Universiteit Leiden

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LIBC Colloquium

Wednesday 5 January 2022
Pieter de la Courtgebouw, 5A23 & via Zoom

Disorder ‘all the way down’: how first principles in biophysics underlie physical, mental and social disorders at different scale levels of organization

What do bacteria, cells, organs, people and social communities have in common? At first sight, perhaps not much. They involve totally different agents and scale levels of observation. On second thought however, perhaps they share everything. A growing body of literature suggests that living systems at different scale levels of observation follow the same architectural principles and process information in similar ways. Moreover, such systems appear to respond in similar ways to rising levels of stress, especially when stress-levels approach near-lethal levels. To explain such communalities, we argue that all organisms (including humans) can be modeled as hierarchical Bayesian controls systems that are governed by the same biophysical principles. Such systems show generic changes when taxed beyond their ability to correct for environmental disturbances. Without exception, stressed organisms show rising levels of ‘disorder’ (randomness, unpredictability) in internal message passing and overt behavior. We argue that such changes can be explained by a collapse of higher order integrative control, which normally synchronizes activity of the various components of a living system to produce order. This collapse is due to the selective overload and cascading failure of highly connected (hub) nodes in a network. Thus, we present a theory by which organic concepts such as stress, a loss of control, disorder, disease and death can be operationalized in biophysical terms that apply to all scale levels of organization. Given the presumed universality of this mechanism, ‘losing control’ appears to involve the same process anywhere, whether involving bacteria succumbing to an antibiotic agent, people suffering from physical or mental disorders, or social systems slipping into warfare. On a practical note, measures of disorder may serve as early warning signs of system failure even when catastrophic failure is still some distance away.

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