The Biological Approach: the Influence of Genes, Biological Structures and Neurochemistry on Behaviour. Genotype and Phenotype, Genetic Basis of Behaviour, Evolution and Behaviour

AO1: Main Assumptions of the Biological Approach:

(1) Everything psychological is at first biological
(2) All behaviour has a physical cause
(3) Biological structure and function are key
(4) Contrasts the cognitive approach view by suggesting that mental processes are not separate from the physical brain.

AO1:The Influence of Genes:

Each individual is born with 23 chromosomes which they’ve inherited from both of their birth parents. There is a suggestion that behavioural characteristics, such as intelligence and mental illness, are inherited in exactly the same way our physical characterisExamples of Genes Biological Approachtics, such as eye colour and height, are. Twin studies are used to determine the likelihood that certain traits have a genetic basis by comparing concordance rates (the extent to which 2 people share the same characteristic). If monozygotic (identical) twins have a higher concordance rate than dizygotic (non-identical) twins it would suggest a genetic basis because monozygotic twins share 100% of their DNA, and dizygotic only around 50%.

What are Genotypes and Phenotypes?

Genotype:
• A person’s actual genetic make-up.
• Occurs at conception.
• Dictates characteristics like eye colour and hair colour.
• Unique to the individual (except in cases of MZ twins)

Phenotype:
• The product of what happens when the genotype interacts with the environment.
Genotype + environment = phenotype
• Explains why MZ twins often have slight differences in personality, adult appearance (hair dye, sun exposure etc).

Genotype / phenotype example; An individual’s genotype might be that they have the genetic potential to be tall, however environmental factors, such as nutrition, will affect how likely the person is to achieve their potential height

 

AO1: Evolution and Behaviour: (proposed by Charles Darwin in the 19th Century).

The main principle of the theory is natural selection. The idea that any genetically determined behaviours that enhances an individual’s chances of survival will continue to future generations. Those with the most adaptive genetic behaviours reproduce and their offspring too have the adaptive genetic behaviours, enabling their survival. It happens naturally in nature, no one decides which characteristics are advantageous, but the possessor of such characteristics are the most likely to survive, (for example, a giraffe has such a long neck due to the fact that they would be able to reach the top of the trees to eat leaves). This happens in a similar way when farmers select one of the cattle, who possess the most desirable characteristics, for breeding; for example, selecting a cow with high milk yield to breed stock who are progressively higher milk producers.

 

AO3 Evaluation of the Biological Approach:

(1) Point: The biological approach is deterministic, claiming that all thought and behaviour is caused by factors outside of our control. Evidence/Example: For example, according to this approach behaviour is caused by our genes and the activity of neurotransmitters in the brain. Elaboration: This is a weakness because it ignores the idea of free will and that we as humans have control over our behaviour – we are not simply pre-programmed by genes.

(2) Point: The biological approach is also reductionist, as it attempts to reduce all aspects of human behaviour down to just one level of explanation. Evidence/Example: For example, all human behaviour is reduced down to just physical processes such as activity of neurotransmitters (e.g. OCD is explained in terms of levels of serotonin in the brain). Elaboration: This is a weakness because it underestimates the role of our environment in behaviour. However, reductionism is also a strength because by isolating just one factor it allows researchers to investigate that factor scientifically.

(3) Point: There is evidence to support the biological approach. Evidence/Example: For example Gottesman (1991) reviewed 40 twin studies (meta-analysis) and found the following concordance rates for schizophrenia: 48% concordance for MZ twins and 17% concordance for DZ twins. Elaboration: This is a strength because Gottesman research highlights the role of genes on the control of human behaviour and therefore supports the role of biology in human behaviour.

(4) Point: The biological approach has had many useful practical applications. Evidence/Example: For example, the biological approach has allowed for the development of many biological treatments (e.g. drug treatments) of disorders such as depression, anxiety etc… Elaboration: This is a strength because it shows that the approach has been put to good use and has been applied to help people and improve people’s lives. 

(5) Point: The biological approach uses highly scientific methods of research. Evidence/Example: for example MRI/CAT scans are used to investigate the brain and the areas of the brain that are responsible for certain disorders/behaviours. Elaboration: This is a strength because it means that research findings are objective.

To have a look at how the biological approach can be applied to abnormality (specifically OCD) click here.

Want to know about Biological treatments of OCD, click this hyperlink.