Copyright ©2003 Winnifred Cutler and Athena Institute for Women's Wellness
Winnifred B. Cutler, PhD.
Dr. Winnifred Cutler's Invited Monograph on Human Pheromone Research for a 2004 Encyclopedia
Over the course of a summer, Japanese beetles can destroy a beautiful rose garden by eating the flowers and leaves. Fortunately, gardeners can fight back with special traps that attract the beetles and hold them for later disposal. The insects head straight for the traps as soon as they get a whiff of a type of chemical called a pheromone that is in the containers. Pheromones are odorless chemical compounds that scientists have long known many insects, reptiles, rodents, and other animals use to communicate with members of their own species. The pheromone in the beetle trap works as a sex attractant. Pheromones that act in this way serve as signals for attracting mates. Other animal pheromones are important for such social behaviors as marking territories and recognizing family members.
Do humans also exchange pheromones that are important in social interactions? Since the 1980’s, researchers have been uncovering more and more evidence that the answer to that question is “yes.”
One of the first indications that primates (the group of animals to which humans, apes, and monkeys belong) use pheromones came in 1971 at Emory University in Atlanta. Emory psychiatrist Richard Michael and his colleagues experimented with female rhesus monkeys that had their ovaries removed. Ovaries are the reproductive organs that produce eggs and sex hormones. The researchers found that these females could not attract male attention when they displayed the “come-hither” signal of an exposed rump. However, the monkeys were able to attract males when their posteriors were smeared with fluid removed from the exposed rumps of signaling monkeys that had their ovaries intact. Later, researchers used chemical analysis to identify the critical substance as an airborne pheromone.
At about the same time that Michael was engaged in his research, Martha McClintock, a psychology student at Wellesley College in Massachusetts, observed that the trash cans in the bathrooms of her dormitory contained more menstrual product trash during certain times of the month than at other times.
This observation led McClintock to study the timing of menstrual cycles in women who live together in college dorms. Menstrual cycles are the cycles of physical changes, including blood and cell loss and maturation of a fertilizable egg, and cyclic variation in the secretion of a number of sex hormones, that recur about once a month in women of childbearing age. The precise timing of the cycles varies from woman to woman. The cycles may also vary from month to month in the same woman and the most fertile cycles are around 29.5 days. In 1971, McClintock published statistical evidence to suggest a phenomenon she called menstrual synchrony—that is, women who live together tend to cycle together.
Scientists at the time were at a loss to explain the cause of menstrual synchrony. Evidence that the cause was human pheromones would come in the 1980’s from my work with George Preti and colleagues, and later in the 1998 work of McClintock and Stern at the University of Chicago.
The first scientifically rigorous experiments supporting the existence of human pheromones were published in 1986 by a research team at the University of Pennsylvania School of Medicine working with men at the Monell Chemical Senses Center. I was the leader of the university team.
Volunteers wore underarm sterile pads which were collected every other day from four apparently fertile women, and 3 men, for 14 consecutive weeks. We then extracted the sweat from the women’s pads and created ten different formula samples (i.e. a Day 1 sweat essence on the first day of the cycle pooled from the 4 women, a Day 3 sample, a Day 5 and so on). From men who do not have a monthly hormone cycle, we pooled all the extracted sweat into one large sample. Later we filtered the 10 separate samples from women and one sample from men to remove the odor and bacteria, leaving only odorless test substances, called either female or male “essences”. These “essences” consisted of over 100 chemical compounds.
Finally, we conducted 2 double-blind, placebo-controlled experiments adhering to competent scientific methodology.
Double-blind means that neither the test subject nor the technician knows what product is being tested until the code is broken at the end of the experiment. Placebo-controlled means that half the testers do not test the experimental substance, they get only an inactive substance. In experiment 1, women whose records showed they had fertile-type cycles of about 29.5 days tested either female essence or placebo. In experiment 2, women whose records showed they had sub-fertile cycles shorter than 26 days or longer than 33, days tested either male essence or placebo.
In the first test group of women with regular menstrual cycles, every other day we applied either placebo (to half the group) or essence (to the other half of the group) in sequence Day 1, Day 3, Day 5 and so on) for 14 consecutive weeks to the upper lips of women. Among the women who tested placebo, the timing of the cycles did not change. But among the group that tested sequential application of female essence, cycles tended to synchronize with the donor day 1 timing.
In the second test group of women (those with excessively short or long cycles) we applied the male essence every other day to half to group, or placebo to the other half of the group for 14 consecutive weeks to the upper lips of women. The cycles of these women receiving male “essence” applications became more normal in length. The women receiving placebo applications continued to record abnormally short and long cycle lengths.
We concluded that the observed cycle changes demonstrated that human pheromones released into the air from underarm glands are important in regulating the timing of menstrual cycles. Furthermore, the experiment with the male essence helped explain my own previous finding that frequent intimate contact with a man tends to make a woman’s menstrual cycles more regular and thus, more fertile.
These intriguing results and a small study I reported in 1987 led me to wonder about the possible unconscious role that the underarm pheromones may play in sexual attraction.
In 1994 and 2000, scientists, including myself, from the Athena Institute (my biomedical research company in Chester Springs, Pennsylvania), San Francisco State University, Brooklyn College, and then Harvard University (2002) published the results of experiments using chemical copies of the pheromones, developed by Athena Institute, on groups of women and men. The women were given either the Athena pheromone formula (Athena Pheromone 10:13tm), or a placebo, which they added to their perfume of choice. The men were given either the Athena Pheromone 10Xtm, or a placebo, for mixing with their aftershave of choice. The subjects, who did not know whether they were testing/wearing the pheromones or a placebo, were asked to record their sociosexual encounters on daily calendars.
These double-blind, placebo-controlled experiments revealed that a significantly larger proportion of the women and men who used the Athena pheromones recorded increases in kissing, petting, sexual intercourse, and other intimate contact with the opposite sex than the subjects who used the placebo.
Researchers are also investigating whether there are other human behaviors besides menstrual synchrony and opposite-sex attraction that may be influenced by pheromones. For example, some researchers have proposed that human pheromones may regulate male “territorial” attitudes and strengthen the mother-infant bond. However, as of May 2003, little new scientific evidence supported these proposals in humans.
Scientists are not sure how pheromones work in humans. Researchers suspect that airborne pheromones may be detected by the olfactory (smelling) system. Scientists have identified two possible sites inside the nose that might serve as receptors for pheromones—the olfactory epithelium and/or the vomeronasal organ (VNO).
The olfactory epithelium is mucus-covered tissue lining the inside of the nose. The VNO consists of two tiny, narrow sacs in tissue behind the nostrils. Pheromones could work by stimulating nerves in the olfactory epithelium and VNO. The nerve impulses may then get transmitted to a part of the lower brain called the olfactory bulb. From there, the impulses may travel to various regions of the brain, including those parts associated with the menstrual cycle and sexual attraction. More research is needed to conclusively trace these putative pheromone pathways in human beings.
Human pheromone research has generated some controversy. Not all scientists are convinced that pheromones play a role in human behavior. Some scientists maintain that, unlike many other animals, human beings probably do not have a functioning VNO. That view is irrelevant if the olfactory epithelium is the operative site. I suspect that the olfactory epithelium, not the VNO is involved in human attraction.
Athena Institute’s two pheromone cosmetic fragrance additives, which are commercially available, have been subjected to three rigorous double blind, placebo-controlled studies of 6 or more weeks of real-life usage. All 3 studies have been presented to medical and scientific conferences; 2 of the 3 have been published in respected, peer review journals. Studies of this caliber are virtually unheard of for cosmetic products like Athena Pheromone 1013tm for women and Athena Pheromone 10X for men. I was invited by the American College of Obstetricians and Gynecologists to present an hour and a half lecture on “Pheromones as Sex Attractants” at ACOG’s annual meeting in 2000. My presentation earned “continuing medical education” (CME) credits for the physicians in my audience.
Scientists expect that continued research will eventually clarify the function that pheromones have in influencing human behavior. I believe researchers will one day learn that the “good chemistry” or “bad chemistry” people feel toward each other is not all that different from the chemistry exchanged between beetles in a garden.
Winnifred Cutler, Ph.D.