Biochemistry in debt

It is a matter of discussion as to whether Freud explained human conduct using a particular culture reference. That culture reference is Victorian society and sexual repression.
Some argue that in today’s society, Freud would have explained his findings using a different narcissism as a source of abnormal behaviour.
Yet the mechanism remains intact: a frustrating gap between reality and desire sets all sorts of psychic disorders. Gaps are unconsciously registered in our minds.

Psychoanalysis is about 100 years old. Still a theory, it could be compared to the Theory of Relativity, although the latter was born from mathematics and more and more experiments have helped testing it right.

Psychoanalysis might have to wait long to be considered real science. Its biochemical basis remain more elusive than evidence to measure relativity. After all, it is about the brain.

Question: Which are the evolutionary basis of the subconscious mind?