- Created by: bintahall
- Created on: 22-03-19 17:54
Early humans were hunter-gathers. Diets included animals and plants of their natural environment. Preferences for fatty food would have been adaptive for them because conditions in the Environment of Evolutionary Adaptation (EEA) meant that energy resources were vital.
Preference for Meat: Fossil evidence suggests that the diet of early humans was from animal-based foods. Meat provided the catalyst for growth in the brain. It is claimed that they couldn't have enough nutrition from a vegetarian diet to evolve.
Preference for sweet foods: Fruits provide vitamins and minerals that are necessary for bodily functions and growth. Making it adaptive for early humans to have evlolved an innate preference for sweet-tasting foods. Research found that the children who prefered sweet over saty tended to be tall for their age. Links to EEA as children then who sought out more calories were more likely to grow and survive.
Taste Adversion: A learned response to eating toxic or spoiled foods - This makes the animal avoid eating the food that made it ill or they associate it with illness. It was discovered by farmers trying to get rid of rats. It was diffcult to get rid of them using poison because the rats would only eat small amounts of new food and if they became ill they would learn to avoid it. Garcia et al studied taste aversion in the lab - rats that had been made ill through radiation after eating saccharin developed an aversion to it quickly.
The adaptive advantages of taste aversion: The odour of food can also be linked to food aversion. Taste aversions must have been developed by ancestors to survive because if they survived from eating poisoned food they would have learned not to consume that same food again.
Neophobia is a natural occuring reluctance to consume new/unusual foods in order to avoid being poisoned. Species that have specialised diets that are restricted to a few specific food sources don't exibit neophobia, whilst those with broader diets do (ie. rats).
In humans, individuals have an expectancy of the way food should look and smell so unfamiliar food would be rejected. Neophobia is stronger in response to animal products than to non-animal products because of the greater illness threat from meaty foods.
Are all food preferences a product of evolution?
Many food references can be traced back to EEA. However, traits that are benefical now (ie. low cholesterol foods) wouldn't have evolved because of it's beneficial effects to ancestors. Many things now are harmful to our health so we are more likely to avoid them to survive. Krebs says there is a mismatch between evolved preferences and modern environments.
Support for evolved preferences for sweet foods
Studies have showed that early exposure to sweet taste isn't necessary for children to develop a preference for sweet-tasting foods - cases such as in Northern Alaska where the people haven't been exposed to sweet foods haven't had a problem accepting them when they have come into contact with other cultures that consume them. Newborn infants show an acceptance response the first time they taste something sweet - a smile and licking of lips which is an innate response.
Real-world application: Taste aversion and chemoth
Cancer treatments such as radiation and chemotherapy can cause gastrointestal illness - paired with food consumption it can cause taste aversion. Bernstein and Webster gave patients a novel-tasting ice cream before chemo and patients aquired an aversion. These findings developed the scape-goat technique - giving cancer patients a novel food with some familiar food prior to chemo. The patient forms an aversion to the novel food and not the familiar food - links to neophobia.
Support for the heritability of neophobia
If neophobia is has adaptive advantages there should be a strong genetic component within it. Food neophobia was measured in a questionnaire in a sample of 468 adult FEMALE twins (211MZ and 257DZ). The heritability estimated for food neophobia was 67% suggesting that 2/3 of the variation in neophobia is genetically determined. This supports the idea the neophobia evolved amoung humans because it protected them from potentially harmful foods.
Neophobia may be maladaptive
Maladaptive: Not adjusting adequately to the environment
Neophobia poses a problem for those who may restrict their diet to foods with inadequate nutritional quality. An Australian study found that neophobia is associated with poor diets in children. However, the consequences of neophobia can be minimised in situations where it may prove to be maladaptive. Research showed that repeated taste exposure without visual and olfactory cues increased the preference for initially unfamiliar foods - this tends to be temporary.