Biological: Evolutionary explanations of anorexia A2
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1) The document discusses two evolutionary theories for anorexia nervosa: the reproductive suppression hypothesis and the 'adapted to flee' hypothesis. 2) The reproductive suppression hypothesis suggests that weight loss was a strategy to suppress reproductive capability during times of food scarcity when pregnancy would have been risky. 3) Symptoms of anorexia may reflect ancestral adaptive mechanisms for migrating during local famines, as food restriction is common in such situations. However, the theories are reductionist and do not fully consider other complex explanations or modern cultural influences.
Biological: Evolutionary explanations of anorexia A2
- 1. Evolutionary explanations relate to the adaptive nature of Anorexia Nervosa – (how they’ve helped the species survive) There are 2 Evolutionary theories: Reproductive ‘Adapted Suppression Hypothesis to Flee’ Hypothesis
- 2. Evolution delays the onset of sexual maturation in response to cues in the environment about the probability of poor reproductive success. It enables the female to avoid giving birth at a time when conditions are not conducive to the survival of her offspring. Anorexia Nervosa is a ‘disordered variant’ of the adaptive ability – when may feel unable to cope with biological, emotional and social responsibility of womanhood.
- 3. REPRODUCTIVE SUPPRESSION HYPOTHESIS basic assumptions weight loss was a strategy for suppressing reproductive capability when food was in limited supply, pregnancy would have been risky for the mother and survival chances for the infant would have been reduced in the absence of contraceptives, weight loss would prevent pregnancy at times when it would be too risky
- 4. REPRODUCTIVE SUPPRESSION HYPOTHESIS based on 2 ‘models’ the reproduction suppression model : because reproduction is costly to females, a female facing conditions temporarily unfavourable to reproduction can increase her lifetime reproductive success by delaying reproduction until conditions improve the critical fat hypothesis : because a minimum amount of body fat (17%) is needed before menstruation begins and additional fat accumulation (22%) is needed to maintain regular ovulation (Frisch, 1985; Frisch and Barbieri, 2002) altering the trajectory of adolescent weight gain, or the loss of five pounds or so, could have been an effective mechanism for controlling sexual maturation and fertility in ancestral females
- 5. REPRODUCTIVE SUPPRESSION HYPOTHESIS selective pressures favouring reproductive suppression? 1. more females than males 2. attention from ‘undesirable’ males
- 6. REPRODUCTIVE SUPPRESSION HYPOTHESIS selective pressures favouring reproductive suppression? 1.more females than males - more competition from other females = not all females can mate… so those that don’t need to ‘save’ up for lost time 2. attention from ‘undesirable’ males - the youngest females are the most vulnerable because they lack emotional maturity/confidence to rebuff unwanted attention = makes sense to delay reproductive ability until older (when more likely to make the ‘right’ choice of a mate)
- 7. Amenorrhea & the onset of puberty is delayed Based upon observations of species ― How are the symptoms passed on because this behaviour (AN) will decrease fertility & can kill? ― General problems with the Evolutionary theory
- 8. Symptoms reflect adaptive mechanisms that caused migration when local famine conditions occurred. Food restriction is a common feature when competition for food, and migration behaviour. Therefore for modern-day individuals, those with a genetic pre-disposition to Anorexia, losing too much weight may trigger ancestral mechanisms. e.g. ‘Holy Anorexia’ in Middle Ages (saints recognised for miraculous ability to live without food)
- 9. Treatment Implications – Guisinger claims AFH ‘relieves therapists of the need to search for familial reasons for Anorexia’. Awareness of this causal influence can help treatment and encourage parents to be more compassionate towards their child. ― This treatment implication is Reductionist as it is ignoring other possible and more complex explanations. ― How have the symptoms been passed on? Anorexia would function effectively in ancestral conditions but can be deadly outside the ecological setting.
- 10. Reductionist – not search for more complex explanation, such as the emotional relationships within families as a cause Deterministic – view that an individual’s behaviour is shaped/controlled by internal forces rather than an individual’s will to do something Cultural Influence – doesn’t acknowledge the importance of cultural influences, e.g. if it is adaptive & innate then why doesn’t it happen in all cultures?