Evolutionary Explanations Flashcards
Early diets
Preferences for fatty foods/meat: nutritious and catalyst for brain growth. Milton says humans wouldn’t have survived on vegetarian diet.
Preference for sweet foods: quickly available sugar and energy, provide vitamins and minerals needed for body functions and growth. Adapted to have innate preference for sweet foods. Mennella found the children who preferred sweet over salty foods were tall for age.
Taste aversion
Learned response to eating toxic, spoiled or poisonous food, results in animals avoiding that food as they know it will make them ill in the future. This was discovered by farmers who tried to get rid of rats. They found that it was difficult to kill the rats by using poisoned bait because the rats would only take a small amount of any new food and if they became ill they would rapidly learn to avoid it. Garcia was the first to study taste aversion in the lab, rats who had been made ill through radiation shortly after eating saccharin developed an aversion to it and quickly associated their illness with the saccharin.
Food neophobia
An extreme dislike and avoidance of anything that is new or unfamiliar. This is a naturally occurring reaction that protects animals from the risk of being poisoned by consuming something that is potentially harmful. This is a survival strategy. Species that have specialised diets and are restricted to just a few specific food sources do not exhibit food neophobia, where is species that have broad and varied diets do. For example rats are extremely neo phobic and if they become ill after eating a familiar and an unfamiliar food. They will avoid the unfamiliar food in the future (Rozin). In humans, neophobia accounts for an individuals reluctance to consume new or unusual foods based on their culture and current diet. Individuals have expectations of how acceptable food should look and smell, so unfamiliar foods that do not fall into what is considered acceptable based on this criteria will be rejected(Dovey). For humans, Martin’s said that food neophobia is stronger as a response to animal products rather than non animal products, this is most likely to evolve because of the greatest illness threat opposed by rotting meat and other animal products relative to no animal products (Fessler).
Evaluation – are all food preferences a product of evolution?
Many food preferences can be traced back to the adaptive pressures of the EEA, but this is not always the case. For example low cholesterol foods consume today would not have evolved because of its beneficial effects for our ancestors. Many things that were important to our ancestors such as saturated animal fats are now harmful to our health so we are more likely to avoid them to survive and lead a healthy life. Krebs also says that the mismatch between evolved preferences for fatty and sweet foods and modern environments can cause major global health epidemics that have emerged such as obesity and type two diabetes.
Support for evolved preferences for sweet foods
Early exposure to sweet taste is not necessary for children to develop a preference for sweet foods. For example people of northern Alaska that have no experience of sweet foods and drinks have come into contact with cultures that regularly consume these. And none of these cases has the culture without sugar rejected the sugar containing foods of the other culture (Bell). Newborn infants show an acceptance response for the first time they taste something sweet such as a slight smile licking their lips and sucking open (Grill and Norgren). These studies provide provides support for claimed evolutionary preferences for sweet foods that would’ve been necessary for body functions and growth in our distant ancestors in the EEA.
Real world application – taste version and chemotherapy
Research on the adaptive origins of taste of version has been helpful in understanding the food avoidance that can sometimes occur during the treatment of cancer. Some cancer treatments such as radiation and chemotherapy can cause gastrointestinal illness. When this illness is paired with food consumption taste versions can result. For example, Bernstein and Webster gave patients a novel tasting ice cream prior to their chemotherapy and the patient’s acquired an aversion to the ice cream. These findings have resulted in the development of the scapegoat technique which involves giving cancer patients a novel food along with some familiar food prior to their chemotherapy. The patient forms an aversion to the novel food and not to the familiar food. This is consistent with adaptive avoidance of novel foods known as neophobia.
