Evolutionary Explanations for Food Preferences (AQA A Level Psychology)

Evolutionary preferences for sweet, salt, fat

• Evolutionary psychology argues that human behaviour reflects the evolutionary history of the species and how  humans have dealt with adaptive problems such as avoiding predators and finding and eating the right types of food for survival

• Human ancestors survived in the environment of evolutionary adaptation (EEA) where it made sense to develop individual food preferences for foods that gave the best chance of the survival of the species

• Individuals with preferences for foods that gave more chance of survival would be more able to live to sexual maturity, reproduce and pass on their food preferences to their children

• Human ancestors faced an unpredictable food supply, the threat of starvation, and a high need to store energy

• Therefore, human ancestors’ preferred foods would be energy-dense non-poisonous food, such as sweet foods, fatty foods and salty foods

• Sweet foods:

  • Sweet foods such as ripe fruit contain many calories and provide an easily accessible source of energy 

  • Sweet foods are rarely poisonous so they would be perceived as safe to eat, while sour or bitter foods may be toxic (Simmen and Hladik, 1998)

• Fatty foods

  • Foods that are high in fat are energy-dense, containing a high number of calories and releasing a lot of energy

  • Meat is high in fat and calories, allowing humans to survive for the long time there may be between one animal kill and another

  • Once fire was discovered, meat could be cooked or smoked to preserve it, make it easier to eat and destroy any harmful bacteria

• Salty foods

  • Salt is important for conducting nerve impulses, contracting and relaxing muscles, and maintaining the proper balance of water and minerals

  • The concentration of salt in the blood must remain at a specific level and regularly needs topping up, as small amounts of salt are lost through sweat and the action of the kidneys

• Preference and avoidance aid survival and are therefore inherited and become common behaviours that have lasted until the present day

• Evolutionary psychologists explain our current preference for sweet, fatty and salty food, such as highly-processed fast food, as an evolutionary adaptation that now has a mis-match with our environment, as we are more sedentary and have less need for energy-dense food (Krebs, 2009)

Preference for fatty and sweet foods is an evolutionary adaptation that is no longer useful.

Neophobia & taste aversion

• Neophobia is an innate tendency to avoid new or unfamiliar foods

• Thus neophobia has a protective function as unknown foods could be toxic and it is better to go hungry than to die 

• Neophobia is found in babies as they move on from milk to solid food and this is when the evolutionary preference for sweet and salty foods can become obvious, as they will usually prefer these (Birch, 1998)

• Neophobia may lead to toddlers refusing to eat foods that are new to them in favour of the foods they are used to

• However, the neophobic reaction to new food will reduce with repeated exposure to the food and once a child gets used to the taste (Birch, 1998)

• Taste aversion occurs when an individual becomes ill after eating a certain food, resulting in them avoiding that food in the future because they associate it with being ill

• Taste aversion happens even if the individual knows it was not the food that made them ill and even if they became ill only once after eating it

• Environmental psychologists explain taste aversion as biological preparedness, which entails being biologically predisposed through evolution to learn through experience to avoid foodstuffs that make us ill, as this has an adaptive survival value

Neophobia starts when babies begin to eat solid foods.

Research which investigates evolutionary explanations for food preferences

• Bernstein & Webster (1980) investigated taste aversion in humans and found that adults given ice cream before receiving chemotherapy developed a taste aversion to eating ice cream as they had a biological preparedness to associate their nausea with the food they had eaten rather than the chemotherapy that had actually caused the nausea

• Steiner (1987) showed that newborn babies’ facial expressions indicate pleasure over a sweet taste and disgust for a bitter taste, suggesting that this preference is innate rather than learned

• Knaapila et al (2007) conducted a twin study and found that, using a standardised questionnaire to measure neophobia, the heritability of this behaviour was 67 per cent, supporting the evolutionary explanation that neophobia evolved from early humans because it protected them from eating harmful foods

Evaluation of evolutionary explanations for food preferences 

Strengths

• The fact that there are only two taste receptors for sweet tastes but 27 for bitter tastes suggests an evolutionarily determined need to avoid bitter-tasting toxic foods

• The idea of an evolutionarily determined preference for sweet tastes is supported by cross-cultural evidence using research on the Inuit people, who, although they had never tasted sweet food before, accepted it immediately (Bell, 1973)

Weaknesses

• There are  individual differences in taste experience, with some people more/less sensitive to bitterness and also taste for salty and sweet foods can be highly personal, which does not support the evolutionary explanation

• Evolutionary explanations for food preferences, neophobia and taste aversion cannot explain cultural differences in food preferences and avoidance

Link to Issues & Debates: 

Evolutionary explanations for food preferences are an example of biological determinism. They are also an example of hard determinism, as none of the explanations for preferences, neophobia or taste aversion allow any room for free will.

The evolutionary explanations are an example of biological reductionism, as they reduce the complexity of eating behaviour to an evolutionary adaptation, without considering the meaning of food in different societies and cultures, in a more holistic approach.