1. UNIT 3C
BIOLOGICAL BASES OF BEHAVIOR: GENETICS, EVOLUTIONARY PSYCHOLOGY AND BEHAVIOR

2. UNIT OVERVIEW Behavior Genetics: Predicting Individual Differences
Evolutionary Psychology: Understanding Human Nature
Reflections on Nature and Nurture

3. BEHAVIOR GENETICS: PREDICTING INDIVUAL DIFFERENCES

4. Biological Psychology
Nervous System
Central Nervous System
Brain
Brain Imaging
Peripheral Nervous System
Building Blocks
Genetics
Evolutionary
Endocrine System
Neurotransmitters
Somatic
Autonomic
Sympathetic
Parasympathetic
Biological Psychology
Spinal Cord
Neurons
Sensory
Motor
We are here

5. INTRODUCTION Behavior genetics Heredity versus the environment
We as humans have identical mechanisms—hunger pains, senses, language development, fearing strangers by 8 months, prefer people who have similar interests to us
How are we different?
Our genes (nature) and our environment (nurture) define us

6. BEHAVIOR GENETICS: Predicting Individual Differences
Behavior Geneticists study our differences and weigh the relative effects of heredity and environment or
NATURE vs. NURTURE
OBJECTIVE 2| Describe the type of questions that interest behavior geneticists.
What are genes, and how do behavior geneticists explain our individual differences?
Behavior geneticists study our differences and weigh the effect and interplay of heredity and our environment (every non-genetic influence, from pre-natal nutrition to the people and things around us)

7. GENES: OUR CODES FOR LIFE
Chromosomes containing DNA (deoxyribonucleic acid) are situated in the nucleus of a cell.
OBJECTIVE 3| Define chromosome, DNA, gene, and genome, and describe their relationships.
Chromosomes=chapters///Genes=words

8. GENES: OUR CODES FOR LIFE
Segments within DNA consist of genes that make proteins to determine our development.
Genes:
46 chromosomes (threadlike structures made of DNA (deoxyribonucleic acid) molecules that contain the genes)
23 are from mom (egg)
23 are from dad (sperm)
Genes (small segments of the giant DNA molecules)—30,000 in your body
Active (expressed/provides the building blocks for physical development
Inactive
**Most of our traits are influenced by our genes (height, intelligence, happiness, aggressiveness)

9. GENOME
Genome is the set of complete instructions for making an organism, containing all the genes in that organism. Thus, the human genome makes us human, and the genome for drosophila makes it a common house fly.
Human genome researchers have discovered the common sequence within human DNA (shared genetic profile)
We share about 96% of the chimpanzee DNA sequence too!
But have different behaviors (Chimpanzees are more aggressive & male dominated)
**Stop to show that many traits and behaviors are inherited:
Have students draw a horizontal line on a sheet of paper.  When the tip of their ring finger is placed on the line, does the tip of the forefinger also reach the line?  (Research indicates that short forefingers are determined by a recessive trait in females, whereas in males, it is dominant.
When interlocking your fingers, do you place your left or right thumb on top? (Particular characteristics are genetically controlled.  Practice or experience has no effect)

10. GENES 101
Dominant Gene – Member of a gene pair that controls the appearance of a certain trait.
Recessive Gene - Member of a gene pair that controls the appearance of a certain trait only if it is with another recessive gene.

11. GENES 101 CON’T
Polygenic Inheritance – Process by which several genes interact to produce a certain trait; responsible for our most important traits.

12. TWIN BIOLOGY
Studying the effects of heredity and environment on two sets of twins, identical and fraternal, has come in handy.
OBJECTIVE 4| Explain how identical and fraternal twins differ, and ways that behavior geneticists use twin studies to understand the effects of environment.

13. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

14. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

15. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

16. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

17. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

18. TWIN AND ADOPTION STUDIES: IDENTICAL VERSUS FRATERNAL TWINS

19. MZ vs. DZ TWINS
The odds of having identical twins is about 3 in 1,000, whereas the birthrate for all twins is about 32.2 in 1,000.
Most (60–70%) monozygotic twins share the same placenta but have separate amniotic sacs.
A small number (1-2%) of monozygotic twins share the same placenta and amniotic sac.
Fraternal twins each have their own placenta and own amniotic sac.

20. Personality, Intelligence
SEPARATED TWINS
A number of studies compared identical twins raised separately from birth, or close thereafter, and found numerous similarities.
Separated Twins
Personality, Intelligence
Abilities, Attitudes
Interests, Fears
Brain Waves, Heart Rate

21. TWIN AND ADOPTION STUIDES: SEPARATED TWINS
University of Minnesota studies on identical twins separated at birth
Separated Twins
Jim Lewis & Jim Springer—born from the same woman, adopted by two different families after being born.  Reconnected after 38 years. Psychologists performed personality, intelligence, heart waves and brain waves testing.  They were virtually as alike as the same person being tested twice.
After 80 pairs of identical twins raised apart were studied, the researchers continued to find similarities with tastes, physical attributes, personality, abilities, attitudes, interests and even fears.
Compared to fraternal twins, identical separated twins are more alike genetically.
**Often times relative strangers can share many things in common→ if we were to do a scavenger hunt of similarities like birthdays, shoe sizes, clothing sizes, favorite food, favorite movie, height, weight, etc… many would have more similarities than differences (if people grow up in similar environments, they will value and have similar stages of development)

22. JIM LEWIS Ohio, Middle Class First wife – Linda, second wife – Betty
Left wife love notes throughout house
Sons named James Alan
Dog named Toy
Woodworking hobby
Circular white bench around a tree in his yard.
Chain smoked Salem cigarettes
Bit his fingernails
Drove a light blue Chevy, watched stock car racing, and drank Miller-Lite
Suffered from high blood pressure and migraine headaches

23. THE JIM TWINS
Jim Lewis calls his 37 year separated twin in February 1980
Everything down to the dog’s name is the same (except sons James Allan vs. James Alan)
When played their voices, they would mistake themselves for their twin
They are the first in Thomas Bouchard’s twin study
Studied 80 pairs of identical twins reared apart
Jim Lewis & Jim Springer—born from the same woman, adopted by two different families after being born.  Reconnected after 38 years. Psychologists performed personality, intelligence, heart waves and brain waves testing.  They were virtually as alike as the same person being tested twice.
After 80 pairs of identical twins raised apart were studied, the researchers continued to find similarities with tastes, physical attributes, personality, abilities, attitudes, interests and even fears.

24. ADOPTION STUDIES
Adoption studies, as opposed to twin studies, suggest that adoptees (who are biologically unrelated) tend to be more different from their adoptive parents and siblings than their biological parents.
OBJECTIVE 5| Cite ways that behavior geneticists use adoption studies to understand the effects of environment and heredity.

25. WHERE IS THE ENVIRONMENT?
Adoptees bear more resemblance in their outgoingness and agreeableness to their biological parents then to their adopted parents
Two adopted children in the same home bear no more resemblance to each other than kids from two separate families.

26. ADOPTIVE STUDIES
Adoptive studies strongly point to the simple fact that biologically related children turn out to be different in a family.
So investigators ask:
Why are children in the same family so different?
Do siblings have VASTLY differing experiences?
Do siblings, despite sharing half of their genes, have different combinations of the other half of their genes?
Ultimate question: Does parenting have an effect?

27. Parenting Influences children’s
Parenting does have an effect on biologically related and unrelated children.
Parenting Influences children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics
“Mom may be holding a full house while Dad has a straight flush, yet when junior gets a random half of each of their cards his poker hand may be a loser.” David Lykken (2001)

28. TWIN AND ADOPTION STUIDES: BIOLOGICAL VERSUS ADOPTIVE RELATIVES
Genetic relatives
Environmental relatives
Genetic relatives (biological parents and siblings)
Environmental relatives (adoptive parents and siblings)
Adoptees (those who are adopted) are more similar to their biological parents than to their caregiving adoptive parents
The environment shared by a family’s children has virtually no significant impact on their personalities
But, parents do influence their children’s attitudes, values, manners, faith and politics (parenting matters!)
7/8 adopted children feel strongly attached to one or both adoptive parents; tend to grow up to be more  self-giving and altruistic
Children do benefit from adoption overall

29. HERITABILITY Heritability “differences among people”
Temperament = A person’s characteristic emotional reactivity and intensity
Heredity predisposes temperament differences
Identical twins have more similar personalities (including temperament) than to do fraternal twins
Ex-physiological tests reveal that anxious, inhibited infants have high and variable heart rates and a reactive nervous system, and that they become more physiologically aroused when facing new or strange situations.
Biologically rooted temperament helps form our enduring personalities
What is heritability and how does it relate to individuals and groups?
Heritability
Herit (similar to inherit—possess something that someone else has given you.  We inherit our traits and qualities from our parents
Ability (capable)—If a trait is genetically passed on from one generation to the next, then it is capable of showing up in the children of people who possess that quality.
A heritable trait is one that is capable of being passed down from parent to child
Heritability refers to the extent to which differences among people are attributable to genes (ex=height)
Just because a trait is heritable does not mean it will affect an individual or that it will be a defining trait of a group.  Heritability only demonstrates the extent to which a trait is explainable by genetics, but not the extent to which the trait will affect behavior in an individual or group outside of environmental influences (ex-raised in a wealthy home vs. a poor home)

30. HERITABILITY
Heritability refers to the extent to which the differences among people are attributable to genes.
What percentage of the difference among people’s height can be attributed to their genes?
OBJECTIVE 7| Explain heritablity’s application on individuals and groups, and explain what we mean when we say genes are self-regulating.
90%

31. HERITABILITY: NATURE AND NURTURE
Influence of adaptation
Nature and nurture work together
Genes (nature) and our environment (nurture) work together like two hands clapping.  Genes not only code for particular proteins, they also respond to environments.
Genes are self-regulating—genes react to different temperatures (cold in cold weather, hot in hot weather)
Human differences result from BOTH genetic and environmental influences
Gene-Environment Interaction
Genes and environment interact (occurs when the effect of one factor (environment) depends on another factor (heredity/genes)
Genetically influenced traits also evoke significant responses in others
EX: A student’s impulsivity and aggression may evoke an angry response from a teacher who otherwise reacts warmly to the student’s model classmates; parents may treat one child harsher than another (the child’s nature—genes and the parents nurture interact)
Our genes affect how people react to and influence us (nature via nurture)

32. GENE-ENVIRONMENT INTERACTION
Genes can influence traits which affect responses, and environment can affect gene activity.
A genetic predisposition that makes a child restless and hyperactive evokes an angry response from his parents. A stressful environment can trigger genes to manufacture neurotransmitters leading to depression.
OBJECTIVE 8| Give and example of a genetically influenced trait that can evoke responses in others, and give another example of an environment that can trigger gene activity.

33. GENE-ENVIRONMENT INTERACTION
Genes and environment affect our traits individually, but more important are their interactive effects.
Rex Features
People respond differently to
Rowan Atkinson (Mr. Bean) than Orlando bloom.

34. NOT NATURE vs. NURTURE
Gene-Environment Interaction is Nature AND Nurture

35. EVOLUTIONARY PSYCHOLOGY: UNDERSTANDING HUMAN NATURE

36. Biological Psychology
Nervous System
Central Nervous System
Brain
Brain Imaging
Peripheral Nervous System
Building Blocks
Genetics
Evolutionary
Endocrine System
Neurotransmitters
Somatic
Autonomic
Sympathetic
Parasympathetic
Biological Psychology
Spinal Cord
Neurons
Sensory
Motor
We are here

37. NATURAL SELECTION AND ADAPTATION
Evolutionary psychology
Natural selection
Mutation
Adaptation
Fitness
How do evolutionary psychologists use natural selection to explain behavior tendencies?
Evolutionary psychologists study the evolution of behavior and the mind using principles of natural selection.
Natural selection = those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.
For example: Dmitry Belyaev & Lyudmila Trut (Russian psychologists) able to transform 45,000 wild foxes into friendly foxes in 40 years
When certain traits are selected—by conferring a reproductive advantage to an individual or species, those traits, over time, will prevail
Our genes give us a great capacity to learn and therefore adapt to life in varied environments.
Genes + experience = wires the brain
**Evolutionary psychology = how genetics and environment interact, leading to changes in genetics to fit the environment.  It is also about how traits that lead to survival are more likely to be passed down.

38. EVOLUTIONARY PSYCHOLOGY
According to evolutionary psychologists, all organisms, including humans, are "gene-producing machines" with the basic motivation of perpetuating their own genetic pool. In short, our genes predispose us to act in ways that enhance their chances of surviving and spreading. This fundamental motive underlies all our behavior.
**Evolutionary psychology = how genetics and environment interact, leading to changes in genetics to fit the environment.  It is also about how traits that lead to survival are more likely to be passed down.

39. Thus their genes are more likely to get passed along.
NATURAL SELECTION
Natural selection is an evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help animals survive and reproduce.
According to natural selection, those organisms that are best adapted to their environment are most likely to survive and reproduce.
Thus their genes are more likely to get passed along.
OBJECTIVE 11| State the principle of natural selection, and point out some possible effects of natural selection in the development of human characteristics.
Evolutionary psychologists study the evolution of behavior and the mind using principles of natural selection.
Natural selection = those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.
For example: Dmitry Belyaev & Lyudmila Trut (Russian psychologists) able to transform 45,000 wild foxes into friendly foxes in 40 years
When certain traits are selected—by conferring a reproductive advantage to an individual or species, those traits, over time, will prevail
Our genes give us a great capacity to learn and therefore adapt to life in varied environments.
Genes + experience = wires the brain

40. EVOLUTIONARY PSYCHOLOGY
Study the origins of behavior and mental processes emphasizing the adaptive or survival value of such traits
Behavioral Genetics attempts to explain differences in populations and attribute how much of that is due to genes
Evolutionary Psychology attempts to explain common behavior BY LOOKING AT WHAT WAS HELPFUL TO SURVIVAL OF THE SPECIES

41. HUMAN TRAITS
A number of human traits have been identified as a result of pressures afforded by natural selection.
Stranger Anxiety:
Why do infants fear strangers when they become mobile?
Parental Love
Why are most parents so passionately devoted to their children?
Phobias
Why do people fear spiders and snakes?

42. EVOLUTIONARY SUCCESS HELPS EXPLAIN SIMILARITIES: OUTDATED TENDENCIES
Genetic traits which helped our ancestors survive may harm us today
A number of human traits have been identified as a result of pressures afforded by natural selection.
Why do infants fear strangers when they become mobile?
Why do people fear spiders and snakes and not electricity and guns?
How are men and women alike? How and why do men’s and women’s sexuality differ?

43. EVOLUTIONARY SUCCESS HELPS EXPLAIN SIMILARITIES
Behaviors that contribute to survival are found throughout cultures
Our emotions, drives and reasoning have a “common logic across cultures”—we have a shared human genome (95% of genetic variation exists within the population)
Ask—why do you eat what you eat? Can the evolutionary perspective explain your eating habits (overeaters/dieters in your family; Latino food vs. Asian food—genetic/environment)

44. LANGUAGE
(Pinker 1994,1997,2002)
All children acquire language without specific instruction
This happens in all cultures at about the same age and in the same stages
The nature of all human languages is the same (nouns, verbs, subjects, questions etc.)
Conclusion: Our brains are hardwired for language. Even identified a gene found only in humans believed to be linked to this.

45. AN EVOLUTIONARY EXPLANATION OF HUMAN SEXUALITY: NATURAL SELECTION AND MATING PREFERENCES
Differing preferences in partners
Male preferences
Female preferences
How might an evolutionary psychologist explain gender differences in sexuality and mating preferences?
Attractiveness
Men judge women as more attractive if they have a youthful appearance, healthy skin, youthful shape
Older men prefer younger women (Hugh Hefner-Playboy bunnies)
Women prefer stick-around dads
Mature, dominant, bold, affluent for long-term mating and investment in their children
**Nature selects behaviors that increase the likelihood of sending one’s genes into the future.

46. CROSS CULTURAL SURVEYS
In a survey of 37 cultures involving more than 10,000 participants, Buss (1989) tested predictions concerning sex differences in mate preferences.
Participants were asked to rate the importance of each of 18 characteristics in a potential mate using a 4-point scale.
'good companion', 'considerate', 'honest', 'affectionate', 'dependable‘. 'fond of children', ‘good earning capacity', ‘industrious' , ‘intelligent’, ‘good sense of humour’ 'physically attractive', 'good looking', 'good cook', and 'frugal'.

47. FEMALES PREFERRED: good financial prospects industriousness
This was mirrored in marriage records in 27 countries, as women consistently married men several years older than themselves.

48. MALES PREFERRED: physical attractiveness youth Chastity
In every culture males preferred females who were younger than them while females preferred males who were slightly older.
Chastity

49. Sprecher et al., (1994).
They measured mate preferences in 13,000 single adults.
Respondents considered 12 possible assets or liabilities in a potential marriage partner using a 7-point scale and indicated their willingness to marry someone possessing such traits.
As in previous studies they found that women were more willing to marry someone who was slightly older than themselves, who was employed, who earned more, and who was better educated, good looks were not high on their list.
Males showed the opposite pattern (i.e. someone younger, attractive, not necessarily employed or intelligent).

50. 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
How might an evolutionary psychologist explain gender differences in sexuality and mating preferences?
Men are more prone to think about sex, initiate sex, sacrifice more to gain sex, desires more frequent sex
Men have a lower threshold for perceiving warm responses as a sexual come-on (more friendly=more sexier)
Women approach sex more relational; men approach sex more recreational
Women send their genes into the future by pairing wisely, men by pairing widely

51. SIGH… Russell Clark and Elaine Hatfield (1978)
“I have been noticing you around campus and I find you to be very attractive. Would you go to bed with me tonight?
Russell Clark and Elaine Hatfield (1978)
Average-looking student research assistants
Women = 0%
Men = 75%
Some men replied “Why do we have to wait until tonight?”
Repeated in 1982 and in the late 1980s with the same results. (50-75% of the men said yes.)

52. Buss & Schmidt, Psychological Review , 100, 204-232, 1993

53. Gender Differences in Sexuality
HUMAN SEXUALITY
Gender Differences in Sexuality
Males and females, to a large extent, behave and think similarly. Differences in sexes arise in regards to reproductive behaviors.
Due to the reproductive reality, it would seem most adaptive for women to find a mate that gives the best genes, resources, and long-term parental care.
Males can pass on as many genes as they can find willing partners.
OBJECTIVE 12| Identify gender differences in sexuality.

54. WHAT DO WOMEN WANT? Healthy looking men Affluent Mature Dominant Bold
(Singh 1995)
Healthy looking men
Affluent
Mature
Dominant
Bold
Offer long-term mating and investment (Gangestad and Simpson 2000)
OBJECTIVE 13| Describe evolutionary explanations for gender differences in sexuality.

55. EXPLANATION OF PARTNER SELECTION IN WOMEN
Females have evolved mechanisms that enable them to detect men that will transfer resources to their offspring (i.e. health and paternal investment ).
These are sometimes referred to as 'good provider' and 'good genes' attributes in the male
OBJECTIVE 13| Describe evolutionary explanations for gender differences in sexuality.

56. WHAT DO GUYS WANT?
A waist to hip ratio (WHR) of about 0.7 (the hour glass figure)
Full lips and small noses
Youthfulness
These features are associated with a strong immune system, high estrogen level, and developmental stability
OBJECTIVE 13| Describe evolutionary explanations for gender differences in sexuality.

57. EXPLANATION OF PARTNER SELECTION IN MEN
Males have evolved mechanisms that enable them to detect females that promise rapid production of offspring, and a disinclination to mate with other men (i.e. health, fertility and faithfulness )
OBJECTIVE 13| Describe evolutionary explanations for gender differences in sexuality.

58. CRITIQUING THE EVOLUTIONARY PERSPECTIVE
Backward theorizing
Impact of social influence
Critiquing the Evolutionary Perspective
What are the key criticisms of evolutionary psychology?

59. REFLECTIONS ON NATURE AND NURTURE