Lecture 15- Understanding human nature: what evidence is required? Flashcards
How can human behaviour be explained by evolutionary theory?
-Evolutionary approaches to human behaviour
-Construct an evolutionary explanation of a pattern
• human emotions: weak data to explore the evolution of disgust
Identify a cost in order to construct an evolutionary ‘benefit’
• human handedness: what maintains a polymorphism with a mildly costly condition
-Ask why a particular behaviour is maintained in the population, despite its substantial fitness cost
• affective psychoses: what maintains a potentially devastating illness?
-these are the approaches,
What is the issue with left handedness study?
-left-handed individuals suffer higher mortality than right-handed people
-the paper just referred to other papers saying that there is a cost
-Argument:
• left-handed people in the minority in all human populations
• several fitness costs allegedly associated with left-handedness
• countervailing benefit must exist to maintain polymorphism
• left-handed people at advantage in sports involving dual confrontations (fencing, tennis, baseball)
• left-handed people at advantage in
aggressive interactions?
Some problems:
• is the cost of left-handedness substantial, and relevant to the societies in this study?
• is homicide rate the best estimate of prevalence of one-to-one fights?
• are there confounding variables that might be driving this correlation?
What is the evolutionary significance of psychosis?
-Julian Huxley, Ernst Mayr and others made a case for examining the evolutionary significance of affective psychosis:
• it is reasonably common and broadly stable across time and cultures
• the major psychoses, schizophrenia and affective psychosis, consist of
severe disruptions of cognition and emotion, which have a basis in the
brain
• the consequences of these disruptions are personally disastrous, coming
early in life and often resulting in suicide, loss of intimate relationships
and loss of capacity to provide for oneself
• the liability of these disruptions depends upon personality and may have a genetic basis
What evidence is needed to establish an evolutionary meaning of psychosis?
• is there a genetic basis to this illness?
• is there a fitness cost?
• what is the nature of the balanced polymorphism that compensates for
the biological fitness cost?
• what is the evidence?
-like psychosis, has a biological basis, does have a fitness cost!
Is there a genetic basis to schizophrenia?
-yes seems like it but cannot entirely rule out environment
Is there a fitness cost to schizophrenia?
Meta-analysis of six publications revealing that patients with schizophrenia: had significantly fewer offspring than healthy controls (fertility ratio (FR)!=! 0.39)!
What seems to maintain the psychosis in the population?
- eminent men have more psychoses so maybe creativity is somehow connected
- psychotic patients usually more creativity
