Response to outside versus internal events Because the human mind can plan ahead, it can predict that something it is going to

do is dangerous. If it is planning an aggressive or sexual initiative, it can predict that this may elicit a dangerous response from a more powerful person or the group as a whole. Moreover, because, due to the repression required for socialization, the early planning stage of such an initiative may be unconscious, we may not know what, Inhibitors,research,lifescience,medical the anxiety is due to. This is the well-known “signal anxiety,” which is used to good effect by psychoanalysts.79 Modular versus nonmodular Because, famously, Inhibitors,research,lifescience,medical evolution is a tinkerer rather than an engineer, there is no clear separation between different anxiety responses or the situations that cause them. Danger may give rise to fight, or flight, or freezing or jealousy or washing or checking or to the construction of fall-out shelters, and all of these activities are accompanied by the dysphoric affect, of anxiety. Whereas GAD is Inhibitors,research,lifescience,medical genetically linked to depression and the trait of selleck products neuroticism,22 panic disorder and agoraphobia are more mixed in their inheritance, while specific phobias such as those of blood, insects, and heights are relatively independent. In the case of avoidance

of aspects of the habitat such as cliffs and caves,

one must suspect that anxiety may have had a function in the splitting of early human groups, as acrophobics abandoned communities living on cliff tops and claustrophobies abandoned communities living in caves; Inhibitors,research,lifescience,medical rate Inhibitors,research,lifescience,medical of group splitting is an important variable in behavioral ecology, having implications for the evolution of natural selection at the group level.80 Basic concepts Psychiatry sadly lacks a coherent science of normal behavior on which to base our study of the pathological.81 Sociophysiology has been suggested as a suitable title for such a science,82 and I hope it can be seen from the above that certain areas of knowledge are necessary for the appreciation of evolutionary psychiatry. These include: The neuroethology of Paul MacLean’s triune brain.27 The changes Thymidine kinase in social competition (and so sexual selection) that, have occurred since the common reptilian and human ancestor.50 The idea of alternative behavioral strategies (particularly escalation and de-escalation) that has been found useful in behavioral ecology.32,33 Fundamental psychological concepts such as the Yerkes-Dodson law, which relates performance to motivation.61,65 I hope that I have shown how these ideas illuminate the possible evolution of the anxiety disorders.