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Resourcd File


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Resourcd File

  1. 1. Evolutionary Explanations of Food Preference Starter: In pairs: One of you is the taster and will be blindfolded. The other will ensure the food ends up in your mouth. You need to: Rate the food 1-10 (1 dislike- 10 like) Try and identify the food Of the foods you like explain why you like them. What do they contain? Wednesday, August 14, 2013 Candice Russell 2013
  2. 2. Sweet – identify foods rich in carbs to provide us with energy Sour – associated with food that has gone off and therefore, should be avoided Salt – critical for functioning of the cells and therefore need to identify Bitter – associated with poisonous plants, should be avoided Umami – a recent discovery which is highly savoury – a meaty taste
  3. 3. Humans split from the great apes about 6 million years ago. Modern apes live on nuts, fruit and plants. Therefore likely our early ancestors were vegetarian. However, we rapidly became omnivores due to the receding forests about 2 million years ago and this is evident in modern hunter gatherer societies. Our digestive system is different from monkeys and apes as theirs is specialised for the digestion of plant material.
  4. 4. EEA: Environment of evolutionary adaptation EEA is the environment from where a species first evolved. As hunter gatherers we required high calorie foods to ensure we could stay alive and live to hunt another day. Our food supplies varied, sometimes there would be feast other times famine. So by developing a preference for calorific foods, ensures that we may have enough energy stored in our bodies to survive if times got tough.
  5. 5. Plenary: I have learnt that One member of the class starts and says one thing they have learnt, the next member of the class repeats the previous persons comment and then adds their own, the third person says the previous two members comments and then adds their own……… Tough being the last person…… Try to add some research if you can!
  6. 6. Evaluation of meat and high calorie preference. Gibson and Wardle (2001) Cordain et. Al. (2006) Abrams (1987) Stanford (1999) Evidence from other primates Are all food preferences a product of evolution? Read through page 90 and summarise the research supporting the preference for calories . Over to you: Summarise the preference for high calorific food and meat, in 50 -75 words and no more. Use the following terms: Environment of evolutionary adaptation, natural selection, survival, protein, amino aids, intelligence, brain development, preference.
  7. 7. Preference for Meat Early hunter gatherers liked organ meat These are high in protein Milton (2008) claims this protein rich diet contributed to the growth of the brain in humans, and lead to our higher intelligence. Therefore, this all suggests that the preference for savoury foods (umami) can be traced back to our environment of evolutionary adaptation (EEA)
  8. 8. Lesson 2: Taste Aversion Why are these little cuties pulling faces? Why survival benefit does disliking sour tastes confer? What survival benefit does disliking bitter tastes confer? Wednesday, August 14, 2013 Candice Russell 2013
  9. 9. Why don’t we like bitter and sour? These receptor help us identify food that has gone off Leads to the facial expression of ‘disgust’ This is seen in human infants and other primates Suggests innate This feeling leads to avoidance
  10. 10. Evidence supporting evolution of bitter taste aversion Sandell and Breslin (2006) screened 35 adults for the hTAS2R38 bitter taste receptor gene. The participants were given a diet that contained vegetables with Glucosinolates. Glucosinilates, are found in broccoli and Brussels sprouts and when taken at really high doses can be toxic. Glucosinolate also gives these vegetables their bitter taste. Participants with the sensitive form of the gene found the vegetable 60% more bitter then the insensitive form of the gene. Read Biological preparedness and explain how this aversion lead to a survival advantage. (prepare to feedback)
  11. 11. Bait Shyness : Association Bait Shyness: Rats given poison were not being killed as they only took a small amount, got ill and then associated the illness with the bait. Garcia (1955) gave saccharin to rats just before exposing them to radiation. They found after exposure the rats developed an aversion to saccharin.
  12. 12. Aversion and chemotherapy Read through the real world application box on page 90. Explain what neophobia is and how the research by Bernstein and Webster supports aversion as an adaptive response.
  13. 13. Adaptive Advantage of Taste Aversion Taste and odour can be linked to taste aversion. The association can occur up to 24 hours after the consumption of food. If you ever got food poisoning from a restaurant, would you go back? Why would this be advantageous to our ancestors?
  14. 14. Medicine effect If we associate a food with recovering from an illness we may have preference for that food. Garcia et. Al (1955) Rats who were given a distinctive flavour when given thiamine injections developed a preference for that Flavour.
  15. 15. Cultural Differences Some food preferences such as sweet and salty are universal. What differences can you suggest? Do these innate food preferences support evolutionary theory?
  16. 16. Some Brief Evaluation  Ignores the role of society, parenting and experience and therefore a reductionist explanation  Could explain the high rates of obesity, we are programmed to like these foods. Still eating lots of calories, even though we are now sedentary unlike our hunter gatherer ancestors.  We do show similarities to other species  Fossil evidence (teeth, digestive system) provide evidence of the shift to meat eating and hunter gatherer societies • Can explain unusual food preferences including morning sickness   explain taste aversion following illness and chemotherapy Nature rather than nurture
  17. 17. Over to you: Write an IDA paragraph that has informed commentary and evidence on taste aversion. ‘Evolutionary explanations of food preferences are on the nature side of the nature nurture debate. They argue that…………..’ Evidence for this comes from……this supports the argument as….. However evolutionary explanations to eating are reductionist because other factors such as……………. You will read these out in class
  18. 18. Lesson 3: You have 15 minutes to complete a detailed plan to group your ideas to together for the essay ‘Discuss evolutionary explantions for food preference’ Show your plan to me, and I will give you suggestions. You will then need to complete your essay in the remainder of lesson time.