Lesson 7- Biological approach- influence of genes & evolution on behaviour Flashcards
Define genetics
Genetics- extent to which psychological characteristic determined by genes 🧬 or environment
Define phenotype
Phenotype- physical, behavioural 🏃♂ & psychological traits- determine characteristics of individuals- impacted by environment as well as genes
Define genotype
Genotype- genetic code written in DNA of individual cells consisting of genes 🧬 person possesses- inherited from parents
How do psychologist study genetics?
By studying twins:
- MZ (monozygotic identical twins)
- OR DZ (dizygotic non identical twins)
Why do psychologists study twins when investigating genetics?
Twin studies allow psychologists to look at concordance rates between twins (chances of both twins inheriting certain trait e.g. depression or intelligence)
E.g. using gene mapping-> finding out that chromosome 13 carries gene for schizophrenia & chromosome 11 carries gene for bipolar depression
What are the evaluation of genetics as an explanation of behaviour?
👎- other models/approaches in Psychology ignored- e.g. 🧠 & 🏃♂ approaches ALSO need to be considered when examining 🏃♂- someone with depression may carry gene for depression BUT might also have faulty & ➖ cognitions
👍- help psychologists screen ppl to see if they carry genes for certain illnesses- involves gene 🧬 mapping- helps psychologists identify ppl at risk from certain illnesses/diseases e.g. depression/cancer etc … ppl get psychological help before become unwell (preventative)
👎- reductionist approach- takes a complex human 🏃♂ e.g. IQ & reduces it down to small components e.g. genes- seems inaccurate as IQ ✖️ solely dependent on genes 🧬 BUT other factors as well e.g. environment
👍- involves using twin & adoption studies- useful when examining MZ (monozygotic twins)- identical- helps psychologists examine concordance rates in relation to 🏃♂- compare to adopted 👶-> research by Gottesman & Shields-> finding certain illnesses e.g. schizophrenia transmitted genetically
What did Gottesman & Shields study in relation to genes?
Role of genes in developing schizophrenia
What was Gottesman & Shields’ method when investigating the role of genes in developing schizophrenia?
Method:
1) Investigated 224 sets of twins from 1948-1993 (… longitudinal study- 25 years)- 106 sets MZ & 118 DZ)- 120 👨 & 104 👩- average age of pps 46 years & pps from range of ethnic backgrounds
2) Conducted in a London hospital 🏥 & 1 twin already had illness of schizophrenia & concordance rates investigated- examined likelihood of healthy twin becoming schizophrenic over ⏰
3) Methods used to diagnose schizophrenia:
- In-depth interviews
- Doctors case notes
- The DSM (Diagnostic & Statistical Manual of Mental Disorders)
What was Gottesman & Shields’ findings when investigating the role of genes in developing schizophrenia?
Findings:
4) 48% of MZ twins both concordant for schizophrenia by end of study
5) 17% of DZ twins both concordant for schizophrenia by end of study
What was Gottesman & Shields’ conclusion when investigating the role of genes in developing schizophrenia?
Conclusion:
6) … schizophrenia does have genetic basis to some extent- especially for MZ twins- for DZ twins genetics ⬇️ prominent (BUT risk is still ⬆️ than for general population- 1%)
What are the evaluation points of the twin study by Gottesman & Shields investigating the role of genes in the developing of schizophrenia?
👎- behavioural approach ignored- identical twins often copy/model each other’s 🏃♂ … could be that healthy twin modelled/copied schizophrenic 🏃♂ rather than getting illness via genetics … full investigation needed
👍- longitudinal study- schizophrenic patients tracked over long periods of ⏰ to monitor development of schizophrenia- very valuable when investigating role of genetics as patients studied over long periods to see if they get illness
👎- interviews with patients- schizophrenia patients often have difficulty with speech & … some patients might’ve found it difficult to communicate symptoms effectively to psychologists/psychiatrists …-> ➖ effect on diagnosis of schizophrenia e.g. delayed diagnosis/-> misdiagnosis in some cases- improved by having range of interviewers- correlate findings to ensure correct diagnosis of schizophrenia given
👍- supports biological (genetics) approach- 48% concordance rates in MZ twins & 17% in DZ twins- … results support biological argument that schizophrenia transmitted by genetics ALSO significantly ⬇️ for normal population (with dissimilar genetics) at 1% concordance rate
Who investigated evolution and when did they do so?
Charles Darwin (1851)
Outline Charles Darwin’s theory of evolution
Darwin focused on natural selection & adaptiveness to environment over ⏰
Genetic 🧬 makeup of individual can undergo random change/mutation due to factor in environment-> characteristic change occurring in future generations of offspring 👶
Change-> ⬆️ chance of survival & reproduction are greater … mutated gene 🧬 passed on & is adaptive
Physical characteristics of species vary- partly be due to genetics 🧬 & environment
What is adaptiveness?
Adaptiveness- important- individuals compete with each other for resources & survivors reproduce (survival of the fittest)
- E.g.- aggression- in human ancestry being aggressive advantageous for survival & reproduction as had ⬆️ access to food (aid survival) & 1st choice of mate selection (select fittest mate to aid successful reproduction)
- Lea (2005)- found aggression genetic 🧬- warrior gene (MAOA gene 🧬 )
Give a real life example of a species that has undergone adaptation mutation
Giraffes 🦒 evolved & their necks got longer to access best 🍁 in 🌳 for food & nutrition
… shorter 🦒 ⬇️ chance of accessing highest 🍁 & …-> poor feeding & survival rate-> them dying out & ✖️ evolving
