198 HOW THE BRAIN MAKES POTENTIALintelligent systems: physiology, development, epige ne tics, and so on. Th ey
function with close reciprocal eff ects such that, for example, just as brain
functions are strongly aff ected by metabolism, so they can also alter
metabolism.
Of course, the evolutionary basis of intelligent systems like brains
is that they are capable of creating (adaptive) individual diff erences on a
scale outstripping that pos si ble through previously evolved systems, or
through gene variation. Intelligent systems are characterized by dynamic,
creative, pro cesses through several layers of regulation. Genes are utilized
as resources in such pro cesses but not as brain architects. Except for rare
conditions, the functional potential of the brain cannot be predicted,
even from a description of the full genome.
Th is was indicated in research by Julia Freund and colleagues. Th ey
collected longitudinal activity data on forty genet ically identical mice
living in one large enriched environment. In spite of the ge ne tic unifor-
mity, the researchers observed the emergence of notable individual dif-
ferences over time. Th ese diff erences correlated positively with individ-
ual diff erences in brain structure. “Our results show,” they concluded,
“that factors unfolding or emerging during development contribute to
individual diff erences in structural brain plasticity and be hav ior.”^44
Searching for individual—or even cohorts—of genes in the hope of pre-
dicting individual diff erences in potential is pointless.
In sum, huge eff orts are being made to clarify what brains really do.
Th ese eff orts need to be cheered. My complaint in this chapter has been
about those that seem to be aimed at dumbing down the brain and rank-
ing brains by using crude criteria. What has evolved, and develops, is a
huge complex of dynamical functions: hierarchically nested but with no
one at the top, no executor, no boss, no gene controller, no chief hormone,
no leading brain center.
If we focus on specifi c axes of development at par tic u lar times, we will
fi nd that individuals vary enormously. But that does not predict poten-
tial for future development. For the vast majority of individuals, most of
the time, development results in functions that are “good enough”— good
enough for the emergence of cognitive pro cesses to be fashioned by the
experience that follows. Let us now turn to considering those pro cesses.
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