Randy Nesse Enlightens the Blogosphere
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Why We Need Hard Science to Settle Blogger Debates

After encountering the debate on evil, human nature, and evolutionary psychology on Fistful of Euros (1 2), Normblog, and Mick Hartley: Politics and Culture, I have decided to join the fray with a perpective I learned in college and medical school.  I had a professor, Randolph Nesse, who was absolutely avid about the topic of evolutionary psychology.  He uses the term "Darwinian medicine," which actually is a bit broader in scope, but includes evolutionary psychology.  His URL is:

http://www-personal.umich.edu/~nesse/

The most important point about evolutionary psychology is that it must be understood in the context of evolutionary process.  This means that natural selection does not act only on fixed traits -- such as height, weight, or strength; rather, it acts on traits (including behavioral tendencies) that adapt with the circumstance.  

For example, it might seem that, if what you want to do is to have a lot of kids, and you are a male, you should pick fights with all the other guys and kill them and take their females.  Note that I am talking about natural selection, not ethics.  Obviously it is not ethical to act in such a manner.  The point is, such behavior is not necessarily advantageous from an evolutionary perspective, either.  There are some circumstances in which you are not likely to win, so the best tactic is to keep a low profile until a better opportunity arises.  Thus, you do not expect natural selection to always favor brute strength.  A capacity to adapt dynamically to the circumstance is at least as important as sheer power.  Thus, a given set of genes could influence a person to act one way in one situation, and another way in a different situation.  

One common misperception of genetics stems from the assumption that genes always map 1:1 with physical traits.  For example, if you have  the gene for brown eyes, you get brown eyes.  Actually, only a small minority of genes act that way. Genes code for proteins, and proteins -- aptly named -- are incredibly versatile chemicals.  It is more accurate to think of genes as factors that exert an influence on a chemical process.  Repeat: they  influence  chemical process; only rarely do they determine  anything.  Thus, having a certain gene will increase or decrease the probability that a given chemical process will occur at any point in time.  

A concrete example of this occurs during childhood, when adult height is determined.  If food is plentiful, the creatures grows up to be big.  If food is scarce, the creatures ends up being small.  But the actual size of the adult is not determined strictly by the genetic makeup of the creature; nor is it directly proportional to the abundance of the food supply.  The final size of the adult is determined by the dynamic interaction between genes and environment.

From this perspective, it would make sense for a creature to be born with the capacity for evil; a capacity that would be activated only in certain circumstances.  As in the example of the relationship between genetic makeup, food supply, and adult size, the ultimate evilness of a person is determined not by "human nature" (genetic constitution) alone, nor by the environment alone; rather, it is determined by the interaction between the two.

This line of reasoning would not lead to the conclusion that some persons are born to be evil; nor would it lead to the conclusion that all persons can be made to be evil if exposed to an environment conducive to evil behavior.  The more logical conclusion is that genes and environment will interact in a highly complex -- and to some extent unpredictable -- manner.  The dice may be loaded, but they still are dice.  

Adopting this paradigm, it no longer makes sense to argue about whether human nature is fundamentally good or fundamentally evil.  The only thing that is fundamental about human behavior is the unpredictability of it.  

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By the way, evolutionists do have an explanation for cooperative behavior.  It is explained by the concept of inclusive fitness.  See:

http://hss.fullerton.edu/sociology/orleans/sociobiol.htm

for a decent explication of the concept of inclusive fitness.

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Who has the best credentials to discuss this:  liberals or conservatives, authoritarians or libertarians?  The biologists have had their say.  I'll leave that question for the social scientists to decide. 
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