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Lecture 4

PSYCH-UA 30 Lecture 4: Evolutionary Psychology Week 4

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New York University
Andersen Susan

1 Tuesday, September 26, 2017 Evolutionary Psychology Chapter 3 Combating the Hostile Forces of Nature Exam- Chapter 1, 2 &3 next Tuesday, Oct 3, 2017 50 multiples choice questions & 3 extra credit multiple choice questions Must have a Pen and #2 Pencil (for scranton) Hostile Forces of Nature ❖ Climate ❖ Weather ❖ Food short-ages ❖ Toxins ❖ Diseases ❖ Parasite ❖ Predators ❖ Hostile Conspecifics Each of these have created problems for us humans. All of these are still issues. Even if we gain more and more knowledge these are still problems. All of these are going to present dangers to us. Even let’s say diseases, even though we have so much medicine and treatments now, so we are not in danger like back in time but it still is a problem. Problem 1: Food Acquisition ❖ Social and cultural aspects of food ❖ Food preferences ➢ Neophobia ▪ Fear of novel food (things you’ve never tried or have never tasted before) 2 ▪ Rats have neophobia as well because they tend to avoid food they’ve never had before • Because it could kill them ❖ In order to get food, it requires you to search for food. ➢ Problem #1 ▪ We have to be able to recognize what food we can eat ▪ We have to hunt for it ▪ We have to be able to consume it We have to get our body working so it can do these things. ❖ We are omnivores so we eat a wide range of food ➢ Nuts, fruits, meat ▪ Because we eat a lot of different kinds of foods it increases our chances of getting toxins & plants have a lot of toxins ❖ Sharing food is a major social activity for humans ➢ Some society exists where people will make a spectacle of sharing food ➢ Food is not only tied into our immediate survival but it is also tied into our social interactive ▪ Living in large social groups has helped us survive ❖ We know there are aspects that are going to affect our ability to get food ➢ How do we fix that? ▪ We have evolved particular food preferences • These preferences are going to help us look for and acquire food that are going to be beneficial to us with minimum consequences o Etc- We have food preferences for glucose ➢ There is evidence to support that even babies(newborn) have preferences for these foods after they are born ▪ They have preferences for sugary substances • It calms them ➢ Humans and rats don’t like overly excessive bitter and sour food ▪ This is because bitter and sour food tens to contain toxins much more than other food 3 ❖ If we have a deficiency of a certain food, we develop that into a food preference ➢ e.x. If you have a deficiency of salt you’ll develop a food preference for salt so that you can have the efficient amount of salt you need to survive Disgust: The Disease-Avoidance Hypothesis ❖ Disgust seems to start out with an issue with food ➢ (I’m not going to touch that, I’m not going to eat that) ▪ Then it morphs into disgust of other things ❖ The emotion of disgust is a hypothesized adaptation that serves as a defense against microbial attack, protecting people from the risk of disease ❖ Women find images depicting disease-carrying objects to be more disgusting than men do, and also perceive that the risk of disease is greater from those objects than men do. ➢ Women are going to have a stronger level of disgust than men do because they need to protect themselves and their babies/newborns Disgust seems to be a crucial part of our navigation in our food acquisition ❖ As we get older, disgust seems to broaden ➢ We start to apply disgust from food to other things ▪ e.x. drinking juice out of a bedpan or a Nazi hat ❖ Individuals who score high on a measure of pathogen disgust find relatively unattractive faces to be especially unattractive compared with people low on pathogen disgust ➢ Disgust helps us to navigate a world where there a lot of toxins that can affect our survival ▪ Caring for someone who is injured changes disgust • e.x. Parents changing diapers of a newborn, parents can suppress this response of disgust because they know they have to help their kin(child) o You can suppress it when they are infants, but when they get a bit older, the disgust you’ve suppressed comes back 4 ➢ Social and cultural issues are going to affect what we eat Evolved Mechanisms to Combat Natural Toxins ❖ Gagging ❖ Spitting ❖ Vomiting ➢ If you drink too much alcohol, your body makes you vomit because it is trying to get rid of the toxin (alcohol) ❖ Coughing ❖ Sneezing ❖ Diarrhea ❖ Pregnancy sickness ➢ Another evolved behavioral mechanism ➢ When a woman first becomes pregnant, woman tend to develop pregnancy sickness in the first 3 months ▪ Heightened sensitivity to certain foods ▪ Could be disgust to a certain food, vomiting • 75%-90% of women report pregnancy sickness • 55% of women vomit • Almost 100% of pregnant women report food eversion ▪ This is all to protect the mother and offspring ▪ Eversion to things like coffee, alcohol, vegetables, eggs and meat ▪ No eversion to things like bread and cereal because they are very likely to not contain any toxins ➢ Aversions: ▪ Coffee ▪ Alcohol ▪ Vegetables ▪ Eggs ▪ Meat ➢ Preferences 5 ▪ Bread ▪ Cereal The Embryo Protection Hypothesis ❖ Attempts to explain why women have morning sickness ❖ Adaptation to prevent ingestion of teratogens ➢ Teratogens- Toxins that are harmful to a developing baby ❖ Evidence ➢ Foods women find most repugnant contain highest doses of toxins ▪ The food that woman tend to avoid tend to have high levels of toxins • Evidence 1- They tend to avoid meat because it contains higher levels of toxins • Evidence 2- Food aversion tends to happens when the fetus is most vulnerable to disease and toxins (4-6 weeks after conception) ❖ Sickness occurs at the point in embryonic development when fetus is most vulnerable to toxins ❖ Sickness decreases (and almost disappears entirely) coinciding with end of critical period for organ development ➢ When the fetus’s organs have all been formed (between 12-15 weeks after conception) they undergo further refinement, but their structure is already set, this is when pregnancy sickness start to slowly disappear because the fetus is not vulnerable to disease anymore ❖ Women who do not have pregnancy sickness are three times more likely to experience spontaneous abortion (miscarriage) ❖ Evidence suggests the existence of morning sickness across cultures ❖ All this evidence suggests that pregnancy sickness is an evolved behavior that helps us to protect our developing offspring so that it has the best chance of survival once it is born 6 Fire and Cooking ❖ Evidence supporting Wrangham’s cooking hypothesis 1. Cooking food provides a predictable increasing its net energy value 2. Cooking renders food more easily digestible 3. Cooking is a human universal 4. The human brain requires a tremendous number of calories to function, and fibrous fruits and other raw foods rarely can provide enough 5. On exclusively raw-food diets, humans fare poorly, and among women, many lose the ability to reproduce. ➢ Cooking using heat allows us to have a process to transform raw foods so that we are able to get more net energy out of it ➢ People who follow a raw food diet have very poor health ▪ Especially women who follow a raw food diet • Women who follow a raw food tend to lose their fertility ➢ Researchers say that there is not a lot of evidence that suggests that people used fire to cook food so this hypothesis may be wrong Antimicrobial Hypothesis ❖ Attempts to explain why humans use spices ➢ Use of spices ▪ Spices kill or inhibit the growth of microorganisms and prevent he production of toxins in food 7 • Particularly bacteria o Bacteria is what causes food to become toxic ▪ The use of spices will reduce the presence of bacteria which makes the food safer to consume ❖ Evidence ➢ Most widely used spices (onion, garlic, allspice, oregano) are the most powerful in killing bacteria ➢ More spices (and more potent spices) are used in hotter climates ▪ We actually see more use of spices in hotter climates, because microorganisms are more likely to grow more likely in hotter climates ➢ Food poisoning occurs more frequently in countries that use fewer spices The Frugivory By-Product Hypothesis ❖ Attempts to explain why humans drink alcohol ➢ Because humans don’t gain any benefits from drinking alcohol ❖ Fruits contain high amounts of sugar and ethanol ➢ We like alcohol because we likely fruits as they contain a lot of sugar and ethanol ❖ Alcohol consumption is a by-product of adaptive fondness for ripe fruit ➢ We like ripe fruits so we grow fond of alcohol ➢ The smell of alcohol that is emitted by the fruit tells us whether the fruit is ripe or not ❖ Evidence ➢ Primate shave been eating fruit for at least 24 million years ➢ Heritability for alcoholism The Hunting Hypothesis 8 ❖ “Man the hunter” ❖ Potentially responsible for evolution of human intelligence, language, tool making, etc. ❖ Evidence ➢ Humans consume far more meat than any other primate ➢ Difficult for humans to get all essential nutrients from an exclusive vegetarian diet ➢ Digestive system ➢ Fossil record of teeth ▪ Fossil record of teeth from our human ancestors five us a clue with what their diet was • There was heavy wear and tear that showed that diet was made from some vegetarian diet and a lot of meat which protected the enamel from breaking down. Exam Prep- How do we get a by-product? How does it relate to adaptations? Which theory is the best at explaining adaptation? ~Adaptation by natural selection is going to be the best of the theories we have to explain the emergence of adaptation. 9 Thursday, September 28, 2017 The Provisioning Hypothesis ❖ A prediction that humans and primates are going to invest significantly in their children, primarily the males ➢ Helps us explain how hunting evolved ➢ If a human or primate male is interested in taking care of their children, they need to do so in an economical way, meat is a very economical source of food, vegetables and fruits are not economical so survival would be difficult ▪ This makes us have males who are hunters ❖ Human males are unique among primates in parental investment in children ❖ Strong male coalition ➢ Males would go out in groups to hunting and if one was successful, the successful one will share his gains with the other hunters. ❖ Reciprocal altruism ➢ If we have one hunter who is successful and the other are not and the successful hunter shares his gains and if that successful hunter is not successful another time, the other hunters will share their gains with him ➢ What makes hunting important is that males and primates want to invest in provision for their children. ❖ Sexual division of labor ➢ Humans consume far more meat than any other primate ➢ Difficult for humans to get all essential nutrients from an exclusive vegetarian diet ➢ Digestive system The Show-Off Hypothesis ❖ Men hunt not to provide for own family, but to gain status benefits of sharing their bounty with neighbors ➢ Men hunted to show off their status ➢ Hunting helps men to gain status ▪ When they gain status, they are going to be more likely to survive 10 ➢ These males are willing to show others that they have a lot and they are willing to share with others because they have a lot ▪ And that in return is going to help them gain status ➢ Males could hunt to provide for their family and children but they also are show- offs so they could gain status The Gathering Hypothesis ❖ “Woman the gatherer” ❖ Potentially responsible for evolution of human intelligence, language, tool ma
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