Evolution and the Brain
are bits of writing from many sources such as personal correspondence,
posts to on-line discussion groups, notes, and occasionally even some journaling.
All of this is informal in nature, but contains some interesting and/or
[Posted to the neuroscience
group on MySpace.com]
>...unless we start
behaving like the monkeys that we are.
I love this line.
This is off the topic, but there's a great observation by Carl Sagan in
"Dragons of Eden" in which he points out that we're a species that was
evolutionarily selected to do intuitive Newtonian physics.
We might have trouble
getting our heads around the math, but when it comes to calculating the
force required to propel us from one branch to the next, primates had tremendous
selective pressure in the form of gravity. Those who couldn't intuit the
math met their end on the ground a hundred feet below.
in the emergency room
The other night
I ended up in the emergency room with severe abdominal pain. Understandably,
I thought it was appendicitis, but fortunately it was only (?!?) a kidney
stone. Here's the interesting bit: In diagnosing me, both a doctor and
nurse independently asked (among other things) if I had been pacing. Indeed,
I had. This is apparently a nearly universal symptom of kidney stones.
Now consider this,
what other ailments characterized by intense pain would induce pacing?
Nearly every other condition of this sort would reduce the victim to lying
on the floor (e.g., food poisoning, stab wounds, broken bones, etc.). However,
a kidney stone is helped on its way out of the body by physical movement...
and this is exactly what I was compelled to do. In fact, I couldn't keep
still (seriously, even more so than usual) while I was lying in the ER
bed. And sure enough, the stone was gone (thankfully!) within a few hours.
It never ceases
to amaze me just how finely tuned the nervous system is to deal with situations
that you would think are "once in several lifetimes." You wouldn't imagine
evolution would have the opportunity to select for them. I, for one, am
very thankful it did!
Just like the movements
induced by the kidney stone, I was thinking of other reflexive behavior
developed by evolution.
While these are dramatic during pregnancy, they are present at other times
as well, though usually to a smaller extent. A friend of mine used to participate
reflexes. These were presumably designed to catch fur, so their usefulness
is somewhat doubtful now, especially given the proportionately weaker (though
more massive) baby compared to another primate cousin. Even more surprising
is the fact that these same reflexes are present in the feet where grasping
is completely ineffectual.
-The diving reflex.
Babies spontaneously seal the top of the trachea and calmly produce a kicking
motion that propels them through the water as efficiently as one could
expect given the biomechanics of their cute little forms.
will vs. evolutionarily-selected altruistic behaviors expressed only during
[Leading up to this
excerpt my girlfriend complimented me on "rushing" to her assistance after
the car accident.]
...I don't know
how much of it was conscious and how much was just my "operating system"
doing what it needed to. I guess this gets at the concepts of accountability
and free will.
A related concept
that, on a certain level, could be considered the opposite of "free will"
might be talent. A talent is an innate ability that doesn't require conscious
effort. Sure, people work to develop their talents, but this is often quite
fun for them, so once again this bypasses to some extent the requirement
for determination or "willingness." In "To Kill A Mockingbird," Scout is
told by the family's maid and surrogate mother (I forget her name) about
how Atticus Finch is an amazing shot when hunting. (paraphrasing) "Why,
he would leave here with twelve rounds, then return with ten birds and
complain about wasting ammunition." However, he would never brag about
this, so his kids never knew. When Scout points this out, the maid explains
that Atticus never had to work very hard to be a good shot. As a result,
he was of the opinion that it came from God, so it wasn't his to brag about.
As it relates to
the car crash incident, I don't know how much of this was an act of will-power,
an effort to struggle against what I *wanted* to do in order to act in
a fashion that ran counter to my desires. In all likelihood, I probably
would have done exactly what I did, which was to stay close to you, but
I was on sort of an "auto-pilot" at that moment. I think I was physically
stunned by the accident. I understood completely what had happened, but
I wasn't thinking in a larger framework of what I *could* do at that moment
Like I said, even Pearl [my foster dog; she was on my lap at the time of
the accident] dropped off of my radar for a time. She was yapping for a
few minutes when she was first shaken up [she had slid off my lap and bounced
forcefully against the dashboard], so I calmed her while I was trying to
keep your head up and to get you talking and responding (which you didn't
for several minutes). [This is a story unto itself, by the way. Her subsequent
memory problems were an interesting study as well.]
I think you might
draw a parallel between this and maternal instinct. My dad likes to relate
the story of how when he and my mom brought me home from the hospital,
her maternal instincts just "kicked in." I forget exactly what it was that
she was doing, maybe bathing me or something like that (probably not since
we're talking about my first day home), and my dad was astounded how how
she seemed to know exactly what she was doing. He said, "Where did you
learn to do that?" She replied, kind of surprised herself now that she
thought about it, "I just knew what to do."
Certain innate patterns
of behavior express themselves only at the most opportune moments, and
we don't always know we have them in our repertoire. The most frequently-cited
example of this is when a mother lifts a car to save her children. I don't
know how often this ever occurs in actuality, but it is almost certainly
a real manifestation of this phenomenon. More important than the physical
feat, astounding as it is, is the fact that mothers attempt this *first*
before engaging in any other behavior. From an evolutionary perspective,
this is a good way to select for this trait. Those offspring that were
saved from death beneath that car/rockslide/mammoth carcass just happened
to be carrying a set of those genes that set the stage for Mom's heroism.
I frequently read
people talking in the aftermath of the creation or discovery of long-lived
strains of C. elegans as though it was such a shock to find that aging
and mortality were encoded genetically (as opposed to being predominantly
under the influence of the environment). However, I recently read an interesting
example of longevity being preferentially selected for (or against) that,
in hindsight at least, indicates we should have come to this conclusion
Insects have two
opposing different strategies for avoiding being eaten. Camouflage prevents
them from being spotted to being with. Alternatively, bright coloration
coupled with toxic or at least foul-tasting chemicals dissuades predators
from pursuing that species. Interestingly, those species who employ the
camouflage strategy tend not to live very long past their reproductive
utility. By dying off, their deception is less likely to be uncovered,
thus subsequent generations benefit from their absence. Conversely, brightly
color insects do better to make themselves widely-known. The more of them
who make their presence felt (or tasted!), the fewer the predators who
will chance feasting on their species. Thus, these insects tend to live
well past their reproductive prime.
It's funny how alcohol
simultaneously removes both inhibitions and the ability to act in the absence
of inhibitions. I guess that's a consequence of evolution. Those who were
capable of acting on their stupidity may very well have selected themselves
out of the gene pool.