Evolutionary Explanations Flashcards
How many main food groups are there?
5
Name the 5 main food groups
1) Sweet
2) Sour
3) Salt
4) Bitter
5) Umami
What are sweet foods?
Foods rich in carbs to provide us with energy
What are sour foods?
Associated with food that has gone off and therefore should be avoided
What are salty foods?
Critical for functioning of cells and therefore need to identify
What are bitter foods?
Associated with poisonous plants so should be avoided
What are umami foods?
Highly savoury, meaty taste
What are the 2 main evolutionary explanations of food preference?
1) Environment of Evolutionary Adaptation (EEA)
2) Taste aversion
Outline the Environment of Evolutionary Adaptation (EEA)
Refers to the environment in which a species first evolved - human beings first emerged as a separate species 2 million years ago on African savannah, and natural selection favoured adaptations geared toward survival in that particular environment - for most of our evolutionary history, we have probably lived in hunter-gatherer societies
Outline human beings’ early diets
Diets included the animals and plants that were part of their natural environment - preferences for fatty food would have been adaptive for early humans as conditions of EEA meant energy resources were vital to stay alive - although modern humans more concerned about nutritious value of food, instead what we eat is often rich in calories but not particularly nutritious - in the EEA, calories were not as plentiful as they are today, so it makes sense humans have evolved a distinct preference for foods that are particularly rich in calories
Outline meat preference
Humans began to include meat in their diets to compensate for a decline in the quality of plant foods - fossil evidence suggests daily diet was derived primarily from animal-based foods, in particular animal organs that are extremely rich sources of energy - a meat diet, full of densely packed nutrients, provided the catalyst for the growth of the brain - meat supplied early humans with all 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, like rice and wheat
Outline Milton (08)
Without animals, unlikely early humans could have secured enough nutrition from a vegetarian diet to evolve into active and intelligent creates they became
How was the idea of taste aversion created?
First discovered by farmers trying to rid themselves of rats and they found it was difficult to kill rats by using poisoned bait because rats would only take a small amount of any new food and if they became ill, would rapidly learn to avoid it
What is the main study for taste aversion?
Garcia (55)
Outline Garcia (55)
Rats who had been made ill trough radiation shortly after eating saccharin developed an aversion to it and very quickly associated their illness with the saccharin
What are the adaptive advantages of taste aversion?
It would have helped our ancestors because if lucky enough to survive eating poisoned food, they would not make the same mistake again - once learned, such aversion are hard to shift, an adaptive quality designed to keep our ancestors alive
What is the second part of taste aversion?
The Medicine effect
Outline the medicine effect
There is also evidence that animals can learn a preference that makes them healthier, with any food eaten just before recovery from illness being preferred in the future
What is the main study supporting the medicine effect?
Garcia (55)
Outline Garcia (55) for the medicine effect
Found when distinctive flavour is presented to thiamine-efficient rat and then followed by an injection of thiamine, the animal will acquire a preference for that flavour
What is the study that investigated the kinds of choices children make abot their diet?
Davis (28)
Outline Davis (28)
When this study happened, it was at a time when feeding policies typically imposed a highly restricted feeding regime - children who were living in paediatric unit in USA for several months were offered range of 10-12 healthy foods prepared without sugar, salt or seasoning and were free to eat what they liked - they observed and recorded which foods they chose - findings indicated that children were able to select diet that was consistent with growth and health, and no feeding problem were observed - formed basis of a ‘wisdom of the body’ theory
Name 4 evaluative points about Davis (28)
1) Naturalistic yet controlled environments so reflect daily lives
2) Findings have been used to support different sides of same argument
3) Results have been published in a prestigious peer-reviewed medical journal and cited by researchers
4) Suggests food preferences changes over time and were modified by experience
How have the findings from Davis (28) been used to support different sides of same argument?
They highlight wisdom of body and existence of biological drives - can also be used to demonstrate importance of environment, since types of foods offered were restricted and healthy
Name 7 evaluative points about evolutionary explanations
1) Importance of calories in early diets - Gibson & Wardle (01)
2) Could early human have been vegetarians
3) Are all preferences a product of evolution?
4) Taste aversion in humans - Seligman (70)
5) Detecting toxins - taste aversion
6) Cultural differences
7) Real-world application
Outline Gibson & Wardle (01)
Showed best way to predict which fruit and veg preferred by 4-5 year, not how sweet, much protein, how familiar but how dense in calories - bananas and potatoes particularly calorie-rich, and were more likely to be chosen, thus demonstrating an evolved preference for calorie-rich foods
Explain what is meant by could early human have been vegetarians for evolutionary explanations
Cordain (06) argued consumed most calories from sources other than saturated animal fats - led to suggestion ancestors healthy eaters and may have been vegetarian - however, evidence does not support hypothesis - anthropological evidence shows that all societies display preference for animal foods and fats - nor would it have been possible for early humans to be completely vegetarians because not have been able to get sufficient calories from plants and grains available
Explain are all food preferences a product of evolution?
Many food preferences can be traced back to the adaptive pressure of EEA, but this is not always the case - a trait that is beneficial today (low cholesterol foods) would not have evolved because of its beneficial effects of our ancestors - many things that ae important to our ancestors like saturated animal fats are harmful in modern environments, so we are more likely to lead a healthy life
Outline Seligman (70)
Claimed different species evolved different learning abilities - biological preparedness - this natural selection of differential learning has occurred so that each species has the ability to learn certain associations more easily than others, particularly those associations that help individuals survive
Explain detecting toxins in terms of taste aversion
Long assumed bitter taste evolved ass defence mechanism to detect potentially harmful toxins in plants - Sandell & Breslin (06) screened 35 adults for bitter taste receptor gene - ppts rated bitterness of various vegetables, some of which contained glucosinolates (known for their toxic effects at high doses) and others that did not - those with sensitive form of gene rated glucosinolate-containing vegetables as 60% more bitter than those with insensitive form of gene - ability to detect and avoid naturally-occurring glucosinolates would confer a selective advantage on our ancestors
Explain the cultural differences in evolutionary explanations
Although evolved factors are clearly important in food selection, modified by experience with different foods, with culture partly determining extent of such experiences - however, if ancestors eaten inappropriately and failed get nutrition required for survival, would have died off and any built-in preferences for inappropriate food gone with them - therefore, cultural differences in food preferences may exist, but these are usually a fine-tuning of the evolved preferences discussed above
Explain the real-world application regarding the evolutionary explanations
Research helpful understanding food avoidance sometimes occur during cancer treatment - some can cause gastrointestinal illness - when illness paired with food consumption, taste aversions can result - Bernstein & Webster (80) gave patient novel-tasting ice cream prior to chemotherapy and acquired taste aversion findings resulted in ‘scapegoat technique’ which involves giving novel food along with some familiar food prior to chemo - patient forms aversion to nove food but not familiar food - consistent with an adaptive avoidance of novel foods known as neophobia
Name 3 evaluative points for researching eating behaviour
1) Lab experiments - controlled but may lack ecological validity
2) Questionnaires & food diaries give insight into ppts’ real life but may be inaccurate and recording eating might actually change eating behaviour in ppts
3) Ignores role of society, parenting and experience and therefore reductionist explanation
Name 3 positive evaluative points about evolutionary explanations of eating behaviour
1) Can explain innate food preferences
2) Gives an explanation that can account for both nature and nurture
3) Fossil evidence provides evidences of shift to meat eating and hunter gatherer societies
Name 3 negative evaluative points about evolutionary explanations of eating behaviour
1) Focus on genome lag and obesogenic environment could provide more effective intervention strategies
2) Reductionist and determinist - eating determined by events which happened thousands of year ago
3) Difficult to falsify so question validity
