are bits of writing from many sources such as personal correspondence,
posts to on-line discussion groups, notes, and occasionally even some
All of this is informal in nature, but contains some interesting and/or
about nature or nurture, the earlier in development you can present an
influence, the more dramatic the change will be. An analogy a lot of
use is that development is a rocket and all the influences are "course
corrections." Obviously, the same amount of "thrust" earlier in the
will have a greater influence in altering the trajectory.
like me, it's pretty hopeless. Although, admittedly, people do find
influences. Things like therapy or programs like Alcoholics Anonymous
a constant "push" that helps people to change from their preferred
of behavior to something hopefully a little more healthy.
One of my
likes to view the developmental process as a rocket traveling through
Along the journey there are various "course corrections" that alter the
trajectory. The big questions are what kinds of things can be
and what are the ways they can be influenced? The one principle that
up across most of this (and works with the rocket analogy as well) is
"the earlier, the better." In other words, the sooner the influence is
applied, the greater the effect it will have, particularly if there are
"critical periods" involved.
[Posted to the
group on MySpace.com]
you are often hungry or tired or constantly being sodomized by
there is a good chance that- in anyone's book- your brain is not
I think the
example is more a description of trauma than inactivity. The outcome
seems to be something different than a disposition toward Alzheimer's,
though still pathological. Admittedly, it could still set you up for a
future in that direction, but I'm thinking of the short-term issues.
There is an
passage relating to this in Inside the Brain by Ronald Kotulak (p. 62).
It is neither strictly an analogy nor an example. It's something
between the two.
The quest for
roots of violence --and there may be others besides serotonin and
draws on a wide variety of research, including studies of insects,
reproduction, and heart disease, in addition to chemistry.
more vivid example of the environmental-genetic link to violent
than the Grand Canyon Tiger Salamander, nature's version of Dr. Jekyll
and Mr. Hyde.
live in ponds along an isolated rim of the Grand Canyon. When water and
food are plentiful, the salamander is in it's Dr. Jekyll form --a
peace-loving insect eater. But when the water begins to dry up, food
scarce and living conditions become unbearably cramped. Then some of
salamanders go through an amazing Mr. Hyde transformation.
rapidly alter the function of some of their genes, creating changes in
their physical shape and making them aggressive. Muscles enlarge to
their heads and mouths bigger and they grow a new set of huge teeth,
that allow them to attack and eat other salamanders.
but only for a short time. Once they've gobbled up enough salamanders
reduce crowding, they turn back in Dr. Jekylls. Their heads shrink to
size, their cannibal teeth disappear, and they dine on insects again.
Cornell University behavioral ecologist who is studying the Grand
Tiger Salamander, said many other species undergo cannibalistic
as a result of environmental pressures such as overcrowding.
uses overcrowding as an example of environmental pressures, but life in
an abusive environment of any sort (particularly at a young age!) can
about changes to create an individual brain sculpted for life in an
who grow up in an abusive home tend to have a lot of prefrontal cortex
issues. That is, they are impulsive in a wide range of situations. This
manifests itself as attention deficiencies, acting out, and violent
They also get stuck in emotional states that greatly outlast the
that initiated said state (i.e., they're moody; they suck, pout, etc.).
They would do well if society was built around "fight or flight"
but they have trouble functioning in a world that expects them to be
to focus on problems and communicate with other members of their
I read an
regarding aging that was very interesting, but contained a *huge* and
oversight. The focus was entirely on improved health care with
interest paid to organ regeneration/replacement. The oversight was the
failure to even mention the fact that there is a tremendous body of
indicating that there is a *biologically*programmed* upper limit on the
human lifespan. This is not necessarily permanently set, but it is like
changing your eye color- you had better do it at the genetic level
in life (ideally within minutes of conception!) if you expect the
to be real and effective.
this upper limit come from a variety of sources. One of the most
is the finding involving C. elegans, a type of flatworm relatively
now due to the work of one of this year's Nobel winner. A mutant
of this worm will live as much as 5 times longer than its non-mutant
wild type) relatives. What is especially interesting about this is that
the mutation did not add something that granted an approximation of
but rather it removed a limit that was present already. The
for humans is staggering.
line of evidence in the area is the fact that, while life expectancy
increased over the years, the human lifespan has not. Granted, this
involves looking at a very small number of individuals at the far end
human experience (>100 years), but over time this upper limit should
expected to have changed. The population trend has shifted such that
people can expect to live into their 80s and 90s, but the upper limit
still only(?) a few years past 100. The issue seems to be somewhat
than just repairing organs. Recall that even Dolly the cloned sheep is
thought to be "older than her years" in physiological terms. This is in
spite of the fact that the only part of her physical being that (at
theoretically) predates her conception is her DNA. Oh, biologists will
have work to do for many years to come....
A couple days
I heard a piece on the nature of left-handed brains on NPR and thought
you might be interested in listening to it. It turns out there is an
new(?) element to the nature/nurture influence, a genetic
toward environmental influence (and, conversely, a resistance to such
about 90% of the tasks you could list, but I write and eat (use
left-handed. Go figure.
Check it out
I Grow Up
up the idea that there is an intermediate stage between adolescence and
adulthood, something from age 23 to 30. You aren't future-oriented, but
you aren't that impulsive, reckless teenager you were a few years ago.
I have trouble defining the female version, but the male agenda during
this time typically lacks direction and desire. The angst is gone, but
he doesn't yet have any drive to achieve something concrete. From Fight
Club, "I can't get married; I'm a 30 year-old boy." Exactly.
to figure that out. Typically, people just start to mellow. One telling
thing is that a lot of emotional/psychological disorders are suddenly
after a lifetime of dealing with them up to that point. For example,
personality disorder, ADHD, and low-grade depression (specifically, the
rages typical of men with this disorder) all are much less severe
around that age. No one is exactly sure why, but it's probably in part
due to a maturation of the pre-frontal cortex. That part of the brain
in charge of emotional/impulse control. People with damage to those
have trouble planning tasks/activities. Since all the above-listed
are related to issues of self-control, it isn't surprising that they
be affected by this change of life.
interesting bits about "ontogeny recapitulates phylogeny"
1) In The
of Eden by Carl Sagan, an explanation for this phenomenon is offered
not original to the author, but I no longer have my copy to see if he
anyone). The evolutionary parallel to the developmental pattern comes
because the most sensible way to "implement" changes to a design is to
tack them onto existing structures rather than radically modifying what
already works. Thus, if you are going to develop a cortex, you probably
wouldn't chuck the previous design and try to reinvent the brain stem,
limbic system, etc. Instead, you just add this new bit on top and
with it for a few million years... until it causes enough problems to
to be an evolutionary dead end (e.g., by thinking up nuclear weapons
morning talk shows). Sagan does a better job of explaining this than I.
2) In the
part of the last century "ontogeny recapitulates phylogeny" was applied
in a very different context as a model of child social development, one
that shaped the design of school curricula. Specifically, the thinking
was that children passed through the stages of individual social
in a fashion paralleling the historical development of the human race.
Young children were viewed as little "cave men," and so were allowed to
run around and be wild creatures, playing games mirroring hunting
and the like. As they progressed, they were given more cultivating
reminiscent of an agrarian society. And so on until they became
modern individuals. Although no one would ever admit it, you can still
see remnants of this style of thinking in modern educational design.
how an individual's perspective is shaped by their needs. For example,
a lot of very conservative people (e.g., Nancy Reagan) go against their
stated beliefs when they are confronted with a problem that
impacts their lives. It is unfortunate that at the moment we have a
who notoriously is anything but studious, so he is least likely to be
by "dry," factual evidence. That means all the hard-won knowledge about
the benefits is going to be ignored and progress will be slowed no
the opinion of the people conducting the research or those who most
require the therapies that could be developed. Add to that the fact
time is of the essence when it comes to repairing the damage these
seek to treat, and it's just criminal what is happening in the funding
domain right now.
Guys can be
of bad until they're in their 30s. The reason is that it takes
then before the final stage of brain maturation. This is true for
women as well, incidentally, but before then, you're literally immature
in a biological sense, not just the behavioral one that results from
The part that has to mature is the prefrontal cortex, which is a region
that is involved with long-term planning. When it is damaged in
they tend to be *really* impulsive, like they'll hit someone for
them a drink that was too warm or something. In most people in
20s what this means is that you can hold a job, but you aren't
in settling down and having babies and a mortgage. Once people
in their 30s, they organize their lives around these things, not
together to "totally get wasted" with their friends. A lot of the
marriages people embark on in their 20s crumble, and it's so common
a name for it: We call them "starter marriages." Yeah, it sounds
like Will has a ways to go. He sounds like either short-term fun
or a long-term home economics project.