LO #11: Examine one evolutionary explanation of behavior

Darwin’s Theory of Natural Selection Those members of a species who have characteristics which are better suited to the environment will be more likely to survive, breed and thus pass on these traits

Galapagos Islands Darwin observed that Finches on different islands had different types of beaks that were each suited to getting to the food available in their particular habitat He concluded that the process of natural selection over several generations resulted in adaptation which means the best beak was passed down until it was the only beak

Interesting Fact Darwin did not know how traits were passed down to the offspring through genes

Link from Animals to Humans In The Descent of Man (1871) Darwin noted that humans have a number of behaviors in common with other animals including mate selection love of mother for offspring self-preservation Darwin, thus, laid the foundation for psychologists to study animals as a way of gaining insight into human behavior.

Is this the result of evolution in humans?

Spatial Memory (Matsuzawa, 2007) AIM: to study spatial memory in chimpanzees and humans PROCEDURE: Chimps were taught to recognize numbers 1-9 on a computer monitor Later, chimps and humans were shown numbers flashed briefly on a computer screen in random sequence The numbers were then replaced with blank squares, and the participant had to remember which number appeared in which location and touch the square in the appropriate sequence

Findings Human participants made many errors while chimps showed remarkable memory for the spatial distribution of the numbers Psychologists argue that spatial memory in chimps has adapted over time so that they can find scarce food resources Humans don’t need this skill to survive, so this memory power might now be used by humans to develop language memory

Disgust Study (Fessler, 2006) AIM: To prove that pregnant women experience nausea because it helps them avoid potentially harmful food that their bodies could not fight off with a suppressed immune system. Fact: The immune system in pregnant women is suppressed so that the body won’t try to fight off the foreign genetic material in her womb

METHOD 496 pregnant women were given a survey to determine whether they were experiencing morning sickness They were then asked to consider 32 potentially stomach-turning scenarios (ex. maggots on a piece of meat, a fish hook stuck through a finger) and respond with levels of disgust

FINDINGS Only the disgusting scenarios involving food earned the highest ratings of disgust Women who were in the first trimester of pregnancy scored higher on the disgust scale Fessler concluded that natural selection produced the nausea response in pregnant women so they would avoid foods that were a higher risk for disease, especially during the first trimester when they were most susceptible

Internet Disgust Study (Curtis, 2004) AIM: To compare disgust responses to images of infectious or potentially harmful things to images of harmless things METHOD: 77,000 male and female participants from 165 different countries were shown computer images of harmful and harmless things. For each image they were asked to rank their level of disgust

FINDINGS The disgust reaction was the strongest for images that threatened the immune system Disgust reactions decreased with age Women were more disgusted than men This supports the idea that disgust is a key to successful reproduction and thus survival of the species

Limitations of Evolutionary Evidence Confirmation bias is possible where the research see what they expect to see This is true because some theories are difficult to test empirically We don’t really know what the behavior of early Homo Sapiens was The evidence often underestimates the role of cultural influences

LO #12: Discuss Ethical Considerations in research into genetic influences on behavior Participants should be informed of the aim, procedures, and any potential harm (including implications/predispositions for unwanted condition) and give their consent. This must be done in plain language Right to withdraw

Ethical Considerations (cont.) Confidentiality and privacy should be protected Participants must be informed what will happen to any genetic information obtained as part of the study Reason: Genetic info can be misused by stigmatizing participants, affecting their ability to get jobs, insurance. It can even affect their legal rights.

Ethical Considerations (cont.) Confidentiality can be protected with coding information or anonymizing the sample (this means even researchers cannot link results to individual people) Unfortunately, this limits the scientific results

Ethical Considerations (cont.) Genetic research can reveal unexpected information that may harm participants Some examples are misattributed paternity, adoption, carrier of a genetic disorder Counseling should be available for former participants

Ethical Considerations (cont.) Religious and cultural issues Cultural objections (genetic research incongruent with culture)

Ethical Considerations (cont.) Political misuse of research findings are used to marginalize a group in society (eg. eugenics)