identical versus fraternal twins
Which is more important? What determines most of our behavior? Our genes? Or our environment?
Heredity versus the
NATURE VS. NURTURE
Universal people communicate both verbally and nonverbally enforce rules of etiquette
They avoid incest, fear snakes, and exchange gifts.
Universal people demonstrate modesty in sexual behavior and bodily functions, even if they don’t wear clothes.
Everywhere labor is divided by age and by gender. Men are more aggressive than women; women provide more child care.
Every culture has tools
Everywhere, people form beliefs about death and disease, they plan for the future.
All cultures have taboos, including tabooed utterances.
Sanctions exist for crimes against society, and mechanisms for dealing with theft, murder, and rape are universal.
People everywhere recognize marriage
They mimic, flirt, envy, empathize, joke, and tease
They dance and make music
GENES: OUR CODES FOR LIFE
BLUE EYES?
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
IDENTICAL VERSUS FRATERNAL TWINS
TWIN AND ADOPTION STUDIES
SEPARATED TWINS
U of MN studies on identical twins separated at birth- two Jims (hobbies, habits, dog’s name, son’s name)
Gerald Levey and Mark Newman, both:
Work as volunteer firefighters
Like the same beer (Budweiser)
Are attracted to the same kinds of women
Gerald worked in forestry, Mark worked for the city trimming trees (planned to go to school for forestry)
Both liked to hunt, fish, watch John
Wayne movies and eat Chinese food
Both grew the same sideburns and mustaches
Used the same speaking inflections and hand gestures
Can you find a twin in this class?
Anecdotal evidence
“Virtual twins”
TWIN AND ADOPTION STUDIES
BIOLOGICAL VERSUS ADOPTIVE
RELATIVES
Genetic relatives
Environmental relatives
Children in the same family
Are adopted children more like their biological parents or adoptive parents?
Well, it depends. Their personality traits (how outgoing they are, how friendly, their overall temperament) were much more similar to their biological parents.
Environmental factors have almost no impact on your personality
Do parents even matter?
Parents influence:
Attitudes (such as toward education)
Values
Manners
Faith
Politics
Less credit, less blame
HERITABILITY
“difference among people”
How much of the variation among people can be attributed to genes
IQ: .22 at age 5, .54 - . 62 at old age
Interests (art, science etc.) .36
Psychiatric illnesses:
Schizophrenia (.80), alcoholism
(.50 to .60)
Religiousness: .11 to .22
HERITABILITY OF VARIOUS TRAITS
HERITABILITY
GROUP DIFFERENCES
Heritable differences between individuals does not imply heritable group differences
HERITABILITY
NATURE AND NURTURE
Influence of adaptation
Nature and nurture work together
Genes are self-regulating
They react to the environment
GENE-ENVIRONMENT INTERACTION
Genes and experience
Evocative interactions
Mom likes you better!
NATURAL SELECTION AND ADAPTATION
Adaptation
Fitness
EVOLUTIONARY SUCCESS HELPS EXPLAIN
SIMILARITIES
Behaviors that contribute to survival are found throughout cultures
Why are children often afraid of the dark?
EVOLUTIONARY SUCCESS HELPS EXPLAIN
SIMILARITIES
OUTDATED TENDENCIES
Genetic traits which helped our ancestors survive may harm us today
EXPERIENCE AND FACULTIES
Repeated experiences modify neural tissue. We can change our brains! When is the brain’s plasticity highest?
• Pruning
BRAIN DEVELOPMENT AND
ADULTHOOD
Brain development does not stop when we reach adulthood. Throughout our life, brain tissue continues to grow and change.
A well-learned finger-tapping task leads to more motor cortical neurons (right) than baseline.
PEER INFLUENCE
In many ways, peers play a larger role than parents in shaping our behavior. What causes people to start smoking? Like a certain type of music? Wear certain clothes? Talk the way they talk?
AN EVOLUTIONARY EXPLANATION OF HUMAN
SEXUALITY
NATURAL SELECTION AND MATING
PREFERENCES
Differing preferences in partners
Male preferences
Female preferences
Men tend to look for:
Physical attractiveness and a youthful appearance
A man’s ideal women would look like…
Women tend to look for:
Maturity, dominance, status/affluence, and boldness
So a woman’s ideal man would look like…
Characteristics
Preferred by Males
1. Kindness and understanding
2. Intelligence
3. Physical attractiveness
4. Exciting personality
5. Good health
6. Adaptability
7. Creativity
8. Desire for children
9. College graduate
10. Good heredity
11. Good earning capacity
12. Good housekeeper
13. Religious orientation
Characteristics
Preferred by Females
1. Kindness and understanding
2. Intelligence
3. Exciting personality
4. Good health
5. Adaptability
6. Physical attractiveness
7. Creativity
8. Good earning capacity
9. College graduate
10. Desire for children
11. Good heredity
12. Good housekeeper
13. Religious orientation
CRITIQUING THE EVOLUTIONARY
PERSPECTIVE
Backward theorizing
Impact of social influence
CULTURAL INFLUENCES
Humans have the ability to evolve culture.
Culture is composed of behaviors, ideas, attitudes, values and traditions shared by a group .
VARIATION ACROSS CULTURE
Cultures differ. Each culture develops norms – rules for accepted and expected behavior . Men holding hands in Saudi Arabia is the norm (closer personal space ), but not in American culture.
VARIATION OVER TIME
Cultures change over time. The rate of this change may be extremely fast. In many
Western countries, culture has rapidly changed over the past 40 years or so.
This change cannot be attributed to changes in the human gene pool because genes evolve very slowly.
CULTURE AND THE SELF
If a culture nurtures an individual’s personal identity , it is said to be individualist, but if a group identity is favored then the culture is described as collectivist .
A collectivist support system can benefit groups who experience disasters such as the 2005 earthquake in
Pakistan.
GENDER DIFFERENCES IN
AGGRESSION
Men express themselves and behave in more aggressive ways than do women.
This aggression gender gap appears in many cultures and at various ages.
In males, the nature of this aggression is physical. In the U.S. the male to female arrest rate is 9 to 1. Men are more likely to support war as a solution to international problems
GENDER AND SOCIAL POWER
In most societies, men are socially dominant and are perceived as such.
In 2005, men accounted for 84% of the governing parliaments.
GENDER DIFFERENCES AND
CONNECTEDNESS
Young and old, women form more connections
(friendships) with people than do men.
Men emphasize freedom and self-reliance.
THE NEW FRONTIER: MOLECULAR
GENETICS
Molecular behavior genetics
Genetics and diseases
Genetics and ethics
THE END
DEFINITIO
N SLIDES
= the study of the relative power and limits of genetic and environmental influences on behavior.
BEHAVIOR GENETICS
= every non-genetic influence, from prenatal nutrition to the people and things around us.
ENVIRONMENT
= threadlike structures made of DNA molecules that contain the genes.
CHROMOSOMES
= a complex molecule containing the genetic information that makes up the chromosomes.
DNA (DEOXYRIBONUCLEIC
ACID)
= the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing a protein.
GENES
= the complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes.
GENOME
= twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.
IDENTICAL TWINS
= twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.
FRATERNAL TWINS
= the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.
HERITABILITY
= the interplay that occurs when the effect of one factor
(such as environment) depends on another factor
(such as heredity).
INTERACTION
= the subfield of biology that studies the molecular structure and function of genes.
MOLECULAR GENETICS
= the study of the evolution of behavior and the mind,using principles of natural selection.
EVOLUTIONARY PSYCHOLOGY
= the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations.
NATURAL SELECTION
= the random error in gene replication that leads to a change.
MUTATION
