The Nature and Nurture of Behavior Genes Explaining Similarity Explaining Differences Environmental Differences Gender

The Nucleus Chromosomes Genes Deoxyribonucleic acid (DNA)

Chromosomes Rod shaped structures found in the center of the nucleus of every cell in the body. Each sperm and each ovum contains 23 chromosomes. The chromosomes contain the genes. The fertilized egg (zygote) and all the body cells that develop from it (except the sperm cells and the ova) contain 46 chromosomes.

Karyotype A photograph of a cell’s chromosomes arranged in pairs according to size

Genes The basic unit of genetic information They determine the nature and the function of the cell. The human genes (about 140,000) are referred to as the human genome. A genome is the full set of genes in each cell of an organism.

A Portion of a DNA Molecule

DNA The substance that genes are composed of that determines the nature of each cell and how it will function. At each level of the spiral or rungs of the ladder are particular chemical pairs. The arrangement of these pairs along the DNA molecule determines which kind of proteins that will be formed in the cell.

Terms Gametes: Sex cells (ovum or sperm) Diploid cells: Cells having 2 copies of each chromosome Haploid gametes: Gametes having 1 copy of each chromosome

Meiosis Meiosis takes place in the testicles and ovaries. A diploid cell (having 2 copies of each chromosome) undergoes a special form of cell division to create haploid gametes (having 1 copy of each chromosome). An egg and a sperm fuse together to form a new diploid cell called zygote (a process called fertilization)

Mitosis In the first step of mitosis, all chromosomes are copied, so that instead of 2 copies, the cell briefly has 4 copies of each chromosome. Shortly afterwards, the cell divides in half, resulting in two cells each has a complete copy of the genetic information. These cells grow larger and eventually undergo mitosis.

Gregor Mendel (1800s)

Genotype The genetic makeup of a given individual Recessive Gene The gene pair that determines a trait in an individual only if the other member of that pair is also recessive Phenotype The traits that are expressed in the individual Dominant Gene One gene of a gene pair that will cause a particular trait to be expressed

Stop and Discuss Gametes Zygote Monozygotic twins Dizygotic twins Diploid cells Haploid gametes Chromosomes Genes DNA Meiosis Mitosis

Celera Genomics The Human Genome Project In June 26, 2000, they both made an announcement that the “correct alphabetical order of the 3.12 billion letters” of the human genome had been mapped. It will be many years before the incredibly complex functions of the genome in making and maintaining a living human being are fully understood.

Genetic Engineering Alteration of Human Genes 1- Gene Therapy 2- Germ-line Genetic Alterations Germ-line Genetic Intervention 3- Genetic Enhancement

1- Gene Therapy Genetic alteration of somatic cells to treat disease. Researchers inject genes that are targeted to treat a particular disease in to a patient’s blood stream. When the genes arrive at the site of the defective genes, they produce chemicals that can treat the problem.

2-Germ-line Genetic Alteration Can correct problems for unborn individuals and future generations. It targets the genes in the reproductive cells – the egg and the sperm that combine the DNA to conceive a new human. Scientist might detect defective cells soon after conception, removing them from the mother and placing them in a test-tube culture. Gene therapy could be employed to correct the defects in the cells. The result could be cloning. Parents could some day customize their children.

3-Genetic Enhancement Non therapeutic genetic alteration An attempt to enhance an already healthy genetic makeup by inserting a gene for improvement (e.g. height, intelligence, eye color)

What Do You Think?

Cloning Producing genetic replicas of the organism

Stop and Discuss In your opinion, how ethical are these issues? 1- Gene therapy 2- Germ-line genetic alteration 3- Genetic enhancement

Universal Behaviors Evolutionary Psychology The study of the evolution of behavioral the mind using principles of natural selection Natural Selection The traits that contribute to reproduction and survival will most likely be passed on to succeeding generations.

Universal Behaviors Evolutionary Psychology Belyaev (Tame Foxes) Mutation A random error in gene replication that leads to a change in the sequence of nucleotides; the source of all genetic diversity. Sexuality

David Buss and the International Team (1994) 50 scientists studied: 10,000 people in 37 cultures in 6 continents

Human Sex Differences Are Universal Males Promiscuous Undiscriminating Competitive and concerned about dominance Prefer beauty and health Like sexual novelty Females Devoted and faithful Cautious Less competitive Prefer resources and social status Like stability and security

Innate Human Characteristics Infant Reflexes An Attraction to Novelty A Desire to Explore and manipulate objects An Impulse to play and Fool Around Basic Arithmetic Skills

Language Acquisition Device Innate Mental Module Noam Chomsky Children in different cultures go through similar stages of linguistic development. Children combine words in ways adults never do. Adults don’t consistently correct their children’s syntax. Even retarded children develop language. Infants can derive simple linguistic rules.

Explaining Differences Behavior Genetics The study of the relative power and limits of genetic and environmental influences on behavior

Twin Studies 13,000 pairs of Swedish twins, 7000 Finnish twin pairs, 3810 Australian twin pairs Identical twins are more similar than fraternal twins on both extroversion & neuroticism Battery of questionnaires to 850 U.S. twins Identical twins are more similar inabilities, personality traits, & interests. Reported being treated alike

Separated Twins The Jim Twins Similar in: brain waves voice intonation interests heart rate personality intelligence

Adoption Studies People who grow up together, whether biologically related or not, do not much resemble one another in personality. Adoptee’ traits bear more similarities to their biological parents than to their care-giving adoptive parents

Temperament Studies Traits such as excitability – whether the baby is intense, reactive, fidgety, easy going, or quiet tend to remain steady in later years

Group Differences Of our genetic differences Only 6% are among races Only 8% are differences among groups within a race The rest – over 85% - are individual variations within local groups Some traits are highly heritable: Weight, height, and intelligence

The “Obese” Gene Obese gene causes fat cells to produce leptin. Leptin travels through blood to hypothalamus (regulates appetite) Leptin reduces appetite

The Function of the Protein Leptin Reduces appetite Speeds up metabolism Makes people more active

Why Do People Gain Weight Rapidly? Secretion of leptin is impaires May produce plenty of leptin but their body does not respond to it. Tendency to store calories which have a survival advantage.

Gene-Environment Interaction “Heredity deals the cards; environment plays the hand.” Psychologist Charles L. Brewer (1990)

Environmental Influence Prenatal Environment Experience and Brain Development Peer Influence Culture Gender

Prenatal Care Diet The father’s involvement Age of mother Illness of mother Drug use Alcohol Teratogens

Experiences and Brain Development Rosenzweig and Krech’s experiment on rats: Those living in the enriched environment developed a thicker and heavier brain cortex. Experience preserves our activated connections while allowing the unused connections to degenerate Use it or lose it

Parents and Peers are Complementary Howard Gardner (1998) “Parents are more important when it comes to education, discipline, responsibility, orderliness. Charitableness, and ways of interacting with authority figures. Peers are more important for learning cooperation, for finding the road to popularity, for inventing styles of interaction among people of the same age. Youngsters may find their peers more interesting, but they will look to their parents when contemplating their own futures.”

Culture Variation Across Cultures Variation Over Time Culture and Child Rearing

Gender The Nature of Gender The Nurture of Gender X chromosome Y chromosome Testosterone The Nurture of Gender Gender role

What Is the Role of Parenting? 1- Do parents really produce future adults with a wounded child within by being irresponsible? 2- Should we blame our parents for our failings? 3- Should we shame the parents of troubled children? 4- Should parents be given less credit for children who turn out great? 5- What is the role of parents?