Lesson 7 The Biological Approach: The Influence Of Genes And Evolution On Behaviour Flashcards
Genetics 3 facts:
Every person has 23 pairs of chromosomes and 10,000 genes
Each chromosome is made up of DNA which consists of genes
Genetics involves passing characteristics and key information from one generation to the next
Genetics definition
The extent to which a psychological characteristic is determined by genes or the environment
Genotype definition
The genetic code written in the DNA of individual cells, which are inherited from our biological parents, genotype consists of genes a person possesses and they can be dominant or recessive
Phenotype definition
The characteristics of an individual is determined by expression of physical, behavioural and psychological traits
Further genetics A01
• Individuals might inherit certain characteristics which are carried on genes (on chromosomes).
• Psychologists research genetics by studying twins (MZ monozygotic identical twins, or DZ dizygotic non identical twins).
• Twin studies allow psychologists to look at concordance rates between twins (the chances of both twins inheriting a certain trait e.g. depression or intelligence). 60-80% of intelligence is thought to be genetic!
• For instance from using gene mapping, it has been found that chromosome 13 carries the gene for schizophrenia, and chromosome 11 carries the gene for bipolar depression.
Advantages of genetics
1) An advantage of examining genes and the role they have on behaviour is that gene mapping can help psychologists locate genes on chromosomes which is highly scientific and objective. Therefore investigating genes involves precise methods of investigation which would be supported by science (+)
2) An advantage of studying genetics is that it often involves using twin and adoption studies. This is very useful when examining MZ (monozygotic twins) who are identical as it can help psychologists examine concordance rates in relation to behaviour. The research by Gottesman and Shields would support the idea that certain illnesses such as schizophrenia are transmitted genetically (+)
3) Genetics has the advantage in that it can help psychologists screen people to see if they carry genes for certain illnesses. This would involve gene mapping and it can help psychologists identify individuals who might be at risk from certain illnesses or diseases such as depression or some forms of cancer. This means that people might get psychological help before they become unwell (preventative) (+)
Disadvantages of Genetics
4) A disadvantage when examining the role of genetics is that it is reductionist. It takes a complex human behaviour such as IQ and reduces it down to small components alone such as genes. This idea seems inaccurate, as IQ is not solely dependent on genes; other factors need to be considered such as the environment (-)
5) The role of genes and its effect on behaviour and be criticised, because other models and approaches in Psychology are being ignored. For example the cognitive and behavioural approaches would also need to be considered when examining behaviour. An example is that someone who has depression might carry the gene for depression, but they might also have faulty and negative cognitions which have been ignored. (-)
The role of genes in developing schizophrenia - twin studies: A study by Gottesman and Shields (A01)
• Gottesman and Shields investigated 224 sets of twins from 1948-1993 who appeared on the Maudsley twin register (106 sets of twins were MZ and 118 were DZ). 120 males and 104 females in total took part in the study.
• The average age of the participants’ was 46 years of age, and the participants came from a range of different ethnic backgrounds.
• The study was conducted in a London hospital and was a longitudinal study following the participants’ over a period of 25 years. The study relied on the fact that one twin already had the illness of schizophrenia, and concordance rates were investigated; which examined the likelihood or the chances of the healthy twin becoming schizophrenic over time. The methods that Gottesman and Shields used to diagnose schizophrenia included the following:
• In depth interviews
• Doctors case notes
• The DSM
The result found that:
• 48% of MZ twins were both concordant for schizophrenia by the end of the study
• 17% of DZ twins were both concordant for schizophrenia by the end of the study
Advantages of the study by Gottesman and Shields
A strength of Gottesman and Shields study is that it was longitudinal. This means that the schizophrenic patients could be tracked over long periods of time in order to monitor the development of the illness schizophrenia. This means that longitudinal studies are very valuable when investigating whether schizophrenia is caused by genetics (+)
2) The research by Gottesman and Shields supports the biological (genetics) approach as the results show 48% concordance rates for schizophrenia in MZ twins and 17% concordance in DZ twins. Therefore the results support the biological argument that schizophrenia can be transmitted by genetics (+)
Disadvantages of the study by Gottesman and Shields
The research by Gottesman and Shields ignores the behavioural approach when examining the causes of schizophrenia. Identical twins often copy and model each other’s behaviour, so it could be that the healthy twin has modelled or copied schizophrenic behaviour rather than getting the illness via genetics. Therefore we must investigate fully whether the healthy twin gained schizophrenia via genetics or from observing and copying behaviour (-)
5) The research conducted by Gottesman and Shields could be criticised because it relied on interviews with patients. Schizophrenia patients often have difficulty with their speech and communication and therefore some patients might have found it difficult to communicate their symptoms effectively to the psychologists/psychiatrists. Therefore this issue could have had a negative effect on the diagnosis and classification of schizophrenia (-)
Evolution by Charles Darwin (A01)
• Darwin focused on natural selection and adaptiveness to the environment over time
• The genetic makeup of an individual can undergo a random change/mutation due to a factor in the environment, and this could lead to a characteristic change occurring in future generations of offspring
• The change might mean that survival and chances of reproduction are greater, and therefore this mutated gene will be passed on and is adaptive
• Physical characteristics of a species may vary, and it might partly be due to genetics and inherited characteristics, but we must also acknowledge the environment
• Adaptiveness is important, because individuals often compete with each other for resources, and those who survive will reproduce (survival of the fittest).
• Lea (2005) has found that aggression might be genetic. The warrior gene (MAOA gene - Monoamine Oxidase A) is found within the genotype of 33% of males. Could this mean that the most aggressive males have more chance of survival and passing on their genes? The research is ongoing into this topic.
• In the animal kingdom, evolution can be seen in the giraffe and their long necks. Over time, giraffes evolved and their necks got longer so that they could access the best leaves in the tree for food and nutrition. This means that the shorter giraffes had less chance of accessing the highest leaves, and therefore they might have had poor feeding and survival rates.
• The giraffes with the shortest necks might have died out and not evolved.
Advantages of the Evolutionary Approach
1) Evolutionary ideas can be supported by the nature side of the nature and nurture debate. The evolutionary approach states that our biology (genetic makeup) and interactions with the environment have a direct effect on our behaviour, for instance genetic mutations of genes in giraffes have led to them having very long necks so that they can get enough food in the environment and reach the top leaves from the tree. (+)
2) The evolutionary approach is heavily supported by the work from Charles Darwin and survival of the fittest. This can help explain how certain traits become adaptive within a species such as males being very tall, or giraffes having long necks (+)
3) Evolutionary ideas have their advantages because it means that species will compete with each other in order to seek the best mate to reproduce with. This helps to maximize the chances of healthy offspring being produced who will be healthy and will be able to pass on their genes to the next generation. This helps human/animal species to evolve and adapt (+)
Disadvantages of the Evolutionary Approach
4) A problem of the idea of evolution is that is does not clearly explain some behaviours and how or why they might be adaptive. For instance OCD has been found to be genetic, but it is not clear how OCD can be adaptive and can help aid survival of the fittest. This is not very clear and is not well explained. (-)
5) The idea of evolution can be criticised because it fails to take into account behavioural and cognitive explanations for behaviour. The idea of every species wishing to reproduce and aid survival seems to take away the idea of free will and cognitions, whereby not all members of a species have this drive or will make such decisions. (-)
Key research study in sexual selection by Buss (1989) A01
• Investigated what males and females looked for in a long term partner
• 10,000 participants used across 37 cultures
• They had to rate 18 characteristics (physical attraction, finances etc.) using a 4 point rating scale, where 0 = irrelevant, and 3 = indispensable (highly rated).
• The findings showed that females desired males with good financial prospects, resources and ambition
• Males desired females who had reproductive value and were fertile, and all males universally wanted females who were youthful and younger than them
• The research conducted by Buss seems to support evolutionary explanations for partner preferences
Advantages of research by Buss
2) The research conducted by Buss has cross cultural validity when examining evolutionary explanations of behaviour. 37 cultures were assessed and it seems that from an evolutionary perspective females want to be “protected” and “cared for” by their male partner in terms of resources. This is supported by the fact that females might believe that a man with resources can look after her and their future offspring, this helps aid stability for the family unit (+)
