Chapter 2 Biological and Environmental Foundations

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

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.

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

Chromosomes, Cells, and Sex: Terminology Autosomes The 22 pairs of chromosomes that are not sex chromosomes Sex Chromosomes 23rd pair of chromosomes Determines sex XX = female, XY = male GametesSex cells: Sperm and ova ZygoteSperm and ovum united

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

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

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

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

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

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

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

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 21 st 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

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

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

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

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

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

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)

Importance of Regularly Eating Dinner as a Family

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 %

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

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

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

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

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

Individualistic and Collectivistic Societies CollectivistIndividualistic 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.

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

How Does the U.S. Compare to Other Nations on Indicators of Children’s Health and Well- Being? Well-Being IndicatorU.S. RankCanadian Rank Childhood Poverty2516 Infant Death2616 Teen Pregnancy2821 Education Spending126 Health Spending164

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

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

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)

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

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

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

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