196 HOW THE BRAIN MAKES POTENTIALnetwork of the human brain is responsible for our advanced cognitive
capabilities, rather than a simple expansion of specialized regions of the
brain such as the prefrontal cortex.”^39 Th e simple equation, graded- genes
→ graded- brains → graded- intelligence, looking for “pathways” or “dots to
connect,” ignores what is now known about what the brain is really for
and how it actually works.
In this chapter, I have described the chief functions of the brain as
portrayed in recent research. Th ey include computing statistical patterns
from the vari ous sensory inputs, assimilating their relational par ameters
in the networks, relating these across sensory modes, relating them to
inner needs, and constructing motor outputs according to the perceived
fl ow of information. Even in single cells, adaptable functions are based
not on cue- response routines and linear pro cessing, but on assimilation
of environmental structure. Th at aff ords greater ability to predict future
states, including the eff ects of response. In development and physiology,
such assimilation has evolved to be much deeper.
Th e operation of the brain, as described here, is based on the evolution-
ary extension of that strategy of adaptation. As Steven Quartz and Ter-
ence Sejnowski point out, cortical development in the more evolved
animals is “more extensive and protracted... suggesting that cortex has
evolved so as to maximize the capacity of environmental structure to
shape its structure and function through constructive learning.”^40
As they also point out, the evidence now suggests that cortical connec-
tivity is largely induced by the nature of the prob lem domains confronting
it rather than by predetermined architectures (or, as I would add, pre-
determined diff erences). In sum, diff er ent individuals of a species have the
same complement of initial connections, but the patterns and densities of
connections that develop can vary substantially between individual brains
as a result of experience. Once more, the vast majority will be good enough
for the unknown prob lem domains to be encountered.
Th e evidence for this outside-in development is now quite abundant.
Brain researchers who attribute diff erences in brain networks as causing
individual diff erences in cognition sadly overlook the way that learned
(oft en cultural) diff erences in cognitive and behavioral practice may be
the causes of the brain diff erences. In humans, it was revealed in an oft -
cited study of London taxi drivers. Th ese workers are obliged to internal-
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