Evidence strongly suggests that we are born with genetic predispositions to basic tastes which influence our food choices.
For example, we prefer sweet foods because of the energy/ glucose, salty foods because of the minerals we need, we have adapted to reject bitter or sour foods because they could be poisonous or harmful and we seek high energy foods and these often are foods with fats or sugars. Humans also have a built in preference for meat due to the necessity of protein for grown and repair.
Birch (1999) also believes humans have a genetic predisposition to learn preferences for food by associating them with context and consequences.
Associate learning means that the unpleasant side effects of food mean we are unlikely to eat food that makes us ill. We will also prefer foods that reward our desire for sweet or salty tastes and therefore we consume foods rich in energy and nutrients when available (Birch 1999).
The EEA refers to the environment in which a species first evolved. (Environment of Evolutionary Adaptation.)
Preference for Meat
Human ancestors began to include meat in their diets to compensate for a decline in the quality of plant foods caused by receding forests two million years ago. They daily diet was derived from primarily animal-based foods, in particular animal organs, such as liver, kidneys and brains that are extremely rich sources of energy. A meat diet, full of densely packed nutrients, provided the catalyst for growth of the brain. Meat supplied early humans with all the essential amino acids, minerals and nutrients they required, allowing them to supplement their diet with marginal low-quality, plant based foods that have few nutrients but lots of calories, such as rice and wheat.
Taste Aversion
Taste aversion was first discovered by farmers trying to kill rats, they found that they couldn’t kill rats by poisoning food because rats would only sample a small amount of the new food and if it made them ill, they would rapidly learn to avoid the new food. For this reason, taste aversion was originally known as ‘bait shyness’.
There are adaptive advantages of taste aversion. Research has found that not only taste but odour of food can be linked to illness and consequently linked to a new food aversion. The development of these aversions would have helped our ancestors to survive because, if they were lucky enough to have survived eating poisoned food, they would not make the same mistake. Once learned taste aversions are very hard to shift, an adaptive quality designed to keep our ancestors alive.
Evaluation:
There is conflicting evidence for what the early human diet was. Human’s preference for meat developed during EEA because meat was an important source of saturated fats, which was vital for survival. On the other hand some researchers for example Cordain et al (2006), believe that early humans were vegetarians, getting most of their calories from sources other than saturated animal fats. However, Abrams (1987) has found that societies display a preference for animal foods and fats and that we couldn’t survive completely on plants and grains, which suggest that we need and like protein. Cultural factors are also important for example, the pungency for spicy food, which shows that food preference is not predetermined. However, although these cultural differences exist they do not completely reject the evolutionary approach, they are simply fine tuning of evolved preferences.
Experts have supported the drive to overeat that developed in the EEA. For example Gibson and Wardle (2001) support the importance of calories in an ancestral diet, using children to demonstrate the preference for calorie-rich foods. Children aged 4-5 often chose bananas and potatoes, which are particularly calorie dense. These preferences are still evident today, despite the fact that they are not healthy in a modern world, for example children will choose calorie rich foods rather than sweet foods or protein rich foods or food that is familiar to them. This may explain the incidence of obesity as we are drawn to calorie rich foods. However, there are other modern explanations of these behaviours. Cordain et al (2006) argued that early humans consumed most of their calories from sources other than saturated animal fats, suggesting that they were healthy eaters and may even be vegetarian.
There is evidence to support the claim that taste aversion has evolved as a food behaviour because it has adaptive advantages, such as being healthier, coping with learning abilities and survival. Sandell and Breslin (2000) found that bitter tastes actually evolved as a defence mechanism to detect potentially harmful toxins in plants, creating a selective advantage for our ancestors. Furthermore, taste aversion can be explained by biological preparedness (Seligman 1970).He claimed that different species evolved different learning abilities. The natural selection of differential learning has occurred so that each species has the abilities to learn certain associations more easily than others; particularly those associations that help individuals survive. Research on the origins of taste aversion has been used to help understand the food avoidance that often occurs during chemotherapy in the treatment of cancer. This clam was supported by Bernstein and Webster (1980), who gave patients a new tasting ice cream prior to their chemotherapy and the patients subsequently developed an aversion to that ice cream. This has led to hospital giving patients both a novel (new, different) and a familiar food prior to the chemotherapy, aversion then forms to the new food and not the familiar food.