[extropy-chat] RE: Re: Intelligent Design and IrriducibleComplexity

[Spike]

Cool!  Last time this topic came up, there were other
important things going on.  Now the crew seems more in
the mood to discuss evolution.  I tried on some of these 
memes last time, so some of this essay has repetition, 
but there is also some new material and some actual signal 
among the silliness.  

Evolution is often misunderstood because caricatures
of the theory only deal with half of Darwin's revolutionary
ideas, stressing survival selection and neglecting mate
selection.  The comment is often made that modern technology
allows an end run around natural selection because nearly
all babies survive.  But the same technology that supresses
survival selection hands us the opportunity to throw 
mate selection into high gear.  In slow-breeding mammals,
such as humans, mate selection would be far more effective
in modifying the genome than would survival selection.

It appears that humans are changing anatomically far faster 
than other mammal species.  Consider the diminutive suits
of armor used by humans a mere 20 generations ago.  Most
of the difference can be explained by better modern diets.
But it is also possible that modern humans prefer taller
or larger mates.

Consider also that we humans have structures that are
larger than necessary for optimal survival.  Go get your
Playboy magazine for excellent examples of mate-selection-
optimized humans.  (Or Playgirl, if appropriate.  What 
magazines do bisexuals read?  Playperson?)  Notice that
the attractiveness-optimized female humans have breasts 
that are larger than necessary to feed their infants.  The
optimized males have larger than necessary pectorals, almost
comically enlarged.

OK, put the magazine away and pay attention.  Hey!  Stop that!

Nowthen, ponder the human body from the point of view of
a mechanical engineer.  A well designed machine is stressed
evenly, so that no single part will wear out long before
everything else.  But Cadillacs had tail fins, strictly
for decoration.  My notion is that human bodies have both
over"designed" parts and underdesigned.  Which?

I have already cited female breasts and male pecs.  But the
most outstanding example of overdesign would be our rears.
Both genders seem to prefer mates with protruding buns, resulting
in those curvatious protruding asses.  Compare with other mammals,
particularly the anatomically similar chimps.  They don't 
really have butts like ours.

Whenever you get a chance to go on a 30 km hike, what body
parts are sore the next couple days?  Your quads, mostly.
The vastus medialis, the vastis lateralis, the rectus
femoris, in the lower leg the tibialis anterior, which is doing
so much work when we hike.  But not the gluteus maximus.
It is hard to rip the gluts!  Even if we want to.  Those
muscles are larger and stronger than they need to be.  It
strengthens my point that we have popular exercise tapes called
Buns of Steel, yet they really don't work all that well,
as evidenced by the fact that few people ever get them,
and those that do need to work for hours at very awkward
excersizes to make it happen.

If you need more proof, try this experiment.  squeeze the
quads and walk across the room.  Feel them working?  Now
repeat the experiment pinching your butt cheeks as you
walk across the room.  (Do not let your neighbors see you
doing this.)  Feel how relaxed they are?  If that doesn't
convince you, have your spouse lose the extra clothing
and grab her (or his) buns and have her (or him) walk
in front of you.  This may end up taking an hour or two, 
but today is Sunday and you have nothing better to do.  
(Is there ever anything better to do?)

We also have underdesigned parts.  Human knees are a weak
spot.  Ideally they would have more surface area, so that
the pressure would be reduced.  Yet we humans have chosen
slender legs and nearly invisible knees.  Imagine what 
larger knees would look like on a standing human: big 
knobby things, oy vey!  We have evolved underdesigned
knees, that eventually fail on most of us, especially if
we run.

The point of this essay is to introduce the notion that
we developed large brains for the same reason that we 
developed large asses.  This isn't a new idea, but I do
have a new twist on it.  Geoffrey Miller, in The Mating
Mind, proposes that large brained individuals in a
protohuman population had intelligence-related abilities
that made them more desireable mates.  I propose that
this mechanism is only part of the reason we have large
heads.  The other, and perhaps larger part, is simply
that large headed protohumans were cuter, because they
more closely resembled human infants.  Thus they enjoyed
more mating opportunities their entire reproductive lives.

OK, I am still on familiar ground here, so now starts the
new idea, that just occurred to me recently.

It is well understood that survival selection applies only
to the individual.  However my notion is that survival
selection and mate selection, when taken together, can
operate on the genome at the group level.  When that
concept is understood, it has great explanatory power.

Consider that isolated populations of modern humans can
develop odd notions of beauty, expressed in various body 
modifications such as stretching the neck with rings, 
flattening the heads, binding the feet, our western
practices of tattooing and body piercing, etc.  A
striking example is an African tribe that decided that
wide hips were cool.  Evidently both genders preferentially
selected wide-hipped mates, resulting in this group with
anomalously small trunks with enormous hips.  Perhaps
someone here knows the name of that hip group.

Now consider an isolated population of protohumans,
at the technology level approximately at the level
of modern chimps: they hurled stones as weapons, they
occasionally used sticks as a striking instrument,
but had not controlled fire or made weapons.  What
if that isolated population decided that big heads
were cute, analogous to the big-hip people.  Both
genders began preferentially selecting big-headed
mates, not for their intelligence or ability, but
strictly for their looks.  Then, over a relatively
short time, perhaps as little as a thousand generations,
we could imagine the development of a group of large-
headed protohumans, analogous to the modern wide-hipped 
people.

Here's the punchline: if this group of large-headed
protohumans did develop, we can imagine that they
were accidentally more intelligent than their small-
brained cousins, making them more ideal candidates
to discover and master two very important early 
technologies: the control of fire and the technique of 
hurling a stick lengthwise, the way a spear is hurled.  
A group of fire and spear using protohumans would 
have a biiiig survival advantage over other groups
of protohumans without those two technologies.

If that is the case, then we have an example of
natural selection working at the group level.  But
this only works if we use the term natural selection
to include both survival selection and mate selection.
If we allow natural selection to work at the group
level, we suggest some possible solutions to the
more difficult puzzles of evolution. 

spike