2. +
Nature vs. Nurture?
Why is the nature-
nurture question so
fascinating?
ď§ Controversial
ď§ Fascinating
ď§ Consequential
Michael Jordan provides a clear
example of the interplay between
natural and nurtured talent.
3. +
Animal vs. Human Studies
Other Reasons for Our
Fascination
ď§ Ease of animal study
o History of mating
experiments
o Fast replication
ď§ Obstacles to human
study
o Random
assignment
impossible
o Unethical:
eugenics
Could nonaggressive parents have
taught this dog to be less aggressive?
9. Genetic Foundations of Development
Human Genome Project
⢠Has worked to map the human genomeâthe complete
set of developmental instructions for creating proteins
that initiate the human organism
⢠Genes collaborate with each other and with nongenetic
factors in and outside of body
⢠Whether genes are turned âonâ or âoffâ is affected by both
internal and external events
⢠For example: stress; exercise
14. Genetic Foundations of
Development: Genetic Principles
Dominant-recessive genes
⢠Dominant gene overrides expression of the recessive
gene
⢠Recessive gene exerts its influence only if both genes in
the pair are recessive
Sex-linked genes
⢠X-linked inheritance results when a mutated gene is
carried on the X chromosome
⢠Females are carriers, while males may exhibit an
X-linked disease
15.
16. Genetic Foundations of
Development: Genetic Principles
Genetic imprinting
⢠Occurs when genes have differing effects depending on
whether they are inherited from the mother or the father
⢠Chemical process âsilencesâ one member of the gene pair
Polygenetic inheritance
⢠Most human characteristics are determined by the interaction
of several genes
⢠Gene-gene interaction: the interdependence of two or more
genes in influencing characteristics, behavior, diseases, and
development
17. Figure 6 Some Chromosomal
Abnormalities
Name Description Treatment Incidence
Down
syndrome
An extra chromosome causes
mild to severe intellectual
disability and physical
abnormalities.
Surgery, early
intervention, infant
stimulation, and special
learning programs
1 in 1,900 births at age
20
1 in 300 births at age 35
1 in 30 births at age 45
Klinefelter
syndrome
(XXY)
An extra X chromosome causes
physical abnormalities.
Hormone therapy can be
effective
1 in 1000 male births
Fragile X
syndrome
An abnormality in the X
chromosome can cause
intellectual disability, learning
disabilities, or short attention
span.
Special education, speech
and language therapy
More common in males
than in females
Turner
syndrome (XO)
A missing X chromosome in
females can cause intellectual
disability and sexual
underdevelopment.
Hormone therapy in
childhood and puberty
1 in 2,500 female births
XYY syndrome An extra Y chromosome can
cause above-average height.
No special treatment
required
1 in 1,000 male births
18. Figure 7 Some Gene-Linked
Abnormalities
Name Description Treatment Incidence
Cystic fibrosis Glandular dysfunction that interferes with
mucus production; breathing and
digestion are hampered, resulting in a
shortened life span.
Physical and oxygen therapy,
synthetic enzymes, and
antibiotics; most individuals
live to middle age.
1 in 2,000 births
Diabetes Body does not produce enough insulin,
which causes abnormal metabolism of
sugar.
Early onset can be fatal unless
treated with insulin.
1 in 2,500 births
Hemophilia Delayed blood clotting causes internal
and external bleeding.
Blood transfusions/injections
can reduce or prevent damage
due to internal bleeding.
1 in 10,000 males
Huntingtonâs
disease
Central nervous system deteriorates,
producing problems in muscle
coordination and mental deterioration.
Does not usually appear until
age 35 or older; death likely 10
to 20 years after symptoms
appear.
1 in 20,000 births
Phenylketonuri
a (PKU)
Metabolic disorder that, left untreated,
causes intellectual disability.
Special diet can result in
average intelligence and
normal life span.
1 in 10,000 to 1 in
20,000 births
Sickle-cell
anemia
Blood disorder that limits the bodyâs
oxygen supply; it can cause joint swelling,
as well as heart and kidney failure.
Penicillin, medication for pain,
antibiotics, and blood
transfusions.
1 in 400 African
American children
(lower among
other groups)
Spina bifida Neural tube disorder that causes brain
and spine abnormalities.
Corrective surgery at birth,
orthopedic devices, and
physical/medical therapy.
2 in 1,000 births
Tay-Sachs
disease
Deceleration of mental and physical
development caused by an accumulation
of lipids in the nervous system.
Medication and special diet
are used, but death is likely by
5 years of age.
1 in 30 American
Jews is a carrier.
19. Prenatal Development
⢠Conception: when a single sperm cell unites with an
ovum in a process called fertilization
⢠Prenatal development begins with fertilization and ends
with birth
⢠Approximately 266 days
⢠Divided into three periods: germinal, embryonic, and fetal
20. The Course of Prenatal
Development
The brain
⢠Basic architecture is assembled during the first two
trimesters
⢠Third trimester and first two years of life are
characterized by increased brain connectivity and
functioning
21. +
Mythbusters: 8 Myths about the Human
Brain
1) Einsteinâs brain was different than our brains.
2) We only use 10% of our brain.
3) Listening to Mozart makes you smarter.
4) People are either âright-brainedâ or âleft-brainedâ.
5) Drinking alcohol always kills brain cells.
6) Brain damage is always permanent.
7) The heart is more important for love than the brain.
8) The human brain is larger than any other animal brain.
24. The Course of Prenatal
Development: Hazards
Teratogens
⢠Any agent that can potentially cause a birth defect or
negatively alter cognitive or behavioral outcomes
⢠Severity of damage from teratogens depends on the dose, the
genetic susceptibility, and the time of exposure
⢠Common teratogens:
⢠Drugs
⢠Incompatible blood types
⢠Environmental pollutants
⢠Infectious diseases
⢠Nutritional deficiencies
⢠Maternal stress and advanced maternal and paternal age
25.
26. The Course of Prenatal
Development: Hazards
Both prescription and nonprescription drugs can
be harmful
Psychoactive drugs, which act on the nervous system,
are linked to significant negative outcomes
⢠Caffeine
⢠Alcohol
⢠Fetal alcohol spectrum disorders (FASD) are a cluster of
abnormalities and problems caused by heavy drinking
⢠Cigarette smoking and exposure to environmental
tobacco smoke
⢠Illegal drugs such as cocaine and marijuana
27. The Course of Prenatal
Development: Hazards
Case Study
Dr. Hallam Hurt: âCrack Babiesâ Study
⢠Babies from low-income moms born in 1988 in
Philadelphia
⢠Group 1 : Mothers took crack
⢠Group 2: Mothers did not take crack
What do you think she found?
28. What was that something bigger?
Case Study
From 2013 NPR interview:
âWe evaluated our participants every six to 12 months, when
they were young infants and children. What we found was that
the cocaine exposed and the non-exposed didn't differ from each
other on this evaluation - something we had fully anticipated.
And we did additional evaluations, looking for differences in how
the children played, were they creative, and then we looked at IQ
tests.
And over and over and over again, what we found was that the
exposed and the non-exposed did not differ from each other, but
they lagged behind on the standardized tests and were
performing quite poorly. So over the years, it became
increasingly clear that something bigger than gestational cocaine
exposure was at play.â
29. Case Study
From 2013 NPR interview:
âAnd the other really important thing we found was that when we
did the IQ tests, we found that exposed and non-exposed, the
vast majority were performing at a below-average range. But
there were 32 children who were average and one was above
average. And so, rather than being, sort of, desperately sad
about that, we thought, well let's look at the children who are
performing well and see what factors into their performance,
which was higher than their colleagues.
And we went into the homes of the participants and did a survey.
And what we found was that the more enriching the home
environment, the better the child performed on the IQ evaluation.
The one fact that holds up in virtually every evaluation is that the
more enriched the home, the better the child performed.â
Environmental Factors
30. Birth and the Postpartum Period:
The Birth Process
Stages of birth
⢠Uterine contractions
⢠15 to 20 minutes apart
⢠Cervix stretches and opens to about 10 centimeters
⢠Baby begins to move through the cervix and birth canal
⢠Contractions come almost every minute
⢠Pushing
⢠Afterbirth
⢠Placenta, umbilical cord, and other membranes are
detached and expelled
31. The Apgar Scale
Score 0 1 2
Heart rate Absent Slowâless than 100
beats per minute
Fastâ100 to 140
beats per minute
Respiratory
effort
No breathing for more
than one minute
Irregular and slow Good breathing with
normal crying
Muscle tone Limp and flaccid Weak, inactive, but
some flexion of
extremities
Strong, active motion
Body color Blue and pale Body pink, but
extremities blue
Entire body pink
Reflex
irritability
No response Grimace Coughing, sneezing,
and crying
32. Birth and the Postpartum Period:
Low Birth Weight and Preterm Infants
Three related conditions pose a threat:
⢠Low birth weight infants: weigh less than 5½ pounds
⢠Preterm infants: born three weeks or more before full
term
⢠Small for date infants: birth weights are below normal for
the length of pregnancy
Consequences of low birth weight
⢠As a group, these infants have more health and
developmental problems
⢠Number and severity of problems increase when infants are
born very early and as their birth weight decreases
33. Birth and the Postpartum Period:
Bonding and Attachment
Bonding is the formation of a close connection,
especially a physical bond, between parents and
their newborn
35. Evolutionary Approach
Children come into the world biologically pre-
programmed to form attachments
⢠Will help them to survive
Child produces innate âsocial releaserâ behaviors
stimulate caregiving responses from adults
The determinant of attachment is not food, but
care and responsiveness
Critical period for attachment (2.5 years)
36. The Postpartum Period
Postpartum period: period after childbirth that lasts
for about six weeks
Physical adjustments:
⢠Fatigue
⢠Loss of sleep
⢠Hormonal changes
⢠Involution: uterus returns to prepregnancy size five or six
weeks after birth
This slide explores why humans are so fascinated and invested in the nature-nurture question.
Instructorâs note: Within this discussion, you will explore the complexity of human attributes, emphasizing that consistently they are neither entirely inside or outside our control.
(Click) Discussion question: Why is the nature-nurture question so fascinating?
Student responses will vary.
(Click) Controversial
(Click) Fascinating
(Click) Consequential
Explanation: That some characteristics are inborn while others are acquired is a fundamental and profound human intuition, and it is worth crediting its importance and validity before we begin to pick it apart. Of the three great questions about humansâ relationships with the natural world, only natureânurture is sometimes called a âdebate.â In the history of psychology, no other question has generated so much disagreement and moral indignation: The most fundamental reason we are so fascinated with natureânurture is that our most important moral judgments seem to depend on it. We may admire the athletic skills of a great basketball player, but his height is simply a gift, a payoff in the âgenetic lotteryâ in which we have all been involuntarily entered. For the same reason no one would condemn a short person, much less someone with a real congenital disability: It is, to state the obvious, ânot their fault.â But we do credit the concert oboist for her skills, and perhaps her parents and community as well; we condemn cheaters, slackers, and the violent.
It only adds to our fascination that most interesting human characteristics arenât actually like height or oboe-playing, with our natureânurture intuitions skewed strongly one way or the other. Even the great oboist, we might think, might have some inborn qualityâperfect pitch, or long nimble fingersâthat support and reward her hard work. When we think about ourselves and our ordinary human qualities, they seem under our control in some respects, yet beyond our control in others. Moreover, many of the traits we wonder about are of much greater personal consequence than our height or musicality. What about how much we drink or worry? What about our honesty, our religiosity, or sexual orientation? They all have that same difficult quality, neither fixed by nature nor totally under our own control.
Discussion question: Why is Michael Jordanâs skill at basketball an example of both nature and nurture?
Answer: Michael Jordan, widely considered one of the most naturally gifted American athletes in history, is also well known for diligent practice, spending hours honing his shooting technique. He provides a clear example of the interplay between natural and nurtured talent.
This slide continues the explanation of why humans are fascinated with/interested in the nature-nurture question by acknowledging that the empirical study of this question is far more difficult in humans than it is in nonhuman animals.
Another reason we are so fascinated with natureânurture is that there are difficult obstacles in the way of studying it empirically in humans. In nonhuman animals, experimental methods are available that make finding answers to natureânurture questions relatively straightforward.
Instructorâs note: Begin by sharing the following research example with students: Suppose you are interested in aggressiveness in dogs. You could mate a pair of aggressive dogs and a pair of nonaggressive ones, split their litters in half, and switch half of each litter. You now have puppies born to aggressive and nonaggressive dogs, half of them raised by their own parents, the other half raised by the parents of the opposite type to whom they are not biologically related. Which is a more important determinant of aggression in the puppies: being born to aggressive dogs or being raised by them, and how do the two factors combine? Much of the best and most enduring natureânurture research has been done in this way (Scott & Fuller, 1998), and animal breeders have been doing it successfully for millennia. It is possible, even easy, to breed animals for behavioral traits.
(Click) Other Reasons for Our Fascination
Discussion question: Why can we do studies like this with animals but not with humans?
Answers:
(Click) Ease of animal study
History of mating experiments
Fast replication
(Click) Obstacles to human study
Random assignment impossible
Unethical: eugenics
Explanation: In people, it is not possible to assign babies to parents at random, or to select parents with certain behavioral characteristics for reproduction. (Although history includes horrific examples of such practices, as part of misconceived attempts at âeugenics,â the shaping of human characteristics through intentional breeding.) In typical human families, the childrenâs biological parents also raise them, and as a result, it is very difficult to know whether children resemble their parents for genetic or environmental reasons.
This slide provides another reason for our fascination with the nature-nurture question. Specifically, despite the fact that, as mentioned in slide 4, there are obstacles to studying the question, these obstacles have led to the development of intriguing ways to gain information regarding this question. Here, the instructor is to introduce behavioral genetics and adoption studies.
Lecture Info:
The next reason for our fascination with natureânurture is the converse of the previous one: Although there are difficult obstacles in the way of scientific analysis of human families, clever methods exist that provide partial solutions. The empirical science of how genes and environments work together to generate behavior is called behavioral genetics.
(Click) Adoption Studies
The easiest of these methods to understand is the adoption study. When children are put up for adoption, the parents who give birth to them are not the parents who raise them. It isnât quite the same as the experiments with dogsâchildren canât be assigned to adoptive parents at random, or in order to suit some particular interests of a scientist, but adoption still tells us something interesting.
Discussion questions: If the biological children of tall parents were adopted into a family of short people, what do you think would happen? What about the biological children of a Spanish-speaking family adopted at birth into an English-speaking family? Would this tell you something about the difference between height and language?
This slide complements the discussion from slide 5, as you are to introduce another empirical method derived to circumvent the obstacles to addressing the nature-nurture question: twin studies. Explain the difference between monozygotic and dizygotic twins, and discuss ways in which each may be utilized to gain information relevant to the nature-nurture question.
Instructorâs note: Begin by explaining the basic difference between the two types of twins: Identical, or monozygotic (MZ), twins result from a single zygote and have the same DNA. They are essentially clones. Fraternal, or dizygotic (DZ), twins develop from two zygotes. Fraternal twins are ordinary siblings who happen to have been born at the same time. They share 50% of their DNA.
Discussion question: How might twin studies help us better understand the nature-nurture question?
Answers will vary.
Explanation: To analyze natureânurture using twins, we compare the similarity of MZ and DZ pairs. Identical twins, unsurprisingly, are almost perfectly similar for height. The heights of fraternal twins are like any other sibling pairs: more similar to each other than to people from other families, but hardly identical. This difference in similarity tells us something about the role genetics plays in the determination of height. Now consider speaking Spanish. If one identical twin speaks Spanish at home, the co-twin with whom she is raised almost certainly does too. But in this case, the same would be true for a pair of fraternal twins raised together. For language-speaking, fraternal twins are just as similar as identical twins, so it appears that the additional genetic similarity of identical twins isnât making much difference.
Twin and adoption research designs have much in common; in fact, they are two instances of a much broader class of methods in which similarity among individuals is analyzed in terms of how biologically related they are, a scientific discipline called quantitative genetics. We can do these studies with siblings and half-siblings, cousins, or with twins who have been separated at birth and raised separately (Bouchard, Lykken, McGue, & Segal, 1990; such twins are very rare and play a smaller role than is commonly believed in the science of natureânurture), or with entire pedigrees of extended families.
(Click) Secret Twin Study (hyperlink to video)
Instructorâs note: Consider playing the linked video about the secret study of twins who were separated at birth. Video link: https://www.youtube.com/watch?v=1gwnzW4jOMI. Play the video from 2:35-7:30s. The video touches upon the nature vs. nurture question, emphasizing the nature part of the debate (i.e., similarities between the separated twins) and is a perfect segue into the in-class activity, which offers a different perspective.
This slide introduces the heritability coefficient.
Instructorâs note: Youâll need to explain the role of the heritability coefficient in generating interest in the nature-nurture question.
Lecture Info:
For better or for worse, our thinking about natureânurture has been intensified because the methods of quantitative genetics produce a number, called a heritability coefficient, varying from 0 to 1, that appears to provide a single measure of the role of genetics in a trait. In a general way, a heritability coefficient measures how strongly differences among individuals for a trait are related to differences among their genes. But beware: The previous sentences are qualified with appears to and in a general way because heritability coefficients, although simple to compute, are deceptively difficult to interpret. Nevertheless, numbers that seem to provide simple answers to complicated questions have a strong draw on the human mind, and a great deal of time has been spent discussing whether the heritability of intelligence or personality or depression is equal to this number or that.
Suggested activity: Striking Similarities Among Strangers â 10-15 minutes (Find the details of this activity in the IM > Biology as a Basis of Behavior > Module Four: The Nature- Nurture Question > Activities/Demonstrations)
Using the handout âSimilarities Questionnaireâ, students will pair up with someone in class that they donât know and make note of all the similarities and differences they find.
Discussion questions:
How many similarities did you find between you and your partner?
What might this tell us about the nature-nurture question?
How does this relate to the video we just watched about the twins? What assumptions might we have made about these twins before that this questionnaire encourages us to doubt now? (Answer: We might have assumed that all of the similarities between the separated twins was due to their genetic makeup.)
The epigenetic view and gene Ă environment (G x E) interaction
Epigenetic view proposes development is the result of an ongoing, bidirectional interchange between heredity and environment
Studies of gene Ă environment look at the interaction of a specific measured variation in DNA and a specific measured aspect of the environment
The collaborative gene
Nucleus of each human cell contains chromosomes, threadlike structures made up of deoxyribonucleic acid, or DNA
DNA is a complex molecule that contains genetic information
Double helix shape
Genes, the basic units of hereditary information, are short segments of DNA
Direct cells to reproduce and assemble the proteins that direct body processes
Each has a designated place on a particular chromosome
Mitosis and meiosis
All cells in the human body, except the sperm and egg, have 46 chromosomes arranged in have 23 pairs
These cells reproduce through mitosis: the cellâs nucleus, including the chromosomes, duplicates itself and divides
The two new cells each contain the same DNA as the original
Eggs and sperm are formed through meiosis: a cell of the testes or ovaries duplicates its chromosomes but then divides twice, forming four cells
Each has only half the genetic material of the original
Sources of genetic variability
Combining genes of two parents in offspring increases genetic variability in the population
Mutated genes, or permanently altered segments of DNA, form by chance or environmental damage
Genotype: personâs actual genetic material
Phenotype: observable and measurable characteristics of an individual
Physical and psychological
Range of phenotypes can be expressed for each genotype
Chromosomal abnormalities
Sperm or ovum does not have its normal set of 23 chromosomes
Sex-linked chromosomal abnormalities most commonly involve an extra chromosome (either an X or Y) or the absence of one X chromosome in females
The purpose of this slide is to pique interest in the brain and nervous system. This slide contains an animation for each of the 8 questions. After displaying the statement, ask students whether they think it is true or false. The answers are below. Full citations are in the Brain & Nervous System section of the instructor manual.
(Click) Einsteinâs brain was different than our brain. [FALSE]
According to recent research, there are no neuroanatomical differences between our brain and Einsteinâs. Previous findings demonstrating that there may have been differences were quite likely due to confirmation biases and/or statistical errors, such as the multiple comparison problem.
Â
(Click) We only use 10% of our brain. [FALSE]
This is a very popular myth that has been around for a while. Recent brain imaging tools such as the fMRI demonstrated that though it is not necessary for all the areas of the brain to be active at once, for any given activity, there are usually a number of activated areas.
 Â
(Click) Listening to Mozart makes you smarter. [FALSE]
Currently, there are no findings establishing that listening to classical music makes people smarter. There may be evidence suggesting that learning a musical instrument improves attention, confidence and coordination. In short, listening to Mozart does not have any negative effects and may be pleasant to some, but it does not make people smarter.
Â
(Click) People are either âright-brainedâ or âleft-brainedâ. [FALSE]
People use both their right- and left-hemispheres. Certain functions, such as speech production and facial recognition, etc., tend to be dominated by one side of the brain. However, even these tasks require input from both hemispheres. So, unless an individualâs entire hemisphere is wholly removed or impaired, no one is considered to be completely ârightâ- or âleftâ-brained.
 Â
(Click) Drinking alcohol always kills brain cells. [FALSE]
Consuming moderate amounts of alcohol does not harm brain cells. In fact, some studies have found that a glass or two of wine a day may reduce the risk of stroke. However, too much of anything is never a good thing! Years of alcohol abuse or âbinge drinkingâ can damage neurons, change brain function, and shrink cells.
 Â
(Click) Brain damage is always permanent. [FALSE]
Recovery from brain injury depends on severity and location of the trauma. For instance, concussions are mild brain injuries, usually resulting in only short-term disruptions of brain functioning. With rehabilitation, even a severe brain injury such as a stroke, can allow for the brain to develop new networks and âredirectâ signals through the healthy regions of the brain.
 Â
(Click) The heart is more important for love than the brain. [FALSE]
The brain has a lot (if not everything) to do with love. When two people are in love, neuroimaging techniques show that many areas of the brain âlight upâ and various hormones (e.g., dopamine, norepinephrine, etc.) are released. These chemicals are associated with feelings of excitement and pleasure.
Â
 (Click) The human brain is larger than any other animal brain. [FALSE]
The absolute size of the human brain, though larger than some animal brains, is most definitely not the largest of all animal brains. The brains of animals like elephants and whales are significantly larger than ours.
This slide is optional and can be removed if you do not want to begin this unit by focusing on the evolution of the mammalian brain. If you choose to do so you can point out to students that the human brain has evolved over time and that it differs from the brains of other mammals such as mice, cats and dogs. You can use this as a point to engage students in a discussion about the cognitive abilities of different species. For example, you could initiate discussion by asking:
Do you believe that dogs and cats are about equally intelligent? Why or why not?
What are some of the intellectual capabilities of humans that are not present in dogs or cats?
Four phases of development involve
neural tube
defects
In anencephaly, the head end of the neural tube fails to close, and the highest regions of the brain fail to develop
In spina bifida, incomplete development of the spinal cord
neurogenesis
neural migration
neural connectivity
Other significant hazards:
Maternal diseases and infections
Rubella (German measles), syphilis, genital herpes, HIV/AIDS
Poor maternal diet and nutrition
Overweight and underweight
Lack of folic acid
High maternal anxiety and stress; and depression
Maternal age: adolescents and women 35 years and older
Environmental hazards
Paternal factors
Abnormalities in sperm; smoking during the motherâs pregnancy; age (40 years or older)
Weâll dive into this case again later in the semester!
Childbirth setting and attendants
In the United States, 98.5% of births (2015) take place in hospitals
Midwives: trained health practitioners who help women during labor, delivery, and afterbirth
Doulas: caregivers who provides continuous physical, emotional, and educational support for mother before, during, and after childbirth
After birth, a newborn is weighed and tested
Apgar Scale: widely used to assess the health of newborns at one and five minutes after birth
Given a score from 0 to 10
Heart rate, respiratory effort, muscle tone, body color, and reflex irritability evaluated
The learning / behaviorist theory of attachment (e.g., Dollard & Miller, 1950) suggest that attachment is a set of learned behaviors. The basis for the learning of attachments is the provision of food. An infant will initially form an attachment to whoever feeds it.
They learn to associate the feeder (usually the mother) with the comfort of being fed and through the process of classical conditioning, come to find contact with the mother comforting.
