Nature, Nurture, and Human Diversity Chapter 3

Chapter Overview  Behavior Genetics  Evolutionary Psychology  Parents and Peers  _________________  Gender Development  Reflections on Nature and Nurture

Behavior Genetics and Evolutionary Psychology

Genes are parts of DNA molecules, which are found in chromosomes in the nuclei of cells. DNA (Deoxyribonucleic Acid) GENES: The Building Blocks of Heredity and Development Genes are parts of DNA molecules, which are found in chromosomes in the nuclei of cells. Video GENES: The Building Blocks of Heredity and Development

Chromosomes are made of DNA, which are made of genes. } Chromosome: threadlike structure made largely of DNA molecules DNA: a spiraling, complex molecule containing genes

Chromosomes and Inheritance  The human genome includes 46 chromosomes in 23 sets matched sets; each chromosome has the same gene locations.  This includes the X and Y chromosomes, not a matched set in males, who are missing some genes on the Y.  We received half a set of chromosomes from each biological parent.

How Genes Work  Genes are not blueprints; they are molecules.  These molecules have the ability to direct the assembly ____________________ __________________  This genetic protein assembly can be turned on and off by the environment, or by other genes.  Any trait we see is a result of the complex interactions of many genes and countless other molecules.

8 Some topics:  Natural selection and adaptation  Evolutionary success may help explain similarities  An evolutionary explanation of human sexuality Evolutionary Psychology: Understanding Human Nature __________________ _____________is the study of how evolutionary principles help explain the origin and function of the human mind, traits, and behaviors. Can we may now learn something about evolution by studying the the ways in which humans are alike? VideoVideo

Begin with a species’ genome, which contains a variety of versions of genes that shape traits. Conditions make it difficult for individuals with some traits (some versions of those genes) to survive long enough to reproduce. Other individuals thus have their traits and genes “selected” to spread in the population. Evolutionary Psychology: Natural Selection: How it Works

Evolutionary Psychology  __________________  the principle that, among the range of inherited trait variations, those that lead to increase reproduction and survival will most likely be passed on to succeeding generations  Only the Strong Survive???  __________________  Mutation  a random error in gene replication that leads to genetic damage Evolutionary Psychology

_______________ CCharles Darwin GGalapagos Islands FFinch’s (Beak Size) IImpact on biology RRecent trends in Evolutionary Psychology

Evolutionary Misconceptions Man comes from monkeys? Evolutionary Psychology-Myth vs Reality

Skull Evolution

Take Anthropology….

Primate Similarities…What about behavior? Primate Cooperation Video

16  Dmitri Balyaev and Lyudmila Trut spent 40 years selecting the most gentle, friendly, and tame foxes from a fox population, and having those reproduce.  As a result, they were able to shape avoidant and aggressive creatures into social ones, just as wolves were once shaped into dogs. ___________________ The Domesticated Silver Foxes

17  Why do people so easily acquire a phobia of snakes, more easily than a phobia of cars?  An evolutionary psychologist would note that snakes are often poisonous… …so, those who more readily learned to fear them were more likely to survive and reproduce. Evolutionary Psychology’s Explanation of Biologically Driven Phobias

Evolutionary Psychology Evolution

Evolutionary Psychology _______________________  the study of the evolution of behavior and the mind, using the principles of natural selection  The “Why” of behavior  In what ways could our current behaviors have been advantageous to our ancestors?  Fears-Snakes and Heights  Agression- Violent Species  Sexual Behaviors  What else?? Evolutionary Psychology

AAsk the Class IIn one study __percent of adult video customers were male. MMost romance novel readers are female. MMen __% Women __% “If 2 people really like each other its ok for them to have sex even if they have known each other a very short time.”

 Poll the Class  More women mention affection as a reason for having first sexual intercourse,  Think about sex multiple times per day. Men __% and Women ___%  More likely to attribute friendliness to sexual interest.  More likely to initiate sexual activity. Evolutionary Psychology

 Men preferred __________________ suggesting youth and health  Women preferred ___________________ Evolutionary Psychology

How Many Babies Could You Have?? Women- are fertile ages 13 through 50 –About 1.25 per year –For about 37 years –Which equals about….. – 46 children in a lifetime….at most! Men- are fertile ages 13 through death –About how many a day? Be realistic!! Maybe 5! –365 days a year –for about 67 years –Who has a calculator?? – 122,275 children in a lifetime….Whoa!!!

___________________: Predicting Individual Differences More ways of exploring the origins of the biology of behavior: 1.Understanding genes 2.Twin and adoption studies 3.Gene/environment interactions 4.Evolutionary Psychology Behavior geneticists study how heredity and environment contribute to human differences.

Twin and Adoption Studies To assess the impact of nature and nurture, how do we examine how genes make a difference within the same environment?  study traits of siblings vs. identical twins  see if the siblings vary more than twins Fraternal and Identical Twins Fraternal “twins” from separate eggs are not any more genetically alike than other siblings. Identical twin: Same sex only Fraternal twin: Same or opposite sex

Twin and Adoption Studies How do we find out how the same genes express themselves in different environments? We can study the traits of identical twins as they grow up, or if they were raised separately (e.g., the Minnesota Twin Family Study). ___________________Twins Studies of twins in adulthood show that identical twins are more alike than fraternal twins in:  personality traits such as extraversion (sociability) and neuroticism (emotional instability).  behaviors/outcomes such as the rate of divorce.  abilities such as overall Intelligence test scores.

Critiques of Twin Studies 1.In the more recent years of the Minnesota Twin Family Study, twins have known about each other and may influence each other to be more similar. 2.Coincidences happen; some randomly chosen pairs of people will have similar traits. 3.Environments may be similar; adoptive families tend to be more similar than randomly selected families in education, income, and values. Studies of Identical Twins Raised Apart Similarities found in identical twins despite being raised in different homes:  personality, styles of thinking and relating  abilities/intelligence test scores  attitudes  interests, tastes  specific fears  brain waves, heart rate BUT none of these factors explains, better than the genetic explanation, why fraternal twins have more differences than identical twins.

Searching for Parenting Effects: Biological vs. Adoptive Relatives Studies have been performed with adopted children for whom the biological relatives are known. Findings: Adopted children seem to be more similar to their genetic relatives than their environmental/nurture relatives. Given the evidence of genetic impact on how a person turns out, does parenting/nurture make any difference? Does the home environment have any impact?

Despite the strong impact of ____________ on personality, ___________has an influence on:  religious beliefs  ___________  manners  attitudes  politics  habits Parenting Does Matter