Intelligence & Brains
Intelligence is a sine qua non for every entity that must be responsive to its environment. From viruses and single cells on up, awareness, memory, pattern-matching, and decision-making are essential. Every cell, every organism has a mind.
Complex cognitive abilities evolved multiple times in distantly related animals with vastly different brain structures in order to solve similar socioecological problems. ~ English zoologist Nathan Emery & English psychologist Nicola Clayton
That birds have considerably different brain structures than other modern vertebrates illustrate that evolutionary drives are to functional solutions, not biological forms: which is a caution to not confuse substance with essence. A brain is merely the physical substrate of the mind: a material mirage for intelligence which is energetically based. Plants are more intelligent than animals yet possess no identifiable physiological system for their acumen.
Understanding that intelligence is a universal aspect of life, the idea of convergent evolution in intelligence becomes nuanced. Cognition did not independently evolve multiple times to handle similar socioecological problems.
All thought is symbolic manipulation employing memory. Only the context differs. Specific sets of cognitive frames put an organic entity in a proper mental milieu to deal with its world.
Whereas bodies and behaviors are all that we see, we know that organisms are operationally defined by their minds. Psychology is both species-specific and individual. These principles of cognitive schemas are selfsame throughout the tree of life.
Intelligence is not a product of brains. Intelligence is instead a display of the mind, which was crafted from an evolutionary perspective to certain possibilities, inclinations, and limitations.