Psychopathology: Genetic and Evolutionary Perspectives

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Psychopathology Genetic and Evolutionary
Perspectives

• Charles Crawford
• Department of Psychology
• Simon Fraser University
• E-mail crawford
• Website http//www.sfu.ca/faculty/crawford

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David Rosenthals 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?

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What Behaviour Geneticists Want

• Mode of inheritance
• Biochemical pathways
• Relation between alleles and physiological
  development
• Relation between physiological development and
  behaviour

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When Mendel's Laws Dont 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

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Heritabilities for a Mental and Physical Traits
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Personality Disorders Traits
Personality
Heritability
Environmental Variance
Disorder Traits
Shared
Non Shared
Rejection
0.35
NA
0.65
Restricted Expression
0.5
"
0.5
Self-harm
0.41
"
0.59
Social avoidance
0.53
"
0.47
Stimulus-seeking
0.4
"
0.6
Submissiveness
0.45
"
0.55
Suspiciousness
0.45
"
0.55
Jang, Livesley, Jackson, 1996
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Meaning of Heritability

• For geneticists
• Proportion of variation in a trait due to genetic
  differences in a population
• For evolutionists
• The opportunity for natural selection to operate
  on the trait in a population

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Focus of Genetics

• How genetic differences between individuals
  produce differences between individuals in a
  constant environment.

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Darwins Finches beaks
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Beaks Tools For Survival, Growth, and
Reproduction
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E.O. Wilsons 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

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Fever as an Adaptation

• Raising body temperature to help the body fight
  parasitic infections
• Processes information about the invaders and the
  bodys ability to resist them
• Benefit destruction of parasites
• Costs energy requirements, damage to body

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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

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Male Scorpionfly Mating
Male tactics Dead insect Proteinaceous
mass Forced copulation
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Scorpionfly Mating Tactics and Environmental
Conditions
Environment
Mating Tactic
(male-male competition)
Low
Dead insect courtship
Genetically
innate
Proteinaceous mass courtship
2
Medium
"mental"
h
0
mechanism
High
Attempted forced copulation
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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?

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Genes The Evolutionary Perspective
Are genes involved in producing the similarities
in these identical twins who were separated
until middle age?
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Are genes involved in producing the differences
between these identical twins?
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Identical Triplet Scorpionflies Reared in
Different Environments
Environment
Mating Tactic
(male-male competition)
Low
Dead insect courtship
Genetically
innate
Proteinaceous mass courtship
2
Medium
"mental"
h
0
mechanism
High
Attempted forced copulation
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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?

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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?

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Personality Disorders Traits
Personality
Heritability
Environmental Variance
Disorder Traits
Shared
Non Shared
Rejection
0.35
NA
0.65
Restricted Expression
0.5
"
0.5
Self-harm
0.41
"
0.59
Social avoidance
0.53
"
0.47
Stimulus-seeking
0.4
"
0.6
Submissiveness
0.45
"
0.55
Suspiciousness
0.45
"
0.55
Jang, Livesley, Jackson, 1996
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Non Zero Heritability of the Tactics
High
Dead insect
Ancestral reproductive success
Proteinaceous mass
Forcible copulation
Low
Low
High
Genetic differences in competitive ability
Parasite resistance, growth rate, ...
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Blue Gill Sunfish Another view
Cuckolder
Ancestral Reproductive Success
Parental
Growth Rate/competitive ability h2 0.0
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Blue Gill Sunfish Adaptation
Cuckold
Fast
Predators Resources
Growth Rate
Strategies
Tactics
Proportion of cuckolders In the population
Slow
Parent
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When Mendel's Laws Dont 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

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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

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Toward an Evolutionary Classification of Behaviour

• Adaptation failure
• Cybernetic dysfunction
• Organic dysfunction
• Problematic behaviours
• True pathologies
• Pseudopathologies
• Quasinormal behaviours
• Adaptive-culturally variable

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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, Korsakoffs psychosis

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Adaptation functioning Then and now
Now Contribution to well being
Yes
No


Yes
Adaptive- culturally variable
Pseudo pathologies



Then Contribution to fitness





True pathologies
Quasinormal behaviours
No
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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, Korsakokffs syndrome
• Autism
• Maternal diabetes, hypertension
• Malfunction of or cost of adaptation

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Adaptive-Culturally Variable Behaviours

• Behaviours that vary in time space, but that
  serve adaptations original function.
• Examples
• Language learned - Swedish, English, Portuguese,
  Esperanto, etc
• Athletic sports - Baseball, cricket, hockey
• Co-operation, reciprocity
• Cheating, self deception, theft, war,...

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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.

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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

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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

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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?

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Genetic Variation Remainsh2 0.0

• Specific genes affects adaptations development -
  Genetic perspective
• Balanced polymorphism
• Sickle cell anaemia
• Psychotherapy?
• Genetic variation remains, but not related to
  adaptations function - Evolutionary Psych.
• Psychotherapy?

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David Rosenthals 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?