1. Gender-Role Standards and Stereotypes
Sex stereotypes that men are more aggressive than women and women more interpersonally sensitive than men are very robust, even among more educated people, both sexes, all social classes.
Probably because they have some truth in them!
Keep in mind that male/female distributions overlap.

2. Gender differences
NOTE: There are overlaps in all of these areas so that, for example, some girls are more physically aggressive than some boys. Physical Sex Differences:
Girls more advanced physically throughout childhood; they mature earlier and their development stops sooner.
Boys have larger lungs and heart, and they are superior at activities involving gross motor activities and strength; males more likely to suffer a wide range of developmental disorders (speech defects, ADHD, mental retardation), genetic defects (because of x-linkage; WHY?), and are more susceptible to malnutrition and disease.
Boys are more physically active; in preschool they are more likely than girls to play in a physically active style in larger groups away from the teacher.
Girls tend to have a few intimate friends
Boys have a larger number of "pals"—guys they hang out with but don't have close, intimate, confiding relationships.

3. Gender differences Cognitive Sex Differences:
Girls superior at verbal abilities (vocabulary, reading comprehension, verbal creativity) during early to middle childhood. These differences become attenuated as children get older, and disappear by adolescence.
Boys have greater visual-spatial ability beginning around age 10. (Visual-spatial ability is involved in manipulating objects in two- or three-dimensional space, reading maps, aiming at a target.)
Boys also excel at mathematics beginning around age 12.
Some studies indicate that boys have a higher IQ on average than girls by late adolescence (~4 IQ points).
Theory: Girls' development ends sooner than boys, and boys continue to develop. This is controversial.
Girls superior in Conscientiousness: Focused attention, responsibility, dependability, delay of gratification.
Conscientiousness is strongly correlated with school success.

4. Gender differences Social Sex Differences:
Boys more aggressive, especially physical aggression and direct verbal assault. (Girls use indirect forms of aggression such as exclusion, negative gossip.)
Boys more into risk-taking and sensation seeking as well as curiosity and exploratory behavior; boys attracted to physically dangerous occupations
Girls more compliant with demands of parents and teachers. (Conscientiousness)
No sex differences in attachment classification. However, Girls more nurturant and dependent. (Affectional System) Infant girls more attracted to faces and may recognize mother's face earlier.
Girls more fearful of possible personal threats and dangers. No sex differences for social phobias, or possibly more common among boys.

5. Gender differences Sex Differences in Atypical Development:
Boys more likely to have genetic defects, physical disabilities, mental retardation, reading disabilities, speech defects, and school and emotional problems.
Boys are more likely to have genetic defects because of x-linkage: Boys only have one X-chromosome and therefore any recessive gene on the X-chromosome is expressed. Girls are likely to get a dominant normal gene from their father's X-chromosome.
Boys are "the less canalized sex"—they are more open to environmental influences, including negative environmental influences. This may be seen as a high risk strategy. Boys are more vulnerable to stress such as family disharmony.
The evolutionary theory of sex (see below) implies that boys are expected to be the high risk sex in general; this is related to the finding that boys are more aggressive and more attracted to sensation seeking. Both aggression and sensation seeking are high risk/high reward undertakings.

6. Developmental Patterns of Gender Typing
15- to 36-month-old toddlers have clear preferences for toys that are "gender appropriate"; but girls are more likely than boys to choose "gender inappropriate" toys.
In general, the male role is more clearly defined: there is a narrower range of activities considered appropriate for males.
Boys who play with "girl" toys or retreat in the face of aggression "fear derision" (p. 558). "Although we tolerate tomboys, we reject sissies" (pp. 558).
The condemnation comes from both parents (especially fathers) and peers.
Based on survey data, boys in the US like guns, boxing, wrestling and karate, team sports, and fixing and making things more than girls. Girls prefer dolls, sewing, cooking, dancing, and looking after younger children more than boys.
Parents encourage these patterns by, for example, assigning household tasks.
"Even in the 21st century, girls are more likely to make beds, clean, prepare meals, wash dishes, and do laundry. Boys are more likely to fix things, take out the garbage, and mow lawns" (p. 559).

7. Stability of Gender Typing
Masculinity and femininity develop early and are stable personality characteristics.
This is not surprising, since many of the traits that show sex differences are linked to personality systems.
There is some change in later adulthood as men become more nurturant and expressive, especially in old age.
Probably due to less testosterone.

8. Biological Factors in Gender Differences: HORMONES AND SOCIAL BEHAVIOR
Women have small amounts of the male hormone testosterone and men have small amounts of female hormones like progesterone and estrogen. In childhood, the differences are quite small, but they increase markedly in adolescents and adults.
There are two surges of hormones, prenatally and during adolescence.
The surge of hormones prenatally affects behavior in childhood, and the surge during adolescence activates and enhances the early predispositions created by the prenatal surge.
These are critical periods for the effects of hormones on later behavior.

9. Biological Factors in Gender Differences: HORMONES AND SOCIAL BEHAVIOR
Animal studies: Young, Goy, and Phoenix (1967) injected female monkeys with testosterone prenatally or around the time of birth.
Genetic female offspring were pseudohermaphrodites. Their genitalia were more masculine (large clitoris), and their behavior was also masculine (more aggressive, more mounting behavior [a male mating behavior], more rough and tumble play, more socially dominant).
Similar behaviors are elicited in genetically female rodents injected with testosterone.

10. Biological Factors in Gender Differences: HORMONES AND SOCIAL BEHAVIOR
NOTE: Levels of testosterone are also influenced by the animal's experience. Animals that have been repeatedly defeated in fighting have lowered testosterone, and winners have elevated testosterone as a result of their experience.
This also occurs with humans: Winning an athletic event results in a surge in testosterone.

11. Biological Factors in Gender Differences: HORMONES AND SOCIAL BEHAVIOR
Human Studies: Girls who have received testosterone or testosterone-like hormones prenatally have masculinized behavior.
These girls are genetic females but their genetalia are typically masculinized at birth (enlarged clitoris, fused labia that resemble a scrotum).
They often receive an operation to make her appear more feminine.
These girls have masculinized behavior: Tomboyish, liked vigorous athletic activities, simply utilitarian clothing; little interest in dolls, babysitting, or caring for younger children, jewelry, cosmetics, or hair styles.
They also had a more male-type achievement pattern and male-type attitudes toward sexuality. They preferred boys as playmates and boys' toys.

12. Biological Factors in Gender Differences: HORMONES AND SOCIAL BEHAVIOR
HORMONES AND COGNITIVE SKILLS
There is evidence for a critical period for brain organization and hemisphere lateralization (males more lateralized).
Testosterone surge prenatally is responsible. This surge makes females process verbal information better and males process spatial information better.
Female fetuses exposed to abnormally high levels of androgens are better at spatial abilities.

13. Sex differences in Spatial Reasoning
Water task; Light bulb in a car going uphill:
Male advantage is only found for spatial (geometric) ability, not for computational ability, basic math skills or algebra.
Biological influences do not rule out environmental influences.
Text notes that the differences are relatively small (but small differences lead to large differences in proportions at the high end of the distribution).
Girls enroll in progressively fewer math courses over the high school and college years. Even girls with superior math ability seem less interested in math as they get older (e.g., 34% of advanced physics classes). But the gender gap is narrowing.

14. BRAIN LATERALIZATION:
Brain becomes increasingly specialized with age, with right hemisphere more specialized for spatial tasks and left hemisphere more specialized for verbal tasks. Women who suffer left hemisphere damage are less likely to have damage to verbal abilities.
In a task where children had to identify objects inside a bag, sight unseen, boys were better when feeling with their left hand (controlled by the spatial centers in the right hemisphere). For girls there was no difference between hands in their ability to identify objects.
In a rhyming task where subjects were asked if nonsense words rhymed, both sides of women's brains were activated. For men, only the left hemisphere (underlying verbal abilities) was activated.

15. Evolutionary Psychology: Theory of Sex: Robert Trivers (1972)
1.) MALES DEFINED AS SEX WITH SMALL GAMETES, FEMALES ARE SEX WITH LARGE GAMETES  
2.) FEMALES TEND TO INVEST MORE IN REPRODUCTION THAN MALES.
TYPICAL MAMMALIAN FEMALE: PREGNANCY, LACTATION, CAREGIVING'VERY HIGH COST IN TIME AND ENERGY TYPICAL MAMMALIAN MALE: SPERM'VERY LOW COST .

16. Evolutionary Psychology: Theory of Sex: Robert Trivers (1972)
3.) ECONOMICS 101: WHEN YOU HOLD VALUABLE RESOURCES, YOU DON'T GIVE THEM AWAY.
FEMALES EXPECTED TO BE SELECTIVE, DISCRIMINATING MATERS
FEMALES WANT: MALES WHO WILL INVEST IN OFFSPRING, MALES WITH GOOD GENES, HIGH SOCIAL STATUS, ETC.

17. Evolutionary Psychology: Theory of Sex: Robert Trivers (1972)
4.) ECONOMICS 101: MALES DO NOT HOLD RESOURCES. THEREFORE THEY MUST COMPETE IN ORDER TO GET THEM. THIS RESULTS IN THE PREDICTION THAT MALES WILL BE MORE AGGRESSIVE.
IN GENERAL, MALES MUST COMPETE FOR FEMALES, AND THE MAIN OBSTACLE IS OTHER MALES:
ELEPHANT SEALS: DEFEATING MALES IN COMBAT
CHINESE EMPERORS: CONTROLLING MALES AND FEMALES
MOVIE STARS
SUCCESFUL HUNTERS in hunter-gatherer societies;
RICH MEN IN ALL SOCIETIES ARE ATTRACTIVE TO FEMALES (The Anna Nicole Smith phenomenon)

18. Evolutionary Psychology: Theory of Sex: Robert Trivers (1972)
4. (Cont.) MALES HAVE MORE TO GAIN BY BEING HIGH ON AGGRESSION, RISK-TAKING, SENSATION-SEEKING, SOCIAL DOMINANCE: SUCCESSFUL MALE CAN MATE POLYGYNOUSLY,
SUCCESSFUL FEMALE CAN MATE ONLY ONCE.
EVEN IN A MONOGAMOUS SYSTEM, SUCCESSFUL MALES WILL HAVE ACCESS TO HIGHER QUALITY FEMALES (MORE NURTURANT, MORE PRONE TO FIDELITY, HIGHER INTELLIGENCE, ETC.) RISK-TAKING AND SOCIAL DOMINANCE PAY OFF MORE FOR MEN.  
THEREFORE MEN GAIN MORE BY CONTROLLING SOCIETY (PATRIARCHY), AND THEY GAIN MORE BY GOING TO WAR.

19. Evolutionary Psychology: Theory of Sex: Predictions
WHEN GENGHIS KHAN AND THE MONGOLS CONQUERED MOST OF ASIA, THEY REALIZED AN ENORMOUS GENETIC PAYOFF BECAUSE THEY ESTABLISHED HAREMS WHEREVER THEY WENT.
THE MONGOL Y-CHROMOSOME IS STILL FOUND AT HIGH FREQUENCIES IN ALL THE AREAS THEY CONQUERED. ~32 million direct descendants
A MONGOL FEMALE WOULD NOT HAVE SIMILARLY BENEFITED BY THIS SORT OF CONQUEST.

20. Evolutionary Psychology: Theory of Sex: Predictions
FEMALES ADOPT A MORE CONSERVATIVE STRATEGY: HIGHER ON FEAR, BEHAVIORAL INHIBITION.
FEMALES ALSO EXPECTED TO BE MORE NURTURANT AND LOVING AS MATE DISCRIMINATION SYSTEM (females benefit by choosing males who love them and are willing to invest in their children) AND BECAUSE OF ITS ROLE IN NURTURANCE (females who are high on affectional system are prone to nurturance).

21. Evolutionary Psychology: Theory of Sex: Predictions
Male sexual jealousy more directed at ensuring paternity confidence.
Female sexual jealousy more directed at ensuring continued affection as a sign of continued support.

22. The End