Psychopathology: Genetic and Evolutionary Perspectives Charles Crawford Department of Psychology...
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Transcript of Psychopathology: Genetic and Evolutionary Perspectives Charles Crawford Department of Psychology...
Psychopathology: Genetic and Evolutionary Perspectives
Charles CrawfordDepartment of Psychology
Simon Fraser University
E-mail: crawford
Website: http://www.sfu.ca/faculty/crawford
David Rosenthal’s Genetic Theory and Abnormal Behavior
Of all the facts of life, the most important is evolution. If psychology is to take its legitimate place among the family of life sciences, it must eventually integrate its basic theories and facts with those of evolution. If we are to understand abnormal behavior, we must do so in the context of a psychology so conceived and so formulated. These three simple statements constitute the conceptual framework that hopefully will lend vitality and a sense of orientation to the chapters that follow. (Rosenthal, 1970, p 1).
Evolution is rarely mentioned in remainder of the book Why?
What Behaviour Geneticists Want
Mode of inheritance Biochemical pathways Relation between alleles and
physiological development Relation between physiological
development and behaviour
When Mendel's Laws Don’t Work
Incomplete penetrance Only some individuals with gene are affected
Variability in expressivity Intensity of expression varies between
individuals
Many genes affect the trait Producing a normal distribution
Measure H2
Stanford-Ben IQ 0.65
Otis IQ 0.68
Head width 0.75
Height 0.81
Weight 0.78
Heritabilities for a Mental and Physical Traits
Personality Disorders Traits*Personality Heritability Environmental VarianceDisorder Traits Shared Non Shared
Rejection 0.35 NA 0.65Restricted Expression 0.5 " 0.5Self-harm 0.41 " 0.59Social avoidance 0.53 " 0.47Stimulus-seeking 0.4 " 0.6Submissiveness 0.45 " 0.55Suspiciousness 0.45 " 0.55
*Jang, Livesley, & Jackson, 1996
Focus of Genetics
How genetic differences between individuals produce differences between individuals in a constant environment.
Darwin’s
Finches’
beaks
Beaks: Tools For Survival, Growth, and Reproduction
E.O. Wilson’s Definition of Adaptation
An anatomical structure, a physiological process, or a behavior pattern that makes an organism more fit to survive and reproduce in competition with other members of its species
Examples: Beaks of finches Binocular vision Bipedalism
Note the word “ancestral” not in the definition
Blue Gill Sunfish: Lifehistories
Parental Grow slowly, mature late Courtship, paternal care
Cuckolder Grow fast, mature at young age Young - sneak fertilisations Old - mimic females
Genetic strategy
Parental
h2 > 0
Cuckolder
nest + courtship + care
sneaker female mimic
h2 = 0
Be havioural t act ics
Male mat ing st rat e gie s and t act ics in Blue gill Sunfish
Ge ne t ic st rat e gy
Parental
h2 > 0
Cuckolder
nest + courtship + care
sneaker female mimic
h2 = 0
Be havioural t act ics
Male Scorpionfly Mating
Male tactics•Dead insect•Proteinaceous mass•Forced copulation
Environment
(male-male competition)
Low
Medium
High
Mating Tactic
Geneticallyinnate"mental"mechanism
Dead insect + courtship
Proteinaceous mass + courtship
Attempted forced copulation
h2 = 0
Scorpionfly Mating Tactics and
Environmental Conditions
Adaptation Defined A set of genetically-coded decision processes
that enabled ancestral organisms to implement cost-benefit analyses in response to specific sets of environmental contingencies, and
that organized the effector processes for dealing with those contingencies so that the allele(s) producing the decision processes were reproduced better than alternate allele(s) Examples: fever, beaks, recognizing kin, warfare
What is the role of gene differences in producing behavioural differences?
Are genes involved in producing the similarities in these identical twins who were separated until middle age?
Genes: The Evolutionary Perspective
Are genes involved in producing the differences between these identical twins?
Environment
(male-male competition)
Low
Medium
High
Mating Tactic
Geneticallyinnate"mental"mechanism
Dead insect + courtship
Proteinaceous mass + courtship
Attempted forced copulation
h2 = 0
Identical Triplet Scorpionflies Reared in Different Environments
Conclusion
Gene differences do not produce the behavioural differences
Genes that all male scorpionflies have enable then to choose the tactics used
The design of their mating processes is innate It limits their ability to use other mating tactics Dose zero heritability mean genes are not involved
in behavioural differences?
Logic for Innate Design
If alleles at a large number of loci are necessary for the development of a complex adaptation,
if sexual recombination continually reshuffles alleles at these loci,
then, it is unlikely this reshuffling has a major effect on the adaptation's functioning.
Therefore, the genetic design of an adaptation is likely innate.
But what of the non zero heritabilities?
Personality Disorders Traits*
Personality Heritability Environmental VarianceDisorder Traits Shared Non Shared
Rejection 0.35 NA 0.65Restricted Expression 0.5 " 0.5Self-harm 0.41 " 0.59Social avoidance 0.53 " 0.47Stimulus-seeking 0.4 " 0.6Submissiveness 0.45 " 0.55Suspiciousness 0.45 " 0.55
*Jang, Livesley, & Jackson, 1996
Non Zero Heritability of the Tactics
Ancestralreproductivesuccess
Genetic differences in competitive ability: Parasite resistance, growth rate, ...
Low
High
Low High
Dead insect
Proteinaceous mass
Forciblecopulation
Blue Gill Sunfish: Another view
Growth Rate/competitive ability: h2 > 0.0
Parental
CuckolderAncestralReproductiveSuccess
Blue Gill Sunfish: Adaptation
StrategiesGrowth Rate
Fast
Slow
Tactics
Cuckold
Parent
Predators Resources
Proportion of cuckoldersIn the population
AncestralGeneticVariation
Variability exhausted
Variability not exhausted
Development freed from geneticInfluences
Genetic influences on developmentRemain
Genetic variation remains andaffects adaptation’s functioning
Genetic variation remains, buy isnot related to adaptations function
Affects of NaturalSelection on GeneticVariation
Remaining Genetic Influences onDevelopment
Selection Acts on GeneticVariation
Possible Outcomes when Natural Selection Meets Genetic Variation
When Mendel's Laws Don’t Work
Incomplete penetrance Only some individuals with gene are affected Adaptation-environment interactions
Variability in expressivity Intensity of expression varies between individuals Adaptation-environment interactions
Many genes affect the trait Producing a normal distribution Genetic variation at protein level
Evolutionary Psychology
Stresses that existed in ancestral environments Finding a mate
The psychological mechanisms that evolved to deal with those stresses. Evaluating physical features as guide to health
The way those mechanisms function now. Men and women on TV
Toward an Evolutionary Classification of Behaviour
Adaptation failure: Cybernetic dysfunction Organic dysfunction
Problematic behaviours: True pathologies Pseudopathologies Quasinormal behaviours
Adaptive-culturally variable
How Adaptations Fail: A Computer Analogy
Adaptation's cost-benefit structure provides inadequate or inappropriate decisions because of:
Cybernetic dysfunction - Failure of the adaptations information processing system True altruism, nursing failure
Physiological dysfunction - The neural hardware in which the information processing system is realised PKU, Korsakoff’s psychosis
Adaptation functioning: Then and now
Now: Contribution to well being
Adaptive-culturallyvariable
Yes
Yes
No
No
Pseudopathologies
Quasinormalbehaviours
Truepathologies
Then:Contribution to fitness
True Pathologies
Have deleterious consequences for individuals possessing them, irrespective of whether they are living in an ancestral or current environment.
Examples: PKU, brain damage, Korsakokff’s syndrome Autism Maternal diabetes, hypertension
Malfunction of or cost of adaptation
Adaptive-Culturally Variable Behaviours
Behaviours that vary in time & space, but that serve adaptation’s original function.
Examples: Language learned - Swedish, English, Portuguese,
Esperanto, etc Athletic sports - Baseball, cricket, hockey Co-operation, reciprocity Cheating, self deception, theft, war,...
Pseudopathologies
Behaviours that contributed to ancestral fitness, but that are no longer adaptive, ethical, or normal. Excessive male sexual jealousy Prostitution Anorexic behaviour Teenage gangs
More will emerge as we move further and further from our ancestral environment.
Quasinormal Behaviours
Behaviors that would have detracted from ancestral fitness, but that have become culturally acceptable and even encouraged Adoption of genetically unrelated children. Innocent until proved guilty. Recreational sexual behaviour. True altruism Equal treatment of women
Not result of evolved adaptation to produce them
Quasinormal: Why they can be problematical
The cues for managing behaviour may be inadequate
• Adoption of unrelated children
Not all members of a social group will make the same cost-benefit analysis, producing conflict Feminism, polyandry, stock market
Conflicting inputs to information processing mechanisms may produce psychological conflict Recreational sexuality, innocent until proved guilty
AncestralGeneticVariation
Variability exhausted
Variability not exhausted
Development freed from geneticInfluences
Genetic influences on developmentRemain
Genetic variation remains andaffects adaptation’s functioning
Genetic variation remains, buy isnot related to adaptations function
Affects of NaturalSelection on GeneticVariation
Remaining Genetic Influences onDevelopment
Selection Acts on GeneticVariation
Possible Outcomes when Natural Selection Meets Genetic Variation
Genetic Variation Exhausted: h2 = 0.0
Development freed from genetic influences The tabula rasa Therapy?
Genetic influences on development remain Constraints on possible change Therapy?
Genetic Variation Remains:h2 > 0.0
Specific genes affects adaptation’s development - Genetic perspective Balanced polymorphism
• Sickle cell anaemia
Psychotherapy?
Genetic variation remains, but not related to adaptation’s function - Evolutionary Psych. Psychotherapy?
David Rosenthal’s Genetic Theory and Abnormal Behavior
Of all the facts of life, the most important is evolution. If psychology is to take its legitimate place among the family of life sciences, it must eventually integrate its basic theories and facts with those of evolution. If we are to understand abnormal behavior, we must do so in the context of a psychology so conceived and so formulated. These three simple statements constitute the conceptual framework that hopefully will lend vitality and a sense of orientation to the chapters that follow. (Rosenthal, 1970, p 1).
Would evolution still be rarely mentioned in remainder of the book?