Evolution and the Brain

The following 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 useful information.

Monkeys
[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.

Evolution 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!

Reflexes
Just like the movements induced by the kidney stone, I was thinking of other reflexive behavior developed by evolution.
Other finely-tuned reflexes:
-Food cravings. 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 in
Curiously vestigial reflexes:
-Babies' grasping 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.
Another strange reflex:
-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.

Free will vs. evolutionarily-selected altruistic behaviors expressed only during emergency situations
[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.

Longevity
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 much earlier.
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.

Subcortical and/or evolution
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.




Copyright Alexplorer.

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