ILLUSIONS OF WHAT GENES ARE FOR

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here is a more or less standard narrative about the origins of indi-
vidual diff erences in intelligence. Th e narrative is widely accepted
among psychologists and members of the public and has been for a
long time. It goes something like this. Each gene produces a protein. Th e
proteins then combine like cog wheels to form the cognitive “machine”
in the brain (or produce other proteins that do so). Diff er ent individuals
have inherited more or less “good ” variants of some of the genes. Because
of that, the power of the machine (for solving prob lems encountered in
the world) also varies. So we get individual diff erences in intelligence.
To most psychologists and behavioral ge ne ticists, intelligence—or g—
is the variation in that power. Th ere is no agreed-on scientifi c theory
about what the power- that- varies actually is; except that it lies in variable
genes. Th is is the ge ne tic model that drives estimates of heritability in
human potential, and the genome- wide scans for the variant genes that
create it. Of course, every one tacitly recognizes that a whole lot of devel-
opmental pro cessing is going on between the genes and assembly of the
cognitive machine, much of it infl uenced by the environment. But all that
is left as a kind of agnostic black box. As we have seen, into that black box
is poured an awful lot of hunches, intuition, and unconscious ideology—
not to mention the rather crude mechanical model of cognition.
In the past couple of de cades, however, that agnosticism has been
changing. Th e box has been slowly prized open by molecular and cell
biologists, and many others who study, not statistical models based on

4. REAL GENES, REAL INTELLIGENCE

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