Female orgasm. Do non-human primates experience them too, and why do they exist?
Female orgasm rate increases with male dominance in Japanese macaques (Troisi & Carosi, 1998) —
Case Study
General
discussion
on female
non-primate
orgasm
- Much of the evidence suggestive of copulatory orgasm in female nonhuman primates
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-
The study
- Data collected: For each copulation (sequence of >=2 mounts involving intromission and
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-
Conclusion
derives from observations of sudden behavioural changes that occur during copulation
(Chevalier-Skolnikoff, 1974; Wolfe, 1979)
- E.g. Observable characteristics: Clutching reaction (e.g. female turns her head to
look back at her partner, reaches back with one hand and grasps the male),
muscular body spasms, and characteristics vocalisations
Since physiological changes associated with orgasm in women are well known (e.g.
vaginal, anal and uterine contraction, hyperventilation, increase in blood pressure and
heart rate), investigators have studied the physiological correlates of the above observable
characteristics to determine whether this behavioural response is homologous with
orgasm in the human female
A conservative interpretation of all these findings is that, under specific circumstances,
female nonhuman primates find genital stimulation positively reinforcing and may
experience orgasm (Hrdy, 1981). The occurrence of female orgasm appears to be highly
variable however: not all individuals experience orgasm, and those that reach orgasm do
not do so consistently.
pelvic thrusts by the male), the observer recorded the time between the first and last
mounts, the number of mounts, the number of thrusts during each mount, and the
presence or absence of male ejaculation and female clutching reaction
Results: Females who experienced at least one orgasm did not differ in terms of age or
dominance rank from those who were never observed to reach orgasm. Correlational
analysis confirmed that the frequency of orgasms was not correlated with female age or
dominance rank.
Analysis:
- Although these results indicate that the level of sexual stimulation influenced the
threshold for female sexual climax, the relative weakness of the univariate
correlations and the low value of the adjusted R2 suggest that other factors could
play a role in triggering female orgasm
- Levels of sexual stimulation and the frequencies of female orgasms recorded in pairs
involving partners of different dominance rank were compared
- Percentage was highest in pairs formed by high-ranking males and low-ranking
females; lowest in pairs formed by low-ranking males and high-ranking females
- Limitation of this study: Like other primatologists (e.g. Allen & Lemmon, 1981) who have
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studied sexual behaviour in macaques, the frequency of clutching reactions was used as a
measure of the occurrence of copulatory female orgasm
- There is no conclusive evidence that the clutching reaction of female macaques
corresponds to a subjective experience of orgasm homologous with the sexual
climax of women
What the data can tell instead:
- Physical stimulation plays a significant role in facilitating clutching reactions
- However, it is not the only variable influencing female orgasmic response
- The proximate mechanisms that control orgasmic threshold in female macaques are
more responsive to social stimuli and less constrained by physiological limitations
than previously thought
Implications
on
functional
analysis of
female
orgasm in
non-human
primates
- The finding that male rank influences the probability of orgasmic response places in
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question the alternative hypothesis (Symons, 1979; Gould 1987) that female orgasm is an
incidental by-product of male orgasm
Our findings provide indirect evidence that primate female orgasm is an adaptation whose
evolutionary function is selective mate choice
- Human studies support the hypothesis that female orgasm has evolved as a female
choice adaptation
Compared with recent human studies, studies of proximate causation of female orgasm in
nonhuman primates have focused on a limited number of variables with a major emphasis
on physical stimulation
- The present study shows the importance of one social factor: the dominance rank of
the male partner [— relate to year 1 essay]
- However, it is likely that males features other than rank may affect the probability of
female orgasmic response. For example, macaque female sometimes show strong
sexual preferences for unfamiliar, newly transferred males, and this can counteract
preferences for high-ranking, resident males (Takahata, 1982). In addition, there is
evidence that male aggression towards females, male affiliative relationships with
infants, and male friendly behaviour towards females all affect females’ mating
preferences (Smuts, 1986; Soltis et al., 1997).
Orgasm in female primates (Allen & Lemmon, 1981) — Case Study & Reason
Orgasm
1.
2.
3.
4.
Changes in blood pressure, respiratory pattern and heart rate
Changes in muscular tension (including vaginal and uterine contraction)
Hormonal changes
Emission of sound
Argument 1
It is possible the orgasm exists in nonhuman female primates
- Even with the paucity of information regarding the sexual responses of the nonhuman
primates, it seems warranted to conclude that the capacity for orgasm in the female did
not appear for the first time on this earth in our species, any more than did the propensity
for continual sexual receptivity (Lemmon & Allen, 1978)
- Case study
- Allen (1977) manually stimulated the circumclitoral area and vagina of several
chimpanzee females
- Most permitted stimulation to continue to sexual arousal
- One allowed stimulation to continue to orgasm on 10 separate occasions. The
female invariably discontinued the stimulations by quadrupedally leaving the
fence after her vaginal contractions had been palpated
- A particular female (both clitoral and vaginal stimulation were being
concurrently provided) reached back to grasp the thrusting hand of the
experimenter and tried to force it more deeply into her vagina. On 2 occasions,
this female’s infant was intensely interfering, during which times vaginal
contractions were taking place. On neither of these occasions did the female
terminate stimulation, whereas she did in similar instances of interference
during earlier stages of her response.
- Other sexual responses detected included transudate secretion, clitoral
tumescence, vaginal thickening and expansion, hyperventilation, involuntary
muscle tension, arm and leg spasms, clutching, facial expressions (e.g. low
open grin, low closed grin, eversion of the lips, protrusion of the tongue), and a
panting vocalisation.
- Relatively few blatant emotional responses (e.g. vocalisation) associated with
orgasm in women were manifested by the chimpanzee, even when intense
vaginal contractions were being palpated
Argument 2
What could possibly be the reason for its existence? (propose a theory for its evolutionary
nature)
- More than just to experience highly pleasurable sensations during sexual intercourse — it
is intriguing that ecstatic sensations are felt during the contractions of the perivaginal
musculature, which seems to effectively grip and massage the penis which may often
result in ejaculation in a highly aroused male. It is their hypothesis that the orgasmic
response in the anthropoid female (infraorder: Catarrhini), or perhaps in mammals
generally, has evolved for the (adaptive role) purpose of stimulating the orgasmic
response in the male
- E.g. In human subjects: The female orgasm, as signalled by the woman, invariably
preceded or accompanied the male orgasm (Bartlett, 1956)
- E.g. Rhesus monkey: Frame-by-frame analysis of the film record revealed that the
female’s reaction began before the male’s ejaculation —> there is a reason to think
that the former might in some way be responsible for triggering the latter (Zumpe &
Michael, 1968)
- Another line of evidence: Ethological model of interindividual stimulus interaction
- We now know that the female sex is not passive in sexual intercourse
If that is assumed, then why do so many women fail to reach orgasm at all during coitus, or
reach it only after a consideration duration, and the male still reaches orgasm without being
stimulated by the female’s rhythmic vaginal contractions?
- Incomplete expression of female sexual response: It is not suggested that this adaptive
response has been selected to occur during every possible fertile copulation, but that as a
component of reproductive effort it can function as a means of female choice after
penetration has been achieved. There are, however, instances when vaginal contractions
are not achieved by the female, even when sexual intercourse has been reported to be
desirable. [LINK TO HRDY FROM BOSLEY] Reasons:
- Male perspective — The ejaculatory threshold of the male fluctuates in relation to
the number of orgasms he obtains over time… Therefore, if men today copulated
more often, their ejaculatory thresholds would rise to a more species-typical level
and orgasm would result from appropriate stimulation rather than from inappropriate
sources, ie, from vaginal contractions instead of from vaginal corrugation or
constriction
- Female perspective — It has been well documented that many women cannot reach
orgasm as quickly as can the average man because of psychological inhibition —
can be attributed to the female’s naturally selected propensity to be relatively more
discriminating in the partners she chooses for sexual intercourse than is the male —
sex is not just a means of production
- Female perspective — Inadequate control and development of the vaginal muscles
Letter: Primate female orgasm (Phoebus, E. C., 1982) — Case Study
Critique 1
Allen & Lemmon’s article: It suggests a proximal mechanism for the evolution of female
orgasm in that it postulates a process which would optimise conceptive probabilities by
encouraging spermatozoa to arrive in the right place at the proper time
Heart rate (HR) in the unrestrained copulation of gang-caged rhesus females (Phoebus,
1977) SUPPORTS their hypothesis
- HR peak rates were achieved before the final mount (on average about the fourth second
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of the final mount) — this suggests that either the male somehow initially communicates
that he is going to ejaculate on the current mount, or that the female indicates or initiates
(by contractions) the finality of the mount. It does not seem likely that they achieve
simultaneous orgasm independently
Video records do show that the peak in female HR does anticipate the clutching reaction
Critique 2
Allen & Lemmon's article: Only touched upon individual differences apparent among
members of the same species including human
It is his impression that an individual adult’s patten of sexual response (including the
physiological) is much more similar to its former responses than it is to that of any other
individual. This being true even with different partners and in spite of the apparent stereotypy
of rhesus sexual behaviour. —> seem more important to the mechanism of mate selection
then those involving fitness
Limitations
of current
studies
- Recent efforts to measure physiological changes in the sexual response of nonhuman
primates have been rewarding in that they tend to refute the prevailing assumption that
female orgasm is a phenomenon exclusive to the human female. The problem is that
these studies, including my own, have been limited to artificial and contrived social
situations making generalisation difficult.
Monkey facts to human ideologies: Theorising female orgasm in human and nonhuman primates,
1967-1983 (Bosley, 2010) — Reason
- Lloyd implies that controversy grew up around the evolution of female orgasm precisely because it had
been observed initially in so few primates apart humans
- Lloyd sees adaptationists and antiadaptationists
- Hrdy saw anthropocentrists and antianthropocentrists (those who define female orgasm as a uniquely
human attribute vs those who lobby to extend the orgasmic franchise to nonhuman primates)
- Hrdy found significantly more women and feminists numbered among the latter group, while the
former was composed of more “traditional” (male) scholars
Implication
- “how female monkeys and apes [got] their orgasms back, and what the story [has] to do
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with the white, middle class branch of the Women’s Liberation Movement” (Haraway, 1989:
357)
Defending Symons’s theory of female orgasm, Lloyd insists that “there is nothing
inherently antifeminist about the thesis being explored here.” (2005, 141) For Lloyd, calling
female orgasm a by-product — untoward semantics aside — is a salutary move for
women, insofar as it divests their orgasms of reproductive significance and thereby
(presumably) deprives men of a crucial ideological wedge for exerting control over
women’s sexuality.
Is female orgasm adaptive in an evolutionary sense, and if so, how?
Morris
Adaptationist & anthropocentrist — “Making sex sexier” (Morris, 1967: 65)
Promotes monogamy
- As humans developed a larger brain capacity and required a longer childhood, Morris
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reasoned, greater parental investment was needed to ensure the survival of offspring —>
the female was able to secure this investment from the male by, in effect, “making sex
sexier”. To cement the “pair-bond” (38), it was imperative that she be available for sex
whenever her partner might seek it. Orgasm facilitated this situation, acting as a
behavioural reward to fashion the female into a willing and accommodating sexual partner.
VS Hrdy: Because Morris understood the pair-bond as a uniquely human institution and
because female orgasm had evolved to promote it, there was no room in his account for
orgasm to occur in nonhuman primate females
Symons
Non-adaptationist — It is a byproduct of the selective advantage orgasm confers on males
- By way of an infamous and widely cited analogy to male nipples, he argued that female
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orgasm is a by-product of the selective advantage orgasm confers on males — that,
although orgasm serves no adaptive function in females, it persists because both sexes
develop from the same biopotential plan, and the clitoris is the female analogue of the
penis. Consistent with this view, Symons acknowledged that the clitoris has no known
function other than “to generate sensation — presumably pleasure — during
copulation” (1979: 88)
Because the occurrence of the female orgasm during reproductive sex is “sporadic”, it
could not have enhanced reproductive fitness enough to promote direct selection for the
trait (1979: 89)
- On anthropocentrism
- Symons, who denied that orgasm had ever conferred a selective advantage on
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Hrdy
females of any species, was not especially interested in resolving the matter of
whether nonhuman primate females experience orgasm — his argument did not
require that they do or they do not but only that they do not reliably during copulation
Female orgasm was “most parsimoniously interpreted as a potential” possessed by
all mammals but one that has been consciously cultivated in our own species alone
(90)
Adaptationist — Evolved as a behavioural reward
Promote promiscuity
- Female orgasm evolved as a behavioural reward — however, the behaviour rewarded was
not commitment to a single male but rather copulating with as many males as possible —
a promiscuous female would enjoy a selective advantage over a more sexually reserved
one
- 1. Consorting with many males would allow a female primate to assess the
“capabilities” of each and to arrange to copulate with the fittest male available near
the time of ovulation (1981: 150)
- 2. By copulating with many males, a female confused the paternity of her offspring,
thereby protecting them from infanticide and perhaps even encouraging multiple
males to contribute to their care
Is it a uniquely human phenomenon, or does it occur in nonhuman primates as well?
Compare
Symons
and Morris
- Symons: Orgasm in females is like unicycle riding in bears — it has no adaptive function in
a natural habitat, but it may nonetheless emerge in the context of an adaptive way of life
- Morris: Female orgasm was a component of a particular way of life, namely, the hunting
way of life
- Disagree: On the precise means by which female orgasm was woven into the system of
adaptations constitutive of human sociality
- Agree: Both arguments reduce to the ontological claim that female orgasm belongs to the
domain of culture rather than nature
- E.g. Symons likened women’s orgasms to “agriculture, the wheel, and indoor
plumbing” (1979, 95)
Symons
and Morris
VS Hrdy
- “I disagree that ‘female orgasm is extremely unlikely to occur in nature’” (1979, 312)
- Feminist anthropologist Zihlman noted approvingly that, for Hrdy, in contrast to her mostly
male colleagues, “female sexual responses such as orgasms are not merely incidental or
functional for male sexuality… [but] sexual enjoyment is a central part of female
nature” (1985, 371) — Zihlman’s phrase is felicitous, for Hrdy’s primate females were a
powerful proxy for female nature in a variety of registers
Male-female, female-female, and male-male sexual behaviour in the stumptail monkey, with special
attention to the female orgasm (Chevalier-Skolnikoff, 1974) — Case Study
My critique: Use Troisi & Carosi to critique this (Under limitation section)
Point
- Females as well as males can experience orgasm, and the orgasmic patterns of the two
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Evidence
sexes are very similar — both showing body rigidity followed by muscular body spasms
accompanied by the same facial expression and vocalisation
An examination of stumptail females’ behaviour during coitus reveals two indications that
orgasm does occur: the reaching-back and clutching behaviour, and the postejaculatory
phase
However, the unmistakable observation of orgasm in female stumptail monkeys during
homosexual interactions and strong evidence for the occurrence of female orgasm in this
species during heterosexual coitus, plus to coital behaviour of females in other macaques
species, suggest that females of at least some of these species also experience
Female homosexual behaviour — the encounters observed clearly show a naturally occurring
complete orgasmic behavioural pattern for female stump tails
- On 3 recorded occasions, the female mounter displayed all the behavioural manifestations
of orgasm generally displayed by males: a pause followed by muscular body spasms
accompanied by the characteristic frowning round-mouthed stare expression and the
rhythmic expiration vocalisation
- Besides being behaviourally homologous to the orgasmic behaviour of the male, the
orgasmic response of the female stump tail monkey is essentially identical to the behaviour
reported by Masters and Johnson (1966) in the human female. At orgasm, involuntary
muscular tension occurs throughout the human female’s body: the muscles of the arms and
legs contract spasmodically; if the hands are not already grasping something, they, as well
as the feet, display involuntary grasping-like spasms; and the muscles of the face contract
into a characteristic grimace. In addition, a number of other physiological changes (which
could not be detected during this observational study) occur during orgasm: the uterus and
the rectal and urethral sphincters contract, and respiration rate and blood pressure often
increase.