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

120 REAL GENES, REAL INTELLIGENCE

space is also crucial; variations lead to diff er ent consequences for the cell
and its responses.
Consequently, much current research is exploring the ways in which
signals are integrated either on a given receptor or in crosstalk between
receptors. In at least some receptors, the bound ligand has to be actively
released from the receptor before the signal works. It is done by mem-
brane enzymes (proteases), activation of which depends on specifi c com-
binations of environmental factors. “Proteases therefore act as regulatory
hubs that integrate information that the cell receives and translate it into
precise out going signals.”^12
Another kind of interaction at this level is the way that the receptors can
signal to one another. In that way they can “negotiate” over the structure of
the messages sent on to the intracellular pro cessing. As Christof Niehrs
explains, “What emerges is an intricate network of receptors that form
higher- order ligand– receptor complexes routing downstream signaling.”^13
In multicellular systems, of course, the cells are not just responding to
one another but also collectively to the changing environment outside.
Th at requires an intelligent physiology, as described in chapter 5. How-
ever, it is still the statistical structure of the changes that matters and that
forms the basis of a living intelligence. Even at this level, closest to the
genes, then, the environment is emphatically not a loose collection of
in de pen dent factors to which the cells respond, in stimulus- response
fashion, under gene control. Th is real ity makes the additive statistical
models of the behavioral ge ne ticist quite unrealistic.

Internal Signaling
Signals already integrated at receptors then initiate a variety of internal
responses, depending on the patterns gathered in the signal structure.
Th is is signal transduction. A vast internal signaling network extracts
further structure from that passed on from receptors. Once assimilated,
that structure will permit prediction of what is likely to follow and will
indicate the best response. In their paper in Science in 2008, Ilias Tagko-
poulos and colleagues showed how even bacteria could “capture the dy-
namical, multidimensional structure of diverse environments by forming
internal repre sen ta tions that allow prediction of environmental change.”^14

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