ANT276 Midterm 1 Flashcards
1
Q
Sexual Behavior
A
any behavior that might contribute to the reproduction success, such as behaviors that are employed in mated, courtship, or pair bonding
2
Q
Homosexual
A
Sexual and/or romantic relationships between members of the same biological sex. Used in older literature on non-human animals but NOW is reserved for discussing humans
3
Q
Same-sex sexual behavior
A
sexual interactions between members of the same sex. NOW the most commonly used term to referring to homosexual behavior in animals
4
Q
13th century philosopher & priest Thomas Aquinas
A
argued for the unnaturalness of homosexuality bc it didn’t happen between animals
5
Q
French Naturalist George-Louis Leclerc de Buffon
A
- earliest observation of SSB in several bird species
6
Q
1800s on SSB
A
Only male-female pairings allow for successful propagation of genes, making them the primary drivers of evolution
7
Q
1834, entomologist August Kelch
A
- Discovered two male doodlebugs having sex
- “sexual perversion in male beetles”
- first modern scientific account of SSB in animals
- one bug was dominating the weaker bug
- believed it MUST have been a female but later agreed it was coercion (rape)
- later discovered the big bug was the one actually taking it in
8
Q
Karl Heinrich (1880)
A
argued that SSB between insects has no basis as justification for homosexual behavior in animals, including humans
9
Q
Henri Gadeau de Kerville
A
- said some doodlebugs are driven to same-sex sex by lack of females but there are others who seem to prefer it
- only between males
10
Q
20th century
A
Scientific Study:
- comparisons to humans to understand “cause” of “sexual perversion” with efforts to find a “cure”
- increase in captive and wild studies on primate behavior
Societal attitudes:
- homosexuality is pathological and can be cured
- public & politicians compelled to insert their value judgement and righteousness in animal behavior
- AIDS crisis, centering “family values”
- Rams & bulls exhibit homosexual preferences (ppl didn’t want to accept this
- animal sexuality was the only form of queer sexuality the US was willing to consider (after aids crisis)
11
Q
Presumption of Heterosexuality
A
- assumption that all courtship and mating activity is heterosexual unless proven otherwise
- study of laughing gulls
- DNA analysis is now being used to determine the sex of nesting birds
12
Q
Terminological denials of homosexual activity
A
- same sex behaviors in animals not being coded as sexual
- SSB often requires an alternate function such as social dominance or aggression but heterosexual behaviors do not
13
Q
Inadequate or inconsistent coverage
A
- not a lot of stats of SSB
- “only this percent of the population displays SSB”
- leads to false “novel” claims about a behavior or assumption that it’s rare
14
Q
Omission or Suppression of Information
A
- silence & stigmatization of SSB in animals
- report of Killer Whale SSB behavior was eliminated in a US document
15
Q
Natural selection
A
- process in which populations adapt & change, requires that genes increase an individual’s fitness in order to be passed on to offspring
- individuals with traits that are better adapted to their environment will more likely survive and reproduce
16
Q
darwin
A
- variation in beak size
- beak size is heritable
- drought selected for birds with larger beaks
17
Q
reproduction is critical
A
only m-f allow for the successful propagation of genes -> primary drivers of evolution
18
Q
natural selection
A
struggle for existence
19
Q
sexual selection
A
struggle for mates
20
Q
traits can evolve if they increase reproductive success even at the cost of survival
A
21
Q
mate competition
A
- intrAsexual selection
- direct competition for access to mates
- physical fights
- selection for weapons
- male-male competition
- reproductive success limited by females
22
Q
mate choice
A
- intErsexual selection
- goal: attract mates
- courtship displays
- selection for extravagant traits
- Female mate choice
23
Q
Antiosogamy
A
sexual reproduction wherein males & females produce gametes of different sizes
- smaller gamete (sperm)
- larger gamete (egg)
24
Q
bateman’s principal
A
male reproductive success increases with number of mates, but female reproductive success does as one fit mate was enough to successfully complete fertilization
- data was inconsistent
25
females are not passive
- competitive
- sexually assertive
- have just as much of a say as males do in reproduction
- promiscuous mating in female langurs confuses paternity & reduces the risk of infanticide
- hyaenas are bigger and more dominant than males
26
parental investment theory (1972)
- " Typical" species: females tend to invest more in offspring than males, gestation & lactation, and provide most post-parturition care.
- Females should be choosy
- Since there are less fertile females than reproductive males, males need to compete
27
animals don't only have sex to reproduce
- form social bonds
- reduce tension
- out of boredom
- it feels good
- female Japanese macaques have sex with females just bc they WANT TO
28
two sex roles: competing males & choosy females
- reversable & changing sex roles
- hermaphroditism
29
anchor bias
- we tend to rely too heavily on the first piece of information they receive on a topic
30
confirmation bias
we tend to find what we are looking for
31
jay birds
- went in research for alpha males
- found out the birds fighting each other were females
- must be PMS
32
ockham's raxor
- central tenet of science to trust the evidence and choose the simplest explanation
33
Proximate
an explanation in terms of immediate factors that cause a behavior to occur
- what and how?
34
ultimate
an explanation in terms of the process and force of evolution
- why?
35
why do male geladas have red chests?
mechanistic answer: because of good genes
developmental answer: because males have reached puberty
functional answer: bc they ward off rival males
evolutionary answer: bc they evolved sexual skin on the chest rather than the butt
36
SSB exists bc these behaviors are adaptive
- fitness benefits outweigh the costs
- can be a beneficial evolutionary strategy
37
why is SBB adaptive?
- dominance expression
- heterosexual practice
- skewed sex ratios
- social glue & bonding
38
dominance expression
- same-sex interactions establish and reinforce dominance hierarchies
- mounting is a display of dominance
- most cited explanation
- very little evidence (Squirrel monkeys & stump-tailed macaques)
39
heterosexual practice or attraction
- learning opportunities for immature individuals during play
- mimicking heterosexual copulations may prompt interest from heterosexual partners
evidence: flamingos "play" provides opportunities to practice territory defense.
limitations: adults still engage in SSB, some don't and do just fine
40
Social glue & bonding
- SSB reduce tension & prevent conflict
evidence: Alliance formation and male friendships in dolphins, G-G rubbing in bonobos solidifies social bonds
limitations: hard to link to reproductive success, SSB exists in temporary friendships
41
The vast majority of animals engage in sex with both sexes. SSB & DSB are likely the ancestral state.
42
hormones
- chemicals that act like messengers to coordinate and maintain different functions in your body.
43
testosterone
- sex hormones that plays a key role in development of male reproductive tissues, secondary sexual characteristics and libido
- testosterone's role in "bad" behavior is largely a myth but it has been linked to dominance-seeking and mate-seeking behaviors in animals
44
estrogen
- estrogens play a key role in development of female reproductive tissues, secondary characteristics, and possible libido (undertested)
- critical role in female reproduction, ovulation, pregnancy, and lactation
45
adult hormonal theory
- adult homosexual men should have lower testosterone, or higher estrogen
- women should exhibit the opposite pattern
46
“Such evidence of possible
hormonal causation is remarkably
sparse in the medical and
psychological literature, and it has
usually resulted from poorly
controlled studies.” – Ellis 1962
Males use identify as homosexual have T levels within
the range of normal male T levels.
* Most studies, and metaanalysis, show no difference in T
between gay and straight men.
* Few studies for women who identify at lesbians but the
same trend is true, within the range of normal T for
women and no difference.
* When administered, T increased presumed sexual
attraction.
47
Castration studies -> SSB in captive macaques
1984 Heino Meyer-Ballburg analyzed results of 27 studies undertaking this theory and found
no difference between testosterone and estrogen level of homosexual and heterosexual men
48
Prenatal hormone theory
Prenatal exposure to hormones are responsible for different
sexual orientations. Hormones have an important developmental effect; fetal exposure
can result in reorganization of the brain causing more ”masculinized” or “feminized”
expression
49
Pseudohermaphrodite females
females with male-
typical genitalia, disrupted ovarian cycle, difference in
body morphology, different socialization patterns.
Higher rates of SSB early in development but not
later.
50
2d:4d ratio is supposedly affected by fetal androgen exposure
- Females tend to have larger 2D to 4D
ratios than men.
- Women with congenital adrenal
hyperplasia which results in elevated prenatal androgen have lower “more masculinized” ratios.
51
2D:4D ratio
“A lower 2D:4D is associated with lower body
fat percentage, greater bone mineral
content, greater bone mineral density, and
greater good luck, especially in men
Spurious associations (that is, false positive
findings) are likely to account for
statistically significant findings in situations
where a weak physiological basis
exists for a relation between a predictor and
outcome.”
52
the "gay" brain
In 1991 Simon LeVey published in Science (the world’s top journal) claiming that he had
found that the region INAH3 of the brain was a different size in gay and straight men.
* There were nineteen homosexual men, all of whom had died of AIDS; sixteen presumed
heterosexual men, six of whom had been intravenous drug abusers and had died of
AIDS; and six presumed heterosexual women.
* Concluded that this region, which controlled for homosexuality
53
the "gay" gene: the fruit fly
1963 Kulbir Gill found a fruit fly mutation that “altered
courtship” behavior”. He named the gene “fruity” this was
later changed to “fruitless”.
* Manipulated a gene in fruit flies that produced males who
courted other males. “Conga line” of male-male ”genital licking”
* Found no effect on females
Not quite: researchers just removed a male’s ability to
discriminate between male and female fruit flies. Males were
still mating with females but when with males, would also mate
with males.
* “a mutation that leads to a mimic of bisexuality.”
54
Fru
In a 2005 study, female flies were given male version of the
gene fruitless, females initiated courtship with other females
or males engineered to produce female pheromones.
* When Males with female Fru and females with male Fru were
introduced, sex roles reversed: females were the aggressors,
and males were passive
- Found they could ”turn on and off” same-sex behavior in flies
by both genetically altering GB AND by feeding the flies drugs
that can alter synapse strength.
55
Scala naturae
a feature of religious ideas of
a hierarchy of living things with the deity at the top
as the most perfect (humans at the top)
56
homologous
traits that are similar to one another due to shared ancestry
57
analogous
traits that have a similar function but evolved independently in different groups of species
58
lemurs & lorises
Very little evidence of same sex sexual behavior in these taxa.
* Verreaux’s Sifaka lemur males mount other males possibly as often as 14% of
the time but it appears rare
- lesser bushbaby females mount each other when in heat
59
New world monkeys
- Female squirrel monkeys court and mount each other
* Females form short consortships with other females
* Same-sex partnerships help with parenting
* 25% of courtships were between females
60
old world monkeys
SSB is very common in Old World monkeys
* 65-75% recognized genera engage regularly in same-sex behavior
* 76% exhibit male-male SSB & 70% female-female SSB
* Variation in how often SSB occurs, it is the primary form of sexual behavior in a
wide variety of macaque species
61
apes
Bonobos have one of the most varied and extensive repertoires of same-sex behavior in any
animal.
* G-G Rubbing plays an important role in bonobo females forming social bonds, SSB between
males common as well.
* 40-50% of sexual interactions are same-sex. In females, 75% of sexual interactions occur
between females.
62
gorillas
Male gorillas engage in SSB with other males, 90% of all sexual activity of bachelor males is
SSB.
* Female gorilla’s frequently have sex with other females in their group, exhibit clear preference
for particular female partners.
* Co-sexual groups, 9% of all sexual activity is F-F, 7-36% of sexual activity is M-M
63
apes
Young males engage in SSB with some evidence of female-female SSB
* 9% of orangutan sexual encounters in some populations involve male mounting
* Proportion is probably higher but we know less about sexual behavior in this species in general
* Recent research suggests it’s common in wild populations as well as captive populations
64
chimpanzees
Male and female chimpanzees engage in a variety of same-sex activity but it is most common in
males.
* M-M sexual behavior is roughly 29-33% of sexual activities in males. Recent studies estimate
up to 60% of sexual behavior.
* We know less about females but likely a similar range.
65
phylogenetic consideration
Difficulties in applying the comparative method to
same-sex behavior:
1. Sexual behaviors vary widely between species.
2. Rates differ with little regard for rates of social
behavior or sexual behavior more broadly.
3. Focus has been heavily skewed towards male-
male homosexual behavior
66
humans are different
- We form pair bonds and life-long attachments with
different and same-sex individuals
* We have sex for pleasure
* Some individuals exhibit only homosexual
preferences throughout their lifetime
* We have a suite of emotions, from empathy to love,
that separates sex from attachment
* We have (and can express) identity, attraction, and
desire.
67
kin selection (gay uncle) theory
Homosexual males may help in raising their
siblings, allowing siblings to reproduce more successfully. Inclusive fitness versus direct
fitness (Wilson 1975, 1978)
68
gay uncle theory assumption
Indirect fitness benefit of more relatives would compensate for the presumed
fitness costs associated with SSSA and same-sex sexual behavior.
69
gay uncle theory disapproved
Contrary to predictions from the kin selection
hypothesis of male homosexuality, we found no
evidence that gay men are generous to their
relatives.
70
gay uncle theory problems
1) Advantage of having a homosexual family member would need to be quite
large
2) Why homosexuality? Poor solution to nepotistic altruism.
