Thursday, May 23, 2019

A recent paper claims that human traits are basically produced by genes and luck

Authors of a paper published earlier this year in Behavior Genetics have made arguments similar to those of  HBD writers Greg Cochran and JayMan: psychological traits are basically the result of 1) genes, and 2) noise. 

Years ago, behavioral geneticists discovered that the environments shared by siblings have little impact on how you turn out. By contrast, the environment you experience that is unique to you appeared to be about as important as genes -- both of them explaining roughly half of the story.   

The authors, two Russians from St. Petersburg University (they're Russians, so they must be evil) explain that research trying to identify specific factors from the unique environment that are important has been mostly unsuccessful.  Factors like illnesses and accidents typically explain less than 3% of the examined traits.

In addition, genetic research (mostly experiments on animals) has shown that traits depend a great deal on stochasticity--a fancy term for randomness, or "luck."  For instance, ultraviolet rays increase genetic mutation rates in organisms, but exactly which genes will be affected is a stochastic process. Random genetic errors that occur in the early stages of embryonic development will be more consequential; in this case, all the descendants of the initial mutant cell will also be mutant. 

Complex organic systems like the human body or brain are especially likely to be shaped by random events. For example, in female embryos, one of the two X-chromosomes is inactivated as a Barr body.  Each cell will make a random 'decision' which X-chromosome (the paternal or maternal) gets inactivated, and the 'decision' is maintained in subsequent cell divisions.  As a result, the female becomes mosaic.  In heterozygous females with the EDA mutation, you get ectodermal dysplasia which leads to an absence of perspiratory glands.  Depending on what X-chromosome is active, some skin areas are defective in sweating, while other areas are normal. The mosaicism is random.  Even identical twins raised in very similar environments will differ significantly.

Another human example is the growth of synapses in the developing brain.  While the number and locations of these connections are under some genetic control, research has demonstrated a significant stochastic component.  So again, identical twins raised the same will end up with brain wirings that are somewhat different, this is simply due to random differences in development, and it can cause behavioral differences.

These authors do not mean that these random factors are actually causal factors that simply have not been identified yet. They are claiming that pure randomness is simply a key part of our development, and the hard determinist view is simply incorrect.

They don't touch the political implications of all this, but I'll jump in.  To summarize, it's only a little bit of a simplification to say that we may be the product of genes and random events.  Genetic research is also telling us that hundreds or thousands of genes influence a trait, but each only a trivial bit, so simple pathways for intervention and improvement might be hard to find.  And you can't control randomness, so there seem to be fewer and fewer possibilities for government to step in and effectively address social problems -- at least in ways acceptable to liberals.  The old-time conservative who contended that human nature is tragically flawed and that one must resign oneself to human limitation seems more and more like a prescient, wise person.     


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