EVOLUTIONARY EXPLANATIONS - created from Mind Map

Página 1

IN THE EEA

fatty foods high in calories preferred to provide energy to stay alive & find the next meal. in modern humans, we are concerned with nutrition of food but we still end up eating foods high in calories.

fruit & veg that 4-5 year olds will pick can be predicted not by sweetness, protein or familiarity but by how dense in calories. bananas & potatoes are dense & were more likely to be picked by the kids, demonstrating evolved preference for calorie rich foods.

included meat in diet due to decline in quality of plants. ate primary organs e.g. liver, kidneys, brain rich in energy. helped brain growth. supplied essential amino acids, minerals etc. & supplemented meals with plant foods rich in calories e.g. rice.

not all food preferences are product of evolution. modern preference such as low-cholesterol foods would not have evolved because it did not benefit our ancestors as saturated fats were beneficial to them but harmful in modern environments so we are more likely to avoid them.

though some argue that ancestors would have been vegetarian, anthropological evidence shows all societies displayed preference for animal foods & fats. It would also not have been possible to survive by being vegetarian as they would not get sufficient calories from the plants available.

challenging study: reported human dental structure, digestive system etc. are more similar to herbivores suggesting consumption of plants is more natural for human bodies & humans don't have innate preference for meat

more likely that long term food scarcity led to meat eating. supported by fact that meat is not naturally palatable for humans. real carnivores eat meat raw, with guts & all & only humans have to cook it to make it palatable.

also meat has to be introduces to youngsters' diets, suggesting no evolutionary determined preference for meat.

TASTE AVERSION

avoiding food that can cause illness/death. rats would only take small amount of new food & if they became ill from the poison they would rapidly learn to avoid it. In lab, rats given saccharin & made ill by radiation, avoided saccharin.

helped ancestors survive. if lucky enough to survive eating poisoned food, would avoid in future so is adaptive quality designed to keep ancestors alive.

'medicine effect' occurs when learning preference just before recovery from illness. presenting distinctive flavour to thiamine deficient rat & giving thiamine injection after, rat will acquire preference for that flavour.

assumed bitter taste evolved to detect potentially harmful toxins in plants. pp's screened for bitter taste receptor gene & had to rate bitterness of vegetables containing glucosinolates, toxic in high doses. those with sensitive form of gene rated glucosinolate-containing veg as 60% more bitter than insensitive pp's. ability to detect & avoid naturally occurring glucosinolates confers selective advantage on ancestors explaining why gene is qidespread today.

additionally, children are sensitive to bitter taste & often cannot swallow bitter tasting medicines & vomit them back up as their body rejects the poison it thinks it ingested. many are sweetened to be successfully swallowed & ingested. suggests evolutionary ability to detect & reject bitter tasting compounds

IDA: helpful in understanding food avoidance in chemotherapy, cause gastrointestinal illness. when paired with food consumption, taste aversion occurs. Resulted in development of scapegoat technique, giving patients novel food with familiar food prior to chemo. Form aversion to novel food but not to the familiar.

modern day human products may reflect our evolved food preference e.g. hamburgers, pizza, sugary foods sell well because they correspond to an evolved desire for fat & sugar. search for ultimate causes in food preference may mask more proximate causes e.g. advertising, laziness etc.

theory only takes into account nature side of the nature v. nurture debate seeing food preferences as biologically determined by genetic means, neglecting nurture side, like influence of environmental learning & cultural factors in eating behaviours so is reductionist.

EVOLUTIONARY EXPLANATIONS