Biological Level of Analysis

1. Biological Level of Analysis Session 20

2. A quick recap of last session... With reference to relevant research studies, to what extent does genetic inheritance influence behaviour? .

3. How do genes influence behavior? • Genes influence behaviour indirectly. • There is usually more than one gene involved in a behaviour • Genes influence the production of proteins that affect the anatomy (e.g. brain structure) and physiology (chemical processes) of the body • Some behaviours are more genetically influenced than others • There is an interaction between environmental, biological, cognitive and genetic factors in the development of behaviour

4. Task • Read through pages 52-56 of your textbook about genetic research and intelligence • Make a note of anything important then arrange this into a mind map of how you would respond to the question in an exam With reference to relevant research studies, to what extent does genetic inheritance influence behaviour?

5. With reference to relevant research studies, to what extent does genetic inheritance influence behaviour?

6. Introduction • State what you are doing in the essay: • This essay will attempt to consider the merits or otherwise of the influence of genetic inheritance on behaviour.  • Outline the overarching principle: • According to the third principle of the biological level of analysis (BLA), behaviour is innate and inherited because it is genetically based (we are predisposed to a specific behaviour due to genetics).

7. Introduction • Describe genetics and the importance of research into genetics: • It is argued that people have a genetic predisposition. • Genes are segments of DNA inherited by the offspring from the parent. • Behavioural Genetics is the understanding of how genetics and environment contribute to individual variations in human behaviour, where the premise is that the inheritance of DNA influences behaviour. • It cannot be said that a single gene is responsible for a specific behaviour – but it is a building block. • But genetics alone does not affect behaviour- environmental factors also • Genes are complex  • It is unlikely that a single gene is responsible for such complex behaviours as schizophrenia or depression.  • There is no causal relationship between a single gene and a specific behaviour.

8. Introduction • Describe genetics and the importance of research into genetics: • It is thought that what is inherited is the gene that can lead to the development of the specific behaviour, not the behaviour itself. • This means that an individual may have a genetic predisposition to a behaviour but without appropriate environmental stimuli, the behaviour will not be manifestedDon't forget to state that behaviour is bi-directional, explain.

9. Introduction • Describe type of studies used in genetic research • Twin studies  • Used in genetic research to study the correlation between genetic inheritance and behaviour due to the common genetics shared by twins. • Monozygotic twins (MZT) identical - share 100% genetic material. • Dizygotic twins (DZT) fraternal - share 50% genetic material.  • It is usually further explored, by studying the twins either separated or together to make a correlation of their behaviour.  • Adoption studies  • Allow researchers to study the comparison between genetic and environmental influence on behaviour. • Adopted children share no genes with their adoptive parents but 50% of genes with their biological parents.  • Family studies • Study behaviour between family members who have similar genetics to different degrees. Inheritance 

10. Introduction • Outline behaviour you are looking at: Intelligence • Intelligence is an aspect of behaviour that has been studied in relation to genetics. • It was questioned whether intelligence was attributed to genetic or environmental factors. Intelligence is difficult to define • IQ tests have been developed by a French person called Binet to measure of intelligence and are used in much psychological research. 

11. And then finally onto the body...

12. Body: Supporting Evidence No. 1 Bouchard and McGue (1981) • Conducted a meta-analysis of 111 studies of siblings. • Investigated IQ correlations between siblings. • Found that there was a positive correlation between kinship and IQ correlation - the closer the siblings were, the more similar their IQ.

13. Body: Evaluation of Evidence No. 1 Bouchard and McGue (1981) • Large study, so generalisable. • However, siblings are raised in the same environment, so influence may not be purely genetic, and it is difficult to differentiate between influence of genetics and environment. • Also, age - the further apart the siblings in age, the less correlated their IQs are expected to be. In order to investigate the role of genetics by itself, identical twins that are raised separately from birth must be studied. Identical twins have a 100% genetic relationship, but if raised in separate environments, any similarity (beyond that expected by chance) in IQ must be due to similarity in genetics.

14. Body: Supporting Evidence No 2 Bouchard et al. (1990) - Minnesota Twin Study • Conducted a longitudinal study since 1979, comparing MZA twins to MZT twins in terms of intelligence (MZA - monozygotic raised apart, MZT - monozygotic raised together) • Each twin completed approximately 50 hours of testing and interviews. • It was a cross cultural study, using participants from all over the world.

15. Body: Supporting Evidence No 2 Bouchard et al. (1990) - Minnesota Twin Study • Results - concordance rates of intelligence from the study • Bouchard et al. concluded a heritability estimate of 70% - 70% of intelligence can be attributed to genetic inheritance. 30% attributed to other factors.

16. Link back to question Connecting Bouchard et al (1990) to question  • This study relates to the effect of genetics on behaviour as the concordance rate between twins shows that their behaviour was affected mostly (70%) by genetics, rather than the environment, where the other 30% may be attributed to other factors in the surrounding environment. 

17. Body: Evaluating Evidence No 2 Strengths • Size of the study means it is more generalisable • Nature of sample - cross cultural • Mean age of participants 41 years, as opposed to previous studies with adolescents Weaknesses • Relied on media coverage to recruit participants • Ethical concerns with the way twins were reunited • Frequency of contact between twins prior to study not controlled. • 'Equal environment assumption' - twins reared together may not have experienced the same environment.

18. Body: Evaluating Evidence • Adoption Studies - investigating environment (no biological/genetic link between parents and child, so correlation in IQ is purely due to environment) Horn et al. (1979) • Conducted a study on parents who raised BOTH adopted and natural children. • All children have the same upbringing, therefore same environment, but some were similar in genetics and some were not. • Found no significant differences in correlation of parent-child IQs between natural and adopted children. • Adoptive parents were wealthy, white, middle class and children were poor, lower class backgrounds, with lower IQ parents. • Conclusion that genetics has little impact - mostly environment.

19. Body: Conflicting Evidence • Adoption Studies - investigating environment (no biological/genetic link between parents and child, so correlation in IQ is purely due to environment) Horn et al. (1979) • Conducted a study on parents who raised BOTH adopted and natural children. • All children have the same upbringing, therefore same environment, but some were similar in genetics and some were not. • Found no significant differences in correlation of parent-child IQs between natural and adopted children. • Adoptive parents were wealthy, white, middle class and children were poor, lower class backgrounds, with lower IQ parents. • Conclusion that genetics has little impact - mostly environment.

20. But wait there’s more... Niche Picking Hypothesis Scarr and McCartney (1983) • Horn et al (1979) findings could be explained by the “niche picking hypothesis” proposed by Scarr and McCartney (1983) • Genes affect an individual’s preference for particular environments  • The environment then affects the development of the individual.  • Genetically similar people will tend to select similar environments, thus leading to similar IQ.  • It is possible that genetic predisposition influences individuals to tend towards environments that accentuate that disposition, thus leading to increased heritability throughout their lifespan. • The niche picking hypothesis supports the influence of genetics on IQ.

21. And finally... • Genetics can influence intelligence as shown by supporting studies on influence of genetics.  • Horn (1979) provided findings to suggest that the environmental factor of race affects intelligence  • Adopted children have a higher IQ correlation with the adoptive family, rather than biological family. • Genetic inheritance influences intelligence, and thus behaviour, to a great extent.  • large amount of supporting research  • the niche picking hypothesis refutes environmental factors  • Although it is important to note that the role of genetics in determining human behaviour and physical characteristics is significant, it is essential to bear in mind that although some characteristics are strongly affected by genetic inheritance, it is not a simple causal relationship, as other factors such as the environment can influence thus alter certain behaviour. 

23. Next Friday Oral Presentations... • Each of you will be assigned a learning outcome today • You need to make an oral presentation to outline a model exam answer like we have just done • You will then present to the class This will help you all to revise!

24. Presentation Requirements • You must accompany your presentation with visual aids either a PowerPoint presentation or a Prezi presentation • Try to make it interesting by using pictures, videos, tables etc

25. Presentation Requirements • Follow the structure we have been practising • Your presentation will be posted on the website • If you need help, ask • Late submissions will suffer mark deductions • You have the mark scheme in your assessment outline (see website if you’ve lost it) This accounts for 10% of your final grade