Issue 46 (Spring 2011)  Pages – 39-46

Previously-held ideas about the intrinsically pathological nature of hallucinations and delusions are being challenged by findings from epidemiology, neuroimaging and clinical research. Population-based studies show that the prevalence of psychotic symptoms is far greater than had been previously considered. Therefore it may be timely to re-evaluate our perspective on these psychotic symptoms and their meaning in an evolutionary context. These symptoms may hold the key to understanding the persistence of psychosis in the population. We discuss how these findings also have implications for the public perception of stigma and the development of new therapies that directly engage with the psychotic symptoms. These therapies have the potential to increase patient satisfaction with treatment, increase adherence and ultimately lead to better outcomes.

Keywords: psychosis; psychotic symptoms; evolution; hallucinations; psychotherapy  

Nothing in biology makes sense except in the light of evolution.

Theodosius Dobzhansky

Hallucinationary experiences are as old as humankind and, until the nineteenth century, these experiences were generally attributed to mystical sources such as gods or demons. Esquirol (1845) first proposed the use of the term hallucination as it is currently understood, making a distinction between normal sensory experiences and „pathological‟ hallucinations. Over the twentieth century, hallucinations have generally been regarded as…