In the study of human evolution and psychology, a few definitions guide the discussion on evolutionary mismatch and its connection to psychology. The first definition relates to human behaviour as understood from the point of evolution. During the growth and development phases, human behaviour refers to the potential and embodied capacity for physical, emotional, and social activities. These developmental stages are tied to Darwin’s theory of evolution (Hari, 2019). Evolution in human beings, similar to that of any other animal species, has a predictable life cycle that includes a series of stages, each with its own set of physical, physiological, and behavioural characteristics. A mismatch occurs when these characteristics fail to occur at the required developmental phase.
Human psychological processes evolved to handle environmental inputs and transform them into behavioural outputs that improve survival or reproductive chances. On the other hand, modern worlds are radically different from those in which human psychological processes developed. Many inputs now vary in quantity and strength or no longer have the same fitness associations, leading to maladaptive production from many pathways (Durisko et al., 2016). This evolutionary mismatch mechanism presents consequences for psychological science and policy. Mental disorders such as autism, Attention-Deficit Disorder (ADD), chronic depression, Obsessive-Compulsive Disorder (OCD), and Alzheimer’s disease are associated with an evolutionary mismatch that is viewed as an impairment of Darwinian fitness.
Evolutionary mismatch leads to behavioural changes in adolescents, such as alcoholism and drug abuse, increasing the risk for mental illnesses. According to Hari (2019), depression is a major mental disorder in adolescents resulting from the evolutionary mismatch. In this case, the mismatch is characterized by a disconnection from meaningful work, childhood trauma, and the disconnection from a hopeful and secure future. From the evolutionary perspective, meaningful work and connectedness to others was the norm. The evolutionary mismatch has led to an increased disconnection from others translating to a desire for personal satisfaction through deviant behaviour. The lack of satisfaction has, in turn, led to an increase in mental disorders.
Darwinian logic indicates that the physical characteristics that make people vulnerable to mental illness developed to serve an adaptive purpose in the modern world. A good example of a mental illness that developed for adaptive reasons is chronic depression. According to recent studies, inflammation is a fundamental cause of many cases of depression (Durisko et al., 2016). However, the evolutionary mismatch has led to divergent cultural and lifestyle adaptations that have left current generations at a higher risk for mental illnesses. Modern generations’ search for personal identity and individual destiny deviates from the stable evolutionary identities. The increased pressure for creating an autonomous identity is a deviation from the evolutionary adaptation to traditional identity. This represents a sociological transition that has led to increased burden over current generations leading to mental disorders such as chronic stress.
Despite the issue of a natural section, alleles that accelerate the risk of the disorder have developed due to their ability to enhance fitness in specific conditions. In certain situations, they are maladaptive, and in others, they are beneficial. The issue present today is that human genomes are operating in a setting that is vastly different from the one for which they were “made.” Unlike the acute immune insults that ancestors faced, many of the immune insults that modern man faces are chronic. Many people nowadays consume a species-inappropriate diet and neglect exercise. Insufficient sleep and an imbalanced microbiota have contributed to constant inflammation. As a result, people suffer from inflammation-related health issues, including depression. All these ills are brought about by evolutionary mismatch demonstrated in the dietary and cultural changes that have reduced the body’s ability to handle psychological changes, causing many mental disorders.
References
Durisko, Z., Mulsant, B. H., McKenzie, K., & Andrews, P. W. (2016). Using evolutionary theory to guide mental health research. The Canadian Journal of Psychiatry, 61(3), 159-165.
Hari, J. (2019). Lost connections: Why you’re depressed and how to find hope. Bloomsbury Publishing.