology in the University of Cambridge.

He is survived by his wife, Doris (nee Rich), a sociologist and a Fellow of Lucy Cavendish College, and by one son and one daughter.

Professor John Thoday, FRS, Arthur Balfour Professor of Genetics, University of Cambridge, 1959-83, was born on August 30, 1916.

He died on August 25, 2008, aged 91

Genetics is now so influential that it is easily forgotten that it is a relatively young branch of science, and many of those who established its present importance were active in research only from the 1950s onwards. One of those individuals was John Thoday, former professor of genetics at Cambridge University, who has died aged 91.

He was born in Derbyshire to botanist parents who inspired his interest in the subject from an early age. When he was six, the family moved to Bangor on the appointment of his father, David, to the chair of botany at the University of North Wales. John went on to read genetics there, during which time he developed an interest in the genetic basis for heritable variation. Graduating in 1939, he began study for a PhD at Trinity College, Cambridge.

The timing was not good. His studies were interrupted by war service in aerial photographic intelligence for the RAF, which took him to postings in Cairo and Algiers. In later years he would relish recounting his experiences of the heat, the dust, the flies and the chaos and confusion of war, but also of the camaraderie enjoyed by many of his generation who served.

Demobbed with a commission in 1945, he resumed his academic studies, gaining his first job the following year as a radiobiologist at Mount Vernon hospital in Hertfordshire. This was just after the bombing of Hiroshima and Nagasaki, and the realisation that science urgently needed to know more about the effects of radiation. While at Mount Vernon, Thoday made the significant discovery that the presence of oxygen increases the ability of X-rays to break and damage chromosomes.

In 1947 he moved to Sheffield University where, over the next decade, he began research into the basis and evolutionary significance of differences between individuals, establishing his reputation. He published an important paper in 1953 on the genetic components of fitness for evolutionary survival, initiating a research programme using the fruit fly drosophila, aimed at locating those genetic factors which contributed to the continuous variation of characteristics such as height, weight or crop yields. Working with such seemingly esoteric characters as the number of hairs on the side of a fly, genetic methods were developed to place such polygenes on the genetic map. The principles and concepts developed in this work were seminal to developments 20 and 30 years later in human genetics.

Having established a department of genetics at Sheffield, Thoday moved to Cambridge in 1960, to the Arthur Balfour professorship. His brief was to build up the department, and despite opposition from many colleagues to his championing what to them was an upstart scientific discipline, he was brilliantly successful. When he retired in 1983, he presided over a thriving research department and had played a significant role both in university administration and as a fellow of Emmanuel College, where he is still remembered as a keen bowls player.

Perhaps his greatest contribution was in highlighting the fundamental importance of genetic differences between individuals in understanding how biology and evolution actually operate. From the 1960s until fairly recently, genetics was divided into two camps. In one camp were molecular biologists who were fascinated by trying to understand the molecules that drove heredity, the structure of DNA and how that information in DNA was expressed in cells and organisms. In the other camp were population biologists who were primarily interested in genetic differences and how these drove the processes of evolution and natural selection. Thoday maintained that although a student might choose to specialise in either the molecular aspects or the whole organism aspects of the subject, they should always be able to understand what the other camp was talking about.

This breadth of approach is particularly relevant today, when DNA sequencing technology allows investigation of genetic variation directly at the DNA level and has brought the molecular techniques into population and evolutionary studies, most notably through the human haplotype mapping project and its successors. This interaction is having a huge impact on our studies of human disease, plant and animal breeding, and of our understanding of the mechanisms that drive evolution. Although the technology for investigating these problems has changed, the concepts that underlie this research were originally set out in the 1950s and 60s by Thoday and others in the same field. His contributions were recognised by his election to a fellowship of the Royal Society in 1965. He served as president of the Genetical Society from 1975 to 1977.

Thoday had a penetrating intelligence and relished the cut and thrust of debate on a wide range of topics. He described himself as an old-fashioned liberal, who believed in democracy despite its defects, and he had a lifelong contempt of and scepticism for views which depended on dogma. In terms of the classic nature versus nurture debate, his understanding of the complex interactions between genes and the environment made him despair equally of genetic determinism and of those who contended that environment lay at the root of society's problems. At a time when many university professors were aloof and distant figures, he could regularly be found in the bar of the local pub playing darts with his staff and research students. Cheerful, ebullient and convivial, he left an indelible mark on genetics.

He is survived by his wife, Doris, a sociologist and Fellow of Lucy Cavendish College, and by a son and daughter.

John Marion Thoday, geneticist, born August 30 1916; died August 25 2008

The Telegraph

15th Sept. 2008

Geneticist who was committed to an experimental approach which provided a foundation for evolutionary theory.

Professor John Thoday, who died on August 25, was Arthur Balfour Professor of Genetics at Cambridge University between 1959 and 1983 and made important contributions to the debate about the interplay of genetic and environmental factors in the process of evolution.
Thoday was committed to an experimental approach to genetics, and he focused his research on the way in which individual species adapt and respond to their environment - a foundation for understanding almost all ecological and evolutionary processes.

Until the 1950s, most evolutionary theorists argued that animal and plant populations can accumulate significant genetic differences only when they are geographically separated to prevent gene exchange. Thoday, however, proposed that selection for adaptation to different 'niches' within a single locality - 'disruptive selection' - could lead to the development of significant genetic differences and even to the development of new species.

In the 1960s, working with JB Gibson, Thoday selected two groups from a single culture of the common fruit fly, Drosophila melanogaster, differentiated by high and low bristle numbers. Although the groups were allowed to interbreed freely, they continued to show significant genetic divergence in subsequent generations, dividing the population into two partially isolated groups.

Genetic separation, Thoday reasoned, was not required for divergence to occur. Instead, divergence might occur in response to such localised mechanisms as the different flowering times in two groups of plants in the same field, or environmental factors, such as the presence of toxic waste near a mining site.

Subsequent modelling supported the feasibility of a disruptive selection mechanism, but all attempts to repeat the outcome of the experiment have failed and the theory of speciation by disruptive selection remains controversial.

Thoday was appointed to lead the genetics department at Cambridge at a time when it was still in its infancy. Though it had been founded in 1912, the university authorities had considered genetics too marginal a subject to include it in the mainstream Part I undergraduate syllabus and the department itself operated on a shoestring from a house in Storey's Way.
It was largely due to Thoday's efforts that the department expanded, moved to larger premises (first to the old Veterinary School site in Milton Road, then, in 1976, to its present location on the Downing site), and established the study of genetics as one of the fundamental biological disciplines in Cambridge both at undergraduate and research graduate level.
John Marion Thoday was born in Derbyshire on August 30 1916, the third son of David Thoday FRS and his wife, Mary, both eminent botanists. Young John inherited his parents' fascination with Botany and from Bootham School, York, went up to read the subject at the University College of North Wales at Bangor, where his father was a professor. At Bootham he had learned to swim the crawl and at Bangor he won all the races in that stroke for three years.

In his third year the Straights Race was swum under the Menai Bridge - a distance of a quarter of a mile. Thoday entered the race and as he crossed the finishing line, none of his rivals was more than half-way across.

On graduation in 1939 Thoday entered Trinity College, Cambridge, where he took a doctorate on the effect of neutrons on chromosomes.

In 1941 he joined the RAF as a photographic intelligence officer and before demob in 1945 served in the Middle East, Algiers and Italy, reaching the rank of squadron leader. After the war he began his scientific career as a member of the cancer research staff at the Mount Vernon Hospital, Middlesex, where in 1947, working with John Read, he discovered the role of oxygen in radiobiology and showed that the therapeutic effect of X-rays on tissue growth is largely due to chromosome breakage.

The same year Thoday was appointed assistant lecturer at the University of Sheffield, where he taught Cytogenetics in the Botany and Zoology departments.

In 1954 he became head of a newly-created department of Genetics, where he remained until his appointment in 1959 to the Arthur Balfour Professorship of Genetics at Cambridge and as a professorial fellow at Emmanuel College.

Although Thoday was instrumental in transforming the status of Genetics at Cambridge, he continued the tradition established by his predecessor, RA Fisher, of holding informal seminars over beer in The Bun Shop, a pub on the corner of Downing Street and Corn Exchange Street – until the establishment was demolished to make way for a shopping centre in the mid-1960s.

By the end of that decade the department, located in spacious, though peripheral, new premises on Milton Road, boasted four university lecturers, two university demonstrators, one senior associate in research and two assistants in research. Though undergraduate numbers remained small until Genetics became a Part I subject in the 1970s, under Thoday's leadership the department was notable for its collegial spirit.

Most of the department lunched at the Milton Arms pub where undergraduates enjoyed trouncing their superiors at darts, and during coffee breaks in the department he was always a major contributor to discussions on genetics and a wide range of other topics. He was very supportive of, and encouraging to, younger staff and students, while being a somewhat controversial figure in the world of professional genetics.

The move to the Downing site in 1976 coincided with beginning of the explosion of molecular biology, and in 1984, the year Thoday retired, the Wolfson Foundation financed the building of a new purpose-built laboratory off Huntingdon Road.

Thoday was a wise and sensible member of the governing body of Emmanuel and played an active role in college social life. He was an enthusiastic player of bowls - a game which has been played at Emmanuel since its foundation in 1584, to the college's idiosyncratic rules; woods which bear his initials are still to be found in the bowls cupboard. As with most things in life, he took his bowls very seriously - even stopping a game one day when another player was singing frivolously and refused to stop.

He presented to the college two chimeric trees (chimeras arise at graft junctions as branches which show characteristics of both of the grafted 'parents', having a layer of cells of one species around a core of the other), one with a layer of medlar on a hawthorn core; the other a layer of creeping broom on a laburnum core.

He was also actively involved in university governance, serving from 1977 to 1981 on the General Board of the Faculties and as chairman of its Needs Committee. He was the author or co-author of numerous papers and articles and was co-editor, with JN Thompson, of Quantitative Genetic Variation (1979). He was elected a Fellow of the Royal Society in 1965.

John Thoday was sustained by a notably happy marriage to Doris Rich, whom he married in 1950 and with whom he had a son and a daughter.

The Times

Sept 12th 2008

The Guardian

Friday 3rd October 2008

Cambridge geneticist who studied how species adapt

Don MacDonald

The Telegraph

15th Sept. 2008

Geneticist who was committed to an experimental approach which provided a foundation for evolutionary theory.

Cambridge News

4th Sept. 2008

Pioneering Cambridge scientist passes away