REAL GENES, REAL INTELLIGENCE 133
tebrates contain hundreds of diff er ent cell types. Th ey all contain the
same (or closely similar) genomes but develop and maintain their sepa-
rate identities by a combination of genomic and epigenomic regulations
(see chapter 5).
Similarly, a population of animals of identical genotypes, reared in al-
most identical environments, can exhibit the full, normal, range of indi-
vidual diff erences in be hav ior expected for the species as a whole. Th is has
been shown in laboratory animals that are bred to be genet ically identi-
cal and raised in the same cage. Th ey exhibit normal variation in physi-
ology and be hav ior, even in immune responses.
Th e members of a famous seven- hundred- year- old herd of ancient wild
cattle (k nown as the Chillingham herd in North umberland, United King-
dom) have become so inbred over countless generations as to be genet-
ically identical. Yet they still exhibit the normal range of morphological
and behavioral characteristics.^31
It Is the System That CountsTh ere is no direct command line between environments and genes or
between genes and phenotypes. Predictions and decisions about form and
variation are made through a highly evolved dynamical system. Th at is
why ostensibly the same environment, such as a hormonal signal, can ini-
tiate a variety of responses like growth, cell division, diff erentiation, and
migration, depending on deeper context. Th is refl ects more than fi xed
responses from fi xed information in genes, something that is fatally over-
looked in the nature- nurture debate.
THE INTELLIGENT CELLIn this chapter, I have taken a closer look at the origins of genes and how
they enter into the development of form and variation. I have also scruti-
nized the environment, its true nature, and how it interfaces with genes
at the level of the single cell. In the standard picture of behavioral ge ne-
tics, individual diff erences arise through this interface as additive sums
of the variable ge ne tic and environmental factors. I have described how
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