Exam 2: Week 9

Question 1

T/F same sex people produce fewer offspring?

Answer 1

True
- Seems to be a costly trait from perspective of natural selection
- The trait is common and possibly increasing in frequency
- likely a cultural evolution rather than genetic but rates of reporting are what may be increasing instead of homosexuality itself
- Gay American men have 10-20% as many children as straight men

Question 2

what are the population estimates for same sex %?

Answer 2

10%
- other studies have 2.8% of men and 1.4% of women

Question 3

what is the Kinsey scale?

Answer 3

sex (gonads, genitalia) is mostly binary but sexual preferences appears to be more of a continuum

Question 4

sexual orientation

Answer 4

same sex behavior in animals/humans ⇒ learning who to love via social and environmental impacts as well as genes

Question 5

what are the evolutionary explanations for sexual orientation? (3)

Answer 5

• Kin selection
• Alliance formation
• Antagonistic pleiotropy

Question 6

T/F in most species studied at some point we see same sex mounting behavior?

Answer 6

True
- not as common as heterosexual behavior
- Often occurring in the context of social relationship ⇒ already in close relationships or are building relationships

Question 7

philopatry

Answer 7

the pattern in terms of which sex stay in the group they are born ⇒ someone must disperse in order to avoid inbreeding and inbreeding depression
- This pattern is the same in chimps and bonobos ⇒ typically male philopatry where males stay in the group they are born

Question 8

how would philopatry affect female relationships?

Answer 8

Females have to go out and make new relationships
- For species where each sex disperses, one sex will disperse further to avoid inbreeding

Question 9

imprinting

Answer 9

a type of learning different from association learning and instead is stereotyped where the first moving thing a baby sees it will fixate on to learn species appropriate behavior ⇒ typically found in birds
- Usually is a parent in the wild but could be anyone

Question 10

prococial

Answer 10

babies that can do a lot of things on their own when born ⇒ humans are the complete opposite

Question 11

how do geese learn appropriate sexual partners?

Answer 11

newly hatched geese exposed to a moving object of reasonable size and emitting reasonable sounds will begin to follow it just as they would normally follow their mother
- A gosling imprinted to a moving box or clucking person will try to follow this object for the rest of its life
- When the goslings reaches sexual maturity, it will make the imprinted object the goal of its sexual drive ⇒ rather than a ember of its own species

Question 12

how do whooping cranes breed?

Answer 12

by dancing with appropriate partner
- Cranes imprinted on people must dance with people to breed
- Because of risks of imprinting, captive condors must be fed by puppets

Question 13

what happens with baby monkeys and maternal care?

Answer 13

baby monkeys need love
- The wire mother had food while the cloth did not but infants showed persistence preference for the cloth mother over the food mother
- When hungry they wouldn’t leave the cloth mother ⇒ they would lean over to nurse but still touch the cloth mother (attachment bond from infant)

Question 14

what happens to monkeys raised by cloth or wire mothers?

Answer 14

they have insufficient social contact and develop poor social skills
- Isolated infants became bad mothers
- shows appropriate sexual behavior depends on childhood social interactions, not just physical maturation

Question 15

how do human children develop models of appropriate sexual partners?

Answer 15

from their parents

Question 16

paraphilias (6)

Answer 16

learned associations between sexual response and unusual stimuli => more common in men
- exhibitionism
- fetishism
- frotteurism
- pedophilia
- sexual masochism and sadism
- voyeurism

Question 17

exhibitionism

Answer 17

wanting to be seen naked

Question 18

fetishism

Answer 18

unusual behaviors during sexual behavior

Question 19

frotteurism

Answer 19

engaging in unwanted rubbing of genitals against another person

Question 20

pedophilia

Answer 20

engaging in sexual behavior/fantasy with prepubescent individuals

Question 21

sexual masochism and sadism

Answer 21

arousal from pain

Question 22

voyeurism

Answer 22

watching sexual behavior of other individuals

Question 23

cases where same sex behaviors that may depend on segregation? (3)

Answer 23

• prisons
• schools
• military

Question 24

T/F different cultures have different definitions of friendship and homosexuality behaviors?

Answer 24

True

Question 25

what do twin studies show us about homosexuality?

Answer 25

in identical twins, if one twin was gay, the other had 50% chance of also being gay - For fraternal twins, the rate was about 20% - Controlled for social settings and exposure to biological parents - there is a genetic element to same sex preference but not 100%

Question 26

how are brothers affects by homosexuality?

Answer 26

Uterine development (mothers antibodies) against proteins from the Y chromosome - The quantity of antibodies increases with each son a woman has which the fetus will swim in ⇒ maternal immune response to male fetuses - This neutralizes the male Y chromosome which may impact their development and leaves some regions of the brain like the typical female arrangement - Fraternal birth order effect: men with older brothers are more likely to be gay (33% increase for each son) - 8-12% of brothers of gay men are also gay compared with the 2-4% of the general population - gay brothers share a specific region of the X chromosome called Xq28 at a higher rate than gay men shared with their straight brothers but subsequent studied failed to replicate this - there is a lo degree of heritability on same sex sexual behavior relative to other traits

Question 27

what do clumps of neurons in the anterior hypothalamus tell us about homosexuality?

Answer 27

larger in heterosexual than homosexual men

Question 28

what are differences in homosexual vs heterosexual sheep?

Answer 28

Examined a sexually dimorphic nucleus (oSDN) in the sheep preoptic area anterior hypothalamus - The oSDN is larger in female oriented rams => Female sheep and gay male sheep have the same size of oSDN - 8-10% domestic rams prefer to mate with other males - Brain difference in sheep parallels brain difference identified earlier in humans

Question 29

Kin selection (homosexuality)

Answer 29

Homosexuality may function like sterile castes in social insects ⇒ predicted homosexual men and women forgo their own reproduction but help their kin reproduce - various studies have failed to support this hypothesis

Question 30

male bonding

Answer 30

homosexual behavior leads to attainment of other resources

Question 31

sparta

Answer 31

spartan boys were drilled under the eagles eye of their older lovers, the erastai, so as to become good warriors ⇒ only the eromenoi who married and raised children were allowed to become erastai themselves

Question 32

alliance formation hypothesis

Answer 32

homosexual behavior promotes male bonding and serves as an honest signal of loyalty and trustworthiness ⇒ intrinsically linked with status - High status males mate with more females than lower status male and have more offspring ⇒ low status males look for less confrontational strategies and may form alliances with other low status males to gain access to reproduction against dominant males - Not just a binary in sexual behavior from people

Question 33

domestication syndrome

Answer 33

homosexuality may be a byproduct of our species ⇒ humans are self domesticated - Selection for particular behaviors causes changes in the physiology and behaviors of the organism - Domestication favors traits such as docility that contrast to typical behavior of wild type males

Question 34

do women tend to be lesbian or bisexual when they aren't heterosexual?

Answer 34

Non heterosexual women tend to be bisexual rather than having exclusive same sex preference - LUGs ⇒ lesbian until graduation refers to an experimental phase for young women in high school and college until choosing a partner later for marriage and producing offspring - we don't know much about lesbians

Question 35

Antagonistic pleiotropy

Answer 35

one allele produces multiple, contrary effects ⇒ on morphology and behavior of an organism - Some alleles may increase reproductive success in some contexts but reduce reproductive success in other contexts

Question 36

what are advantages of having a brother who is gay for females? (3)

Answer 36

possibility that female kin on the mothers side have higher fitness and increased fertility but male kin on the fathers side do not (hierarchical society where women marry up and this Ould increase homosexuality traits in male kin) - More sexual partners for heterozygotes - Increased fertility/feminine attractiveness of sisters ⇒ of gay men who also carry allele - Dedicated dads Note: there is some evidence for this theory

Question 37

Desirable dad hypothesis

Answer 37

heterosexual men who exhibit greater femininity may be more successful in mating, as measured by their greater number of opposite sex partners compared to other men - some degree of femininity in men is a cue of paternal qualities - Women who prefer paternal men have greater inclusive fitness than other women because raising human offspring to maturity requires significant time and effort

Question 38

what is different about masculine appearing men compared to feminine?

Answer 38

- Men with more masculine facial features –larger jawbone, prominent brow ridge, wider cheekbones– tend to allocate more effort toward pursuing potential mates than investing in their offspring in comparison with men having less masculine facial features - Men with masculine bodies had more sex partners and were more likely to cheat and mate poach

Question 39

aggression (psychology)

Answer 39

behavior that is intended to cause harm or pain - This is a human centered perspective but when discussing other species its not necessarily the same ⇒ meant to gain access to a resource

Question 40

aganism

Answer 40

threats and intimidation where there is a meeting conveyed between individuals but maybe not physical ⇒ either the individual will leave or there is an escalation - This is a bigger category than aggression

Question 41

competition

Answer 41

individuals want a resource but there isn’t enough to go around so they compete/fight over it

Question 42

contest

Answer 42

a moment in time when two individuals who are in a competitive interaction for a resource ⇒ may start with threats and intimidation and escalate to aggression

Question 43

what is evidence for adaptation? (5)

Answer 43

- complexity, design features - Directional change through a lineage - convergence in design - varies in a sensible way across biological space ⇒ regress where it is not important - Has a cost

Question 44

what are the brain structures that regulate aggression? Hormones?

Answer 44

amygdala, hypothalamus - Serotonin is negatively correlated with aggression - testosterone promotes male competitive ability (energetic cost)

Question 45

what is the adaptation for canine teeth?

Answer 45

mainly weapons for fighting (not hunting) - Tend to be larger in males - Males spend a lot of energy and effort in conflict with other males for access to mates

Question 46

what does dimorphism signal?

Answer 46

what happens in a particular species ⇒ if males have more pronounced features there was conflict for mating opportunities

Question 47

what are bodily costs for female adaptations?

Answer 47

female primates investment in reproduction - the cost is associated with menstrual cycle and growing the uterine wall for the egg and pregnancy, lactation, carrying the infant, caring for the offspring after weaning with social support, etc.

Question 48

what are bodily costs for male adaptations?

Answer 48

fighting/injuries/energy expenditure, growth of body parts, creation of sperm - When males are 80% larger than females they start to pay more in energy production than females do ⇒ effort and energy in fighting and body size

Question 49

what are examples of costly traits (2)

Answer 49

- Weapons - Larger body size

Question 50

examples of complex design features?

Answer 50

Neuroendocrine systems

Question 51

evolutionary patterns to watch for? (2)

Answer 51

- Directional change - Convergence

Question 52

is aggression a product of natural selection or pathology/aberration?

Answer 52

natural selectiona

Question 53

aggression (evol. def)

Answer 53

a strategic response employed when assessment indicates the benefits are likely to outweigh the costs

Question 54

what are the costs of aggression? (3)

Answer 54

- Risk of injury or death - Time and energy that could be spent doing other things - Investment in body size and weaponry

Question 55

what are benefits of aggression? (4)

Answer 55

- Resources - Mates - Status - Reproductive success ⇒ major benefit

Question 56

why might organisms be aggressive? (2)

Answer 56

- Limited supply of goods needed for survival and reproduction - Competition is universal => Aggression is just one of the possible strategies for competition

Question 57

why don't animals kill each other all the time if they have the capacity to do so?

Answer 57

There are outcomes decided on the basis of asymmetries in strength and motivation - Best to use aggression as a strategic option - The genetically selfish strategy is often to refrain from fighting unless the costs of fighting are likely to be low

Question 58

what groups do fights occur more often with?

Answer 58

males and young people

Question 59

what theories describe why males could be more aggressive than females? (2)

Answer 59

- social role theory - sexual selection theory

Question 60

social role theory

Answer 60

socialisation shapes gender specific identities, expectations, and behavior

Question 61

Sexual selection theory

Answer 61

males are competing for reproductive success, so are more aggressive generally and especially to other males

Question 62

is homicide an adaptation?

Answer 62

20-24 year old men are the most likely to commit homicide when unemployed - people with the longest life expectancy show the lowest homicide rate in areas where they live - the more income inequality the higher the homicide rate - may be an adaptation in times of struggle

Question 63

T/F females can also be aggressive?

Answer 63

True

Question 64

end card

Answer 64

:)