Upcoming SlideShare
Loading in...5

Like this? Share it with your network

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads


Total Views
On Slideshare
From Embeds
Number of Embeds



Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

    No notes for slide


  • 1. Life-Span Development Twelfth Edition Chapter 2: Biological Beginnings
  • 2.  Natural Selection: an evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce • $$ The study of human evolution was put forth by Charles Darwin • Survival characteristics are passed on in genes  Can produce a gradual modification of the population over many generations • Survival characteristics may change based on environmental conditions Adaptive Behavior: behavior that promotes an organism’s survival in the natural habitat
  • 3.  Evolutionary Psychology: emphasizes the importance of adaptation, reproduction, and “survival of the fittest” in shaping behavior • Fit: the ability to bear offspring that survive long enough to bear offspring of their own  Natural selection favors behaviors that increase reproductive success • $$ Evolutionary developmental psychology suggests that the way in which people develop is adaptive
  • 4.  Extended childhood period allows time to develop a large brain and learn complexity of human society Many evolved psychological mechanisms are domain-specific • Information processing Evolved mechanisms are not always adaptive in contemporary society
  • 5.  Why do humans live so long after reproduction? • Perhaps older people improve the survival rate of babies Paul Baltes: benefits of evolutionary selection decrease with age • Natural selection is tied to reproductive fitness • Does not weed out harmful conditions that appear among older adults  Increases our need for culture
  • 6.  Evolutionary psychology approach is just one theory of many • It has its limitations and weaknesses, and its critics Bidirectional view: environmental and biological conditions influence each other • Evolution gives us bodily structures and biological potentialities, but it does not dictate behavior • People create behavior in the context of culture
  • 7.  Human life begins as a single cell Nucleus of each cell contains chromosomes • Chromosomes: thread-like structures made up of DNA • DNA: a complex double-helix molecule that contains genetic information $$ Genes: units of hereditary information that are comprised of short segments of DNA • Genes direct cells to reproduce themselves and to assemble proteins Proteins: building blocks of cells and regulators that direct the body’s processes
  • 8.  Each gene has its own unique location on a particular chromosome • Results indicated that humans have about 20,000 to 22,000 genes Genes collaborate with eachother and with non-genetic factorsinside and outside the body Genetic expression is affected by the environment
  • 9.  All cells in the human body (except sperm and egg) have 46 chromosomes arranged in 23 pairs Mitosis: reproduction of cells • Nucleus (including chromosomes) duplicate, and the cell divides Meiosis: cell division that forms sperm and eggs (gametes) • Each cell divides twice, forming four cells with 23 unpaired chromosomes
  • 10.  Fertilization: fusing of sperm and egg to create a zygote • Creates one set of paired chromosomes (23 from each parent) Child’s sex determined by 23rd pair of chromosomes • XY = male XX = female 11
  • 11.  Combining genes of both parents increases genetic variability • Chromosomes in zygote are not exact copies Identical (monozygotic) twins develop from a single zygote that splits into two Fraternal (dizygotic) twins develop from separate eggs and sperm Gene mutations can permanently alter segments of DNA
  • 12.  Genotype: a person’s genetic material Phenotype: observable characteristics • A range of phenotypes can be expressed for each genotype Dominant-Recessive Genes Principle: a dominant gene always exerts its effects, overriding the potential influence of the recessive gene • A recessive gene only exerts influence if both genes in a pair are recessive
  • 13.  $$ Genetic Imprinting: when genes have differing effects depending on whether they are inherited from the mother or the father Polygenetic Inheritance: characteristics that are determined by the interaction of many different genes • Most characteristics are determined in this manner
  • 14.  Chromosome abnormalities usually involve the sperm and ovum lacking a normal set of 23 chromosomes • Down syndrome: caused by the presence of an extra copy of chromosome 21 Sex-linked abnormalities involve the presence of an extra X or Y chromosome (or the absence of one) • Klinefelter syndrome: males born with XXY instead of XY • Turner syndrome: females born with XO rather than XX, sometimes causing infertility • XYY syndrome: males with extra Y chromosome
  • 15. Fragile X syndrome• $$ is usually characterized by some sort of mentaldeficiency. This deficiency could include having:a. mental retardation.b. a short attention span &c. a learning disability.•occurs more often in males than females; Xchromosome constricted or breaks off
  • 16.  Every individual carries DNA variations, but most do not display a disorder Today, many genetic diseases can be detected prior to and immediately after birth • However, knowledge of genetic flaws leads to difficult choices about how to manage such information Genetic counselors help people make reproductive decisions
  • 17.  $$ Ultrasound Sonography: high-frequency sound waves are directed into the womans abdomen1. used to create a visual representation of fetus’s inner structures Fetal MRI: magnetic resonance imaging designed to diagnose fetal malformations Chorionic Villus Sampling: small sample of placenta is removed to detect genetic and chromosomal abnormalities Amniocentesis: samples amniotic fluid to test for chromosomal or metabolic disorders
  • 18.  $$ Maternal Blood Screening: identifies pregnancies with elevated risk for certain birth defects; such as both Down syndrome and spina bifida Down Syndrome: genetic disorder that causes lifelong mental retardation, developmental delays and other problems. The cause of Down syndrome is one of three types of abnormal cell division involving chromosome 21. Spina Bifida: a portion of the neural tube fails to develop or close properly, causing defects in the spinal cord and in the bones of the backbone.
  • 19.  Infertility: the inability to conceive a child after 12 months of attempting In Vitro Fertilization (IVF): egg and sperm are combined in a laboratory dish; fertilized egg is transferred to woman’s uterus • Success depends on woman’s age • Increases risk of multiple births  Higher risk of life-threatening problems  Health risks to mother  Possible psychological effects on children
  • 20.  Adoption: an alternative to infertility treatment • Children adopted early in life fare better than children adopted later • Somewhat more likely to experience psychological and school-related problems than non-adopted children • No differences in antisocial behavior or self-esteem • Vast majority of adopted children adjust effectively, and most parents are satisfied with their decision to adopt
  • 21.  Behavior Genetics: seeks to discover the influence of heredity and environment on individual differences in human traits and development • Twin studies: compare identical (monozygotic) twins with fraternal (dizygotic) twins • Adoption studies: compare the characteristics of adopted children with their adoptive parents and their biological parents  May also compare adopted and biological siblings
  • 22.  Heredity – Environment Correlations: individuals’ genes may influence the types of environments to which they are exposed
  • 23.  Shared environmental experiences: siblings’ common experiences Non-shared environmental experiences: a child’s unique experiences, both within and outside the family • Shared environment accounts for little of the variation in children’s personality or interest • Heredity influences the non-shared environments through heredity–environment correlations
  • 24.  Epigenetic view: development is an ongoing, bi-directional interchange between heredity and environment • Heredity and environment operate together
  • 25.  The relative contributions of heredity and environment are not additive Complex behaviors have some genetic loading that gives people a propensity for a particular developmental path Our environment is complex, and the interaction of heredity and environment is extensive Much needs to be learned about specific ways in which environment and genetics interact to influence development