SummaryThe traditional disease model, still dominant in psychiatry, is less than ideal for making sense of psychological issues such as the effects of early childhood experiences on development. We argue that a model based on evolutionary thinking can deepen understanding and aid clinical practice by showing how behaviours, bodily responses and psychological beliefs tend to develop for ‘adaptive’ reasons, even when these ways of being might on first appearance seem pathological. Such understanding has implications for treatment. It also challenges the genetic determinist model, by showing that developmental pathways have evolved to be responsive to the physical and social environment in which the individual matures. Thought can now be given to how biological or psychological treatments – and changing a child's environment – can foster well-being. Evolutionary thinking has major implications for how we think about psychopathology and for targeting the optimum sites, levels and timings for interventions.

SummaryWe argue that current debates about attention-deficit hyperactivity disorder (ADHD) can be considered afresh using an evolutionary lens. We show how the symptoms of ADHD can often be considered adaptive to their specific environment. We suggest that, from an evolutionary point of view, ADHD symptoms might be understood to result from an ‘evolutionary mismatch’, in which current environmental demands do not fit with what evolution has prepared us to cope with. For example, in our ancestral environment of evolutionary adaptedness (EEA), children were not expected to sit still and concentrate on academic tasks for many hours a day. Understanding ADHD in terms of such a ‘mismatch’ raises significant issues regarding the management of childhood ADHD, including ethical ones. An approach based on the concept of mismatch could provide an alternative to current debates on whether ADHD results from nature or nurture and whether it is under- or over-diagnosed. It would allow clinicians and policy makers to take both the child and the environment into account and consider what might be desirable and feasible, both in society and for specific children, to lessen the mismatch.LEARNING OBJECTIVES•Grasp the concept of ADHD as an ‘evolutionary mismatch’•Understand the issues raised by this perspective, including ethical ones•Appreciate how a transparent discussion of these issues might inform decisions about management, medication and schooling

Humans lived as hunter‐gatherers for more than 95% of our evolutionary history, thus studying contemporary hunter‐gatherer populations offers insight into the conditions children may be psychologically adapted to. Here, we contrast hunter‐gatherer childhoods with those of WEIRD (Western Educated Industrialised Rich Democratic) societies and consider the implications for children's mental health. Hunter‐gatherer infants receive continuous physical contact and more sensitive and responsive caregiving than is typical of WEIRD societies, due to the extensive involvement of alloparents (non‐parental caregivers) who generally provide 40–50% of their care. Alongside positive attachment outcomes, alloparenting likely reduces the harms of family adversity and risk of abuse/neglect. From late infancy, hunter‐gatherers spend their time in mixed‐age ‘playgroups’ where they learn via active play and exploration without adult supervision. This contrasts with WEIRD norms surrounding the need for adult supervision of children, as well as with the passive teacher‐led classrooms, which could potentially lead to suboptimal learning outcomes and pose difficulties to children with ADHD. Based on this preliminary comparison, we consider practical solutions to potential harms arising from discordance between what children are adapted to and exposed to. These include infant massage and babywearing; increased sibling and extra‐familial involvement in childcare; and educational adjustments.

SummaryEvolutionary science can serve as the high-level organising principle for understanding psychiatry. Evolutionary concepts generate new models and ideas for future psychiatric study, research, policy and therapy. The authors accordingly make the case for the inclusion of evolutionary biology in the postgraduate education of psychiatric trainees.

SUMMARYIssues of sexual reproduction lie at the core of evolutionary thinking, which often places an emphasis on how individuals attempt to maximise the number of successful offspring that they can produce. At first sight, it may therefore appear that individuals who opt for gender-affirming medical interventions are acting in ways that are evolutionarily disadvantageous. However, there are persuasive hypotheses that might make sense of such choices in evolutionary terms and we explore these here. It is premature to claim knowledge of the extent to which evolutionary arguments can usefully be applied to issues of gender identity, although worth reflecting on the extent to which nature tends towards diversity in matters of sex and gender. The importance of acknowledging and respecting different views in this domain, as well as recognising both the uncertainty and likely multiplicity of causal pathways, has implications for clinicians. We make some suggestions about how clinicians might best respond when faced with requests from patients in this area.LEARNING OBJECTIVESAfter reading this article you will be able to: •understand evolutionary arguments about diversity in human gender identity•identify strengths and weaknesses in evolutionary arguments applied to transgender issues•appreciate the range and diversity of gender experience and gender expression among people who present to specialist gender services, as well as the likely complexities of their reasons for requesting medical intervention.