Prosocial Behaviour: Biological Theories of Altruism (DP IB Psychology)

Kin selection theory

• Prosocial behaviour is any form of behaviour that is beneficial to another person or to  society as a whole

• Prosocial behaviour includes the concept of altruism:

  • the donor (helper) gives help to the recipient (person receiving the help)

  • the help is given with no expected gain for the donor

  • the help is given at some cost to the donor

• In essence, altruism is is an act of selfless helping behaviour, which may place the donor in some danger or involve an element of risk

• Biological theories of altruism are based on the theory of evolution as proposed by Charles Darwin (1859):

  • Behaviours persist because they are advantageous to the survival of the species

  • The process of adaptation occurs via natural selection, in which organisms that can adapt successfully to their environment are those that survive.

• Biological altruism is based on the idea that altruistic behaviour must be somehow adaptive for it still to be part of the range of present human behaviours

• In essence, people are altruistic because it is in their DNA to be so:

  • the act of altruism is therefore a reflex

  • altruism is an unconscious and unplanned act

• Kin Selection theory states that:

  • the closer genetically someone is to an individual the more likely it is that they will behave altruistically towards them, for example:

    • someone is more likely to save their mother or their son from a fire than their aunt or their grandfather

• By helping a relative the donor is, in theory, enhancing that relative’s reproductive fitness and, by extension, their own

• The genes shared by the related individuals will then be saved and they will have a better opportunity of reproducing and continuing their genetic line

Neurochemical theory of prosocial behaviour

• A neurochemical theory of prosocial behaviour involves the action of serotonin on mood and emotional state

• Serotonin plays a crucial role in regulating functions such as sleep, mood, a balanced emotional state

• Low or irregular levels of serotonin have been linked to affective disorders such as depression, anxiety and OCD

• Some drugs prescribed for depression are known as SSRIs (Selective Serotonin Reuptake Inhibitors) as they prevent the reuptake of serotonin, ensuring that it is passed onto the postsynaptic neuron as follows:

  • Reuptake occurs when molecules of serotonin do not cross the synaptic cleft i.e. they have not been transmitted to the postsynaptic neuron

  • The ‘spare’ molecules of serotonin are then taken back up into the presynaptic neuron

  • SSRIs work by preventing the reuptake of serotonin in the synaptic cleft back into the presynaptic neuron

  • Prevention of reuptake makes serotonin more accessible in the brain

  • More serotonin is then available to improve the transmission of messages between neurons

• Low serotonin levels have been linked to depressive symptoms (known as the serotonin hypothesis) so ensuring that all available serotonin crosses the synaptic cleft should result in reduced depression and enhanced feelings of wellbeing

• Enhanced feelings of wellbeing are likely to result in increased prosocial behaviour, thus there may be a neurochemical basis for behaviour

Evaluation of biological theories of altruism

Strengths

• It is possible to use clinical methods (e.g. drug therapy) to investigate biological theories which makes them high in reliability as:

  • they tend to use blind or double-blind procedures

  • they use a placebo with the control group

  • they can be replicated 

• Kin selection theory does have its basis in real-world evidence i.e. people across the centuries prioritise the safety and wellbeing of their family over non-family members

Limitations

• It is almost impossible to test evolutionary theories such as kin selection theory as researchers must operationalise variables which have their ultimate causes in behaviours developed across millennia

• A neurochemical theory of a complex phenomenon such as prosocial behaviour is reductionist:

  • It does not consider that prosocial behaviour may occur at a cognitive level

  • It does not consider that prosocial behaviour may be something that is learned via upbringing

  • It does not consider that culture has an influence on prosocial behaviour

Research which investigates biological theories of altruism

• Simmons et al (1977): kin selection theory and kidney donation

• Crockett et al. (2010) : SSRIs and prosocial behaviour

Simmons et al. (1977) and Crockett et al. (2010) are available as ‘Two Key Studies of Biological Theories of Altruism’ – just navigate the Social Responsibility section to find them.