Degeneration hypothesis on psychopathy: beyond the malfunction/adaptation dichotomy


DeokHa Yi



[Abstract] Before the rise of evolutionary psychology, malfunction hypothesis dominated the research of psychopathy. Later, many evolutionary psychologists suggested that maybe psychopathy is adaptation. In this paper it is suggested that maybe psychopathy evolved in recent stratified urban environments. Many think that just one of the malfunction hypothesis and adaptation hypothesis is true. But there is possibility that both are true, just like the fact that degeneration or malfunction of eye of deep cave animal is adaptation.






Before the rise of evolutionary psychology, malfunction hypothesis dominated the research of psychopathy. Some psychologists focused on the genes, others on the environments. Yet they all thought that psychopathy is due to the disturbances of development of the parts that motivate moral behaviors.


Although non-evolutionary psychologists saw psychopathy as malfunction of something, when they describe the episodes of psychopaths they implicitly assumed that psychopaths are specialized to take advantages of other nice people.


Later, many evolutionary psychologists suggested that maybe psychopathy is adaptation. They provided theoretical model for the former non-evolutionary psychologists intuition. According to the frequency-dependent selection model, when there is small fraction of evil people they can reproduce fairly well.


In the stratified urban society, it seems that evil strategy of minority is adaptive. Anonymity makes it easy to do immoral things without getting caught. That was very difficult in the transparent hunter-gatherer society. In stratified society a male who became a member of dominating class by the evil strategies can get enormous reproductive benefit.


The problem is that it is only several thousand years since the emergence of city. That time span is for many evolutionary psychologists too short to evolve a new complex adaptation. And hunter-gatherer society in which our ancestors spent plenty of time is too disadvantageous for an evil strategy to evolve.


Why many evolutionary psychologists tend to ignore the last ten thousand years of human evolution? Because complex adaptation like human eye needs very long time to evolve. And they think evil strategies need complex psychological mechanisms.


Some evolutionary psychologists think psychopathy is r-strategy of r/K selection model. But human female couldnt adopt r-strategy until very recently. Yet there are many female psychopaths. It may be noted that if psychopathy is an adaptation there should be no female psychopath.


Contrary to the evolution of complex adaptation, the degeneration of complex mechanism can be achieved in very short time because of the law of entropy. It needs enormously long time for the eye of vertebrate to evolve. But the eye of the vertebrate who came to live in deep cave can degenerate relatively very quickly.


Malfunction of some part of an animals physiological or psychological systems is almost always maladaptive. So many evolutionary psychologists treat malfunction as an antonym of adaptation. But the example of the degeneration or malfunction of eye of an animal in deep cave demonstrates that sometimes malfunction is adaptive. It is better for the animal to save physiological cost that is needed to develop and maintain eyes.


The transition from egalitarian hunter-gatherer society to stratified urban society makes very dramatic environmental changes just like the transition from bright open land to deep cave. If the degeneration of eye of the cave animal is adaptive, there is no fundamental reason to think that the degeneration or malfunction of some moral modules of the urban human can not be adaptive.


If a gene can break a persons some moral modules selectively and let another modules intact, in some environment the gene can spread. Even if female psychopaths are maladaptive in the urban environment, the great advantages that male psychopaths gain makes it possible for the gene to spread.


According to the anthropologists, the ratio of psychopaths is relatively very low in the small tribal societies. The data tally with the assumption that psychopathy evolved recently like the milk digestion capacity of adult human.