Tuesday, May 14, 2013

Genes, Environment, and Strategic Planning in Human Behavior: a Primer

Most psychiatrists used to agree that, in order to best treat patients with psychological problems, we should use what has been termed the biopsychosocial model. This means that both the behavior problem and/or mental disorder is caused or maintained by a combination of factors including biological and genetic propensities, psychological processes including affects, cognitions, defenses, etc., and social factors such as dysfunctional interpersonal relationships and history of trauma.  Treatment should address all of the important contributing factors.

If fact, there are no biological, psychological, or social factors that are either necessary or sufficient to produce the vast majority of mental disorders and behavioral problems. There are only risk factors, or factors that increase or decrease the odds that someone will develop and/or maintain such problems.  Whichever factor you choose, some people will have none of it and will develop the disorder, while others will have a lot of it and not develop the disorder.

In theory, no one in the field will admit that they favor only focusing on one domain or another, or as philosophers call doing that, reductionism. But lately, psychiatrists in particular are using a bio-bio-bio model. In particular, genetic influences on behavior are grossly exaggerated, despite the fact that any neurobiologist worth his salt knows that no complex human behavior is caused by one gene or one group of genes.

Human beings are not very instinctual. A great deal of what we do is learned.  Hell, we don’t even know how to do something as biologically important as procreate, unless someone tells us how or we discover sexual intercourse through trial and error. (Fortunately, most of us figure it out eventually). We all have the biological urge to merge, of course, but how to go about it? We don’t know innately. Unlike say, a certain species of wasp that always does a complicated mating dance that is identical to that performed by every other wasp of the same species - without the benefit of having seen another wasp do the dance.

It is important to remember that the vast majority of genes in a given cell are turned off. They ain’t doin’ nothin’. They only get turned on by environmental factors. In terms of neurons, the environmental factors that turn them off and on are quite often those from the interpersonal environment. Furthermore, all neural pathways in the brain compete with each other in a Darwinian, survival of the fittest sense. If they are not stimulated by the environment, synaptic connections between neurons weaken and then disappear altogether. If they are stimulated repeatedly, they get stronger (long-term potentiation).

The only exceptions are certain tracts in a part of the brain called the amygdala, which form early in life in response to attachment figures. You know, parents. These synaptic pathways seem to be highly resistant to weakening through the usual process of neural plasticity. They can be overridden but not destroyed. There are, in fact, cells in the amygdala that respond only to a mother’s face, and others that respond only to a father's. Maybe Freud was on to something after all.

And then there’s the matter of a major function of the human brain: the ability to set goals, make mental models of possible strategies for achieving those goals, planning them out, anticipating and visualizing problems that may arise, putting effort into them, revising them along the way as new information becomes available, and then achieving them. This brain function seems to be thought of as non-existent by those who study the "heritability" of human behavior. This, despite the fact that those who design such studies are in the process of doing that very thing!!

Allow me to provide a primer on the nature of human behavior and its antecedents, using human language as the example.

Beginning with linguistics expert Noam Chomsky (whatever you think of his politics being irrelevant), linguists have shown repeatedly that there is a huge genetic component to human language. The human brain structure limits the possible syntactical and grammatical forms language can take, as well as the available sounds.

Noam Chomsky

However, whether you speak Greek or Swahili is entirely determined, 100%, by your environment.

And whether you speak Greek and Swahili is usually determined 100% by your conscious decision to learn a second language and the effort you choose to put into the task.

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