Chapter 2 Biological Beginnings Power Points developed by

The Evolutionary Perspective § Natural Selection and Adaptive Behavior ünatural selection -- the evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce üsurvivors are better adapted to their world than are the non-survivors (Darwin, 1859; Johnson & Losos, 2008) (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 üthe ability to pass your genes to the next generation (Promislow, Fedorka, & Burger, 2006) (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

Evaluating Evolutionary Psychology § Bandura (1998) rejects what he calls “onesided 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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

Genes § Genes -- units of hereditary information üshort segments of DNA § Genes direct cells to reproduce themselves and to assemble proteins § Proteins üthe building blocks of cells üthe regulators that direct the body’s processes (Mader, 2008) (c) 2012 The Mc. Graw-Hill Companies, Inc.

(c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 üOne chromosome of each pair is from the mother’s egg and the other from the father’s sperm üEach parent contributes half of the offspring’s genetic material (c) 2012 The Mc. Graw-Hill Companies, Inc.

The 23 rd Pair of Chromosomes § Slight difference in the 23 rd pair § In females, the 23 rd pair consists of two chromosomes called X chromosomes § In males, the 23 rd pair consists of an X and a Y chromosome § The presence of a Y chromosome is what makes an individual male (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 ümutated gene -- a permanently altered segment of DNA (c) 2012 The Mc. Graw-Hill Companies, Inc.

Genotype and Phenotype § Genotype -- all of a person’s genetic material § Phenotype -- observable characteristics § Phenotypes include üphysical characteristics (such as height, weight, and hair color) üpsychological characteristics (such as personality and intelligence) (c) 2012 The Mc. Graw-Hill Companies, Inc.

Dominant-Recessive Genes Principle § Dominant -- one gene of a pair always exerts its effects § Recessive gene -- exerts influence only if the two genes of a pair are both recessive ümay be overridden by a dominant gene ümay be carried from generation to generation but not expressed in phenotype (c) 2012 The Mc. Graw-Hill Companies, Inc.

Sex-Linked Genes § X-linked inheritance -- mutated gene is carried on the X chromosome ümales have no “backup” copy to counter the harmful gene üfemales have a second X chromosome, which is likely to be unchanged üFemales who have one changed copy of the X gene are known as “carriers” (Turner, 2006) (c) 2012 The Mc. Graw-Hill Companies, Inc.

Polygenic Inheritance § Genetic transmission is usually quite complex üfew characteristics reflect the influence of only a single gene or pair of genes § Polygenically determined characteristics -determined by the interaction of many different genes (c) 2012 The Mc. Graw-Hill Companies, Inc.

Chromosome- and Gene-Linked Abnormalities § Down syndrome -- caused by the presence of an extra copy of chromosome 21 üonce in every 700 live births üwomen aged 16 - 34 are less likely to give birth to a child with Down syndrome (c) 2012 The Mc. Graw-Hill Companies, Inc.

Sex-Linked Chromosome Abnormalities § Klinefelter syndrome -- extra X chromosome § Fragile X syndrome -- results from an abnormality in the X chromosome üX 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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

Gene-Linked Abnormalities § Phenylketonuria (PKU) -- individual cannot properly metabolize phenylalanine, an amino acid üleft 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 ümost often in African Americans üred blood cell becomes a hook-shaped “sickle” that cannot carry oxygen properly (c) 2012 The Mc. Graw-Hill Companies, Inc.

Other diseases that result from genetic abnormalities § § § Cystic fibrosis Diabetes Hemophilia

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, De. Fries, & Fulker, 2007; Vogler, 2006) (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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) (c) 2012 The Mc. Graw-Hill Companies, Inc.

Gene X Environment (G x E) Interaction § The interaction of a specific measured

The Course of Prenatal Development § Fertilization to birth § Prenatal development lasts approximately

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 ü takes place about 10 to 14 days after conception (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 üendoderm üectoderm ümesoderm (c) 2012 The Mc. Graw-Hill Companies, Inc.

The Embryonic Period § The mass of cells is an embryo § Organogenesis -- the process of organ formation during the first two months of prenatal development üorgans are especially vulnerable to environmental influences § Life-support systems for the embryo develop rapidly (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

The Fetal Period § See Figure 2. 8 on page 48 (c) 2012 The

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 üAbout 24 -25 weeks after conception (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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: üAnencephaly üSpina bifida § Folic acid may prevent neural tube defects (c) 2012 The Mc. Graw-Hill Companies, Inc.

The Brain § The generation of new neurons is called neurogenesis § Neuronal migration occurs at 6 -24 weeks after conception § At about the 23 rd prenatal week, connections between neurons begin to form (c) 2012 The Mc. Graw-Hill Companies, Inc.

Prenatal Tests § Ultrasound sonography ü non-invasive ü high-frequency sound waves § Fetal MRI ü Used to obtain more detailed images than ultrasound § Chorionic villus sampling (CVS) ü tiny tissue sample from the placenta is removed analyzed § Amniocentesis ü sample of amniotic fluid is withdrawn and tested for chromosome or metabolic disorders (c) 2012 The Mc. Graw-Hill Companies, Inc.

Prenatal Tests § Maternal blood screening ü Identifies pregnancies that have an elevated risk for birth defects such as spina bifida and Down syndrome § Triple Screen ü Measures three substances in the mother’s blood ü If abnormal, ultrasound is performed, then amniocentesis (c) 2012 The Mc. Graw-Hill Companies, Inc.

Infertility and Reproductive Technology § Approximately 10 -15 couples in the United States experience infertility üDefined as the inability to conceive a child after 12 months of regular intercourse without conception § In vitro fertilization (IVF) ü 25 to 30 percent of pregnancies achieved by fertility treatments result in multiple births (c) 2012 The Mc. Graw-Hill Companies, Inc.

Hazards to Prenatal Development § A teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes üDrugs üIncompatible blood types üEnvironmental pollutants üInfectious diseases üMaternal stress, advanced maternal and paternal age (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

Hazards to Prenatal Development § Prescription drugs ü Antibiotics ü Antidepressants ü Hormones ü Accutane § Psychoactive drugs ü Caffeine ü Alcohol (Fetal alcohol spectrum disorders, FASD) ü Nicotine ü Cocaine ü Methamphetamine ü Marijuana ü Heroin (c) 2012 The Mc. Graw-Hill Companies, Inc.

Hazards to Prenatal Development § Incompatible blood types ü Difference in blood groups -- A, B, O, and AB ü Rh factor § Environmental hazards ü Toxic wastes ü X-ray radiation § Maternal diseases ü Rubella ü Syphilis, genital herpes, HIV/AIDS ü Diabetes (c) 2012 The Mc. Graw-Hill Companies, Inc.

Hazards to Prenatal Development § Other Parental Factors ü ü ü Maternal diet and nutrition Overweight before and during pregnancy Folic acid is important for normal prenatal development Eating fish -- mercury levels Maternal age -- 35 years or older at risk Emotional states and stress ü Anxiety ü Depression ü Paternal factors ü Smoking (c) 2012 The Mc. Graw-Hill Companies, Inc.

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. (c) 2012 The Mc. Graw-Hill Companies, Inc.

The Birth Process § The Birth Process üfirst stage -- contractions cause the woman’s cervix to stretch and open üsecond stage begins when the baby’s head starts to move through the cervix üthird stage is afterbirth üplacenta, umbilical cord, and other membranes are detached and expelled (c) 2012 The Mc. Graw-Hill Companies, Inc.

Childbirth Setting and Attendants § In the United States, 99 percent of births take place in hospitals § Midwives ü Practiced throughout the world ü 95 percent of the midwives who delivered babies in the United States were certified nurse-midwives § Doulas ü A caregiver who provides continuous physical, emotional, and educational support for the mother before, during, and after childbirth (c) 2012 The Mc. Graw-Hill Companies, Inc.

Methods of Childbirth § Medications üThree basic kinds of drugs üAnalgesia üAnesthesia üOxytocics § Natural and Prepared Childbirth üNatural childbirth -- reduce pain with breathing techniques and relaxation üPrepared childbirth -- a. k. a. Lamaze (c) 2012 The Mc. Graw-Hill Companies, Inc.

Methods of Childbirth § Other Non-Medicated Techniques to Reduce Pain üWaterbirth -- giving birth in a tub of warm water ülikely to be less stressful for the baby and the mother üMassage -- reduce pain and anxiety üAcupuncture -- insertion of strategically located needles (c) 2012 The Mc. Graw-Hill Companies, Inc.

Breech or Cesarean Delivery § Breech position -- buttocks rather than head emerge first üCan prevent the baby from breathing normally § Cesarean delivery -- the baby is removed from the mother’s uterus through an incision made in her abdomen üMay be lifesaving but carries the risks of major surgery (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 üheart rate, respiratory effort, muscle tone, body color, and reflex irritability § Anoxia -- an insufficient supply of oxygen (c) 2012 The Mc. Graw-Hill Companies, Inc.

Low Birth Weight and Preterm Infants § Low birth weight -- less than 5½ pounds at birth üVery low birth weight -- under 3 pounds üExtremely 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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

Incidence and Causes of Low Birth Weight § Incidence of low birth weight varies considerably from country to country üRelated to poverty, maternal health status, maternal nutrition § More health and developmental problems than normal-weight infants üAt school age, more likely to have a learning disability, attention deficit hyperactivity disorder, or breathing problems such as asthma (Moss, 2006; Wocadlo, & Rieger, 2006) (c) 2012 The Mc. Graw-Hill Companies, Inc.

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) (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.

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 (c) 2012 The Mc. Graw-Hill Companies, Inc.