 Chapter 2 Biological Foundations: Heredity, Prenatal Development, and Birth DEP 2004 & 2004H Human Development Across the Lifespan Erica Jordan, Ph.D., University of West Florida School of Psychological and Behavioral Sciences

Lecture Guiding Questions  How do genes influence behaviors?  What are the major stages of prenatal development?  What risks factors are associated with prenatal development? Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

How do genes influence behaviors?  Behavioral Genetics: the branch of genetics that deals with inheritance of behavioral and psychological traits  Traits controlled by a single gene typically produce one of two outcomes (either - or)  Most behavioral and psychological traits are more complex  Possible phenotypes fall along a continuum or have multiple possibilities  Result from the instructions/interactions of separate genes—polygenic inheritance  Influence of each specific gene involved is very difficult to determine Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

NEW SLIDE! Research Methods Commonly Used to Study Behavioral Genetics  Twin studies  Comparison of monozygotic twins (identical and from the same fertilized egg) and dizygotic twins (fraternal and from different eggs).  Characteristics commonly shared by monozygotic twins that are often different in dizygotic twins are typically inherited. Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

 _________________________  Comparing adopted children alongside their biological parents and their adoptive parents.  _________________________  Taking samples of DNA from individuals who differ in some way then examining the DNA for differences. Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

More about the way genes influence behaviors: 1. The behavioral consequences of genetic instructions depend on the environment in which those instructions are implemented. - A specific genotype does not always lead to the same phenotype. - Reaction range—range of potential phenotypes for a specific genotype. - Heritability coefficient—the probability that a characteristic is inherited; very sensitive to other factors; range from 0 to Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

2. Heredity and environment interact dynamically throughout development. 3. Genes can influence the kind of environment to which a person is exposed. - Responses from others - —refers to how people seek out their own environments based on their interests and strengths Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

4. Environmental influences typically make children within a family different. - Siblings often have similar experiences - Nonshared environmental influences also occur Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Common Genetic Disorders  Sickle-cell desease  PKU  Huntington’s disease  Down syndrome  Klinefelter’s syndrome  Turner’s syndrome  XYY complement  XXX syndrome Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

From Conception to Birth  Prenatal Development  The changes that turn a fertilized egg into a newborn human Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Period of the Zygote (Week 1 - 2)  Zygote:  Period begins with fertilized egg and ends with zygote is implanted into the uterine wall about 2 weeks later (implantation) Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Period of the Embryo (Week 3 - 8)  Begins when zygote is completely embedded in the uterine wall.  Major body structures are created  Cells become specialized  Growth follows the cephalocaudal principle and the proximodistal principle Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Period of the Fetus (Weeks )  Final and longest phase of prenatal development. Begins when cartilage begins to turn to bone and ends at birth.  Fetus becomes much larger and brain regions grow.  Finishing touches are placed on many systems (eyebrows, skin thickens, vernix covers skin, etc.). Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Risks to Prenatal Development  Parents’ age  Nutrition  Stress  Disease  Drugs  Environmental hazards  Teratogens—agents that cause abnormal prenatal development Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)

Teratogens: Five Principles  Impact depends on the genotype of the organism.  Impact changes over the course of prenatal development.  Affects a specific aspect (or aspects of prenatal development).  Impact depends on the dose.  Damage may not appear until later in life. Adapted from Kail & Cavanaugh's Human Development: A Life-Span View (5th Ed.)