Long Article

Biological Theory

, Volume 7, Issue 3, pp 227-236

First online:

The Evolutionary Rationale for Consciousness

  • Bjørn GrindeAffiliated withDivision of Mental Health, Norwegian Institute of Public Health Email author 

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To answer the question of why we have consciousness, I propose the following evolutionary trajectory leading to this feature: Nervous systems appeared for the purpose of orchestrating behavior. As a rule of thumb the challenges facing an animal concern either approach or avoidance. These two options were originally hard-wired as reflexes. Improvements in adaptability of response came with an expansion of the computational aspect of the system and a concomitant shift from simple reflexes to instinctual behavior, learning, and eventually, feelings. The assessment of positive and negative feelings allows organisms to weigh various options, but for this to be a viable strategy, an awareness of hedonic value is required. This was presumably the first neural attribute to evolve that required awareness, and thus the key force in the evolution of consciousness. The attribute first appeared in the early amniotes (the phylogenetic group comprising reptiles, birds and mammals). Support for this model in current accounts of the neurobiology of feelings and consciousness is discussed.


Amniotes Consciousness Emotions Evolution Mood modules Self-awareness