Professor Sir Michael Rutter died on 23 October 2021. He had made an unparalleled and profound contribution to the science underpinning our understanding of the origins and development of psychopathology in children and young people. The unique combination of reforming motivations, intellectual curiosity and commitment to hypothesis-driven science that made this possible are discussed in the editorial for this issue (Sonuga-Barke, Fearon, & Scott, 2022). I have recently compiled a systematic and comprehensive Digest of his life’s work – 546 journal papers and 52 books published [https://doi.org/10.13056/acamh.13072]. This Editorial Perspective will summarise some highlights of the main areas of his many scientific achievements.

MR’s research covered the following major areas (in alphabetical order): adolescence; attention deficit-hyperactivity disorder; antisocial behaviour/conduct disorder/criminality; assessments of mental states and disorders; autism – 121 of his 546 papers related to this topic; child and later adulthood disorders; classification of child psychiatric disorders; depression; epidemiology; genetics especially gene-environment interplay; head injury/brain dysfunction; institutional care –especially the English Romanian Adoption study; language development; maternal deprivation; the impact of parental mental illness on children; physical health conditions; reading ability; research methods and research designs – especially ‘natural experiments’; resilience, risk and adverse experience; school effectiveness; temperament; the treatment of child psychiatric disorders.

While a body of work of this size and quality can only be very partially commented on in a short editorial, I hope to draw out some of the key research themes and approaches and identify some of the main discoveries/achievements. I refer interested readers to the full Digest to get more information.

Early indications of work to come: There is a strong continuity of themes in MR’s research from the earliest publications onwards. For example, a number of topics emerged from his first research monograph on the psychological well-being of children of sick parents (Rutter, 1966). This monograph was based on MR’s MD theses submitted to the University of Birmingham. It considered whether the adverse effects shown on the children of such parents were due to their experience of parental illness or arose from genetic factors. MR has repeatedly addressed this question of the genetic and environmental joint action on childhood disorders. In this first monograph, he looked at the role of temperamental factors as influencing the reaction of the child to the experience of parental illness. The impact of the experience of separation from the parent and of a ‘broken home’ on the child was also addressed. These questions of gene-environment interaction, temperamental susceptibility to adverse experiences and deprivation of parental care are all major themes that preoccupied MR throughout his career which I will explore below.

Understanding the need to move beyond the clinic: Many of MR’s research interests had their origins in the Isle of Wight Study (Rutter, Tizard, & Whitmore, 1970). This was a ground-breaking large scale epidemiological investigation of the physical and psychological well-being, and educational attainment of 9–10-year-old children living on the Isle of Wight. The Isle of Wight Study was followed later in the 1970s by the Inner London Study where many of the same questions concerning prevalence of problems were repeated in an urban setting. The special value of this epidemiological study in inner London was that it provided a contrasting social context to the Isle of Wight. The rates of emotional disorders, conduct disorders and specific reading retardation were found to be substantially higher in this urban setting.

Seeing the power of longitudinal data: This work in inner London demonstrated marked differences between schools in rates of misbehaviour. However, these were cross-sectional comparisons that could not determine whether the differences were due to school effects or to the characteristics of children at intake. This led MR to design and conduct a longitudinal study to test whether differences between schools could lead to changes in pupils’ behaviour and scholastic attainments. The book Fifteen thousand hours: secondary schools and their effects on children (Rutter, Maughan, Mortimer, & Ouston, 1979) reported the results of this landmark study. The study showed that secondary schools did indeed differ markedly in pupils’ behaviour, school attendance and attainment. These outcomes were strongly associated with characteristics of schools as social institutions. These included the degree of academic emphasis, teacher actions in the classroom, the availability of rewards and incentives, good conditions for pupils and the extent to which children were given responsibilities. Pupils were not only influenced by the way they were treated as individuals but also by the ‘ethos’ of the school. MR argued that the study had ‘the strong implication that schools can do much to foster good behaviour and attainments, and that even in a disadvantaged area, schools can be a force for good’ (Rutter, 1980).

Revolutionising how autism is viewed: MR fundamentally changed our understanding of autism with his work from the mid-1960s onwards. In an early review, he produced some tentative conclusions about the nature and origins of autism which proved very prescient (Rutter, 1968). He concluded that autism is ‘not anything to do with schizophrenia’, it is ‘unlikely that psychogenic or faulty conditioning mechanisms are primary factors in aetiology’, that ‘organic brain abnormalities appear to be primary influences in some cases’, and that an approach which ‘places the primary defect in terms of a language or coding problem appears most promising’. Finally, in an open invitation to the field to study genetics (remarkably for 1968) he stated the ‘importance of genetic factors remains unknown’. He went on to investigate each of these aspects of autism not least in using twin studies to establish clear evidence, for the first time, of the role of genetics in autism (Folstein & Rutter, 1977).

Challenging received wisdom about child rearing: A book published in 1972 entitled Maternal Deprivation Reassessed for a wide readership became a mainstay of courses teaching developmental psychology (Rutter, 1972). The book concludes that ‘The concept of “maternal deprivation” has undoubtedly been useful in focusing attention on the, sometimes, grave consequences of disturbed or deviant care in early life. However, it is now evident that the experiences included under the term “maternal deprivation” are too heterogeneous and the effects too varied for it to have any usefulness. It has served its purpose and should now be abandoned’. The final major study undertaken by MR returned to the question of the impact of early deprivation on development and in the extreme form experienced by children raised in their early years in Romanian orphanages. This English Romanian Adoption study examined the development, now into adulthood, of children adopted into English families. The study has found that the duration of care in the orphanages was related to a number of later, and long-lasting, difficulties. They concluded that: ‘Notwithstanding the resilience shown by some adoptees and the adult remission of cognitive impairment, extended early deprivation was associated with long-term deleterious effects on wellbeing that seem insusceptible to years of nurturance and support in adoptive families’ (Sonuga-Barke et al., 2017).

Formulating the role of risk and resilience factors: MR had an enduring interest in the processes whereby adverse experience creates vulnerability to psychiatric disorders. He showed that vulnerabilities were mediated by a wide range of factors including the person’s biology, the continuity of adverse experiences, the individual’s conceptualisation of stress and the ecological effect of living in cities. He recognised the importance of psychosocial adversity as an influence on child disorders which needs to be appraised alongside the role of genetic factors. The variation in outcome when different children are exposed to a similar adverse event or circumstance is a recurring associated issue in his work. The protective factors that result in the relative absence of an adverse outcome produce resilience and these include the key features of secure and stable affectionate relationships and the experience of success and achievement (Rutter, 2012). He found that characteristics of the person, such as temperament, can also contribute to resilience. MR elaborated the ways in which vulnerability and protective factors are defined and measured. He saw them as contrasting poles of the same concept; protective factors reduce the adverse effect of risk exposure; vulnerability factors do the opposite. In both cases, they have no effects on outcome in the absence of risk.

Teasing apart the interplay between genes and environment: During the course of his research, MR was involved in studies applying quantitative behaviour genetic methods to the analysis of genetic and environmental influences on a range of behaviours. In addition to the twin studies on autism mentioned above, MR developed a collaboration during the 1990s and 2000s with the Virginia Twin Study of Adolescent Behavioural Development. An example of the product of this collaboration was the suggestion that depression before and after age 14 may be aetiologically distinct syndromes (Silberg, Rutter, & Eaves, 2001). MR argued strongly that genetic and environment influences on behaviour should not be considered in isolation. There is a need to understand the role of various kinds of gene-environment correlation. In particular, he asserted the importance of studies of gene-environment interaction in developing insights into the ways in which biology and experience influence behaviour. He suggested that the effects of genes on behaviour can be understood largely by their influence on the extent to which the individual is likely to be exposed to environmental risk and how they affect the susceptibility of the individual to this risk. It is in the interplay between genes and the environment that the processes underling risk and resilience will be found (Rutter, 2005).

From his earliest papers, MR referred admiringly to the approach to scientific discovery of Peter Medawar. The following quote makes clear his endorsement of Medawar’s way of thinking: ‘Of course, it would be quite futile to collect facts without a purpose. As Medawar has described so well, science consists of both discovery and proof, hypothesis and then careful testing to discriminate between alternative hypotheses’ (Rutter, 1971). The title of one of Medawar’s books on the scientific method was ‘The Art of the Soluble’. No-one has been an exponent of this Art to greater effect in the fields of child psychiatry and psychology than Professor Sir Michael Rutter.