The evolutionary explanation assumes that all behaviours are learned through the process of natural selection as humans have adapted behaviours that are advantageous to either survival or reproduction. Surbey argues that adolescent girls wanting to control their body weight represents an evolutionary adaption in which ancestral girls would delay the onset of sexual maturation in response to cues about the probability of poor reproductive success. This is adaptive because it then enables the girl to avoid giving birth at a time when it would have been dangerous to have children as mortality rates during child birth would be very high, thus enabling survivability.
This theory is based off of the fact that a number of species have similar abilities in that they are able to delay or suppress puberty in females when they are subjugated to stress or are in poor condition. Surbey then argues that anorexia is a ‘disordered variant’ of the ability of females to alter the timings of reproduction at a time when they feel that they’re unable to cope with becoming a woman. This is then supported by the fact that the onset of puberty is delayed in prepubescent girls with anorexia and that amenorrhea is a typical characteristic of the disorder. This is because sexual maturity is suspended in these women until the environment is more suitable. This supports the theory because it would explain why anorexia would be adaptive in delaying puberty. A positive for the Reproductive Suppression theory is that it explains why most Anorexia sufferers are female, however it does not explain why there would be any male sufferers at all. If the theory was correct, it would mean that only females should suffer from Anorexia. However, Holland et al supports the idea that Anorexic behaviour patterns enabled sufferers to survive to reproduce and pass on behaviours genetically as she found that there is a 56% concordance rate in anorexia between MZ twins and only 7% in DZ twins.
One issue with this theory is that it is deterministic. This means that anorexia is governed by forces uncontrollable to the individual as it is passed down to them through natural selection and is in their biology, meaning that they have a lack of free will to battle against it. Another issue with this theory is that is reductionist. This means that they are simplifying complex human behaviours into a simple explanation, in this case evolution. This is because the theory does not consider any other explanations to anorexia, other than evolution. One other theory that may explain anorexia is the psychodynamic theory put forward by Bruch which suggests that childhood traumas and conflicts may be the cause.
