Genes, Brains, and Human Potential The Science and Ideology of Intelligence

230 A CREATIVE COGNITION

variation so produced can help steer future evolution in more adaptable,

intelligent, directions. Th at is, intelligent systems are active creators of

variation; variation is not the passive outcome of ge ne tic and environ-

mental forces as in the standard behavioral ge ne tic equations.

Th at early intelligence became incorporated into multicellular organ-

isms and became extended and amplifi ed in developmental systems. It is

exhibited in the vast variety of cell types and functions generated from

a single precursor. Intelligent development is also exhibited in the emer-

gence of body form, in two ways. First, diff er ent members of the same

species develop highly uniform basic characteristics even when they have

diff er ent genes. Th is is canalization, as described in chapter 5. Second,

very diff er ent body forms can develop even in a group of animals with

identical genes, or between parents and off spring, in response to environ-

mental change. Th is is developmental plasticity. Again, we get adaptive

creation of variation, predicting and anticipating change to a far greater

degree than is pos si ble by ge ne tic variation.

Th e communication systems coordinating cells subsequently evolved

as physiological systems. Th ey are highly sensitive to changes both inside

and outside the multicellular body, creating further variation. In turn,

physiology became embedded in ner vous systems with a further leap

in scope for individual diff erences, now in be hav ior. Th e further evolution

of brains produced the emergent properties of cognition, as described

above.

I hope to have shown you the tremendous further scope for variation

in cognitive systems, as in learning, memory, knowledge, thinking, and

so on. In turn, what has evolved is an effl orescence of adaptive variation

that is woefully underestimated by behavioral ge ne ticists of potential.

Let us now look at the implications of all this for individual diff erences.

WHAT VARIES IN COGNITIVE ABILITY?

Th e vari ous models of cognitive functions permit individual diff erences to
appear, theoretically, in a variety of ways. Under strict nativist assump-
tions, there will be few individual diff erences: natu ral se lection of its
critical survival qualities will have ensured common genes and common

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