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Children

Biological

Beginnings

2

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Images of Child Development

• Stories of the Jim and Jim Twins

– Identical twins separated after birth

– Identical lifestyles after 39 years apart

– Part of Minnesota Study of Twins Reared Apart; other twin sets with similar outcomes

What is the Evolutionary Perspective?

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Natural Selection and Adaptive Behavior

• Natural selection– Evolutionary process favors individuals

best adapted to survive and reproduce

• Evolutionary psychology– Emphasizes adaptation, reproduction,

and “survival of the fittest” in shaping behavior

What is the Evolutionary Perspective?

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Brain Sizes of Humans and Primates

What is the Evolutionary Perspective?

Fig. 2.1

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The Genetic Process

• DNA and the Collaborative Gene– Chromosomes: threadlike structures that

come in 23 pairs, one member of each pair coming from each parent

– DNA: complex molecule; double helix– Genes: units of heredity– Human Genome Project

Genetic Foundations

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Cells, Chromosomes, Genes, and DNA

Nucleus (center of cell) contains chromosomes and genes

Chromosomes are threadlike structures

composed of DNA molecules

Gene: a segment of DNA (spiraled double chain) containing the

hereditary code

CellChromosomes

DNA

Fig. 2.2

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The Genetic Process

• Gene activity – genetic expression• Mitosis, Meiosis, and Fertilization

– Mitosis: cell’s nucleus duplicates itself– Meiosis: cell division to form eggs and sperm

(or gametes)

– Reproduction: begins when female gamete (ovum) fertilized by male gamete (sperm)

– Zygote: single cell formed through fertilization; 23 pairs of chromosome

Genetic Foundations

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Genetic Difference BetweenFemales and Males

Fig. 2.4

Genetic Foundations

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Genetic Principles

• Dominant-Recessive Genes Principle– Recessive gene is influential only if both

genes are recessive– Phenotype and genotype

• Sex-Linked Genes: X-linked inheritance• Genetic Imprinting• Polygenetic Inheritance

Genetic Foundations

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Fig. 2.5

Dominant-Recessive Gene Principle

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Chromosome Abnormalities

• Chromosome abnormalities – Gamete does not have normal set of 23

• Down syndrome– Chromosomal form of mental retardation

• Phenylketonuria (PKU)– individual cannot properly metabolize an

amino acid; easily detected and prevented

• Sickle-cell anemia – affects red blood cells; recessive gene

influence

Genetic Foundations

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Sex-Linked Chromosome Abnormalities

Klinefelter syndrome

Disorder in males; extra X chromosome

Fragile X syndrome

Abnormality in X chromosome;becomes constricted or breaks

Turner syndrome

Female disorder; X chromosome

missing or partially deleted

XYY syndrome

Disorder in males; extra Y chromosome

Genetic Foundations

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Prenatal Diagnostic Tests

• Ultrasound sonography: high-frequency sound waves directed into abdomen

• Chorionic villi sampling: sample of the placenta

• Amniocentesis: sample of amniotic fluid• Maternal blood or triple screening• Noninvasive prenatal diagnosis (NIPD)

Reproductive Challenges

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Infertility and Reproduction

• Infertility– inability to conceive after 12 months of

regular intercourse

• In vitro fertilization (IVF)• Gamete intrafallopian transfer (GIFT)• Zygote intrafallopian transfer (ZIFT)• Adoption - screened in/out couples

Reproductive Challenges

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Caring for Children

• Increased diversity of adopted children and adoptive parents

• Effective parenting of adopted children

– Be supportive and caring

– Be involved and monitor the child

– Be a good communicator

– Help the child develop self-control

– Face challenges with a positive approach

Reproductive Challenges

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Behavior Genetics

• Behavior genetics

– Influence of heredity and environment on individual trait and developmental differences

– Twin studies

• compare behavioral similarity of identical (monozygotic) twins with behavioral similarity of fraternal (dizygotic) twins

– Adoption studies

Heredity and Environment

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Heredity and Environment

• Heredity-environment correlations– Passive genotype-environment– Evocative genotype-environment– Active (niche-picking)

• Heredity-environment interaction has complexities

• Individuals influence environments, yet individuals “inherit” environments

Heredity and Environment

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Nature and Nurture

• Shared environmental experiences– Siblings’ common experiences

• Parents, family orientation, SES, neighborhood

• Nonshared environmental experiences– The unique child

Heredity and Environment

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The Epigenetic View

• Development is the result of ongoing, bidirectional interchange between heredity and environment.

• Conclusions About Heredity-Environment Interaction– Operate cooperatively– Relative contributions are not additive– Many complex behaviors have some genetic

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Heredity and Environment

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The End

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