Biological Beginnings Chapter 2 © 2013 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for

Biological Beginnings

Chapter 2

© 2013 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.

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Chapter Outline

• The evolutionary perspective• Genetic foundations of development• Reproductive challenges and choices• Heredity-environment interaction: The nature-

nurture debate


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The Evolutionary Perspective

• Natural selection and adaptive behavior• Evolutionary psychology


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Natural Selection and Adaptive Behavior

• Natural selection - Evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce

• Adaptive behavior - Promotes an organism’s survival in the natural habitat


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Evolutionary Psychology

• Emphasizes the importance of adaptation, reproduction, and survival of the fittest in shaping behavior

• Evolutionary developmental psychology– Interest has grown in using the concepts of

evolutionary psychology to understand human development

– Psychological mechanisms are domain-specific


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• Connecting evolution and life-span development– Benefits conferred by evolutionary selection

decrease with age– Natural selection primarily operates during the

first half of life


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– Older adults • Weaken biologically • Need culture-based resources

– Cognitive skills, literacy, medical technology, and social support


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Figure 2.2 - Baltes’ View of Evolution and Culture Across the Life Span


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• Evaluation– Evolution gave us biological potentialities but it

does not dictate behavior– People have used their biological capacities to

produce diverse cultures• Aggressive and peace-loving, egalitarian and autocratic

– Studying specific genes in humans and other species and their links to traits and behaviors• Best approach for testing ideas coming out of

evolutionary psychology© 2013 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part.

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Genetic Foundations of Development

• The collaborative gene• Genes and chromosomes• Genetic principles• Chromosomal and gene-linked abnormalities


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The Collaborative Gene

• Human life begins as a single cell• Nucleus of each cell contains chromosomes– Chromosomes: Threadlike structures made up of

deoxyribonucleic acid – DNA: A complex double-helix molecule that

contains genetic information

• Genes: Units of hereditary information, are short segments of DNA


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Figure 2.3 - Cells, Chromosomes, DNA, and Genes


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• Genome-wide association method - Identify genetic variations linked to a particular disease

• Human genome consists of many genes that collaborate:– Both with each other and with nongenetic factors

inside and outside the body


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• Activity of genes is affected by their environment

• Stress, radiation, and temperature can influence gene expression

• Exposure to radiation changed the rate of DNA synthesis in cells


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Genes and Chromosomes

• Mitosis, meiosis, and fertilization– Mitosis: Reproduction of cells– Meiosis: Cell division that forms sperm and eggs

(gametes)– Fertilization: A stage in reproduction when an egg

and a sperm fuse to create a single cell, called a zygote• Zygote: A single cell formed through fertilization


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Figure 2.5 - The Genetic Difference Between Males and Females


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• Sources of variability– Combining the genes of two parents in off spring

increases genetic variability– Identical twins (monozygotic twins) • Develop from a single zygote that splits into two

genetically identical replicas, each of which becomes a person


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– Fraternal twins (dizygotic twins) • Develop when two eggs are fertilized by different

sperm, creating two zygotes that are genetically no more similar than ordinary siblings


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– Mutated gene - Permanently altered segment of DNA

– Susceptibility genes - Make the individual more vulnerable to specific diseases or accelerated aging

– Longevity genes - Make the individual less vulnerable to certain diseases and more likely to live to an older age


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– Genotype: Genetic heritage– Phenotype: Way an individual’s genotype is

expressed in observed and measurable characteristics


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Genetic Principles

• Dominant-recessive genes principle– One gene of a pair always exerts its effects

(dominant), overriding the potential influence of the other gene (recessive)

• Sex-linked genes– When a mutated gene is carried on the X

chromosome, the result is called X-linked inheritance


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Genetic Principles

• Genetic imprinting– Occurs when the expression of a gene has

different effects depending on whether the mother or the father passed on the gene


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Genetic Principles

• Polygenic inheritance– Polygenically determined - Determined by the

interaction of many different genes– Gene-gene interaction - Studies that focus on the

interdependence of two or more genes in:• Influencing characteristics, behavior, diseases, and

development


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Figure 2.6 - Some Chromosomal Abnormalities


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Gene-Linked Abnormalities

• Phenylketonuria (PKU)– Metabolic disorder that, left untreated, causes

mental retardation– Early tests for better outcomes

• Sickle-cell anemia– Blood disorder that limits the body’s oxygen

supply– Can cause joint swelling, as well as heart and

kidney failure


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• Cystic fibrosis– Glandular dysfunction that interferes with mucus

production– Breathing and digestion are hampered, resulting in

a shortened life span

• Diabetes– Body does not produce enough insulin, which

causes abnormal metabolism of sugar


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• Hemophilia– Delayed blood clotting causes internal and

external bleeding

• Huntington’s disease– Central nervous system deteriorates, producing

problems in muscle coordination and mental deterioration


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• Spina bifida– Neural tube disorder that causes brain and spine

abnormalities

• Tay-Sachs disease– Deceleration of mental and physical development

caused by an accumulation of lipids in the nervous system


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Dealing with Genetic Abnormalities

• Every individual carries DNA variations that might predispose the person to serious physical disease or mental disorder

• Genes that are missing, nonfunctional, or mutated can be associated with disorders

• Knowledge of genetic flaws might bring important costs as well as benefits


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Reproductive Challenges and Choices

• Prenatal diagnostic tests• Infertility and reproductive technology• Adoption


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Prenatal Diagnostic Tests

• Ultrasound sonography• Brain imaging techniques• Chorionic villus sampling• Amniocentesis• Maternal blood screening• Noninvasive prenatal diagnosis (NIPD)• Fetal sex determination


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Infertility and Reproductive Technology

• Infertility - Inability to conceive a child after 12 months of regular intercourse without contraception

• In vitro fertilization (IVF) - Eggs and sperm are combined in a laboratory dish– Fertilized egg is transferred into the woman’s

uterus

• Success rate of IVF depends on the mother’s age


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Adoption

• Social and legal process that establishes parent-child relationship between persons unrelated at birth– Increased diversity of adopted children and

adoptive parents– Outcomes for adopted children• Adopted children fare much better than children raised

in long-term foster care• Children who are adopted very early are more likely to

have positive outcomes


Heredity-Environment Interaction:The Nature-Nurture Debate

• Behavior genetics• Heredity-environment correlations• Shared and nonshared environmental

experiences• The epigenetic view and gene x environment

(g x e) interaction• Conclusions about heredity-environment

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Review, Connect, Reflect

• In groups of 3-4 complete the Connect & Reflect sections on page 72 (international version).

• We will discuss these sections in class.

• 30 minutes…GO!

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Behavior Genetics

• Seeks to discover the influence of heredity and environment on individual differences in human traits and development– Twin study: Behavioral similarity of identical and

fraternal twins is compared


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Biological Beginnings Chapter 2 © 2013 by McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for