1. Biological Beginnings
Chapter 2
Biological Beginnings
PowerPoints developed by Nicholas Greco IV, College of Lake County, Grayslake, IL
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2. The Evolutionary Perspective
Natural Selection and Adaptive Behavior
natural selection -- the evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce
survivors are better adapted to their world than are the non-survivors
(Darwin, 1859; Johnson & Losos, 2008)
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3. Evolutionary Psychology
Emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in shaping behavior
Fit -- the ability to bear offspring that survive long enough to bear offspring of their own
the ability to pass your genes to the next generation (Promislow, Fedorka, & Burger, 2006)
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4. Evolutionary Developmental Psychology
Humans take longer to become reproductively mature
Humans require time to develop a large brain and learn the complexity of human societies
Thus, length of childhood period is extended
Evolved mechanisms are not always adaptive in contemporary society
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5. Evaluating Evolutionary Psychology
Bandura (1998) rejects what he calls “one-sided evolutionism”
An alternative is a bidirectional view, in which environmental and biological conditions influence each other
Evolution gave us bodily structures and biological potentialities
People have used their biological capacities to produce diverse cultures -- aggressive and pacific, egalitarian and autocratic
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6. Genetic Foundations of Development
Each of us carries a “genetic code” that we inherited from our parents
A fertilized human egg carries this human code
Fertilized human egg cannot grow into any other species
Each of us began life as a single cell which contained our entire genetic code
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Chromosomes
Nucleus of each human cell contains chromosomes
Chromosomes -- thread-like structures made up of deoxyribonucleic acid, or DNA
DNA is a complex molecule that has a double helix shape, like a spiral staircase, and contains genetic information
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Genes
Genes -- units of hereditary information
short segments of DNA
Genes direct cells to reproduce themselves and to assemble proteins
Proteins
the building blocks of cells
the regulators that direct the body’s processes
(Mader, 2008)
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Human Genome Project
Preliminary map of the human genome -- the complete set of developmental instructions for creating proteins that initiate the making of a human organism
Each human has approximately 20,500 genes
Human genome consists of many genes that collaborate both with each other and with non-genetic factors inside and outside the body
Genetic expression is affected by their environment
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Mitosis
All body cells, except the sperm and egg, have 46 chromosomes arranged in 23 pairs
Body cells reproduce by a process called mitosis
During mitosis, the cell’s nucleus—including the chromosomes—duplicates itself and the cell divides
Two new cells are formed, each containing the same DNA as the original cell
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Meiosis
Sex cell division is different type of cell division
Eggs and sperm (or gametes) are formed in meiosis
A cell of the testes (in men) or ovaries (in women) duplicates its chromosomes but then divides twice, thus forming four cells
Each of these has only half of the genetic material of the parent cell
By the end of meiosis, each egg or sperm has 23 unpaired chromosomes
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Fertilization
Zygote -- an egg and a sperm fuse to create a single cell
In the zygote, the 23 unpaired chromosomes from the egg and sperm combine to form one set of 23 paired chromosomes
One chromosome of each pair is from the mother’s egg and the other from the father’s sperm
Each parent contributes half of the offspring’s genetic material
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14. The 23rd Pair of Chromosomes
Slight difference in the 23rd pair
In females, the 23rd pair consists of two chromosomes called X chromosomes
In males, the 23rd pair consists of an X and a Y chromosome
The presence of a Y chromosome is what makes an individual male
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15. Sources of Variability
Combining genes of two parents increases genetic variability in the population
Chromosomes in the zygote are not exact copies of the parents
Another source of variability comes from DNA
mutated gene -- a permanently altered segment of DNA
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16. Genotype and Phenotype
Genotype -- all of a person’s genetic material
Phenotype -- observable characteristics
Phenotypes include
physical characteristics (such as height, weight, and hair color)
psychological characteristics (such as personality and intelligence)
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17. Dominant-Recessive Genes Principle
Dominant -- one gene of a pair always exerts its effects
Recessive gene -- exerts its influence only if the two genes of a pair are both recessive
may be overridden by a dominant gene
may be carried from generation to generation but not expressed in phenotype
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Sex-Linked Genes
X-linked inheritance -- mutated gene is carried on the X chromosome
males have no “backup” copy to counter the harmful gene
females have a second X chromosome, which is likely to be unchanged
Females who have one changed copy of the X gene are known as “carriers”
(Turner, 2006)
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19. Polygenic Inheritance
Genetic transmission is usually quite complex
few characteristics reflect the influence of only a single gene or pair of genes
Polygenically determined characteristics -- determined by the interaction of many different genes
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20. Chromosome- and Gene-Linked Abnormalities
Down syndrome -- caused by the presence of an extra copy of chromosome 21
once in every 700 live births
women aged are less likely to give birth to a child with Down syndrome
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21. Sex-Linked Chromosome Abnormalities
Klinefelter syndrome -- extra X chromosome
Fragile X syndrome -- results from an abnormality in the X chromosome
X chromosome becomes constricted and often breaks
Turner syndrome -- females have either an X chromosome missing or part of one X chromosome is deleted
XYY syndrome -- male has extra Y
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23. Gene-Linked Abnormalities
Phenylketonuria (PKU) -- individual cannot properly metabolize phenylalanine, an amino acid
left untreated, phenylalanine builds up in the child, producing mental retardation and hyperactivity
Sickle-cell anemia -- genetic disorder that impairs the body’s red blood cells
most often in African Americans
red blood cell becomes a hook-shaped “sickle” that cannot carry oxygen properly
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25. Other diseases that result from genetic abnormalities
Cystic fibrosis
Diabetes
Hemophilia
Huntington disease
Spina bifida
Tay-Sachs disease
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Behavior Genetics
Behavior genetics seeks to discover the influence of heredity and environment on individual differences in human traits and development
Behavior geneticists often study either twins or adoption situations
(Plomin, DeFries, & Fulker, 2007; Vogler, 2006)
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Behavior Genetics
In a twin study, the behavioral similarities between identical twins is compared with the behavioral similarities between fraternal twins
In an adoption study, investigators seek to discover whether the behavior and psychological characteristics of adopted children are more like those of their adopted parents
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28. Heredity-Environment Correlations
Passive genotype-environment correlations occur because biological parents, who are genetically related to the child, provide a rearing environment for the child
Evocative genotype-environment correlations occur because a child’s characteristics elicit certain types of environments
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29. Heredity-Environment Correlations
Active (niche-picking) genotype-environment correlations occur when children seek out environments that they find compatible and stimulating
Niche-picking refers to finding a setting that is suited to one’s abilities
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The Epigenetic View
Development is the result of an ongoing, bidirectional interchange between heredity and the environment
Heredity and environment operate together—or collaborate—to produce a person’s intelligence, temperament, height, weight, ability to pitch a baseball, ability to read, etc. (Gottlieb, Wahlsten, & Lickliter, 2006)
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32. Gene X Environment (G x E) Interaction
The interaction of a specific measured variation in DNA and a specific measured aspect of the environment
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33. The Course of Prenatal Development
Fertilization to birth
Prenatal development lasts approximately 266 days
Three periods
Germinal
Embryonic
Fetal
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The Germinal Period
First two weeks after conception
Creation of the fertilized egg (the zygote)
Cell division
Attachment of the zygote to the uterine wall
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The Germinal Period
Blastocyst -- consists of an inner mass of cells that will eventually develop into the embryo
Trophoblast -- outer layer of cells that later provides nutrition and support for the embryo
Implantation -- the attachment of the zygote to the uterine wall
takes place about 10 to 14 days after conception
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The Embryonic Period
Occurs from two to eight weeks after conception
Rate of cell differentiation intensifies
Begins as the blastocyst attaches to the uterine wall
Every body part eventually develops from these three layers
endoderm
ectoderm
mesoderm
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The Embryonic Period
The mass of cells is an embryo
Organogenesis -- the process of organ formation during the first two months of prenatal development
organs are especially vulnerable to environmental influences
Life-support systems for the embryo develop rapidly
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38. Life-Support Systems for the Embryo
Amnion -- bag containing a clear fluid in which the developing embryo floats
Umbilical cord contains two arteries and one vein and connects the baby to the placenta
Placenta consists of a disk-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join
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The Fetal Period
Fetal period begins two months after conception and lasts for seven months
Three months after conception -- fetus is about 3 inches long; weighs about 3 ounces
By the end of the fifth month, the fetus is about 12 inches long and weighs close to a pound
At birth, the average American baby weighs 7½ pounds and is about 20 inches long
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The Fetal Period
See Figure 2.8 on page 48
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Three Trimesters
The germinal and embryonic periods occur in the first trimester
The fetal period begins toward the end of the first trimester and continues through the second and third trimesters
Viability (the chances of surviving outside the womb) occurs at the beginning of the third trimester
About weeks after conception
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The Brain
By the time babies are born, they have approximately 100 billion neurons
The basic architecture of the brain is assembled during the first two trimesters
The third trimester and the first two years of postnatal life are characterized by connectivity and functioning of neurons
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The Brain
The neural tube develops out of the ectoderm and forms at about 18 to 24 days after conception
Two birth defects related to the failure of the neural tube to close are:
Anencephaly
Spina bifida
Folic acid may prevent neural tube defects
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The Brain
The generation of new neurons is called neurogenesis
Neuronal migration occurs at 6-24 weeks after conception
At about the 23rd prenatal week, connections between neurons begin to form
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Prenatal Tests
Ultrasound sonography
non-invasive
high-frequency sound waves
Fetal MRI
Used to obtain more detailed images than ultrasound
Chorionic villus sampling (CVS)
tiny tissue sample from the placenta is removed and analyzed
Amniocentesis
sample of amniotic fluid is withdrawn and tested for chromosome or metabolic disorders
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Prenatal Tests
Maternal blood screening
Identifies pregnancies that have an elevated risk for birth defects such as spina bifida and Down syndrome
Triple Screen
Measures three substances in the mother’s blood
If abnormal, ultrasound is performed, then amniocentesis
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47. Infertility and Reproductive Technology
Approximately couples in the United States experience infertility
Defined as the inability to conceive a child after 12 months of regular intercourse without conception
In vitro fertilization (IVF)
25 to 30 percent of pregnancies achieved by fertility treatments result in multiple births
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48. Hazards to Prenatal Development
A teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes
Drugs
Incompatible blood types
Environmental pollutants
Infectious diseases
Maternal stress, advanced maternal and paternal age
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49. Hazards to Prenatal Development
The dose, genetic susceptibility, and the time of exposure influence both the severity of damage to an embryo or fetus and the type of defect
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50. Hazards to Prenatal Development
Prescription drugs
Antibiotics
Antidepressants
Hormones
Accutane
Psychoactive drugs
Caffeine
Alcohol (Fetal alcohol spectrum disorders, FASD)
Nicotine
Cocaine
Methamphetamine
Marijuana
Heroin
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51. Hazards to Prenatal Development
Incompatible blood types
Difference in blood groups -- A, B, O, and AB
Rh factor
Environmental hazards
Toxic wastes
X-ray radiation
Maternal diseases
Rubella
Syphilis, genital herpes, HIV/AIDS
Diabetes
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52. Hazards to Prenatal Development
Other Parental Factors
Maternal diet and nutrition
Overweight before and during pregnancy
Folic acid is important for normal prenatal development
Eating fish -- mercury levels
Maternal age years or older at risk
Emotional states and stress
Anxiety
Depression
Paternal factors
Smoking
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Prenatal Care
Involves a defined schedule of visits for medical care
Provides screening for manageable conditions and treatable diseases
Includes comprehensive educational, social, and nutritional services
Centering Pregnancy is a new program that is relationship-centered and provides complete prenatal care in a group setting.
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The Birth Process
The Birth Process
first stage -- contractions cause the woman’s cervix to stretch and open
second stage begins when the baby’s head starts to move through the cervix
third stage is afterbirth
placenta, umbilical cord, and other membranes are detached and expelled
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55. Childbirth Setting and Attendants
In the United States, 99 percent of births take place in hospitals
Midwives
Practiced throughout the world
95 percent of the midwives who delivered babies in the United States were certified nurse-midwives
Doulas
A caregiver who provides continuous physical, emotional, and educational support for the mother before, during, and after childbirth
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Methods of Childbirth
Medications
Three basic kinds of drugs
Analgesia
Anesthesia
Oxytocics
Natural and Prepared Childbirth
Natural childbirth -- reduce pain with breathing techniques and relaxation
Prepared childbirth -- a.k.a. Lamaze
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Methods of Childbirth
Other Non-Medicated Techniques to Reduce Pain
Waterbirth -- giving birth in a tub of warm water
likely to be less stressful for the baby and the mother
Massage -- reduce pain and anxiety
Acupuncture -- insertion of strategically located needles
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58. Breech or Cesarean Delivery
Breech position -- buttocks rather than head emerge first
Can prevent the baby from breathing normally
Cesarean delivery -- the baby is removed from the mother’s uterus through an incision made in her abdomen
May be lifesaving but carries the risks of major surgery
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Apgar Scale
Used to assess the health of newborns at one and five minutes after birth
A score, or reading, of 0, 1, or 2 on each of these five health signs
heart rate, respiratory effort, muscle tone, body color, and reflex irritability
Anoxia -- an insufficient supply of oxygen
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60. Low Birth Weight and Preterm Infants
Low birth weight -- less than 5½ pounds at birth
Very low birth weight -- under 3 pounds
Extremely low birth weight -- under 2 pounds.
Preterm -- born three weeks or more before full term
Small-for-date -- birth weight is below normal when the length of the pregnancy is considered
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61. Incidence and Causes of Low Birth Weight
Incidence of low birth weight varies considerably from country to country
Related to poverty, maternal health status, maternal nutrition
More health and developmental problems than normal-weight infants
At school age, more likely to have a learning disability, attention deficit hyperactivity disorder, or breathing problems such as asthma
(Moss, 2006; Wocadlo, & Rieger, 2006)
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62. Nurturing Low Birth Weight and Preterm Infants
Kangaroo care -- a way of holding an infant so that there is skin-to-skin contact for two to three hours per day over an extended time in early infancy
Massage therapy -- firm stroking with the palms of the hands three times per day for 15-minute periods
Bonding -- formation of a connection, especially a physical bond, between parents and the newborn in the period shortly after birth
(Feldman & others, 2003; Field & others, 1986)
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The Postpartum Period
Postpartum period -- lasts for about six weeks after childbirth or delivery or until the mother’s body has completed its adjustment and has returned to a nearly pre-pregnant state
Physical and psychological adjustments
Involution -- process by which the uterus returns to its pre-pregnant size
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64. Emotional and Psychological Adjustments
Baby blues -- two to three days after birth, many women begin to feel depressed, anxious, and upset
Postpartum depression -- a major depressive episode about four weeks after delivery
Fathers also undergo considerable adjustment in the postpartum period, even when they work away from home all day
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65. Postpartum Blues and Postpartum Depression Among U.S. Women
See Figure 2.11 on page 64
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