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Neural Plasticity
Volume 2007 (2007), Article ID 59676, 17 pages
Review Article

Anxiety from a Phylogenetic Perspective: Is there a Qualitative Difference between Human and Animal Anxiety?

1EA3248 Psychobiologie des Émotions, UFR Sciences et Techniques, Université François-Rabelais, Tours 37200, France
2Department of Psychology, Université Catholique de Louvain, 10 place Mercier, Louvain-la-Neuve B-1348, Belgium

Received 3 November 2006; Revised 19 February 2007; Accepted 15 March 2007

Academic Editor: Georges Chapouthier

Copyright © 2007 Catherine Belzung and Pierre Philippot. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A phylogenetic approach to anxiety is proposed. The different facets of human anxiety and their presence at different levels of the phylum are examined. All organisms, including unicellular such as protozoan, can display a specific reaction to danger. The mechanisms enabling the appraisal of harmful stimuli are fully present in insects. In higher invertebrates, fear is associated with a specific physiological response. In mammals, anxiety is accompanied by specific cognitive responses. The expression of emotions diversifies in higher vertebrates, only primates displaying facial expressions. Finally, autonoetic consciousness, a feature essential for human anxiety, appears only in great apes. This evolutive feature parallels the progress in the complexity of the logistic systems supporting it (e.g., the vegetative and central nervous systems). The ability to assess one's coping potential, the diversification of the anxiety responses, and autonoetic consciousness seem relevant markers in a phylogenetic perspective.