I have been thinking once again about the premise that the human
organism is a chaotic system -- or rather about about the alleged
implications of that assertion.

The body has many feedback mechanisms that act as "attractors",
tending to pull us back into equilibrium in response to changes
and stresses.  The insulin/glucagon axis is a classic example,
but of course there are many others.  The NeanderThin claim, as I
understand it, is that these attractors are our evolutionary
heritage, and they function best in response to stimuli with
which we have evolutionary experience.  When we expose ourselves
to stimuli with which we have no evolutionary experience, the
results are unpredictable because we have no feedback mechanisms
to deal with these stimuli.

Thus, when we eat margarine we are rolling biochemical dice.  The
metabolic consequences could be negligible or severe, with no way
to know in advance.

The point at which things become even more speculative is the
suggestion that by returning to the "initial conditions" of the
paleolithic diet, we can return to the same equilibrium that our
paleolithic ancestors enjoyed.  It seems to me that it is in the
nature of chaotic systems that this may or may not be true.  A
system pushed far enough from its "native" equilibrium point may
not be able to find its way back to that point, but may reach a
different equilibrium point instead.

Consider obesity.  Let's grant the premise that obesity is an
auto-immune disease caused by a diet-driven push beyond the
stable boundaries of what our bodies are adapted to deal with.
As a result, most obese people are pushed into some other
equilibrium point: a new "setpoint", maintained by newly
differentiated fat cells, elevated levels of lipoprotein lipase,
and so on.  If we simply return to the "initial conditions" of
paleolithic diet, will those fat cells disappear, and will the
LPL levels normalize?  In short, is there any reason to believe
that the metabolic changes are reversible simply by reverting to
paleolithic ways of eating?  I don't think there is anything in
chaos theory to imply such a thing, and by definition there would
have been no evolutionary pressure to make such metabolic changes
reversible.

Not the cheeriest line of thought, I grant you.

Todd Moody
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