- According to the evolutionary approach current human behaviour can be understood in terms of how it may have been adaptive in our ancestral past. It has been suggested that in modern society we tend to eat more calorie rich food due to it being adaptive for early humans.
- Preferences for fatty calorie rich foods would have been adaptive due to conditions in the environment of evolutionary adaptation (EEA) meaning that energy resources were vital in order to stay alive and also to find the next meal.
- Calories were not as plentiful as they are today and so humans and animals would have evolved a distinct food preference for foods that are particularly rich in calories.
- Furthermore out ancestors diets consisted of plant food until the decline of the quality of plant food available to them due to receding forests. This forced them to include meat in their diet which they obtained from animals and fed on the fattiest part of the animal such as the liver or brain (therefore being high in calories).
- By including meat in their diet they increased in intelligence due to the meat being a catalyst for the growth and development of the brain. This helped ensure their survival as they were a more developed species and so this enabled them to adapt to new situations and continue the survival of the human race. Therefore this adaptive response to eating meat has been passed into modern society explaining our preference for meat.
+ A strength of this theory is that there is supporting evidence. Stanford (1999) observed chimpanzees in Tanzania's Gambe National Park. He discovered that the chimpanzees faced similar problems of that our ancestors faced 2 million years ago. When the chimpanzees managed to kill, after coming close to starvation, they went straight for the fattest part of the animal rather than the more tender and nutritional parts.
+ This therefore provides support for the theory as it shows how species have adapted a preference for calorie rich meat foods due to it significantly aiding survival and helping to avoid starvation.
+ Furthermore Gibson and Wardle looked at the importance of high calorie foods; when asking children aged 4-5 to select a fruit or vegetable they found that the most popular choices were the fruits densest in calories. This illustrates that our food preferences can be explained by our ancestors need for high calorie foods in order to survive and these adaptive preferences have been passed down to current generations due to it increasing our chances of survival.
+ Due to their being consistent evidence to support this theory where the main assumptions have been supported by other researchers it can be argued that this theory must be high in external reliability. Due to this we can be sure that the evolutionary adoptions of having a preference for high calorie foods and meat are likely to be one of the key influences in our food preferences.
- However there are methodological issues with the supporting evidence which in turn weakens the evolutionary theory. Many of the studies in this area of psychology have been based upon animal observations. This presents itself as a flaw as it means we cannot generalise the findings of the research accurately to humans. This is due to animals such as chimpanzee’s having a different biological makeup to humans, therefore it is possible that we may not have adapted in the same way as that of the animals used in the studies, and so findings may prove to be false.
- As the findings cannot be generalised, the population validity of the study is reduced, therefore meaning the external validity of the theory is also reduced.
- Due to this reduced validity it may not be accurate to conclude that evolutionary factors are the main reason for our food preferences, so when developing suitable treatments for eating disorders it will be harder to create effective and appropriate treatments as we cannot be sure they will work as expected for all types of people.
- Another explanation for how our food preferences are determined in evolutionary terms is through taste aversion. This was a concept first discovered by farmers who were trying to kill rats. They found they were unable to kill the rats because of them only eating a small amount of new foods 'poison' and if that new food made them ill then they would avoid it.
- This leads to taste aversion of certain foods which would have enabled our ancestors to better survive the EEA, as we are programmed to avoid a food if we become ill after eating it. These taste aversions would have given our ancestors an evolutionary advantage as any foods that make them ill would have been avoided in the future, therefore ensuring we evade being poisoned and these preferences would have been passed down through natural selection.
- However there are problems with this evolutionary explanation as it is based upon the evolutionary approach which in itself has issues, such as being speculative. This means that the explanation does not have a factual basis and is highly subjective so it is difficult to prove that the explanation is valid.
- With food preferences we can never exclude factors such as cognitive influences and personal emotions/thoughts and therefore the taste aversion explanation can never be tested scientifically, so a cause and effect relationship between this and food preferences can never be established.
- This weakens the specific evolutionary explanation to food preferences as it suggests that there may be other factors involved in explaining why people develop preferences to certain foods other than evolutionary factors which have been passed down through generations.
- The evolutionary approach to explaining food preferences lies on the determinist side of the deterministic-free will debate. For example it assumes that our food preferences are determined by genes and characteristics which have been passed down from our ancestors which gave them an adaptive advantage.
- Therefore the theory suggests that we cannot control our preferences for food as they are innate responses which determine the food we eat, and overlooks the notion of free-will and the fact that human behaviour is affected by many other factors such as thoughts, emotions and social factors.
- A strength of this is that people who are at risk of an eating disorder can be identified, as can those with a certain gene which may lead to conditions such as overeating and therefore treated before the problem develops further.
- However, it can also be considered as a weakness as it may lead to many people with eating disorders feeling as though they have no control over their eating. Therefore many people may not make an effort to help themselves get better, leading to labelling and self-fulfilling prophecies which can have a negative effect on a person's state of mind.
1. Evolutionary approach - food preferences
+ Supporting evidence: high external reliability
Stanford (1999) - Chimpanzee's in Tanzania's Gambe National Park
Gibson and Wardle - Children aged 4-5, fruit or vegetable?
- Animal observations: cannot generalise
Cannot be generalised and so population validity is reduced = reduced external valdity
2. Evolutionary approach - taste aversion
+ Supporting evidence: farmers and rat poison
- Speculative: no factual basis and highly subjective therefore difficult to prove it's validity. Cannot be tested scientifically so no cause and effect can be established.
3. Deterministic - assumes our food preferences are determined by genes and characteristic from ancestors, suggesting we cannot control our preferences.