The observation of homologous behavioural patterns of related species, for example between humans and primates, provides insights into the evolutionary-hierarchical principles of brain development. Congenital behaviours in the form of instinctive movements, are found in humans in pure form almost exclusively in the newborn or infant, since early ontogenesis at least partially represents phylogenetic history. In the adult human being residuals of instinctive actions can still be observed in rudimentary form, for example in the greeting gestures, which can be assigned to the instinctive humility behaviour of many mammals. A further possibility to observe instinctive movements or actions in humans are—according to Jackson’s principle of dissolution—disease processes associated with focal or diffuse cerebral lesions. Depending on the severity of the brain dysfunction, these instinctive movements occur reflexive or automatically. In the dissolution of brain function thus phylogenetic and ontogenetic stages of development are exposed or repeated.