10/2/96 - Begin Phase II: Comparative Sexual Behavior
10/4/96: The female lab rat has a very short estrus cycle--about 5 days
long. When living without a male, she has only follicular phases, and has
no luteal phase. Thus, she does not undergo preparation of the uterus on
each cycle, as is typical of many mammals.
In a study by Wilson, Adler & LeBoeuf, we showed that the female uses
information from the serial intromissions delivered by the male to signal
her when she DOES need a luteal phase, and uterine preparation. That is,
if she participates in a normal sex behavior series, the vaginal and
cervical stimulation from the penile intromissions starts a neuroendocrine
reflex: the stimulation information is sent to her brain via nerves and,
when sufficient stimulation has been received, the endocrine efferent is
activated, consisting probably of P-RF from the hypothalamus, LtH from the
pituitary, and the formation of a corpus luteum and its secretion of
progesterone for the uterus. If she is artificially kept from having
sufficient stimulation, the fertilized eggs do not implant, and she has no
litter of pups.
10/7/96: _Mus domesticus_ = the laboratory mouse:
The mouse is NOT the same species as the rat. They are not even in the
same family. But there many similarities, and some differences, in their
sexual behavior patterns. In this recap I will highlight the differences.
When the male intromits, he continues with 10-100 pelvic thrusts; this is
called an intromission/thrust series (no ejaculation). He may continue
with 1-100 more Intro/Thrust series before ejaculating. A vaginal plug
does form. The PEI is extremely variable, across inbred strains of mice,
from 1 hour to 24 hours or more. The female has a short (follicular phase
only) estrus cycle, unless mating has occurred. Then she has a
neuroendocrine reflex that stimulates a luteal phase, with progesterone
and preparation of the uterus. I am not sure what the proximal stimulus
is -- maybe the plug, or according to Tom McGill, the swelling of the tip
of the penis at ejaculation.
10/9/96: _Canis familiaris_ = the domesticated dog:
10/11/96: _Crocuta crocuta_ = the spotted hyena:
10/14/96: _Mirounga angustirostris_ - the elephant seal
10/16/96: Cervus canadensis
(also known as Cervus elaphus canadensis - It closely resembles
the 'red deer' of England and Scotland (Cervus elaphus
10/18/96: _Papio papio_ - the baboon
10/21/96: _Homo sapiens_ - human beings (Masters & Johnson book)
Psychosexual Development (per John Money)
Review
** EXAM 2 - Monday, October 28 **
_Rattus norvegicus_ = laboratory rat; nocturnal, puberty around 90-100
days of age in male; somehwat earlier in female. Sex behavior scoring
system devised by Frank Beach.
Male: Mount, Intromission, ICI, ML, IL, ejaculation,
EL,
PEI; Series 1, Series 2 -- Series 6 or so. 8-10 Intros on Series 1; fewer
on subsequent series. 'Sexual exhaustion' when PEI get above 30 minutes.
Male usually does the pacing, but if he is slow, the female will
increase the pace, by nibbling at the male, or even mounting him.
Why does this species have this complicated sexual pattern?
Partial answer, for the male: He needs continued stimulation from serial
penile intromissions, to achieve ejaculatory threshold. If PEI's are
artificially lengthened, he may fail to reach ejaculation.
This special neuroendocrine reflex appears to be one of several adaptive
mechanisms evolved within this species to maximize the number of offspring
that they can produce. In addition to the short cycle (except when
needed), the female also has a very short gestation period of 22 days, and
produces 8-15 pups at a time. She weans the pups in about 3 weeks, and in
about 3 months they in turn are capable of reproducing.
She gestates for about 21 days, has a
litter of about 6-12 pups, and nurses them for about 3 weeks. Lab mice
mature early (60-80 days), although we have had some females become
pregnant as early as 25 days of age! Again, this species seems to have
evolved mechanisms that allow production of large numbers of conspecifics.
Student Lecturers: Katie Hook & Nancy McLaren
This species' name is an invention: most authorities believe that wild
canids have been domesticated by different groups at different times, and
the result is now mixed in what we call Canis familaiaris.<>\br>
Both sexes become sexually mature at around 1 year - smaller breeds a bit
sooner. The bitch has a 9-day poestrus, with vaginal swelling, and
bleeding (NOT menstruation); she will not accept copulation while in
proestrus, though the male will try. When she will 'stand' for the male
signals the beginning of her 9-day estrus period. Intromission is
achieved by the male, without erection (he has a penile bone: os penis);
then the base of his penis swells (the bulbus glandis), and 'locks' into
the vagina for 30-60 minutes. He dismounts and turns, and the pair stay
'locked' during this period. This seems to allow him time to fertilize
the female, as the male dog has no seminal vesicle, and his initial
secretions have no sperm.
Dogs castrated just after puberty seem to have little or no dimunition in
sex drive, or aggressive drive, according to LeBoeuf, although they cannot
'lock' as their penis and bulbus are too small.
Gestation is about 63 days. Interestingly, if the female is not
fertilized, she starts a 60-day long luteal phase, called
pseudopreganancy, with uterine development (no fetuses of course), and
mammary development. This has fooled many owners to believe she is
pregnant. Bitches show choice of mates, although they do not seem to
discriminate between castrate and intact males.
Student Lecturers: Kelsey Hartman & Mike Clapp
Sexual & social behavior of Crocuta crocuta (the spotted
hyena). Student Lecturers: Kelsey, Mike, Missy
The spotted hyena lives in sub-saharan Africa. The females are large
(about 160 lbs), mean and dominant to the males (about 140 lbs). The
female morphology mimics that of males, with a clitoris (about 6 inches)
which exceeds the size of the male's penis (about 4"), and the female even
has a mock scrotum. The animals erect their penis or clitoris, as part of
their greeting ceremony.
The animals have an anal gland which exudes a white paste which they use
for marking ('pasting'). The female's cycle is about 14 days, although
she if more often pregnant or nursing. She allows the male to approach
her (barely!) during peak estrus, and he mounts and thrusts, trying to
ntromit into her modified clitoris, which also contains the urethra and
is in effect her vaginal opening as well. The male may have to try
several times. He has perhaps three mounts with intromissions during
their series. It may be that his ejaculation is on mount/intromission #2
or #3. Gestation is about 110 days, with usually two cubs born. One cub
usually kills the other (especially if both were female), and is then
reared as a singleton. Nursing may be for a year. Top-ranked females
pass on their rank to their female offspring. Males leave the pack, after
puberty, and are wanderers. The hyenas eat almost anything they can get,
including Buffalo, carrion, insects, lions, etc. They seem to follow a
principle of least effort, in obtaining food. Ranking cubs start eating
meat early, and grow faster than lower-ranked cubs. Hyena jaws are so
powerful that they can crack even the hip bones of cattle and buffalo, and
they can digest the bose fragments in about 24 hours.
The extreme masculinization of the females seems to be due to their
placenta passing maternal androgens, especially androstenedione, through
to the fetuses, instead of filtering it out, as if more usually the case.
Why, is a harder question. It may be an adaptation to allow the females
to gain size and ferocity, for competing within the pack, and for killing
prey. But it does serve as a strong reminder that the external genitalia
respond to androgens by taking up the male form, in either sex.
Student Lecturers: Autumn van Kirk and Laura Hodgkins
The elephant seal is a true seal (cannot walk on its hind flippers), and
is so well adapted to the ocean that individuals have been found thousands
of miles from land. The species does however, return to land for mating,
once per year, usually on a remote island.
About December each year, large adult males begin 'hauling out' on the
island of Ano Nuevo, near Santa Cruz, CA, where Burney LeBoeuf has been
studing the species for many years. The males then fight for dominance.
Only a few males win; the others find some quiet spot, and 'sleep it off'
for a few months, or even return to the ocean. About January the pregnant
females and juveniles reurn to the island, and the females give birth
within a few days to a pup of about 100 lbs. They nurse the pup for about
3 weeks, and with their extremely rich milk, get it up to about 300 lbs.,
when it is called a 'weaner'. The females, pups, and juveniles aggregate
into a large group called a pod. The alpha male patrols his pod or harem,
and tries to keep all other males away.
Fights between adult males are common early on but, after establishing a
top position, a top male only has to bellow and threaten away rivals. The
long nose of the male amplifies the bellow, and it can be heard for
miles.
Just before she finishes nursing, the female comes into estrus. Before
this she will not accept the advances of males, who try mounting
practically anything. All animals who are not estrous females discourage
the bull seal by squirming and even hitting their hind fins against his
penis. However, when in heat, the female will raise and spread her hind
flippers, and allow intromission. The 4000 lb., 16 foot-long male has a 4
ft. penis, but still must bend 90 degrees to effect intromission with the
much smaller, 1000 lb., 12 ft female. Intromission lasts several minutes
and apparently includes fertilization. The male will interrupt coitus to
go fight a threatening rival. The males often injure or even kill pups
that can not get out of the way in time. Pups also drown, as they are
weak swimmers for their first year.
After the initial copulation, the female tends to go back to sea. There
may be a 2d or 3rd copulation, even in the shallows. It is difficult to
be sure who is siring. The female has a 2-month delay of implantation of
the fertilized egg, and then a 9-month regular gestation period. This
allows her to remain on an annual cycle, and meet her conspecifics once
per year, at the same time, same place. Occasionally this adaptive delay
mechanism fails, and the female delivers 2 months early--usually at a
location far from her proper breeding grounds. This is dangerous for both
the female and pup, but of course, she had no choice.
High rank is so important for the males to mate, that they are not usually
big and strong enough to compete successfully until they are about 10
years of age.
They may hold a top rank for a few years, and then will be defeated. The
few top males do almost all the mating. This may constitute strong
genetic selection for size and strength in the species.
While on land for the breeding season, the adults do not eat, so they lose
quite a bit of weight. By the time they go back to sea, their skin looks
quite loose. After the adults leave in about March, the weaners stay
in place for one year. They gradually learn to swim and fish.
The adults return once in midyear, for molting,
not sex.
There is a southern elephant seal -- circumpolar and along the southern
coasts of S. America. It is
even bigger than its cousin, the northern elephant seal discussed here.
The elk we see in Rocky Mountain park and other Colorado locations are
known as Wyoming elk. This is a large, modern member of the deer group,
and probably arose in the Himalayas, and then migrated to Europe (as red
deer), and to North America, as wapati or elk. Our elk is a bit larger
than the red deer, with males at about 800 lbs., and females at about 600
lbs.
The males who have been living in bachelor herds most of the year, go into
rut about September each year. This is the beginning of their mating
season. The mature males have magnificent large antlers, and begin making
urine wallows and rolling in them, urinating on themselves and wiping it
on trees, thrashing bushes, and bugling to attract elk does. The males
compete with each other by locking antlers and puching. The loser is the
one who gets pushed. The males also have 'running' competition in which
two males will run side by side, back and forth for about 100 yds, looking
for a high-ground or other advantage for the fight. They often injure
each other, but seldom fatally, despite the dangerous antlers.
Does who are attracted by the bugling assemble near the males, and seem to
check them out (size, health, looks, symmetry of antlers, etc.) There
attributes probably signal strength and health, to the female. Once the
does begin to form a harem, the bull or stag elk actively herds them, to
keep them in his harem.
The stag will approach a female to mate by using a special head-high gait,
and with many licking motions, to signal that he is no danger, and will
lick the female. If she lets him approach, he will often put his neck
across hers, to see if she will stand. If she is not ready, she will
leave, shaking her head from side to side, or will lie down. If she lies
down, the male tends to lick her.
If the female is ready for mating, she will stand when the male puts his
neck on hers. The stag then quickly moves to her rear, and mounts, and
achieves a very quick, short, intromission with a short leap forward and
upward, when all 4 feet leave the ground. He ejaculates during this short
intromission. He tries to inseminate all the does in his harem, and
will threaten, or fight, other males who try to intrude. The animals,
especially the males, lose weight during the many activities of the
rut, as they eat little or nothing then.
The pregnant cows (or does) gradually leave the harem, and form a herd
with other females, and juveniles. During their 8 1/2 month gestation,
they eat mainly grass, which is adequate for their nutrition and, later,
milk production, although it is not adequate for the males. To form the
bone for new antlers each year, the males must browse on bushes and other
plants that have a high mineral content. If they find only grass, their
antlers are deformed or missing.
The males cast their antlers after the rut, and may even try to eat them,
which probably signals their demand for minerals. Prior to the next rut,
the males will grow new antlers, with a vascularized skin covering
("velvet"). When 'in velvet' the antlers are very sensitive, and the
males will use their forefeet for sparring, holding the antlers well
clear. They have also been seen to masturbate, by gently rubbing the
velvet in a bush. The velvet dies and sloughs off just before rut,
leaving 'hard horn' (bone, actually) for fighting.
The females give birth about May to a single, large, (~30 lbs.) calf or
fawn. She hides it near the herd, for a few days while it gains strength,
nursing it about 5 times a day and staying overnight with it. After these
few days, the mother and young re-join the herd proper, and the the
youngster is able to run and keep up with the herd quite well. Just
before the birth, the female chases off her yearling offspring, so she can
attend to the new calf. If her calf happens to die, she may re-adopt the
yearling, and let it continue to nurse. But while the calf is young, she
keeps the yearling back 30 feet or so, to its disappointment. In later
years, it may be seen that the mother infant bond is still present, as
dams and their grown offspring are seen doing things together, such as
acting as nurse or guard for each others new offspring.
The male is on an annual tesosterone cycle. When out of rut, androgen
supported tissues, such as testes, neck muscles, mane, etc. are much
smaller than when he is in rut, with high androgen.
Student Lecturers: Dan Berkey and Jill Ridley
There are several species of baboon, with some differences (of course)
between them. These large powerful monkeys live in troops ranging in size
between 30 - 100 or individuals, across most of Africa. They are Savanah
dwellers, but their home range of 4-6 sq. miles is limited by the
availabilty of tree to climb for protection at night, and from lions.
The sexes are dimorphic, with the females about 40 lbs and the males
about 80 lbs. The females seem to be more important for the constancy of
the troop, as the males sometimes leave and join a new troop, after
puberty.
The males form a dominance hierarchy, although DeVore reports the
formation of a 'central hierarchy' of 3 males who support each other
in fights, and can dominate all, although individually they would
lose the fight.
The females have a combined estrus/menstrual cycle of about 33-35 days,
with the first 18 or 19 day follicular phase called 'tumescence' since
their genitalia and rump swell and become bright red. This is followed by
a
period of 15-16 days called detumescence, when the swelling subsides. It
appears that ovulation is at the end of the tumescence or turgescence, and
menstruation is at the end of detumescence or deturgescence.
Newborn young are highly attractive to the troop members, and the object
of great curiosity. Females with newborns are allowed to stay in the
highly protected center of the troop, flanked by pregnant females and
juveniles who, in turn are flanked by adult males. This gives great
protection to the mother and young, as the males will stand-off most
predators with the exception of lions (then, all climb trees).
For about a week before peak tumescence and (presumably) ovulation, the
female will mate with lower ranking males. About the time of ovulation,
she ofter forms a consort pair, with a ranking male, for a few days during
which they stay together and copulate often. High-ranking males are not
bothered by other males while in consort, but low ranking males often
find themselves threatened or attacked during the consort pairing.
Copulation consists of a several mounts and intromissions. It is not
certain just when ejaculation occurs. The female will assist the male
in achieving intromission. During mounts, the male's full weight is
on the female, as his hind feet grab her on the ankles.
Gestation is about 6 months. The infant needs a great deal of care from
the mother, and gets it. Lower ranking mothers seem to have to let other
troop members examine their baby, but ranking mothers may keep others at
arms length. The mother's rank seems to transfer to the infant. Males
are quite good with the infants, and will let them climb over them, and
will stop fights among youngsters if the fight seems to be getting out of
hand.
The troop is a valuable protective mechanism. If a member can't keep
up, it is usually doomed, as the troop moves slowly, but doesn't wait for
the sick or injured. Troops are curious about other troops, and will
'visit' near water holes, but will then re-aggregate and move on. Troops
often mix with impala or other ungulates, and gain the extra protection
from the specialized senses of the other species.
As a ground-dwelling, social primate, baboons may have something to
teach us about early human evolution. Troop cohesion seems to depend a
good deal on mutual grooming, not on sex -- there isn't that much sex, as
the females are usually pregnant or nursing. There are, however, many
mounts. Most of these seem to be dominance/submission mounts, not sex.
Student Lecturers: Kaisa McDonnall, Erin Zumwalt, & Hillary Bouderman
The husband-wife pair of William Masters and Viginia Johnson are noted for
their detailed physiologic investigations of human sex, and for their many
expositons in articles, newpspapers and TV. In their book which was
reviewed in class they had collected data from over 300 men and over 300
women during sex, using cameras, movie camera, and electronic
recordings.
Their summary of typical responses is an average of male or female
responses for each phase.
They stress that details vary among individuals, and across occasions.
However, they did find considerable constancy in physiologic responses
across coital and masturbatory occasions, and between men and women.
They describe sex as occurring in 4 phases: Excitement, Plateau,
Orgasmic,
and Resolution. (see handout, for typical responses during each
phase).
Due to the intimate nature of the act, and the need for observers and
recording equipment, they counsel their couples for several sessions
before making measurements. They report that females adapt more easily
than males, who are quite shy. They have obtained sex responses from
persons aged 18-89, including from some who have artificial (surgically
constructed) vaginas (whose responses are quite similar to those of
non-treated women).
Student Lecturers: Kari Mau & Jeanne Heustis
John Money's views about our development of gender identity and gender
role have been very influential, especially in the press and on TV. From
the large number of sexual anomalies that he has treated or collaborated
in the treatment of, he concludes that babies of either sex can be reared
successfully as the other sex IF parents and significant others like
siblings, playmates, teachers, etc. are quite consistent in treating the
child either as female or male. However, reversals or inconsistencies in
treatment are likely to result in non-optimal development, and may result
in transvestitism, transexualism, homosexuality, paraphilias, etc.
Among Money's many observations is one that involves children that go
through puberty somewhat earlier or later than expected: those whose
puberty is delayed a few years tend to be treated as children (as younger
than they are) by parents and friends. They may not be able to overcome
this habit after they do undergo puberty. -Those who have an early
puberty tend to be treated as older than they are --sometimes being
expected to be ready mentally and physically for tasks that are actually
beyond them
Money's theories were challenged severely by the report of the guevedoces
syndrome, in the Dominican Republic. Some of the babies born with
ambiguous genitalia are reared as girls. But, about age 12, they develop
a penis, scrotum, and the testes lower into the new scrotum. They change
their gender, begin dating girls, and sometimes marry and sire
children.
We discussed in class some possible resolutions or partial resolutions
between this phenomenon, and Money's theories. The last assigned reading
for this phase is about the guevedoces syndrome.