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Flashcards by chloe.brandon, updated more than 1 year ago
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Created by chloe.brandon
over 8 years ago
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| Question | Answer |
| In order to understand the adaptive problems faced by our ancestors we must understand the environment that they lived in. What is this? | The environment of evolutionary adaptation (EEA) refers to the environment in which the species first evolved. |
| What does natural selection do? | Favour the adaptations that enhanced our survival. |
| For most of our evolutionary history, where might we have lived? | In a hunter-gatherer society. |
| What did the diets of early humans in hunter-gatherer societies include? | Animals and plants that were part of their natural environment. |
| Why would preferences for fatty food have been adaptive for our ancestors? | Conditions in the EEA meant that energy resources were vital in order to stay alive and also find the next meal. |
| What are modern humans more concerned with? | The nutritional value of food (vitamins, minerals and other things necessary for a healthy diet). |
| What do we eat instead? | Food that is actually rich in calories but not particularly nutritious. |
| What was different in the EEA in terms of calories? | They weren't as plentiful as they are today, so it makes sense that we have evolved a preference for foods that are rich in calories. |
| Why did human ancestors include meat in their diets? | To compensate for a decline in the quality of plant foods caused by receding forests 2 million years ago. |
| What does fossil evidence from groups of hunter-gatherers tell us about their daily diet? | Primarily animal based in particular animal organs such as liver, kidneys and brain which are extremely rich sources of energy. |
| What did a meat diet full of densely packed nutrients provide? | A catalyst for brain development. |
| What did Milton (2008) claim? | That without animals it is unlikely that early humans could have secured enough nutrition from a vegetable diet to evolve into the active and intelligent creatures they became. |
| What did meat provide the early humans with? | All the essential amino acids, minerals and nutrients they required, allowing them to supplement their diet with low-quality plant based foods that have few nutrients but lots of calories (rice and wheat). |
| Are all food preferences a product of evolution? | A trait that is beneficial today (e.g. consumption of low cholesterol foods) would not have evolved because of it's beneficial effects. |
| What was important to our ancestors? | Many things (such as saturated animal fats) are harmful in modern environments, so we are more likely to avoid them to survive and lead a healthy life. |
| When was taste aversion (bait shyness) first discovered? | By farmers trying to get rid of rats. They found it was difficult to kill them by using poisoned bait because rats would only take a small amount of any new food, and if they became ill, would rapidly learn to avoid it. |
| Who were the first to study taste aversion in a lab? | Garcia et al (1955). |
| What did they find? | Rats who had been made ill through radiation shortly after eating saccharin, developed and aversion to it and very quickly associated their illness with the saccharin. |
| Not only taste but what else has been linked to illness and consequently to the development of a food aversion? | Odour of food. |
| Why would the development of taste aversions have helped our ancestors to survive? | If they were lucky enough to survive poisoned food, they would know not to make the same mistake again. |
| What other properties does taste aversion learning have that would have enhanced our survival in the EEA? | It can still be acquired up to 24 hours after the consumption of food, as reaction to poisoned food in the natural environment is often delayed. |
| Once learned can it be forgotten? | Taste aversions are very hard to shift, making them an adaptive quality designed to keep our ancestors alive. |
| What is the 'medicine effect'? | There is evidence that animals can learn a preference for the foods that make them healthier, with any food eaten before recovery from illness being favoured in the future. |
| What did Garcia et al (1955) find? | When a distinctive flavour is present to a thiamine-deficient rat and then followed by an injection of thiamine the animal will acquire a preference for that flavour. |
| Explaining taste aversion in humans, what did Seligman (1970) claim? | Different species evolved different learning abilities, something he called biological preparedness. |
| Why has natural selection of differential learning occurred? | So that each species has the ability to learn certain associations more easily than others, particularly those associations that help individuals survive. |
| What have scientists assumed about bitter taste? | It evolved as a defence mechanism to detect potentially harmful toxins in plants. |
| Which study provides direct evidence in support of this hypothesis? | Sandell and Breslin (2006) - screened 35 adults for the hTAS2R38 bitter taste gene. |
| What did the participants do? | Rated the bitterness of various vegetables, some of which contained glucosinolates and others that did not. |
| What are glucosinolates well known for? | Their toxic effects at high doses. |
| What did those with the sensitive form of the bitter taste receptor gene rate the glucosinolate-containing vegetables? | 60% more bitter than those with the insensitive form of the gene. |
| What would confer a selective advantage on our ancestors, that would explain why such genes are widespread today. | The ability to detect and avoid naturally-occurring glucosinolates. |
| What is a common way to test evolutionary hypotheses? | Through comparisons with a different species. We might question why the same food preferences are found in other species. |
| We cannot travel back to the EEA to see what adaptive problems were faced by our ancestors, so what can we do? | We can study a related species (e.g. chimpanzees) who face similar adaptive problems today. |
| Alternatively what can we do? | We may look for modern-day human products that reflect our evolved food preferences. |
| Give an example. | Hamburgers, pizza and sugary foods sell well because they correspond to and exploit evolved desires for fat, sugar etc. |
| What might a search for 'ultimate' causes in food preference mask? | More 'proximate' causes such as advertising, availability and laziness etc. |
| Is there evidence from other primates to support our need for meats and fatty foods? | Anthropologist Craig Stanford's observations of chimpanzees in Tanzania's Gombe National park (1999) showed that these animals face the same problems as our ancestors. After coming close to starvation for nearly year, when they do kill they choose the fattiest parts (brain, bone marrow etc.) than flesh. |
| Are there cultural differences? | Although children tend to crave sugary foods and the need for fatty foods is universal, however innate responses don't account for the food likes and dislikes we have after infancy. |
| Give an example. | Spicy foods were initially rejected yet across the world chilli is second only to salt as a food spice. |
| What can taste aversion not account for? | Why nowadays we still choose to eat sour and bitter foods such as some sweets and lemons. |
| Is there a real world application? | The adaptive origins of taste aversion have helped to understand the food avoidance that can sometimes happen during cancer treatments. |
| What do some cancer treatments such as radiation and chemotherapy cause? | Gastrointestinal illness which when paired with food consumption can result in taste aversions. |
| What did Bernstein and Webster (1980) do? | They gave patients a new tasting ice cream before their chemotherapy meaning that the patients acquired a taste aversion to that food as they think it is the food that has made them feel ill as opposed to the chemotherapy. |
| What did these findings result in? | The development of the 'scapegoat technique' which involves giving patients a new food along with a familiar food before treatment so the patient forms an aversion to the new food not the familiar. |
| This is consistent with an adaptive avoidance of unfamiliar foods known as? | Neophobia. |
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