Charles Darwin first recorded his ideas on ‘transmutation’, a word used to signify the changeable nature of species, in 1844. However, he did not publish his ideas then but instead embarked on painstaking studies of molluscs and other subjects for many years in his home-based laboratory, publishing widely and making some novel discoveries in the area of mollusc biology. We will never know whether he would have got around to publishing his theory of evolution if it had not been for the work of a young naturalist called Alfred Russel Wallace, who forwarded his own (remarkably similar) ideas on the subject to Darwin in 1858. As a result, the two men had their findings jointly presented to the Linnaean Society one and a half centuries ago this year, on July 1st 1858, ^{Reference Darwin and Wallace2} an event that initially passed by relatively quietly, but that was soon to rock the scientific establishment and society as a whole. Darwin's notebooks prove that he had been developing his theories on ‘transmutation’ for the previous 20 years, based on his observations on the HMS Beagle and his own ‘home-work’ on molluscs and numerous other subjects. Potential reasons as to Darwin's delay in publishing his findings include his wish to produce as much supportive scientific evidence as possible, ambivalence about publishing a Godless theory in a religious society and, at a personal level, a reluctance to offend his devoted wife Emma, who was a devout Christian. ^{Reference Quammen3}

Charles Darwin contributed directly to modern psychology and psychiatry in the form of his book The Expression of the Emotions in Man and Animals, which was effectively the first textbook on human evolutionary psychology and psychiatry. ^{Reference Darwin4} His indirect contribution is far more significant, and involves the application by many others of evolutionary principles to psychology and psychiatry. ^{Reference Nesse5–Reference Buss7} However, despite the universal acceptance of evolutionary theory in all branches of the biological sciences, evolution is effectively ignored in mainstream medicine and in psychiatry and psychology, partly because of difficulties with providing empirical evidence or ‘proof’, and partly because of the corruption and perversion of such ideas in the abuses of Social Darwinism and eugenics. Perhaps most importantly, there is only an emerging evidence base on the clinical applications of evolutionary theory to psychology and psychiatry, and this area remains a challenge to researchers and clinicians with an interest in the subject.

Despite these problems and shortcomings, an undeniable fact remains that evolution is one of the central platforms of biology and, if psychology and psychiatry are to be considered as belonging to the biological (as opposed to the social) sciences, then evolutionary theory must have relevance to the study of the human mind. ^{Reference Abed8}

In a time when ‘biological psychiatry’ has taken on hopelessly reductionistic connotations, for example relating the complexity of human emotions and psychopathology to often questionable and over-simplistic neurotransmitter theories, psychiatry and psychology were never more in need of the fresh perspectives that evolutionary theory would bring to the study of the human mind. A 21st-century presentation to the Linnaean Society is needed, this time on evolutionary psychology and psychiatry.