Our immediate ancestry remains uncertain at this time, but what is clear is that we are all African. This chapter will start with the current debates on the emergence of Homo sapiens and the changes we see in the subsequent 200,000 years in terms of our behavioural and cultural development. We have already shown that the ‘march of progress’ image – so culturally famous from t-shirts to posters – of a line of ever more upright and ‘civilised’ walking ape-to-man creatures is wrong. There has never been a single line, and we are not the apotheosis of evolution. A second myth is that ‘we evolved’ 200,000–300,000 years ago and since then have been static, with only technology progressing. However, humans have continued to change with time. The third conceit is the focus on ‘our’ move ‘out of Africa’ 50,000–60,000 years ago. This idea is problematic: it culturally assumes a non-African terminus as our destiny and is a very Eurocentric view of the world. It is true that a subpopulation of hunter-gather sapiens, most likely Yoruba peoples from around what is now Tanzania, left that continent at around that time, and from that group the rest of the world’s populations emerge. But this is to downplay the fact that for 80% of our species’ existence we have all been entirely African, and a genetically small subgroup left for the last 20% of that time. History is written by the ‘victors’, and much anthropology has been written by Western academia. In 2020, it was estimated that fewer than 2% of whole sequenced genomes have as yet come from Africa (Maxmen, ), and we lack ancient DNA from Africa greater than 15,000 years old (partially due to climactic reasons). However, the tide has begun to turn, and the next 10 years look very exciting in this regard.

Throughout human evolutionary history, infants and children have been dependent on adult caregivers for survival. The care that adults give is greatly influenced by prevailing conditions, including the availability of food and their social contacts, and also by their own experience of care. We use an evolutionary perspective to discuss possible reasons why children may suffer trauma at the hands of their parents and consider how children have adapted in response to such trauma to maximise their chances of survival in order to reach reproductive age and produce their own offspring. We examine how child maltreatment might differ at the hands of mothers, fathers and step-parents and discuss parent–offspring conflict, life history theory, attachment theory and differential susceptibility to help explain the complexity of childhood trauma. We end with recommendations for clinical practice.

For most of human evolutionary history our species lived as hunter-gatherers; hence, much of our cognition and behaviour is adapted to this way of life. Given the magnitude of the sociocultural, economic and lifestyle changes experienced by Homo sapiens over the last 10,000 years, in particular the last several hundred years, aspects of human psychology may be maladapted to modern ways of life. This process of maladaptation following changes in the physical or social environment is referred to as ‘evolutionary mismatch’ and has been hypothesised to contribute to the high prevalence of mental disorders in industrialised societies. However, very few studies have examined the prevalence of these pathologies among contemporary hunter-gatherer populations; thus, empirical support for such diseases of modernity hypotheses is lacking. In this chapter, we review the limited existing research and theorise about the key differences between hunter-gatherer and industrialised societies that are likely to have profound implications for mental health. Specifically, we contrast the strong social support networks, egalitarianism, explorative modes of learning, sensitive child-rearing practices and present orientation of hunter-gatherers with corresponding features of industrialised populations. We argue that mismatches in these domains are partially responsible for of a vast array of mental illnesses, ranging from common mood disorders to behavioural pathologies and psychotic spectrum disorders. We hope that this chapter stimulates the generation and testing of mismatch hypotheses and, eventually, trials of interventions based on mismatch reduction. We end by offering suggestions for methodological approaches to this future research.

Anxiety disorders make sense only in the evolutionary context of the origins and functions of normal anxiety. Anxiety is an adaptation that adjusts diverse aspects of individuals in ways that increase fitness in dangerous situations. Subtypes were partially differentiated by different dangers. Anxiety is not fully differentiated from other aversive emotions, especially low mood. Anxiety disorders result when regulation systems fail. Explaining them requires considering five possible reasons for vulnerability. However, much harmful anxiety arises from normal mechanisms. These insights are valuable in the clinic, and they suggest new research initiatives.

An evolutionary perspective on drug use and addiction poses two primary questions that complement the proximate models of mainstream medicine. These are: why are humans motivated to repetitively seek out and consume non-nutritional substances, and why do plants (which are the sources of the majority of such chemicals) manufacture substances that can alter the functioning of the human nervous system? We propose that these questions can have a real bearing on our understanding of the phenomena of abuse and addiction that complements models of proximate causation. The evolutionary perspective recognises that addiction can only arise through the interaction of substances with evolutionarily ancient systems designed to promote the pursuit of rewards associated with increased fitness in the ancestral environment. Thus, neglecting the phylogenetic history and function of such systems necessarily results in an incomplete understanding of this phenomenon. Evolution can also help us to understand human uniqueness and especially the role of cumulative culture and gene–culture co-evolution in shaping the human body and mind. Hence, the evolutionary perspective enables a deeper understanding of the human vulnerability to substance abuse and addiction. The chapter concludes by considering the clinical and public policy implications of the evolutionary perspective presented.

Science has become increasingly interdisciplinary, marked by the rapid expansion of social science fields melding with ‘natural’ sciences previously considered less relevant for the study of humans. Psychology in particular now depends heavily on insights from medicine, biology, sociology, genetics and cognitive science and has done so for years. By grounding itself in evolutionary theory, moreover, psychology has moved towards a more mature science of human mind and behaviour. The crime sciences – criminology and criminal justice – are poised to make similar progress. While already interdisciplinary fields, we make the case that the evolutionary and cognitive sciences can unify existing knowledge about crime and justice, can help to pose new and interesting questions to study and can push the fields forward in ways that will benefit not only the scientific world, but society in general as well.

Psychopharmacology is the scientific study of the effects of drugs on thoughts, emotions and behaviour as well as the therapeutic implications of their role in treating mental disorders. Psychopharmacology focuses on understanding relevant mental processes as the key to finding new medications and improving clinical outcomes in mental disorder. Interconnected with this, neuropsychopharmacology is the complementary discipline of the study of the basic neural mechanisms that drugs act upon to influence behaviour. Progress has been slow in recent decades with no major new classes of medication being added to the psychiatric formulary. We suggest that evolutionary thinking brings novel additional scientific perspectives to psychiatry and its basic sciences that highlight the evolutionary history of cell communication, neurotransmission and substances that can alter the brain in various ways. Evolutionary perspectives of function and phylogeny also provide a deeper understanding of how natural as well as artificial chemicals (i.e. psychotropic medications) utilise evolved neuronal pathways for their actions. Evolutionary theory can thereby help us to understand the psychological effects and side effects of psychotropic medications as well as assist in the discovery and testing of new drugs.