[extropy-chat] Desirability of Singularity (was Are ancestor simulations immoral?)

[Anders Sandberg]

Martin Striz wrote:
> Very well, I just find it to be a nontraditional use of the term
> "efficient."  To me that is a measure of the percentage of input
> energy that gets used to do the work of the system, versus the
> percentage that is lost as heat, etc.  By that measure, neurons are
> pretty efficient.  There's very little heat loss.   Your head isn't
> warm due to heat loss.  It's kept warm on purpose because enzyme
> kinetics are optimized for 37 C.

And why that temperature? In the end 37 C is a kind of compromise. Higher
body temperature means faster kinetics for many processes, faster nerve
conduction velocities (increasing body temperature by 0.2 degrees improves
cognition in some tests; beyond that there is no improvement) but also
higher metabolic costs (increasing exponentially with higher temperature)
and in males increased mutation frequency. Basal body temperature seems to
be set by evolutionary adaptation to a particular environment and
ecological niche, varying within related species quite a bit and it is
possible to push the enzyme kinetics quite a bit with sufficient
evolution.

Instead of using pumped ion gradients to power action potentials the
nervous system could have used passive membrane conduction with local
Ranvier-node-like amplifiers, which would likely have produced a far less
energy consuming system. This is more similar to the invertebrate nervous
system, actually. But the rewards for fast reactions and coevolutionary
driving likely got us mammals stuck with these expensive, energy wasting
central nervous systems. I'm certain radically different solutions are
possible, but since terrestrial evolution had such a wide array of ion
channels and pumps going long before Ediacara it used them.


Todays fun neuroscience fact: the spinal cord system for regulating
urination appears to be lateralized in humans but not other animals.
Gert Holstege, Micturition and the soul, The Journal of Comparative
Neurology Volume 493, Issue 1 , Pages 15 - 20


-- 
Anders Sandberg,
Oxford Uehiro Centre for Practical Ethics
Philosophy Faculty of Oxford University