Evolutionary explanation for behaviour

Question 1

Outline the process of evolution

Answer 1

patterns of behaviour can be inherited as a means of adapting to our environment and increasing our chance of survival

The environment presents challenges to the individual - those who adapt best have a greater chance of survival and thus passing genes to their offspring

• natural selection
• sexual selection
  
  • those with best genes, are more attractive, and more chance of getting a mate

adaptation - slow changes over time to allow a species to better survive in their environment

Human behaviours are to some extent a manifestation of a persons genes

• as genes mutate they cause behavioural changes
• if behaviours are attractive and advantageous, someone will mate with a person with gene
• gene gets passed on to offspring and process continues

Question 2

define disgust

Answer 2

Disgust is a universal response, stimulating in a feeling of revulsion or strong disapproval aroused by something unpleasant or offensive, developed as a protective mechanism against potential threats of harm or ostricisation. - emotional response, resulting in physical responses including nausea, gagging, and avoidance

Many people share disgust for some things
- suggests it is evolutionary

Question 3

Curtis et al

Answer 3

Aim: to determine if disgust adapted as a protective response against disease
If disgust is adapted to protect against disease
- be felt more strongly with a disease-salient stimuli
- operate similarly across cultures
- more pronounced in females due to maternal role
- less potent as an individual’s reproduction potential declines
- more strongly evoked by contact with strangers

Participants: 40,000 respondents to a web survey (37,000 were eliminated from 77,000)

• eliminated for incorrect filling out of the survey
• under 5 or over 80
• had seen the BBC programme - exposed to hypothesis
• internet access to participate in research study
• 165 countries, questions in english
  
  • 91% from Europe and North America

Procedure

• respondents answered demographic questions
• Respondents were then asked to rate 20 images on a Likert scale (1-5)
  
  • there were 7 pairs within these images, one disease-salient and one not

Results
Correlated with hypothesis

Conclusions
Disgust is supported as being an evolutionary behaviour designed to protect individuals from disease. Stimuli that are perceived as being disease salient evoke greater disgust especially in groups with reproductive potential

Evaluation

• ethnocentric to western societies
• everyone had to have internet access
• everyone had to be able to understand/speak english

Reliability:

• results correlated with other research studies
• very repeatable/ procedure

Validity:

• high ecological validity as the images shown were of real everyday things
• high internal validity, quite controlled

Question 4

Fessler et al

Answer 4

Aim: to determine if disgust sensitivity varies across pregnancy in a manner that compensates for changes in the vulnerability to disease

Participants:

• self selected sample (web questionnaire)
  
  • posted on pregnancy related websites
• 691 women, 496 after discards - mean age 28
  
  • discarded if:
    
    • under 18 or over 50
    • chronic health problems
    • 195 were discarded

Procedure

• web questionnaire consisting of 31 items, disgust measured on a Likert scale + true or false questions
• catagorised questions in domains like food, contact with animals, hygiene
• demographic questions and pregnancy questions
• rated current level of nausea before beginning

Results
Consistent with the researchers’s prediction, women in the first trimester exhibited greater overall disgust sensitivity than women in later stages of pregnancy, and disgust sensitivity in the food domain was elevated.

Conclusion
Thus, researchers concluded that disgust is correlational with higher immunosuppression seen in first trimester pregnancies, meaning disgust must be strongly connected to a protective mechanism against disease.

Evaluation

• Self-reported sample, which raises issues with validity due to related possibilities of inaccuracies from self reported bias
• artificiality - not shown a thing just described
• eliminated invalid responses
• was it in a specific language? ethnocentricity?
• Big sample size
• Clear target population (also reflected by sample)