2.2 TO WHAT EXTENT DOES GENETICS INFLUENCE BEHAVIOR? Back up your response with research BEHAVIORAL GENETICS Behavioral genetics deals with the understanding of how both genetics and the environment contribute to individual variations in human behavior. Is a single gene responsible for complex behaviors? NO, behaviors is brought about through a series of building blocks (genes) DIATHESIS STRESS MODEL Diathesis stress model argues that depression may be the result of the interactions of a “genetic vulnerability” and traumatic environmental stimuli in early childhood. BUT…..do all siblings raised in the same environment develop depression …..? There is no single cause and effect relationship between genes and behavior. GENETIC RESEARCH GENETIC RESERCH Method of Study: Correlation How different variable may co-vary No manipulation of the variables, thus no cause and effect can be established. TWIN STUDIES, FAMILY STUDIES & ADOPTION STUDIES Twin Studies Monozygotic (100%) vs dizygotic (50%) The higher the genetic relationship, the more similar the individuals should be in the trait being inherited. Concordance rate = correlation found in twin studies. Family Studies More representative of the population Adoption Studies Allow the comparison of biological and environmental influences Not representative of the population Criticized for selected placement INTELLIGENCE (REFERENCE PG 54) Is intelligence inherited or is it the result of the environment? What is intelligence? How can it be measured? BE A THINKER: ON THE INTERNET YOU WILL FIND FREE IQ TEST. GO ONLINE AND TAKE AT LEAST THREE DIFFERENT TESTS. EACH TEST SHOULD GIVE YOU A SCORE. 1. 2. 3. Do you think that these tests appropriately evaluate your intelligence? Do you feel that the tests were adequate? Why or why not? How would you change the tests to make them reflect more accurately what you consider to be your intelligence? RESEARCH IN INTELLIGENCE Meta-analysis: the statistical synthesis of the data from a set of comparable studies of a problem that yields a quantitative summary of a pooled result. Example: Bouchard and McGue (1981) reviewed 111 studies of IQ correlation between siblings from research on intelligence from around the world. Results: the closer the kinship the higher the correlation for IQ. BOUCHARD (1990) MINNESOTA TWIN STUDY IS A longitudinal study (1979) of MZ raised apart vs MZ raised together. 70% IQ attributed to genetic inheritance 30% IQ to other factors Criticism of the study: Self selected sampling. Bouchard relied on the media to recruit participants Ethical concerns about reuniting the twins No adequate control to establish frequency of contact between twins prior to study. Cannot assume twins raised in same environment received identical treatment. SCARR & WEINBERG (1977) AND HORN ET AL., (1979) ADOPTION STUDIES Adoptive children and natural biological children raised by the one biological parent should demonstrate no difference in IQ if environment is the contributing factor in intelligence. Researchers found no significant difference in IQ correlations Adoptive parents were wealthy, white, middle class, high IQ Adopted children were from poor, lower class background, with lower IQ parents. WAHLSTEN 1997 Transferring an infant from a low-socio-economic status to a home where parents have a higher socioeconomic status improved IQ by 12-16 points. Enriched environment? CONCLUDING THOUGHT ON INTELLIGENCE Is intelligence based on knowledge or the ability to problem solve? Hainer et al. (1988) “Less Effort Hypothesis” When problem solving (reasoning) individuals with high IQ had lower metabolic rates than those with low IQ Plomin and Petrill (1977) Socio-economic class appears to be an important environmental factor in developing intelligence. “Poverty - not genetic inferiority – is key to understanding the differences in intelligence.” CONCLUDING THOUGHT ON INTELLIGENCE CONT., The Flynn Effect The rise in average scores of IQ tests in most parts of the world over the last century. Neisser, 1997 documented : The average score increase by 3 points every 10 years Cause is unknown Is it an increase in intelligence? Is it the ability to manipulate the test taking process? Does better nutrition , improved education, added technology add to the effect? What effect does the highly visual environment have ? SOCRATIC SEMINAR : THE NATURE OF INTELLIGENCE IB Question: To what extent does genetic inheritance influence behavior? THE SEMINAR WILL FOCUS ON 3 QUESTIONS 1. 2. 3. How do we define intelligence – and why does it matter? To what extent is intelligence biological? (what are the strengths and limitations of a purely biological argument?) Can intelligence change over time? What are the implications for schools if we find that intelligence has a biological basis and cannot be changed? You will use the information gathered to create a graphic organizer to answer the question: To what extent does genetic inheritance influence behavior? 2.2 WHAT ROLE DOES EVOLUTION HAVE IN BEHAVIOR? DARWIN,(1871) “THE DESCENT OF MAN” Humans have a number of behaviors in common with animals. Mate selection Love of mother to offspring Self-deprivation Facial expressions humans share with primates. Humans share many of the same feelings as animals EVOLUTION AND SPATIAL MEMORY TETSURO MATSUZAWA (2007) Do chimps have better spatial memory than humans? Read study EVOLUTIONARY PSYCHOLOGY As genes mutate, those that are advantageous are passed down through natural selection. Evolutionary Psychologist attempt to explain how certain human behaviors explain the development of our species over time. Natural selection does not select the behavior – it only selects the mechanisms that produces the behavior. Fessler (2006) – evolution of disgust. (pg. 58) Curtis et al., (2004) EXAMINING THE EVOLUTIONARY ARGUMENT – THINGS TO CONSIDER Difficult to prove empirically susceptible to conformational bias - they see what they expect. Little is known about behavior of early Homo sapiens Cultural differences are often overlooked as a role in evolutionary differences. ETHICAL CONSIDERATIONS IN RESEARCH INTO GENETIC INFLUENCES OF BEHAVIOR How will the participants privacy be protected? What will happen to any of the genetic material obtained from the study? Informed, written consent must be given, with the full understanding of the aim of the research. Confidentiality and full anonymity Protect from insurance co., employers, police military etc. What do you do if the results show information that can harm the participant? Misidentified paternity, adoption, genetic disorders.