Explanations for food preferences

Sees humans as having genetic variability b/ween individuals. Specific genes handed down by parents + if particular person's genes suit environmental conditions they're in, then have adv, as more able to exploit environment to survive + reproduce -> next gen. Natural selection, genes become widespread through population. Those w/ genetic variability that help locate sufficient amounts of safe, nutritious foods - selective adv. Allow them to survive + pass on to children. According to this explanation, how eating behaviour shaped.

Most evolution thought to have occurred during Environment of Evolutionary Adaptiveness (EEA) - nomadic hunter gatherers, risk of death high. Daily battle to find food. Many foodstuffs only available periodically, made sense to evolve methods of detecting + avoiding poisonous foods. Made sense to evolve preferences for certain foods (energy rich), consumption increased survival chances. Preferences for these foods more likely to survive, reproduce, pass on food preferences to offspring - widespread through population, still there today.

Made sense to overeat, fat stored, excess energy.

Evolutionary theory - preference for sweet-tasting foods becoming widespread, as sweetness associated w/ high energy, non poisonous content - sweet foods aid survival. Acted upon by natural selection to become universal food preference.

Salt necessary for maintaining neural + muscular activity + water balance. Contains sodium chloride, essential for hydration - too much salt harmful. Concentration of salt in blood must remain at specific level, regularly needs topping up - small amounts lost through sweat + action of kidneys.

Salt deprivation -> salt cravings, animals travel long way to find salt. For early humans, salt a commodity exchanged for other goods, w/ industries coming up from salt mining + trading.

Ability to detect + reject bitter + sour tastes makes evolutionary sense - indicate presence of poisons. Plants produce toxins to discourage being eaten, evolutionarily beneficial to develop ability to dislike bitter + sour tastes. Herbivorous animals eat plants only + evolved high tolerance levels to toxins contain in these foodstuffs - by having livers that can break Dow + neutralise poisonous compounds.

Humans - innate ability to detect bitter tastes, around 30 genes that code bitter taste receptors - as each receptor able to interact w/ several compounds, means humans can detect a wide variety bitter-tasting substances. Children especially sensitive - makes evolutionary sense, as young children not had sufficient environmental experiences to develop learned + culturally acquired taste preferences.

Humans - no innate tendency to eat meat. Intro'd into children's diets at relatively late stage of development - many children reluctant to eat it. Vegetarians don't suffer ill health from lack of meat, or later pref for meat.

Humans - omnivores. Some meat eating occurs among other primates, eg chimpanzees, others vegetarian eg gorillas. Not much evidence for when meat eating occurred for humans. Evidence from prehistoric sites suggest around 1.5 million years ago. Fire - cooked meat - could be preserved for later use. Natural selection, tendency to eat meat emerging predominance of humans more able to digest meat + have resistance to harmful pathogens in it.

Advs of meat from being rich in fat - high in energy, available year-round (adv over plants - seasonal). Some argue meat eating -> advances in intelligence (providing energy to allow brain growth), others see as more indirect effect (development of hunting skills). Disadvs - dangers of hunting it, toxins contained in it, transmissible diseases across species - viewpoint HIV transmitted to humans from monkeys through consumption of 'bush meat'.

Innate tendency to avoid new foods. Evolutionary POV - contradictory, humans need varied diet for nutritious to live. Neophobia protective function - new, unknown foods could be toxic. Learning experiences w/ innate predispositions to learn certain food preferences can change initial neophobia reaction to new food preference.

Newborn babies - only milk. Neophobia begins at weaning to solid foods. Neophobic reaction to new food will diminish w/ repeated exposure to food, infant learns it's safe. Reduction in neophobia also generalises to similar-tasting new foods.

Occurs when individuals eat foodstuff + become ill - avoid that foodstuff b/c associate it w/ being ill. Effect requires only one experience of illness, resistant to extinction. Effect still occurs even if individual knows it wasn't foodstuff that made them ill.

Initially taste aversions seem prime eg of classical conditioning - previously neutral CS (food) becomes paired w/ UCS (illness) to produce UCR (vomiting), causing individual to avoid foodstuff in future. Often, vomiting may not occur straight after eating, contradicts CC. 

What actually happens - biological preparedness, entails humans (+ other animals) being bio predisposed through evolution to form certain associations b/ween certain stimuli more easily. Associations involve stimuli essential for survival eg avoiding toxic foodstuffs. Primed by evolution to learn through experience to avoid foodstuffs that make us ill, as this has adaptive survival value. 

Eating generally social event, so influence children's eating habits. When infant moves to solid foodstuffs, mother's eating behaviour affects child's eating behaviour - evidence suggests food mother eats in pregnancy + after birth impacts child's eating habits during transition to solid food. Flavours transmitted through via amniotic fluid + breast milk. 

Social learnign plays role, research indicates observing what others eat imitated by children. Plays role in breaking down neophobias. SL effect carries on in later childhood, facoured adults + peers important models fo rchildren to observe + imitate. Importance of role models depends upon relationship between them.

OC through reinforcements also plays part. Children given foods as rewards for approved behaviour, greater preference for foods occur. If children given rewards for eating new foodstuffs, eg vegetables, foods eaten to gain reward become less preferred. Restricted foods become more desirable.

Overall, preferences + eating habits resembe that of parents as share genetic FPs transmitted by evolutionary forces, as well as learning parents' FPs - same environmental influences.

Eating influenced through cultural circumsances, as cultural + sub-cultural groups have diff eating practices. Transmitted to children via reinforcement + social learniing, + inc consumption of diff foodstuffs + diffs in traditions of prep + eating practices marking special occasions. Cultural eating practices also found in local cuisine. 

Certain cultural practices -> restrictions eg excluding pork. Cultural influences generally flexible + newcomers often adopt particular food habits of local culture.

Overall, cultural influences eating behaviour directly, usually has moderating role on other variables to determine individual food preferences + eating practices. 

Logie (1991) found human tongue has specific receptors for detecting sweetness - not the case for other tastes, detected by non-specific receptors - also more receptors for detecting sweetness than other tastes - implies sweet tastes more important + preference has genetic component shaped by evolution.

Read + McDaniel (2008) - point out genes alone not thought to be responsible for variations in sweetness reception in humans. Leptin (protein hormone) - inhibitory effect on taste reception cells, reduces amount of sweetness signals transmitted to brain. During times of food scarcity, less leptin produced - sweet foods appear less attractive.

Beauchamp (1987) found people w/ sodium deficiency (salt starved) have innate response to ingest salt + find it more tasty, less horrible in high concentrations + eat more of it than related family members. Appears to be an evolutionary determined mechanism - helps maintain sodium levels in body, suggests high adaptive survival value.

Individual differences in salt preference - not what evolution would predict - would predict standard universal preference. Zinner (2002) found 23% neonates had salt preference + higher blood pressure than other babies, + at least 1 grandparent w/ hypertension (indicative of high salt consumption). Suggests genetic basis to individual diffs.

Many medicines are naturally bitter tasting - revolting to children (especially sensitive to these tastes). Children given such medicines vomit them back up - bodies reject poison they believe they've eaten. Many children's medicines sweetened so they can be swallowed. Suggest evolutionary ability to detect + reject bitter-tasting compounds.

Finch + Standford (2004) believe humans adapted to eat diverse foods, inc meat - allowed exploitation of new environments, especially harsh ones devoid of abundant plant foods, suggesting adaptive advantage to meat eating.

Kendrick (1982) - studies cultural groups noted for longevity - found common factor was vegetarianism - suggest is a disadv of meat eating - shorter life span.

Birch et al (1987) - found 2 y/os given most exposure to unfamiliar fruits + cheeses reduced neophobia of foodstuffs more quickly. Effect occurred as much w/ opps to smell food as eat it, suggests learning new foods not toxic that reduces neophobia, supports idea of neophobia having adaptive survival value.

Not all children neophobic - some appear less neophobic than others, has adaptive value eg children more willing to eat unfamiliar foods + act as 'guinea pigs' to test out foodstuffs. If found them non-toxic, behaviour would be observed + imitated by more neophobic children.

Rzoska (1953) - found rats given poison bait-balls ate small, sub-lethal amounts of them + quickly developed a long-lasting aversion to them - demonstrates strength of taste aversion.

Birch (1992) found mothers' eating behaviours, attitudes + child-feeding practices influence children's food preferences + eating behaviour when they move on to solid foodstuffs, illustrating important of social influences in shaping food preferences.

Animal studies often used, but problem is difficult to generalise findings to humans, who have more complex cognitive processes, which affect their eating behaviour.

Cultural eating practices often reflect local environmental conditions, eg seasonal/non-availability of foods, coupled w/ ability to transport + keep foodstuffs in hygienic conditions. Eg, makes sense not to eat meat in cultures where meat goes off easily + becomes poisonous.

W/ increase in world population mobility, developments in transport systems + modern food hygiene practices, eg wider availability of refrigeration, eating behaviours more global + less based on individual cultural locations.