Transcript of "Evolutionary explanations of food preference"
Evolutionary Explanations of Food Preference
Evolutionary Theory of Food Preference What foods do you prefer.•When you get home from college tonight whatfoods might you reach for if you need a snack?•When you go to the supermarket and you’re hungry,what foods would you tend to buy to satisfy thishunger?
Evolutionary Theory of Food Preference What does the Evolutionary Theory suggest about human behaviour? Good for Adaptive Survival Evolutionary theory suggests that: • Organisms should behave so as to maximise the survival of their genes or their inclusive fitness (the probability that their biological relatives will survive). •Therefore, Natural Selection (survival and reproduction of the fittest) occurs. How is this relevant to eating behaviour?•Those who are best equipped to obtain sufficient food and remain health were more likelyto survive.•This means that humans have evolved to have certain food preferences that give themthe best chance of choosing good food with enough necessary nutrient to promotesurvival.
Learning Objectives: Evolutionary Explanation of Food Preference.(1)The tendency to binge eat (why do we prefer foods that are high in fat?)(2) Why do we have a preference for sweet foods?(3) Why do we have a preference for salty foods?(4) Is there any research supporting these food preferences?
A01 (1) Tendency to Binge Eat In our evolutionary past food supplies were limited or erratic. Our ancestors couldn’t rely on a continual source of food for their daily nutritional needs. It is believed by evolutionary psychologists that such times encouraged maximisation of stored energy i.e. binge eating would have been considered adaptive. -Sweet, fatty or salty foods would be particularly sought after since they are vital requirements to our diet and relatively rare in the ancestral environment. Any human that quickly learned that such high fat foods provide more energy, deliberately sought these foods out and consumed as much as possible would be most likely to survive. Thus, it would be advantageous to overeat in times of plenty and then expend as little of those calories as possible in readiness for times of scarcity.Commentary: A02•The obesity problems encountered by much of the western world in today’s society are testament toan inability to escape this evolutionary pressure. (Steven and Price, 2000).•Nowadays many people have a problem with overeating and gaining weight. The increased levels ofobesity in the developed world suggests that people as predicted by Evolutionary Theory find ithard to ignore high fat food offerings now that they are readily and cheaply available.•Furthermore, although exercise could alleviate these evolutionarily led behaviours,another evolutionary hangover is to conserve energy and people now do thisby not exercising and using labour-saving devices such as lifts, cars and dishwasher etc.
We Luurve the Cake!! A01 (2) Preference for Sweet Foods •Argument that humans have evolved a preference for specific tastes. •Sweet taste signifies ripeness, high concentration of sugar, quick fix of calories. •A preference of sweet foods would encourage the consumption of ripe fruit and would have an evolutionary advantage for our ancestors. A02There is considerable empirical support for the idea that we have an innate “sweet tooth”. Researchhas shown that people of all ages will choose sweet foods over other tastes (Meiselman, 1977).Even 3 day old infants demonstrate this preference (Desor et al, 1973).Bell et al (1973) gave sweet sugary foods to Eskimos in Northern Alaska whohad previously lacked sweet food and drink in their diets. They found that, in allcases, cultures previously without sugar did not reject the sugar containing food anddrinks of the other culture, suggesting that a preference for sweet tastes is notculturally learned.
Preference for SweetA02 Foods...SCIENTIFIC SUPPORTThere is also physiological support for thepreference for sweet food. The human tongueseems to have specific receptors for detectingsweetness. This is not the case with othertastes, which are detected by non-specificreceptors. There also appears to be morereceptors for detecting sweetness than anyother taste. All this evidence suggests thatthe taste of sweet foods is more important tothe body than any other taste, again implyingthat that the sweet preference has asubstantial genetic component (Logue, 1991).
Preference for Salty FoodsPreference for Salty Foods A01Salt is essential for the body to function properly. We lose saltthrough sweating and the action of the kidneys and therefore it needsto be kept at a constant level. As with fatty foods, it may be that thebody has developed a proclivity to consume salty foods wheneverpossible, as they would have been relatively difficult to find. “I think my wife is trying to kill me Officer”A02We are not born with an innate preference to salty food,but it develops in childhood. Two year old children have beenfound to universally reject foods without the expected amountof salt in them (Beauchamp, 1987).
Evolutionary Avoidance of Dangerous Foods A01Humans are omnivores- we eat a wide ranging diet that includes meat. In many waysthis is hugely advantageous, as it allows us to exploit many different food sources.However, it also leaves us open to a variety of plant toxins and infections fromfood that has gone off. This is particularly true of meat, which is still a major sourceof food poisoning today. The main problem with A02 Evolutionary theory is the inability to test it. Evidence has to instead be gained from observations of species change, fossil records or studies on primates.
As a species we have evolved several methods to cope with this problem…CookingThis was introduced a least half a million years ago and solves this problem bykilling bacteria in meat during the cooking process. In addition, cooking alsomakes meat tender and easier to chew. This is evidenced by the fact that our chewing teeth, the molars, have significantly decreased in size during evolution (Lucas et al, 2006).Taste Aversion LearningGarcia, Rusiniak & Brett (1977) made wolves sick with lamb’s meatcontaminated with a mild poison wrapped in sheepskin, when allowed toapproach live sheep the wolves would approach, sniff and then leave thesheep alone **ELABORATION** Why is it an evolutionary advantage that we avoid foods that have made us sick?
As a species we have evolved several methods to cope with this problem…Food Neophobia (neophobia means ‘fear of the new’)Animals have a powerful tendency to avoid foods they have not come acrossbefore, although this may become dull, Frost (2006) identified that we tendto show greater likings for foods as they become more familiar. **ELABORATION** How does this support the evolutionary theory?Morning sickness is most common in early pregnancy, when the baby’s organs are stillforming and it is most vulnerable. The foods most avoided by pregnant women dueto their ability to trigger sickness are those which appear to have the greatestchance of damaging the embryo. For example, alcohol, coffee and tea all containcaffeine which can damage the developing organs and meat and eggs are commonsources of bacteria which could lead to harmful infections. This sickness reactiontherefore helps the mother avoid foods that may be detrimental to her pregnancy,while the vomiting prevents any toxins entering the bloodstream and affecting her baby
Approaches: Evolutionary ... Issues: Unfalsifiable Also, don’t forget..AO3..Debates: How Science Works....... Be critical
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