Proximate and evolutionary studies of anxiety, stress and depression: synergy at the interface

While enormous progress has been made in unraveling the proximate physiolog ical mechanisms that account for anxiety, stress, and low mood, these state s continue to give rise to considerable conceptual confusion. This is, in p art, because proximate studies have neither been adequately distinguished f rom, nor integrated with, evolutionary explanations for the adaptive functi ons of anxiety, stress, and mood. A complete biological explanation that in corporates both proximate and evolutionary explanations will be of great va lue to better define the border between normal and pathological, to help to explain why pathological anxiety and depression are so common, and to prov ide a much-needed basis for sensible decisions about when different pharmac ological manipulations are likely to be helpful or harmful. Ideally, evolut ionary considerations should provide a conceptual framework within which th e biological significance of the proximate mechanisms can be better underst ood, and the proximate findings should provide tests of evolutionary hypoth eses. Studies at the interface between evolutionary and proximate explanati ons will be difficult, but important to better understand individual differ ences in vulnerability and the etiology of diseases that result from dysreg ulation of anxiety and mood. (C) 1999 Published by Elsevier Science Ltd. Al l rights reserved.