Biological and Environmental Foundations

1. Biological and Environmental Foundations Chapter 2

2. Genotypes and Phenotypes • Genotype • Individuals’ unique genetic makeup • Phenotype • Directly observable characteristics • Example: hair color, eye color, height, etc.

3. Genetic Foundations • Chromosomes – rodlike structures inside the nucleus of each cell in the body • store and transmit genetic information • Genes – segments of DNA located along the chromosomes • DNA – substance of which genes and chromosomes are made.

4. DNA and Mitosis • Mitosis – when DNA duplicates itself • Each new cell receives an exact copy of the original chromosomes • Allows one-celled fertilized ovum to develop into a complex human being composed of many cells

5. Chromosomes, Cells, and Sex: Terminology

6. How New People Are Formed • New people are created when two gametes (sex cells) combine • Normal # of chromosomes in a cell = 46 • Gametes are formed through a cell division process called meiosis • Meiosis – when the number of chromosomes in each cell is halved • Gametes only have 23 chromosomes • When they combine, the new zygote again has 46 chromosomes

7. Twins • Fraternal/dizygotic • 2 ova are released and fertilized • Genetically no more alike than regular siblings • Identical/monozygotic • Occurs when a zygote that has started to duplicate separates into two clusters of cells that develop into two individuals • Have same genetic makeup

8. Alleles • Two forms of the same gene • Remember, except for the XY pair in males, all chromosomes come in corresponding pairs • Two forms of each gene occur at the same place on the chromosomes • One inherited from the mother and one from the father • Each pair = Allele • Homozygous – alleles from both parents are alike • Child will display the inherited trait • Heterozygous – alleles from each parent differ • Relationships between the alleles determine the trait that will appear

9. Dominant – Recessive Inheritance • Occurs in many heterozygous pairings • Only one allele affects the child’s characteristics • Dominant allele – one that affects the child’s characteristics • Recessive – one that has no effect on the child’s characteristics • Example: • allele for dark hair is dominant – D • Allele for blonde hair is recessive – d • DD = dark hair • Dd = dark hair • dd = blonde hair

10. X – Linked Inheritance • When a harmful allele is carried on the X chromosome • Males are more likely to be affected because their sex chromosomes do not match (XY) • Females – any recessive allele on one X chromosome has a good chance of being suppressed by a dominant allele on the other X • But the Y chromosome is only about 1/3 as long and lacks many corresponding genes to override those on the X • Example: hemophilia

12. Incomplete Dominance & Polygenic Inheritance • Incomplete Dominance • A pattern of inheritance in which both alleles are expressed • Results in a combined trait intermediate between the two alleles • Example: • Sickle cell trait – heterozygous • One dominant and one recessive = carrier • Sickle cell anemia – child inherits two recessive genes • Polygenic Inheritance • Many genes influence a characteristic • Complex, still don’t know a lot about it

13. Genomic Imprinting and Mutation • Genomic imprinting • Alleles are imprinted, or chemically marked, so that one pair member (either the mother’s or the father’s) is activated, regardless of its makeup • Often temporary • Mutation • A sudden change in a segment of DNA • Perminant

14. Chromosomal Abnormalities • Most defects result from mistakes during meiosis when the ovum and sperm are formed • Chromosome pair does not separate properly • Part of a chromosome breaks off • Down Syndrome • Problems with the 21st chromosome • Failure to separate properly during meiosis, baby inherits 3 chromosomes • Sex Chromosome Abnormalities • Presence of an extra chromosome (either X or Y) or absence of one X in females

15. Environmental Contexts for Development • Family • Socioeconomic status and family functioning • Affluence • Poverty • Neighborhoods, towns and cities • Cultural context

16. Family Influences on Development • Family – social system of interdependent relationships • Direct • 2 – person relationships • Example: parent-child, marital partners, siblings • Indirect • Third parties • Interaction between any two family members is affected by others present in the setting • Example: parents who have a warm, considerate marital relationship praise and stimulate their children more • Adapting to change • Changes from within and outside the family • Example: birth of a new baby, change of occupation

17. Socioeconomic Status (SES) • Social status • Years of education • Job prestige and skill required • Economic status • Income

18. SES and Family Functioning • Timing and duration of family life cycle • Lower SES – marry and have children earlier, have more children • Higher SES – marry and have children later, have less children • Values and expectations • Lower SES – tend to emphasize external characteristics (obedience, politeness, neatness, cleanliness) • Higher SES – emphasize psychological traits (curiosity, happiness, self-direction, cognitive and social maturity) • Education, status of women • Education of women fosters patterns of thinking that greatly improve quality of life for both parents and children

19. SES and Family Functioning (cont.) • Communication and discipline styles • Lower SES – greater use of coercive discipline and physical punishment • Higher SES – tend to use discussion techniques and teach children how to make independent decisions • Children’s cognitive development • Lower SES – less likely to provide stimulation for children • Higher SES – more likely to provide simulation

20. Risks of Affluence • Affluent parents – highly prestigious jobs and six-figure incomes • Children: • More likely to use alcohol and other drugs • Report high levels of anxiety and depression • Report less emotional closeness and supervision from parents • Unavailable parents • Overscheduled (never around) • Demanding (make excessive demands for achievement)

21. Importance of Regularly Eating Dinner as a Family

22. Poverty: Who Is Poor? • 15.1% in the United States as of 2012 • Parents under age 25 with young children (50 %) • Elderly living alone, especially women (50%) • Ethnic minorities • Women • Children under 18 (22%) • Hispanic children 35 % • Native-American children 32 %*** (not updated) • African-American children 38 % • http://www.npc.umich.edu/poverty/

23. Poverty: Homelessness • On any given night, approximately 350,000 people in the U.S. have no place to live • 23 % of homeless are families with children • Majority with children under age 5 • Poor school attendance • Approximately 25 to 30% who are old enough do not attend school • Health issues • Developmental delays • Homelessness mostly due to: • Decline in availability of government-supported, low-cost housing • Release of mentally ill people from institutions who receive no help to adjust to ordinary life

24. Benefits of Strong Community Ties for Children and Adults • Social interaction, activities – reduce family stress and enhance adjustment • Frequent contact with friends, relatives, regular religious service attendance • Cooperation to provide clean, safe environment • Participation in important tasks • Mutual assistance

25. Neighborhoods • Neighborhood resources have a greater impact on low SES young people • Impact can be either positive or negative • In-school and after-school programs • Provide enrichment activities – associated with improved academic performance and reduction in emotional and behavior problems • Neighborhood organizations and informal social activities • Predict increased self-confidence, school achievement, and educational aspirations

26. Towns and Cities • Rural areas and small towns • Youths more likely to be given important tasks (caring for livestock, operating a snowplow, playing in the town band) • Usually alongside adults – instill strong sense of responsibility and teach practical and social skills • Stronger connections between settings (ex. Schools serve as community centers, more frequent parent-teacher interaction) • Active involvement in the community is likely to be greater throughout the life span • Public places are relatively safe and secure

27. Extended Families • Three or more generations live together • More common in minority cultures • Benefits • Reduces stress of poverty • More employed adults in the household • Assistance for all generations • Grandparents play large roll in guiding younger generations • Adults who face employment, marital, or child-rearing difficulties receive assistance and emotional support • Caregiving is enhanced for children and the elderly • Generally enhanced emotional bonds and support

28. Individualistic and Collectivistic Societies Collectivist Individualistic People define themselves as part of a group Stress importance of group goals over individual goals Value interdependent self More common in Asian societies People define themselves as separate entities; separate from other people Largely concerned with individual/personal needs and goals Value independent self More common in western societies like the U.S.

29. Public Policies and Lifespan Development • Public policies – laws and government programs designed to improve current conditions • Example: if homelessness increases • Build more low-cost housing, raise minimum wage, increase welfare benefits • Example: Obamacare

30. How Does the U.S. Compare to Other Nations on Indicators of Children’s Health and Well-Being?

31. Policies for the Elderly • U.S. was behind the curve in policies to protect the elderly • Social Security – awarded in the U.S. in 1930s • Decade behind most Western nations • 1960s – federal spending on programs for the elderly expanded • Medicare, national health insurance program • Only 4% of federal budget for the elderly goes to programs other than Social Security and Medicare (which are working so well…) • Most Area Agencies on Aging operate at regional and local levels • Communal and home-delivered meals, self-care education, elder abuse prevention, etc • Poorly funded – help far too few people in need

32. How Much Does Heredity Contribute to Behavior? • Heritability estimates • Measures extent to which individual differences in traits are due to genetic factors • Ranges from 0 to 1.00 • Obtained from kinship studies • Compares the characteristics of family members • What percent of the time do family members/twins show a trait • Ranges from 0 to 100% • Example: heritability value for intelligence in children = .50 • Suggests that differences in genetic makeup explain about half of the variation in intelligence

33. Heredity and the Environment • Range of reaction • Each person’s unique, genetically determined response to the environment • Can apply to any characteristic • 2 important points • Shows that because each person has a unique genetic makeup, we respond differently to the same environment • Sometimes different genetic – environmental combinations can make two people seem similar (when in reality they are not)

34. Ben’s intelligence increases steadily with the quality of the environment • Linda’s rises sharply, then falls off • Ron’s begins to increase only after the environment becomes modestly stimulating

35. Genetic – Environmental Correlation • Our genes influence the environments we are exposed to • Changes with age • Passive correlation • Younger ages • Child has no control over its genetic influence on environment because parents provide environments influenced by their own heredity • Evocative correlation • Children evoke responses from the environment that are influenced by their own heredity • Responses strengthen child’s original style • Ex. Active friendly baby is likely to get more social stimulation than a passive quiet infant • Active correlation • Children extend their experiences beyond immediate family • Niche-Picking – Actively seek environments that fit with their genetic tendencies • Ex. Well-coordinated muscular child spends more time at after-school sports & musically talented child joins school band and plays violin

36. The Epigenetic Framework • Views relationship between heredity and environment as bi-directional • Genes affect people’s behavior and experiences but their experiences and behavior also affect gene expression • Epigenesis – development results from ongoing, bidirectional exchanges between heredity and all levels of the environment

37. Example: providing a baby with a healthy diet increases brain growth • Leads to new connections between nerve cells, which transform gene expression • Opens the door to new gene-environment exchanges like advanced exploration of objects • Further enhances brain growth and gene expression