IB syllabus says: Genetics & Behavior Key principle demonstrated: patterns of behavior can be inherited

Mini presentations groups: Remember to ask some questions at the end Group 1: Intro to evolutionary psychology (include a video clip) Group 2: Fessler’s study Group 3: Curtis study Group 4: Evaluative points/ LAQ essay plan

Evolutionary Psychology Evolutionary Psychology is grounded in the principle that over time, genes that are advantageous are passed down through natural selection. (the most genes that benefit survival most are passed on to the next generation) This is based on Darwin’s (1959) Theory of Evolution outlined in his book The origin of the species Evolutionary psychologists attempt to explain how certain human behaviors have evolved over time. It is important to note that natural selection cannot select for behavior, it can only select for mechanisms that produce behavior

Studying the ultimate causes of behaviour Evolutionary Psychology looks at the Ultimate Causes of behaviour This requires the understanding of a traits of people our original (i.e. ancestral) environment. ( this is called the ‘The Environment of Evolutionary Adaptiveness’ - EEA 1.5 to 2.5 million years ago ) Understanding ultimate causes of behaviour is important. Evolutionary psychology seeks to explain behavior in terms of its ultimate causes Activity: watch the born to survive video 15 mins in

An evolutionary explanation of behavior: Disgust One example of evolutionary research is the study of emotions such as disgust. Fessler (2006) carried out research on disgust. He argues that the emotion of disgust allowed our ancestors to survive long enough to produce offspring, who in turn passed on the same sensitivities to us.

Fessler (2006) investigated nausea/sickness experienced by women in their first trimester of pregnancy. During that period, an infusion of hormones lowers the expectant mothers immune system so as not to fight the new foreign genetic material in her womb. Fessler hypothesized that the nausea response helps to compensate for the suppressed immune system. He carried out research to test his theory: An evolutionary explanation of behavior: Disgust

Fessler’s (2006) study of an evolutionary basis for disgust in pregnant women Aim: To investigate whether the ‘morning sickness’ experienced by pregnant women has an evolutionary basis. Procedure: A sample of 496 healthy pregnant women aged between 18 and 50 years old was used. The women were asked to consider stomach churning scenarios such as: -Walking barefoot and stepping on an earthworm -Someone accidently sticking a fishhook through their finger -Maggots on a piece of meat in a outdoor trashcan Before asking the women to rank how disgusting they found the scenarios (using a survey), Fessler posed a series of questions, designed to determine whether they were experiencing morning sickness. For those in the first trimester, they found the scenarios involving food most disgusting.

Fessler’s (2006) study of an evolutionary basis for disgust in pregnant women Findings & Conclusions: In keeping with Fessler’s theory, women in the first trimester of their pregnancy scored much higher on scores across the board on disgust sensitivity than their counterparts in the second and third trimester. According to Fessler, many diseases that are most dangerous are food borne, but our ancestors could not afford to be picky about what they ate all the time. Natural selection may have helped compensate for the increased susceptibility to disease during this risky period in pregnancy, by increasing the urge to be picky about food. That sensitivity seems to diminish as the risk of disease and infection decreases – this is consistent with the view that disgust is a protection against disease. Evaluation: MECG?

Curtis et al. (2004) Internet survey on disgust responses Aim: Curtis et al. (2004) aimed to carry out research on the Internet to test whether there were patterns in people’s disgust responses. Procedure: They used an online survey in which participants were shown 20 images. For each image, they were asked to rank their level of disgust. Among the 20 images were seven pairs in which one was infectious or potentially harmful to the immune system, and the other was visually similar but non-infectious—for example, one pair was a plate of bodily fluids and a plate of blue viscous liquid. There were participants from 165 countries.

Findings & Conclusions The findings confirmed that the disgust reaction was most strongly elicited for those images which threaten one’s immune system. Interestingly, the disgust reaction also decreased with age. As the graph below shows, disgust reactions were higher in young people than in older people. In addition, women had higher disgust reactions than men. Once again, this supports the idea of disgust as a key to successful reproduction. Curtis et al. (2004) Internet survey on disgust patterns

The original survey can be found at veys/disgust veys/disgust

In spite of such evidence, there are some things to consider when examining an evolutionary argument. Since it may be difficult to test empirically some evolution- based theories, researchers may be susceptible to confirmation bias— that is, they see what they expect to see. Little is known about the behaviour of early Homo sapiens, so statements about how humans used to be are hypothetical. Evolutionary arguments often underestimate the role of cultural/nurture/the present environmental influences in shaping behavior. Evaluative points for evolutionary theory

The theories are speculative – its difficult to carry out experiments to clearly prove the theories The researcher Hayes (2005) states that there is a tendency to ignore findings that don’t fit in with the theory – confirmation bias Evolutionary explanations have also been criticised as being too concerned with passed events (the EEA – 1.5 and 2.5 million years ago ) – the world is very different now – our environment has changed a lot. But evolutionary psychologists use the concept of ‘genome lag’ to explain why such behaviours still exist today. Stephen Rose (2005) he thinks that evolutionary psychology gives a ‘Flintstone’ view of mankind The approach is known as Genetic Determinism – Focus on present also useful method of explanation. It can also be seen as Genetic Reductionism also. Evaluative points for evolutionary theory

Possible LAQ exam question: Discuss the extent to which genetic inheritance influences behavior with reference to relevant research studies. This question uses the command term “discuss” which means that you should present a balanced view that includes a number of arguments that address the way in which genetic factors influence behavior. You should present evidence from research and you should arrive at a conclusion based on the arguments presented.

LAQ Essay Plan Intro – This paper will discuss one evolutionary explanation of behavior focusing on the emotion of disgust – Natural Selection: the most genes that benefit survival most are passed on to the next generation (based on Darwin’s Theory of Evolution) – General Evolutionary Psychology, Fessler’s study, and Curtis’ study – Thesis: although there are several limitations to the research into the effects of evolution on behavior, the research does show a clear link between inherited genes and behavior. 1 st – General Evolutionary Psychology Theoretical Background – Darwin’s Theory of Evolution – Natural Selection

2 nd – Fessler’s study – Give the aims, procedures, findings & conclusions, and evaluation – Connect back to the question 3 rd – Curtis’ study – Give the aims, procedures, findings & conclusions, and evaluation – Connect back to the question 4 th – General Evaluative Points for evolutionary theory Conclusion