Unit 3C Biological Bases of Behavior: Genetics, Evolutionary Psychology, and Behavior

Genes: Our Codes for Life Chromosome = threadlike structures made of DNA molecules that contain the genes. DNA (deoxyribonucleic acid) = a complex molecule containing the genetic information that makes up the chromosomes. Genes = the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing a protein. Active (expressed) vs. inactive Genome = the complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes.

Twin and Adoption Studies Identical Versus Fraternal Twins Identical twins = twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms. Fraternal twins = twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.

Twin and Adoption Studies Identical Versus Fraternal Twins The Jim Twins

Twin and Adoption Studies Thomas Bouchard: Jim Twins Separated Twins Studies Findings: Began study with the “Jim Twins” Since 1979 have studied over 130 sets of “separated twins” The twins were tested for mental skills, such as vocabulary, visual memory, arithmetic, and spatial rotation. They were given lung-function tests and heart exams and had their brain waves measured. They took personality tests and IQ tests and were quizzed about their sexual histories. Altogether, each twin was bombarded with more than 15,000 questions. Bouchard's team reached a controversial conclusion: For people raised in the same culture with the same opportunities, differences in IQ reflected largely differences in inheritance rather than in training or education When they compared identical twins raised in different families, like the Jim twins, with those raised in the same family, they found each pair's IQ scores to be similar. It was as if it didn't matter in which family the twins had been raised

Heritability Heritability = the proportion of variation among individuals that we can attribute to genes “difference among people” can be attributed to genes.

Gene-Environment Interaction Genes and experience interact Evocative interactions: Environment triggers gene activity A baby with a social predisposition raised in : family/isolation Genes EVOKE significant responses from our Environment

Who would be more likely to be a: Office Employee, Model, Insurance Sales, Actor, Selected for mating

Natural Selection and Adaptation Evolutionary psychology : the study of the evolution of behavior and the mind. Natural selection : traits that lead to increased reproduction and survival will be passed on. Mutation : a Random error in gene adaptation that leads to a change

Evolutionary Success Helps Explain Similarities Outdated Tendencies Genetic traits which helped our ancestors survive may harm us today Sweets and fats were once hard to come by and they helped prepare our ancestors to survive famines. Today this predisposition may be leading to an obese society.

Rate the following characteristics in terms of their importance to you in choosing a mate. Use the following scale: 3 = indispensable 2 = important but not indispensable 1 = desirable but not important 0 = irrelevant 1. ambition and industriousness 2. chastity (no previous experience in sexual intercourse) 3. dependable character 4. desire for home and children 5. education and intelligence 6. emotional stability and maturity 7. favorable social status or rating 8. good cook and housekeeper 9. good financial prospect

Rate the following characteristics in terms of their importance to you in choosing a mate. Use the following scale: 3 = indispensable 2 = important but not indispensable 1 = desirable but not important 0 = irrelevant 10. good health 11. good looks 12. mutual attraction—love 13. pleasing disposition 14. refinement, neatness 15. similar education 16. similar religious background 17. similar political background 18. sociability

3C–4 includes the 18 traits that have been used over several decades in research investigating mate preferences. David Buss reports outcomes for these items in a comprehensive study of 37 cultures. For the international samples: both sexes rated mutual attraction-love, dependable character, emotional stability and maturity, and pleasing disposition as most important and chastity, similar religious background, and similar political background as least important. In terms of sex differences:, Buss found good support for the evolutionary hypothesis that “good looks” and “chastity” are rated more important by males and that “good financial prospect” and “ambitious and industrious” are rated more important by females.

Studies suggesting men have a stronger tendency towards sex An Evolutionary Explanation of Human Sexuality Gender Differences in Sexuality Studies suggesting men have a stronger tendency towards sex Gender refers to the biologically and socially influenced characteristics by which people define male and female. One of the largest reported gender differences is women’s greater disapproval of and lesser willingness to engage in casual, uncommitted sex. In comparison to women, men think more about sex, are more likely to initiate sex, and make more sacrifices to gain sex.

Differing preferences in partners An Evolutionary Explanation of Human Sexuality Natural Selection and Mating Preferences Differing preferences in partners Evolutionary psychologists apply the principle of natural selection to explain women’s more relational and men’s more recreational approaches to sex. Compared with eggs, sperm are cheap. While a woman usually incubates and nurses one infant at a time, a man can spread his genes by impregnating other females. Women most often send their genes into the future by pairing wisely, men by pairing widely. Women increase their own and children’s chances of survival by searching for mates with economic resources and social status. Being attracted to healthy, fertile-appearing partners increases men’s chances of spreading their genes widely.

Critiquing the Evolutionary Perspective Backward theorizing Impact of social influence

Reflections on Nature and Nurture Nature and nurture jointly form us. That is, we are products of natural selection and heredity as well as cultural, family, and peer influences. But we are also open systems—that is, creators as well as creatures of our worlds. We respond to the world’s response to us, and the stream of causation runs through our present choices. Our hopes, goals, and expectations influence our future. Our decisions today design our environments tomorrow.

Respond to the following statements with a number from 1 = strongly disagree to 5 = strongly agree. 1. I will be able to achieve most of the goals that I have set for myself. 2. When facing difficult tasks, I am certain that I will accomplish them. 3. In general, I think that I can obtain outcomes that are important to me. 4. I believe I can succeed at most any endeavor to which I set my mind. 5. I will be able to successfully overcome many challenges. 6. I am confident that I can perform effectively on many different tasks. 7. Compared to other people, I can do most tasks very well. 8. Even when things are tough, I can perform quite well.

Research indicates that it is an important component of well-being. Selfefficacy: is our sense of being competent and effective in shaping our future. Research indicates that it is an important component of well-being. To score their scale, students simply add up the numbers they placed in response to the eight items. Scores can range from 8 to 40, with higher scores reflecting a greater sense of self-efficacy. higher scores are positively related to self-esteem. More generally, researchers have found that those with strong feelings of self-efficacy are: less anxious, less depressed, and more persistent. They have a higher need for achievement and are more conscientious. They also live healthier lives and perform better in school.