Theos-Talk Archives (March 1998 Message tt00114)

Here's some new scientific information on another sense,
different from the five that we currently know of sight, touch, smell,
taste, and hearing. It's basically a from of "chemical
communication".

-- Eldon

----

CHEMISTRY BETWEEN PEOPLE IS MORE THAN JUST A SAYING

by Thomas H Maugh II

[from the LOS ANGELES TIMES, March 12, 1998]

After decades of speculation, false leads and heated controversy,
University of Chicago scientists finally appear to have proved
the existence of human pheromones -- odorless chemicals released
by one person that affect the behavior of another.

Psychologists Martha K. McClintock and Kathleen Stern report
today in the journal Nature that they have identified two
pheromones collected from the underarms of women -- one that
lengthens the menstrual cycle and one that shortens it.

The compounds may eventually find use in helping infertile women
conceive, but the confirmation of pheromones' existence may have
much greater ramifications for the individual human psyche and
human social behavior.

Researchers suspect that other pheromones may control sexual
activity, human compatibility, group behavior and other social
activity, just as they do in animals.

Now that two pheromones have been found, some speculate that it
will become easier to identify others.

The report "clearly shows, for the first time, that the potential
for chemical communication involving sexual function has been
preserved in humans during evolution," according to psychologist
Aron Weller of Bar-Ilan University in Israel.

McClintock and Stern’s paper "is going to be a classic," added
Charles Wysocki of the Monell Chemical Senses Center in
Philadelphia. "Now we need to find out how [the pheromones]
work."

The term "pheromone" was coined 39 years ago by researchers
studying insects. They found that insects secreted odorless
chemicals that could alter the behavior of other insects of the
same species. Pheromones have subsequently been shown to induce
a variety of behaviors in virtually all insects and animals.

The chemicals determine, for example, with which partners
hamsters mate, how dominance relationships develop among male
elephants and when rat mothers wean their pups. Female monkeys
in heat release a pheromone that serves as an aphrodisiac to
males.

But it has never been clear whether humans secrete and respond to
pheromones in the same manner as other animals.

The first evidence that they might was collected by McClintock
when she was an undergraduate at Wellesley College in the late
1960s. In a now-famous paper published in Nature in 1971, she
documented that the menstrual cycles of women living closely
together in dormitories or other social groups became
synchronized.

"This was one of the first real examples of social interactions
affecting basic biology," McClintock said.

Other researchers have confirmed her finding and observed the
same effect in lesbian couples.

In the current study, McClintock and Stern identified 29 women,
ages 20 to 35, with a history of regular ovulation. Nine of the
women wore cotton pads placed over the axillary glands under
their armpits for eight-hour periods in the early portion of

their menstrual cycle and, later, during ovulation. The pads
were then cut into quarters, moistened with alcohol and frozen.

They were collected in this fashion because animal studies had
shown that different pheromones are secreted at different times
of the cycle.

Then, each day for two months, the pads were wiped under the
noses of the other 20 women in the study. The pads collected
early in the menstrual cycle were found to shorten the menstrual
cycle in 68% of the women exposed to them.

In contrast, the pads collected later, during ovulation,
lengthened the menstrual cycle in 68% of the women exposed to
them. Cycles were shortened by one to 14 days and were
lengthened by one to 12 days.

McClintock had previously developed computer simulations showing
that this kind of lengthening and shortening of the cycle
produces the menstrual synchronization she observed in her
earlier studies. She had also demonstrated an identical effect
in rats and isolated the rat pheromones that produce it.

The new study, she said, "demonstrates that humans have the
potential to communicate pheromonally."

Unlike earlier, heavily criticized studies that have attempted to
demonstrate the presence of pheromones, McClintock’s "is a very
well-done piece of work," Wysocki said. "I doubt that there will
be any serious criticism because of the elegance of design and
execution."

George Preti of Monell, who led one of those earlier studies, was
pleased to see McClintock’s findings. "This bears us out, shows
that we were right," he said.

Researchers must now find out what the pheromones are and how
they work, a process that may take years because they are present
in such small amounts.

In most other animals, but not all, pheromones are detected by a
special organ in the nose called the vomeronasal organ or VNO.

Until a few years ago, most scientists believed that humans did
not possess a VNO. Although researchers have now shown that it
is present in humans, many experts, perhaps a majority, still
think that it is vestigial tissue with no function. (Plastic
surgeons remove the VNO during cosmetic surgery on the nose.)

But McClintock noted that there are other ways pheromones could
work their magic. For example, there might be other receptors in
the nose, or pheromones might simply be absorbed through tissues,
like cocaine is absorbed, she noted.

Once the pheromones are identified, most agree, they could be
used to regulate fertility. For example, the compounds could be
used with women who are infertile because of irregular menstrual
cycles. On the other hand, they could also be manipulated to
provide birth control by making women less fertile.

Despite the new proof of the existence of human pheromones,
experts cautioned, there is still no evidence that hormones
influence other types of sexual behavior. Perfumes and
fragrances purporting to contain human pheromones, Wysocki said,
"have never been shown to produce reliable and valid responses"
in members of the opposite sex.