1. Chapter 4

2. Children inherit many physical features from their parents. This may include: skin color, eye color, being tall or short, etc. Many aspects of our behavior are influenced by our genes. Genes seem to influence us broadly. Science has shown that certain aspects of our personality can be influenced by genetic factors. Our socialness, our ability to be aggressive, alcohol and drug use, kindness, depression, and anxiousness can be influenced by genetics. This is never the sole cause of our behaviors, though, as environmental plays a significant role. NATURE: GENETIC INFLUENCES ON BEHAVIOR

3. Gregor Mendel was an Austrian monk were helped to discover genetics in the 1860’s. He studied pea plants and selectively breed them. Later studies using mice in mazes showed that genetics helps them to find the exit. A study completed on mice and selective breeding of aggressive female mice showed that mice bred from these females were even more aggressive. Even when embryos of aggressive mice were put into the wombs of passive mice, the baby mice were still aggressive. GENETIC STUDIES OF NONHUMAN ANIMAL BEHAVIOR

4. It is more difficult to study the role of human behavior (and aggressiveness) in humans as it would be unethical to do the mice experiment. There is not the same amount of experimental control with human beings. Any conclusions involving experiments with human beings need to be cautious. Most people will look at twins to learn about genetics as identical twins have the same genetics. GENETIC STUDIES OF HUMAN BEHAVIOR

5. Identical twins are called monozygotic twins. This means a single fertilized egg begins to grow in the normal way through cell division in the mother’s womb. Monozygotic twins results when the growing cluster of cells breaks apart into two separate clusters early in pregnancy. These twins are identical in appearance, but also in genetic structure. Fraternal twins (dizygotic twins) are formed when the female produces two separate eggs that are fertilized by two different sperm cells from the father. These twins are not genetically identical. These twins share about 50% of their genetics. Scientists like studying both types of twins because they grow up in the same environment. Most studies have determined that intelligence is mostly directed by genetics. Monozygotic twins have almost identical I.Q.’s. STUDIES OF TWINS

6. Genes sometimes influence human behavior. Studies have shown that adopted children are closer in I.Q. to their biological parents than they are to their adopted parents. STUDIES OF ADOPTED CHILDREN

7. People used to think that personal characteristics were derived from the blood. “That person came from bad blood.” Now, we know that characteristics tend to come from genes – found in the nuclei of all human cells. It was in the last half of the 20 th century that genes have actually been seen, with the aid of electron microscopes. All cells of the body contain microscopic cells called chromosomes. These are long strands of deoxyribonucleic acid or DNA for short. It looks like a double ladder that doubles back on itself called a double helix. The outside of the ladder is composed of sugars. Chemical compounds called nucleotides are located on the twin rails of the double helix. MOLECULAR GENETIC MECHANISMS OF INHERITANCE

8. There are four different types of nucleotides in DNA: adenine (A), thymine (T), guanine (G), and cystine (C). The many possible sequences of A, T, G and C carry the genetic code. Genes are the basic biological units of inheritance. Each of the chromosomes of a normal human cell contains thousands of genes. Human chromosomes are arranged in 23 pairs. When cells divide in the normal process of repair or tissue growth, they create exact copies of themselves. When sex cells are formed, the chromosome pairs split, so the resulting cell has only 23 unpaired chromosomes. When a sperm unites successfully with an ovum, this is called fertilization. The new cell that is created is called a zygote. The zygote gets 23 pairs of chromosomes from the dad and 23 from the mom. GENES, CHROMOSOMES, AND DNA

9. When small changes occur in cells, these are called mutations. Most mutations are so devastating they cause death in the human being. Some of these mutations are carried in the genes and are passed on to future generations. Polymorphic genes – genes with more than one version. These are partly responsible for the differences in human behavior. Siblings receive copies of the genes from their parents randomly, siblings have an average of 50% of getting the same polymorphic genes. POLYMORPHIC GENES

10. If children get two conflicting genes (such as blue eyes from the dad and brown eyes from mom), it depends upon which gene is dominant. Overall, dominant genes tend to win over. Brown eyes tend to be dominant over blue eyes. Blue eyes would be considered a recessive gene. A recessive gene has been inherited from both parents and there is no dominant gene providing instructions. Some other dominant genes include: dark hair, curly hair, farsightedness, and dimples. Some recessive traits are: blue eyes, light hair, normal vision, and freckles. DOMINANT AND RECESSIVE GENES

11. Traits controlled by a large number of genes are called polygenic traits. Traits like intelligence and personality tend to be polygenic. It will take scientists quite a while to figure out how these polygenic traits work together. X and Y Chromosomes and Sex – males have an X and Y chromosome. Females have two X chromosomes. These codes create different signals to the body. They develop different glands (ovaries versus testes), the ability to have and nurse children, and sex differences in height and weight. POLYGENIC TRAITS

12. When chromosomes are damaged or malformed, abnormalities of body and behavior often result. Down Syndrome is an example of this, which is present in the 21 st chromosome. Kids with Down Syndrome have physical irregularities (a thickened tongue and skinfold in the corner of the eye). Mental retardation is the serious aspect of Down Syndrome. CHROMOSOME ABNORMALITIES

13. DNA (genes) located in cells is made up of protein that makes up structures and parts of organs. When the cells that make up our neurons and endocrine glands differ in their constituent proteins, those structures often operate differently. Gene differences determine differences among people in the size and function of every area of the brain. Genes also influence the structure and function of our endocrine glands. The hormones and neuropeptides secreted by the endocrine glands influence our behavior by influencing the functioning of our neurons and many organs. GENES AND BEHAVIOR

14. Height is strongly influenced by genes, but it is not the only factor influencing it. The average height in some countries has increased by more than 3 inches since WWII owing to improvements in nutrition and medical care. The environment is a major concern for humans as some of the chemicals found in our water and food can affect mental processes and behavior. There are studies that show that high levels of mercury, lead, and other heavy metals might influence neurotransmitter functioning and reduce I.Q. in children. Drinking alcohol during pregnancy may impact the level of aggressiveness and rule-breaking behavior in childhood. NURTURE: ENVIRONMENTAL INFLUENCES

15. It is impossible to understand human behavior and diversity without considering the role of culture, ethnic identity, and gender identity. Culture – is defined as patterns of behavior, beliefs, and values that are shared by a group of people. Culture influences everything from language and superstitions to moral beliefs and food preferences. An ethic group – is composed of the descendants of a common group of ancestors, usually from a particular country or area. Ethic identity – refers to each person’s sense of belonging to a particular ethnic group and of sharing that group’s beliefs, attitudes, skills, music, ceremonies, and the like. CULTURE, ETHNICITY, AND IDENTITY

16. There are cultural differences in parenting concerning collectivist cultures such as: China, Japan, and India. The central focus is on the family and the larger culture, not the well-being of each individual. In Western cultures, like the U.S., the center is on the individual and not on the overall community. Most parents in the U.S. believe that being shy and inhibited puts children at a disadvantage. They prefer for their children to be outgoing and assertive. In Chinese families, being shy and inhibited is an advantage. These qualities help a child to fit into groups better. Chinese parents will reward shy behavior. Chinese parents will also structure their children’s time and will teach mathematics at a young age. This does make a difference in the math scores of Chinese children as compared to American children. This mathematical teaching does not appear to be harmful to these kids. CULTURE AND PARENTING

17. The Gene Environmental Correlation – the genes and environments that influence our psychological characteristics often are not independent of each other but are correlated. Genes and environments can become correlated in two ways: 1) Passive gene-environment correlation – the genes and environments that influence a person’s behavior and mental processes often become linked or correlated, passively. This tends to come naturally. Active Gene-Environment Correlation – antisocial behavior is moderately influenced by genes (aggressiveness and disobedience). Children with these tendencies will tend to act in a way that isolates them more. Teachers and parents often respond to this behavior with demeaning or harsh punishments. Intelligent students tend to ignore these students as they do not like their behavior. These students tend to seek out other aggressive students to be friends. INTERPLAYING OF NATURE AND NURTURE

18. Gene-environmental interaction – genes can influence environment and an environment can influence genes (human behavior). This is why different people will react differently given the same scenario. Genes tend to control the amount of neurotransmitters that flow from nerve cells given different scenarios. The discovery that gene expression is variable. This means that the gene does not lead to the synthesis of proteins in the same way in different environments. A gene might be expressed under conditions of extreme stress (resulting in protein synthesis), but remain silent (resulting in no protein synthesis) when life is easy. GENE-ENVIRONMENT INTERACTION

19. There are biological and psychological aspects of being a different sex. A person’s sex is defined as biologically by his or her male or female genitals. Genital structure is determined by the Y and X chromosome. Gender – is the psychological experience of one’s sex, which helps to distinguish between gender identity and gender roles. Gender identity – is the subjective experience of being female or male. Gender role – refers to all the behaviors that are typically “masculine” or “feminine” in our culture. SEX, GENDER, AND HUMAN DIVERSITY

20. The infant’s name, what they wear, how they are talked to, all influence the gender of the baby. Children quickly learn what is expected of them given their gender. Feminine behaviors are expected of females. Masculine behaviors are expected of males. These are thought to be discreet categories, but they are not. Psychologists tend to think of gender roles on a continuum, with people having both masculine and feminine traits. Androgynous – people that have both masculine and feminine traits. A man with most female and male traits would be considered androgynous. These people are more likely to adapt to a variety of situations, because they are more flexible in their approach to life’s demands. GENDER IDENTITY AND GENDER ROLES

21. Many psychologists view discussions of gender to be important as long as feminine traits or masculine traits are not seen as “inferior”. Only biological women can give birth, be pregnant, and breastfeed babies. Men tend to have more upper body strength than women. Women and men are much the same in their cognitive abilities. Women do tend to perform a little better in language skills, verbal memory, perceptual speed, and fine motor skills. Men tend to perform slightly better in science and social studies. Men tend to get better scores on tests of spatial and mechanical reasoning, the ability to mentally rotate objects, estimate the speed of moving objects, and navigation through three-dimensional space. In the past, males used to test better in math, but that is no longer true. Women are now better prepared for jobs in math, but most do not seem interested. Women will attribute their grades to hard work whereas men tend to attribute good grades to their intelligence. GENDER SIMILARITIES AND DIFFERENCES

22. Women tend to be more interested in careers that help others. Men tend to be more interested in careers that are competitive, dominant, assertive, and include science, engineering, and math. Women are more apt to be anxious, depressed, and have low self-esteem. Men are more apt to engage in physical aggression and risky behavior and are more apt to commit more types of crime. There are many exceptions to the rule though as many men are kind, compassionate, and nurturing. GENDER DIFFERENCES IN EMOTION AND SOCIAL BEHAVIOR

23. Men think about sex more often, masturbate more often, and prefer to have sex more frequently than women do. On average, men tend to pick a woman that is younger, physically attractive, and does housework. Men are more likely to be sexually jealous, controlling of their relationships, but are more likely to think casual sex for themselves is okay. (This is straight out of the textbook.) Women tend to prefer men that are older, have good character, and have good earning potential. Women tend to be more scared of their partners having an emotional affair versus a physical affair. Men seem to be equally upset by emotional and physical affairs. GENDER DIFFERENCES IN MATING AND SEXUAL BEHAVIOR

24. Brain studies now suggest there are differences between the male and female brain. There are differences concerning levels of estrogen, testosterone, and other sex hormones during gestation (creating a gender differences). The cerebral cortex in males is about 10% bigger than that of females. There is a greater volume of white matter (myelinated axons) in men, with no sex difference in the amount of little gray cells. The right hemisphere is a little bit bigger with both sexes during childhood. This is interesting as the right hemisphere deals with spatial understanding. There are sex differences in the corpus callosum. This band of 200 million neurons connecting the two cerebral hemispheres grows in size during childhood as its neurons become fully encased in the myelin sheaths that speed neural impulses. By adulthood the corpus callosum is bigger in women than men, possibly relating to a better ability to use both sides of the brain. SEX DIFFERENCES IN THE BRAIN

25. An interesting gender difference has been found in the cortical activity during the performance of verbal tasks. When adult men and women performed a rhyming activity task, there was activation only in the verbal areas of the left hemisphere with men. Women showed activation in both hemispheres. This is consistent with the superior language skills with women. When children grow older, the amygdala increases in size more rapidly with males. The hippocampus increases in size more rapidly with females. The amygdala deals with aggression. The hippocampus deals with some aspects of memory. Human scientists are far from understanding the brain and how it works. The brain is not fixed during life, but is constantly changing. SEX DIFFERENCES IN THE BRAIN

26. In 1859, Darwin published The Origin of Species in which he proposed that the immense variety of plant and animal species in the world arose over many years from a few common ancestors through the process of natural selection. Natural selection – “survival of the fittest”. Darwin wrote that there were variations in genes that helped animals adapt to their environment. Today, these variations are known as mutations. The fitness means reproducing offspring who pass the mutated gene on to future generations. GENETICS AND PSYCHOLOGICAL THEORY (DARWIN, JAMES, AND FUNCTIONALISM)

27. Evolutionary psychology – is the assumption that our evolutionary past holds the keys to understanding our current psychological characteristics. These psychologists believe that our traits today evolved from selective traits from the past. Evolutionary psychologists further believe that variations in our genes that are one source of human diversity arose in our evolutionary past. Evolutionary psychologists believed that gender roles arose in our prehistoric past because the pressures on males and females were different. These psychologists believed that these differences were hardwired. EVOLUTIONARY PSYCHOLOGY