[Paleopsych] NYT: A Critic Takes On the Logic of Female Orgasm

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A Critic Takes On the Logic of Female Orgasm
http://www.nytimes.com/2005/05/17/science/17orga.html

[I thought Victorian women were supposed to be completely sexless. So which is 
it?]

    By [2]DINITIA SMITH

    Evolutionary scientists have never had difficulty explaining the male
    orgasm, closely tied as it is to reproduction.

    But the Darwinian logic behind the female orgasm has remained elusive.
    Women can have sexual intercourse and even become pregnant - doing
    their part for the perpetuation of the species - without experiencing
    orgasm. So what is its evolutionary purpose?

    Over the last four decades, scientists have come up with a variety of
    theories, arguing, for example, that orgasm encourages women to have
    sex and, therefore, reproduce or that it leads women to favor stronger
    and healthier men, maximizing their offspring's chances of survival.

    But in a new book, Dr. Elisabeth A. Lloyd, a philosopher of science
    and professor of biology at Indiana University, takes on 20 leading
    theories and finds them wanting. The female orgasm, she argues in the
    book, "The Case of the Female Orgasm: Bias in the Science of
    Evolution," has no evolutionary function at all.

    Rather, Dr. Lloyd says the most convincing theory is one put forward
    in 1979 by Dr. Donald Symons, an anthropologist.

    That theory holds that female orgasms are simply artifacts - a
    byproduct of the parallel development of male and female embryos in
    the first eight or nine weeks of life.

    In that early period, the nerve and tissue pathways are laid down for
    various reflexes, including the orgasm, Dr. Lloyd said. As development
    progresses, male hormones saturate the embryo, and sexuality is
    defined.

    In boys, the penis develops, along with the potential to have orgasms
    and ejaculate, while "females get the nerve pathways for orgasm by
    initially having the same body plan."

    Nipples in men are similarly vestigial, Dr. Lloyd pointed out.

    While nipples in woman serve a purpose, male nipples appear to be
    simply left over from the initial stage of embryonic development.

    The female orgasm, she said, "is for fun."

    Dr. Lloyd said scientists had insisted on finding an evolutionary
    function for female orgasm in humans either because they were invested
    in believing that women's sexuality must exactly parallel that of men
    or because they were convinced that all traits had to be
    "adaptations," that is, serve an evolutionary function.

    Theories of female orgasm are significant, she added, because "men's
    expectations about women's normal sexuality, about how women should
    perform, are built around these notions."

    "And men are the ones who reflect back immediately to the woman
    whether or not she is adequate sexually," Dr. Lloyd continued.

    Central to her thesis is the fact that women do not routinely have
    orgasms during sexual intercourse.

    She analyzed 32 studies, conducted over 74 years, of the frequency of
    female orgasm during intercourse.

    When intercourse was "unassisted," that is not accompanied by
    stimulation of the clitoris, just a quarter of the women studied
    experienced orgasms often or very often during intercourse, she found.

    Five to 10 percent never had orgasms. Yet many of the women became
    pregnant.

    Dr. Lloyd's figures are lower than those of Dr. Alfred A. Kinsey, who
    in his 1953 book "Sexual Behavior in the Human Female" found that 39
    to 47 percent of women reported that they always, or almost always,
    had orgasm during intercourse.

    But Kinsey, Dr. Lloyd said, included orgasms assisted by clitoral
    stimulation.

    Dr. Lloyd said there was no doubt in her mind that the clitoris was an
    evolutionary adaptation, selected to create excitement, leading to
    sexual intercourse and then reproduction.

    But, "without a link to fertility or reproduction," Dr. Lloyd said,
    "orgasm cannot be an adaptation."

    Not everyone agrees. For example, Dr. John Alcock, a professor of
    biology at Arizona State University, criticized an earlier version of
    Dr. Lloyd's thesis, discussed in in a 1987 article by Stephen Jay
    Gould in the magazine Natural History.

    In a phone interview, Dr. Alcock said that he had not read her new
    book, but that he still maintained the hypothesis that the fact that
    "orgasm doesn't occur every time a woman has intercourse is not
    evidence that it's not adaptive."

    "I'm flabbergasted by the notion that orgasm has to happen every time
    to be adaptive," he added.

    Dr. Alcock theorized that a woman might use orgasm "as an unconscious
    way to evaluate the quality of the male," his genetic fitness and,
    thus, how suitable he would be as a father for her offspring.

    "Under those circumstances, you wouldn't expect her to have it every
    time," Dr. Alcock said.

    Among the theories that Dr. Lloyd addresses in her book is one
    proposed in 1993, by Dr. R. Robin Baker and Dr. Mark A. Bellis, at
    Manchester University in England. In two papers published in the
    journal Animal Behaviour, they argued that female orgasm was a way of
    manipulating the retention of sperm by creating suction in the uterus.
    When a woman has an orgasm from one minute before the man ejaculates
    to 45 minutes after, she retains more sperm, they said.

    Furthermore, they asserted, when a woman has intercourse with a man
    other than her regular sexual partner, she is more likely to have an
    orgasm in that prime time span and thus retain more sperm, presumably
    making conception more likely. They postulated that women seek other
    partners in an effort to obtain better genes for their offspring.

    Dr. Lloyd said the Baker-Bellis argument was "fatally flawed because
    their sample size is too small."

    "In one table," she said, "73 percent of the data is based on the
    experience of one person."

    In an e-mail message recently, Dr. Baker wrote that his and Dr.
    Bellis's manuscript had "received intense peer review appraisal"
    before publication. Statisticians were among the reviewers, he said,
    and they noted that some sample sizes were small, "but considered that
    none of these were fatal to our paper."

    Dr. Lloyd said that studies called into question the logic of such
    theories. Research by Dr. Ludwig Wildt and his colleagues at the
    University of Erlangen-Nuremberg in Germany in 1998, for example,
    found that in a healthy woman the uterus undergoes peristaltic
    contractions throughout the day in the absence of sexual intercourse
    or orgasm. This casts doubt, Dr. Lloyd argues, on the idea that the
    contractions of orgasm somehow affect sperm retention.

    Another hypothesis, proposed in 1995 by Dr. Randy Thornhill, a
    professor of biology at the University of New Mexico and two
    colleagues, held that women were more likely to have orgasms during
    intercourse with men with symmetrical physical features. On the basis
    of earlier studies of physical attraction, Dr. Thornhill argued that
    symmetry might be an indicator of genetic fitness.

    Dr. Lloyd, however, said those conclusions were not viable because
    "they only cover a minority of women, 45 percent, who say they
    sometimes do, and sometimes don't, have orgasm during intercourse."

    "It excludes women on either end of the spectrum," she said. "The 25
    percent who say they almost always have orgasm in intercourse and the
    30 percent who say they rarely or never do. And that last 30 percent
    includes the 10 percent who say they never have orgasm under any
    circumstances."

    In a phone interview, Dr. Thornhill said that he had not read Dr.
    Lloyd's book but the fact that not all women have orgasms during
    intercourse supports his theory.

    "There will be patterns in orgasm with preferred and not preferred
    men," he said.

    Dr. Lloyd also criticized work by Sarah Blaffer Hrdy, an emeritus
    professor of anthropology at the University of California, Davis, who
    studies primate behavior and female reproductive strategies.

    Scientists have documented that orgasm occurs in some female primates;
    for other mammals, whether orgasm occurs remains an open question.

    In the 1981 book "The Woman That Never Evolved" and in her other work,
    Dr. Hrdy argues that orgasm evolved in nonhuman primates as a way for
    the female to protect her offspring from the depredation of males.

    She points out that langur monkeys have a high infant mortality rate,
    with 30 percent of deaths a result of babies' being killed by males
    who are not the fathers. Male langurs, she says, will not kill the
    babies of females they have mated with.

    In macaques and chimpanzees, she said, females are conditioned by the
    pleasurable sensations of clitoral stimulation to keep copulating with
    multiple partners until they have an orgasm. Thus, males do not know
    which infants are theirs and which are not and do not attack them.

    Dr. Hrdy also argues against the idea that female orgasm is an
    artifact of the early parallel development of male and female embryos.

    "I'm convinced," she said, "that the selection of the clitoris is
    quite separate from that of the penis in males."

    In critiquing Dr. Hrdy's view, Dr. Lloyd disputes the idea that longer
    periods of sexual intercourse lead to a higher incidence of orgasm,
    something that if it is true, may provide an evolutionary rationale
    for female orgasm.

    But Dr. Hrdy said her work did not speak one way or another to the
    issue of female orgasm in humans. "My hypothesis is silent," she said.

    One possibility, Dr. Hrdy said, is that orgasm in women may have been
    an adaptive trait in our prehuman ancestors.

    "But we separated from our common primate ancestors about seven
    million years ago," she said.

    "Perhaps the reason orgasm is so erratic is that it's phasing out,"
    Dr. Hrdy said. "Our descendants on the starships may well wonder what
    all the fuss was about."

    Western culture is suffused with images of women's sexuality, of women
    in the throes of orgasm during intercourse and seeming to reach
    heights of pleasure that are rare, if not impossible, for most women
    in everyday life.

    "Accounts of our evolutionary past tell us how the various parts of
    our body should function," Dr. Lloyd said.

    If women, she said, are told that it is "natural" to have orgasms
    every time they have intercourse and that orgasms will help make them
    pregnant, then they feel inadequate or inferior or abnormal when they
    do not achieve it.

    "Getting the evolutionary story straight has potentially very large
    social and personal consequences for all women," Dr. Lloyd said. "And
    indirectly for men, as well."