origin of the elusive female orgasm

The female orgasm may have evolved from an
ancient reproductive trait
The hormonal surge women experience during
orgasm once stimulated ovulation, research
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(CNN) — What is the purpose of the ever-
elusive female orgasm?
In males, orgasm is invariably required for
ejaculation and transfer of sperm, researchers
noted in a piece published recently in the
Journal of Experimental Zoology . "But in
females its function is unclear," wrote Mihaela
Pavlicev, a researcher at Cincinnati Children's
Hospital Medical Center, and Gunter Wagner, a
professor of ecology and evolutionary biology at
Yale University.
  In women, the orgasm does not contribute to
reproductive success and accompanies
intercourse only "unreliably," they said. So, what
gives?
The researchers examined many species of
mammals and proposed that orgasm in women
evolved from an ancient trait that once played a
key role in reproduction.
To discover the big O's reason for being, the
researchers explored its underlying physiology
and focused on the hormonal surge that women
experience while in the throes of passion.
Keeping this foremost in mind, Pavlicev and
Wagner then looked at other mammals. Despite
the enormous diversity of reproductive styles,
they were able to identify core characteristics
of reproduction and track how these features
evolved.
The evolution of ovulation
Certain species of mammals are reflex
ovulators. For example, female cats produce a
mature egg ready to be fertilized by sperm only
when stimulated by intercourse with a male. By
comparison, women are spontaneous ovulators
who produce eggs monthly, independent of
sexual intercourse.
Looking at the distribution of these two types of
ovulation across all the species of mammals,
Pavlicev and Wagner inferred that male-induced
ovulation must have evolved first and
spontaneous ovulation later.
If female orgasm, by causing a hormonal surge,
helped induce ovulation, this means it once
played a direct role in reproduction. Over time,
though, spontaneous ovulation evolved,
rendering the female orgasm unnecessary
  Looking at the evolution of female genitals, the
researchers found additional evidence that
orgasm once played a fundamental role in
reproduction. As females moved away from
reflex ovulation toward spontaneous ovulation,
the clitoris -- the major source of orgasm --
moved away from the location of sexual
intercourse, the vagina.
All this adds up to broader implications for
women, Pavlicev and Wagner suggested: The
low frequency of female orgasm -- only a
quarter of all women reliably achieve orgasm
during intercourse -- is not an individual
woman's failing or a physical impossibility but a
natural consequence of evolution.
Others challenged this theory.
Heated views
Elisabeth Lloyd, faculty scholar at the Kinsey
Institute for Research in Sex, Gender and
Reproduction, found this new theory to be "an
impressive piece of work," yet she also had a
"quibble." (To help prepare the paper for
publication, Lloyd provided comments for the
authors but was not involved in the research.)