Evolutionary medicine asks why natural selection left us with traits that increase vulnerable to diseases. The foci have been on macro traits, such as the size of the birth canal, and micro traits, such as the Apo-e4 allele. However, allostatically stabilized control systems are the essence of life, and control system failures account for most disease. Seeking evolutionary reasons for the vulnerability of cybernetic systems may offer a new horizon for evolutionary medicine. For instance, defense systems whose responsiveness increases after repeated arousal should be vulnerable to runaway positive feedback.  Also, when fitness is maximized at a point close to a cliff on an fitness landscape, minor variations will result in disease for some. This may help to explain the absence of common alleles of large effect for some highly heritable diseases. This symposium will explore these and other evolutionary reasons for the vulnerability of physiological control systems. 

Experts from four fields have contributed:

• Evolutionary medicine and explanations for traits that cause disease vulnerability
• Physiological regulation systems especially vulnerable to failure
• Complex systems analysis of control systems and their modes of failure
• Engineering and failure mode analysis 

•  Randolph M. Nesse (ASU Life Sciences) Fitness cliffs and vicious cycles: Evolutionary explanations for vulnerable control systems
•  Fred Nijhout (Duke University) Homeostatic mechanisms enable the persistence and accumulation of deleterious genes.
• Carl Carlson (Carlson Reliability Consulting) Using Failure Mode and Effects Analysis to advance evolutionary biology research and application
• Jay Schulkin (University of Washington Medical School) Obesity: Biology and Culture
• Ken Buetow (ASU Life Sciences) Complex human disease phenotypes as emergent properties of network variability
• Manfred Laubichler (ASU Life Sciences) Stability vs. Vulnerability: The evolutionary conundrum
• Rustom Antia (Emory University) ''Design principles” for robust immune systems
• Carl Bergstrom (University of Washington) A hygiene hypothesis for anxiety