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The Nature and Nurture of Behavior

The Nature and Nurture of Behavior. Genes Explaining Similarity Explaining Differences Environmental Differences Gender. The Human Cell. The human body is comprised of over 200 different kinds of cells which are the smallest self-contained structures

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The Nature and Nurture of Behavior

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

  2. The Human Cell • The human body is comprised of over 200 different kinds of cells which are the smallest self-contained structures • Cell membrane: the outside layer of the cell • Cytoplasm: is comprised of specialized structures • Mitochondria: are the powerhouses that process nutrients and provide the cell’s energy • Endoplasmic reticulum, Golgi apparatus, and ribosomes: produce proteins • Neucleus: The inner part of the cell

  3. The Nucleus • Chromosomes • Genes • Deoxyribonucleic acid (DNA)

  4. 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.

  5. KaryotypeA photograph of a cell’s chromosomes arranged in pairs according to size

  6. 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.

  7. A Portion of a DNA Molecule

  8. DNA • They determine 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.

  9. 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

  10. 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)

  11. 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.

  12. Gregor Mendel (1800s)

  13. 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

  14. Gametes Zygote Monozygotic twins Dizygotic twins Diploid cells Haploid gametes Genome Chromosomes Genes DNA Meiosis Mitosis Phenotype Genotype Stop and Discuss

  15. Celera Genomics ProjectThe 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.

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

  17. 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.

  18. 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.

  19. 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)

  20. Cloning • Producing genetic replicas of the organism

  21. What Do You Think?

  22. Stop and Discuss • In your opinion, how ethical are these issues? 1- Gene therapy 2- Germ-line genetic alteration 3- Genetic enhancement 4- Cloning

  23. Universal BehaviorsEvolutionary Psychology Evolution The process through which species change across generations Evolutionary Psychology The study of inherited psychological characteristics. Natural Selection The traits that contribute to reproduction and survival will most likely be passed on to succeeding generations.

  24. Universal BehaviorsEvolutionary Psychology Mutation A random error in gene replication that leads to a change in the sequence of nucleotides; the source of all genetic diversity. Sexuality

  25. David Bussand the International Team(1994) • 50 scientists studied: 10,000 people in 37 cultures in 6 continents

  26. 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 Human Sex Differences Are Universal

  27. 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

  28. Language Acquisition DeviceInnate Mental ModuleNoam 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.

  29. Explaining DifferencesBehavior Genetics Behavior Genetics • The study of the relative power and limits of genetic and environmental influences on behavior

  30. 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 in abilities, personality traits, & interests. Reported being treated alike

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

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

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

  34. 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

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

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

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

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

  39. Environmental Influence • Prenatal Environment • Experience and Brain Development • Peer Influence • Culture • Gender

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

  41. 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

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