O+E evolutionary mechs for food preferences

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  • Created by: imanilara
  • Created on: 22-02-16 12:39

Pref for high calorie foods AO1

Modern food prefs explained by the selection prefs developed in the EEA in hunter-gatherer societies.

-Pref for fatty foods adaptive-energy resource when food is scarce
-selection pressure-those who had pref for high calorie foods would survive+pass on this characteristic
-Modern humans are more concerned about the nutritious value in food, however tend to eat foods that are still calorific and unhealthy- we are genetially programmed to do this due to selection pressures in EEA.

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Preference for meat AO1

-Ancestors began to get food from animals when forests started to recede 2 million yrs ago
-Fossil evidence from hunter-gatherers suggests they ate organs such as livers+heart
-These are rich sources of energy
-Milton (2008) suggests that meat intake was the catalyst for larger human brains--without meat diet they would not have become the intelligent creatures they did

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Taste Aversion/Neophobia

Neophobia-fear of new foods-humans and animals display this.
-Liking for new food increases with familiarity (Frost 2006)
-Animals will only eat a small amount of the new food=bait shyness-identified by farmers who tried to kill rats w poison
Taste Aversion-
learned response-linking food to the response of sickness-the food might not have made the person sick, but the sickness might have happened closely to when the food was tasted-usually happens w new food.
-First noted w farmers who could try+poison rats, but they would avoid the poison after falling ill
-Garcia et al (1955) tested in lab conditions-rats made ill w radiation shortly after eating saccharin-they developed taste aversion to saccharin
-Survival value- those who survived eating the foods can avoid it
-Can develop up to 24hrs after eating food-sickness is usualy delayed
-v hard to shift-adaptive value for ancestors-won't eat again 

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Taste Aversion AO1 ...

Medicine effect - animals can learn pref for foods that has made them feel healthier
-Garcia et al gave thiamine deficient rats a distinctive flavour followed by a thiamine injection
-they developed pref for this taste -adaptive

Morning sickness- mothers avoid foods, commonly meat, coffee eggs- Buss 2008
-evol explanation is to protect the baby

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AO2 Pref for high calorie foods

Gibson+Wardle- supporting- best predictor for prefs of 4/5yr olds is not how sweet the food is or how familiar the taste is, but the the most highly calorific- eg bananas and potatoes
-supports that we have evolved prefs for high calorie foods

Stanford 1999- observed chimp behaviour in tanzania
-troop close to starvation, if they kill monkey they will eat fatty parts first (brain) instead of the easier accessible parts that have lower energy
-parallel for what humans in EEA would've eaten like
-fat was rare but necessary for survival

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Preference for meat AO2

Cordain et al (2006) humans consumed most of their calories from other sources other than meat-suggested that early humans followed healthier, veggie diet

Issues are that:

-anthropological evidence (Abrams 1987) shows that all societies displayed pref for saturated animal fats
-they wouldn't have got the sufficient energy needed from just plants and grains

WEAKNESS: in the modern day we do not completely mirror behaviour in EEA
-we are aware that overeating animal saturated fats is unhealthy and may try to avoid it unlike our ancestors-shows that our prefs today are perhaps to do w learned behaviour and the EEA pressures so it is a mixture of Nature/nurture

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Taste Aversion AO2

Seligman 1970-ability to learn taste aversions is due to biological preparedness- we can learn some things easier than others because this is adaptive, eg, monkeys scared of rubber snake but not of rubber flower by observing adults responses, just like they can associate sickness with food but not electric shocks and food.
-It is adaptive-promotes survival

-taste aversion research helping cancer patients who due to chemotherapy can get taste aversion to lots of foods
-Bernstein and Webster- gave novel ice cream before therapy+ aversion developed
-They developed scapegoat technique- give novel food w familiar food, and aversion only happens w new food not familiar
-Consistent w neophobia as an adaptive response

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IDA: Deterministic- some ppl are veggies/don't like sweet foods - they have free will

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