sexual behaviors
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Sexual Behaviors. Why do we have particular preferences? Evolutionary Explanations Sex differences? Psychoneuroendocrinology. Evolutionary explanations. Preferences/behaviors and choices…. 1871 – evolution of characteristics that give organisms a reproductive advantage - PowerPoint PPT PresentationTRANSCRIPT
Why do we have particular preferences?◦ Evolutionary Explanations
Sex differences? Psychoneuroendocrinology
Preferences/behaviors and choices…..
1871 – evolution of characteristics that give organisms a reproductive advantage
“Survival of the fittest” –definition of survival
Sexual selection based on parental investment by each sex◦ kin selection
certain wasp species; certain bird species E.O. Wilson
The sex that invests more in offspring should be more choosy or discriminating
The sex that invests less in offspring should compete more vigorously for opposite sex
amount of time for a woman –
amount of time for a man -
females males
always use posthoc observations to explain behavior
never can be really proven
“The Evolution of Desire: Strategies of Human Mating”
has looked at preferences across MANY cultures from around the world with specific predictions……..
Hypothesis: Men will express greater desire for, or interest in, short-term mates than women
n= 148 college students; 75 men, 73 women
Asked if seeking short-term mate (“ one night stand, brief affair) and independently whether they were seeking a long-term mate (defined as marrige partner)
7 point scale1 – not at all currently seeking
7 – strongly currently seeking
For any given period of time, men will desire a larger number of mates than will women
From Buss and Schmitt, 1993
Which sex would more likely consent to sexual intercourse after knowing the other for a shorter period of time?
From Buss and Schmitt, 1993
Attractive confederate approaches students on University of Hawaii campus
“I have been noticing you around campus, I find you very attractive”…..
a. Would you go out with me tonight?b. Would you come over to my apartment
tonight?c. Would you go to bed with me tonight?
Importance of financial prospects
Age of partner
What is a hormone?◦ chemical substance released that binds to
receptors on other cells
How is this different from a neurotransmitter?
Some chemicals act as both neurotransmitters AND hormones
What is a hormone?◦ chemical substance released that binds to
receptors on other cells
How is this different from a neurotransmitter?◦ travels further distance◦ released by glands
critical for aspects of sexual behavior (and development of sex organs and circuits)
ex. estrogen, testosterone,
these are lipid (fat) soluble and readily cross membranes and so can even bind to receptors in neuronal and cell nuclei
1. organizational effects• critical window for organizational effects
(usually early in development)
1. organizational effects• critical window for organizational effects
effects are usually permanent primary sexual characteristics
• structural AND CNS circuitry
2. Activational Effects• activating established circuits• effects are reversible and usually occur after
puberty• secondary sexual characteristics
genotypic sex vs phenotypic sex ◦ genotypic sex - determined at time of
fertilization
23rd chromosome is sex chromosome
phenotypic sex – ◦ what you see………
Y chromosome controls development of gonads
gonads – sex organs that releases steroid hormones (for males; testes for females; ovaries)
on Y chromosome is a gene - HY antigen ◦ if present- testes will develop ~ 6 weeks after
conception
Y chromosome controls development of gonads gonads – sex organs that releases steroid
hormones (for males; testes for females; ovaries)
on Y chromosome protein is produced- HY antigen ◦ if present testes will develop ~ 6 weeks after
conception◦ if not present – ovaries will develop
Y chromosome controls development of gonads gonads – sex organs that releases steroid
hormones (for males; testes for females; ovaries)
on Y chromosome is a gene - HY antigen ◦ if present testes will develop ~ 6 weeks after
conception◦ if not present – ovaries will develop
◦ up until that time a single “premordial” tissue is identical in male and females
What if this gene inadvertently goes onto an X chromosome?◦ XX male – estimated 1 in 20,000
What if this gene is missing from a male?◦ XY female- estimated 1 in 20,000
"Nature's impulse is to create a female“◦ in the absence of HY antigen (early) or male sex
hormones (later in prenatal development), the organism will develop as female
◦ male hormones (androgens like testosterone and dihydrotesterone) are necessary for undeveloped tissue to develop into male internal and external sex organs
AIS – androgen insensitivity syndrome◦ a genetic abnormality whereby there are
androgen receptors but they do not respond to androgens
females – little body hair males – internal gonads – testes;
what after that? 1 in 65,000 males estimated
often diagnosed at puberty
estimates 1 in 13,000 to 1 in 16,000 overactive adrenal gland releases excess
androgens diagnosed in females at birth – because of
ambiguous genitalia males not usually diagnosed at birth
5 alpha reductase is the enzyme that produces the androgen DHT (dihydrotestosterone)
DHT is important (apparently) for the production of male external genitals
guave doces; Dominican Republic◦ first reported in 1974
early cases – first raised as girls……… What does it say about biology vs vs
environment for determining human sex roles?
intersex condition in which indvl born with ovarian and testicular tissue
can be one on one side; the other on the other or more often one or both gonads is an “ovotestis” containing both
very rare
can see XXY, XX/XY, XX XXY
CNS – clearly affected by both organizational and activational effects of steroid hormones
Rodents have been used to gain a tremendous amount of info about the role of organizational and activational effects of steroid hormones
organizationalorganizational activationalactivational behaviorbehavior
organizationalorganizational activationalactivational behaviorbehavior
castrate malecastrate male give Tgive T no sexno sex
no aggressionno aggression
castrate + T castrate + T injinj
no Tno T no sexno sex
no aggressionno aggression
castrate + T castrate + T injinj
give T give T injectionsinjections
typical male typical male
behaviorbehavior
T normalT normal castrate as castrate as adultadult
little sexlittle sex
little little aggressionaggression
In species that have multiple births; developing embryos can be affected by hormones from surrounding fetuses
0M, 1M and 2Mfemales; exposedto varying levels ofmale hormones from developing sib nearby
aggression male sexual
behavior rough-and-tumble
play sexual
attractiveness onset of puberty AG distance
differences in all of these behaviors depending on whether it is a 0M or 2M female
so data from numerous species that bear multiple offspring at the same time, prenatal hormones can have an influence on later structures and behavior!
What about human conditions?
What are some alternative explanations?
What role does activational effects of T play on male sexual behavior?
So organizational effects of steroid hormones are critical for setting up circuitry for behaviors that are “sexually dimorphic” and activational effects are critical for activating the circuits in lower animals –
What role do activational effects of T play on male sexual behavior?
◦ in rats and lower species – obvious
◦ in humans – somewhat less obvious but definitely still important
McQuay◦ a former school bus driver in prison in TX for
sexually attacking a young boy (1989)◦ 1995 – as he approached parole asked state of TX
to be castrated; claimed he would repeat the crimes if not castrated attempted it himself in cell with a razor lots of people volunteered the money for the cost of
surgery
In a letter to the editor published in The Dallas Morning News on Sunday, McQuay said he expects to be released soon because of his clean disciplinary record.
"... I will be required to look for work and so forth, meaning I will be walking the streets of your city, your community, your neighborhoods," McQuay wrote.
"And without a doubt, there will be children around. You tell me what is likely to happen if I am not castrated before I am released.“
1996 – California became the first state to pass chemical castration law
1996 – California became the first state to pass chemical castration law◦ requires chemical castration of any person found
guilty a 2nd time of specified sex offenses◦ Florida, Georgia, Louisiana, Montana, Oregon,
Texas and Wisconsin followed shortly thereafter with similar laws
Depo-Provera –◦ lowers testosterone and resulting sex drive in
men◦ originally (and still used) as female contraceptive◦ most states say that repeat offenders may be
offered it as a condition for their parole
Danish study◦ 5 out of 117 castrated sex offenders relapsed
over an 18 year period, 1/10th of the rate of non castrated offenders
Depro-Provera cut recidivism rates of pedophiles in California, Texas, and some European countries using it.
Some studies suggest that recidivism falls to 5%; sexual fantasies are lessened
some may not be able to tolerate med◦ headaches, nausea, high blood pressure, possible
diabetes, gallstones, hypertension, increased risk of stroke, loss of bone density
some that have been on it for years must go off