Eating behaviour - evolutionary explanations of anorexia

Question 1

Holland (general support for EE)

Answer 1

• twin study; found much higher concordance rate for MZ twins (56%) than DZ twins (7%) - some genetic influence
• anorexia has genetic basis which may have been generated in EEA
• if genes played no part then evolutionary explanation would be falsified
• if evolution has prepared some people to develop anorexia then the preparedness would have to be encoded genetically
• does not show that any particular evolutionary explanation is right, merely that there might be evolutionary explanation for anorexia

Question 2

Menarche (reproductive suppression hypothesis)

Answer 2

• onset of puberty is delayed in pre-pubertal girls with anorexia

Question 3

Mrosovsky and Sherry (adapted to flee famine hypothesis)

Answer 3

• many species stop eating, even when food is readily available, when they migrate

Question 4

Epling and Pierce (adapted to flee famine hypothesis)

Answer 4

• rats which were starved in the lab would then ignore food and exercise excessively

Question 5

Keel and Klump (general support for EE)

Answer 5

• meta-analysis of cross cultural studies
• concluded that anorexia is not a culture bound disorder
• found in all cultures studied, even in those not exposed to western influence
• however, frequency is proportional to degree of influence; more westernised the society, the more anorexia is found
• universal so suggests evolutionary basis, however also supports sociocultural explanation