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Two Myths...

What role do odors play in the human menstrual cycle?

Do human menstrual odors act as attractants?

Anne Kitchell

Blood-Scented Perfume

Through no fault, nor choice, of their own, women are “blessed” monthly with the outward expression of their inner femininity, that internal cycle of fertility-- intimately characterized by intense hormonal explosions, physiological “expectations” of ensuing life, and emergency trips to particular grocery aisles that men tend to avoid. There one can find shelf upon shelf of products by Kotex, Tampax, Playtex, Always... an infinite demand supplied by a market delicately labeled FEMININE PROTECTION. Heavy or light, thick or thin, disposable, cardboard/ plastic applicator, fresh scent, winged-teen-maxi-supreme all are available to the lucky ladies of the 20th century. Lucky schmucky. In dealing with menstruation, women have to worry about wearing white, watching embarrassing douche commercials about beach walks with mom, and smelling like blood and dead fish. Even worse is the common rhetoric defining PMS which generally includes emotional rollercoasters and hyper-bitchiness. Instead of being respected as necessary evils associated with being the propagators of all humankind, the insufferable menstrual unpleasantries women endure, unfortunately, are viewed and accepted by society as physical and mental limitations.

A woman can’t be trusted to make decisions because every four weeks she becomes completely irrational. A woman can’t fly a fighter because at the first of every month she becomes uncontrollably trigger-happy. No women astronauts or sailors are allowed; there is a problem with the disposal of certain FEMININE PROTECTION in space and sea, and no one wants to be trapped in an enclosed area with an hysterical PMSer. Women can’t go swimming during menstruation because the sharks will attack, and definitely NO HIKING-- the bears will come out of the woods drawn to dinner (or maybe a mate) by Jane’s blood-scented perfume. Whatever! Some husband who didn’t want his poker-playing, beer-drinking, dirty-joke telling camping trip with the buddies spoiled by the presence of his “shackle” made that up! Sound scientific documentation supporting such anecdotal, gender-biased malarkey is hard to find; actually one is more likely to run across studies concluding quite the opposite.

... UNBEARABLE ...

Such a study was published in the Journal of Wildlife Management in 1991 in answer to concerns regarding black bears’ attraction to menstrual odors and subsequent attacks on female hikers. The death of two menstruating women attacked by grizzlies in Glacier National Park in 1967 apparently prompted the government to print brochures warning women to avoid bear country during periods of active menstruation. However, the examination of factors surrounding hundreds of grizzly and black bear attacks produced neither evidence that supported a causal relation between human menstruation and attacks nor revealed any published records concerning black bear responses to menstrual blood. The U.S. Forest Service conducted a series of experiments (Rogers et al., 1991) which tested the responses of both male and female black bears to human menstrual odors. The first experiment involved the spin-cast introduction of 15 used tampons (in clusters of 5) to adult male black bears foraging in a garbage dump. Each presentation, therefore, gave the bears a choice between the garbage and tampons. If the bears ate (like they did the garbage), closely sniffed, or rolled on the tampons, then they were considered to have paid attention to the tampons. Of 22 presentations, the bears ignored the used tampons 20 times (twice casual sniffs were observed), effectively preferring the garbage in every instance. In a second experiment, seven bears feeding on piles of corn were offered groups of six used tampons. Six of the bears sniffed the tampons and then returned to their piles of corn. A yearling male tasted one of the tampons, quickly dropped it and returned to the corn.

A third experiment placed four used tampons, an unused tampon, a tampon soaked in non-menstrual human blood, and a tampon containing rendered beef fat in the middle of a heavily traveled bear path with the used tampons interspersed among the others. Ten out of ten bears ate only the tampons soaked in beef fat. In a fourth experiment, women on different days of their period accompanied and contacted bears who were accustomed to human interaction and were known to investigate attractive odors. Eleven encounters involved women wearing tampons and one crazy woman wearing clothing through which her menstrual blood was soaking. Of the twelve encounters with the women, the ten bears did not pay any attention to the lower torsos of the women. Another woman wearing external pads during two of her menstrual cycles hand-fed four female bears and walked within two meters of adult male bears during bear mating season and did not receive any attention. Rogers et al. (1991) concluded that the lack of interest of the bears to menstrual odors does not prove that such odors are never attractive to bears (similar experiments resulted in tampon feasts by polar bears lacking attractive buffets); however, menstrual odors essentially were ignored.

References

Rogers, L L., G.A. Wilker, and S.S. Scott. 1991. Reactions of black bears to human menstrual odors. J. Wildl. Manage. 55(4):632-634.

See also
Cushing, B. 1983. Responses of polar bears to human menstrual odors. Int. Conf. Bear Res. and Manage. 5:270-274.

Herrero, S. 1974. Conflicts between man and grizzly bears in the national parks of North America. Int. Conf. Bear Res. and Manage. 3:121-145.

-------. 1985. Bear attacks. Nick Lyons Books, New York, N.Y. 287pp. Insert bear picture

Darwin's Sexy Nose

Bear attacks, among other less-desired responses to a woman’s menstrual perfume, do not seem to be frequent consequences of the olfactory influences involving human menstruation. Many scientific journals suggest that human males, on the other hand, respond to vaginal cyclic scents. Doty et al. (1975) described a study which concluded that “the odors of human vaginal secretions vary in both intensity and pleasantness across the stages of the menstrual cycle.” Men were asked to rate both the intensity and pleasantness of odors arising from used tampons from consecutive phases of the menstrual cycle. It was found that even though there was considerable variation across cycles from the same donor, men claimed secretions from pre-ovulatory and ovulatory stages were less intense and more pleasant than during the other phases. Data fell short of providing substantial support to the idea that particular staged menstrual odors were “attractive” to men, and due to heterogeneity of results it “is unlikely that humans can use vaginal odors reliably to determine the general time of ovulation.”

“Unlikely” does not mean impossible, and the logical jump made (before or after) with studies such as the aforementioned is to attempt to bridge some evolutionary gap between man and ape, providing a reasonable explanation as to the importance of menstrual olfactory cues in communicating courtship rituals and defining timed mating behaviors in early man. In the December 1974 edition of Science, scientists from Emory University of Medicine published the volatile fatty acid content as determined by gas chromatography of 682 vaginal samples from human females. They noted that fatty acid content “increased during the late follicular phase of of the menstrual cylce and declined progressively during the late luteal phase.” The same volatile aliphatic acids found in the human samples (i.e. acetic, propanoic, methylpropanoic, butanoic, methylbutanoic, and methylpentanoic) have been found ubiquitously in the vaginal secretions of many primate species such as the rhesus monkey, anubis baboon, patas monkey, pigtail monkey, crab-eating monkey, and squirrel monkey. Although scant information is available on the importance of these compounds in humans, say Michael et al. (1974), “The same substances possess sex-attractant properties in other primates.” Interestingly, it was noted that similar attraction reactions resulted when human vaginal secretions where exposed to rhesus monkeys, and that women on oral contraceptives had lower acid amounts and showed no rhythmic changes during their cycle. There is evidence to suggest in rhesus monkeys that other odorous, non-aliphatic compounds present in vaginal secretions serve as distinct cues to males during the preovulatory phase of the menstrual cycle (Goldfoot, 1981).

So did man at one time in his early development use scent, like today’s primates, as an important reproductive communicator? Acceptance of the arguement further implicates that somewhere along the evolutionary line of man, menstrual olfactoy cues became obsolete. The subsequent weakening of human’s conscious attraction to vaginal odors resulted in the degeneration of sense of smell found in humans today. Of course, whether one makes the leap connecting primate olfactory cues to early man’s equally intrinsic ability to detect estrous of Cro-magnon Jane or not, it must be accepted that supportive, documented science just does not exist in a less correlative form.

References

Doty, R.L., M. Ford, G. Preti, and G.R. Huggins. 1975. Changes in the intensity and pleasantness of human vaginal odors during the menstrual cycle. Science 190: 1316- 1317.

Goldfoot, D.A. 1981. Olfaction, sexual behavior, and the phermone hypothesis in rhesus monkeys: A critique. Am. Zool. 21(1): 153-164.

Michael, R.P., R.W. Bonsall, and P. Warner. 1974. Human vaginal secretions: Volatile fatty acid content. Science 186: 1217-1219.

see also
Bieber, I. 1959. Am. J. Psychother. 13: 851.

Michael, R. P. 1972. Acta. Endocrinol. Suppl. 166: 322.

Michael, R.P., E.B. Keverne, and R.W. Bonsall, 1971. Science 172: 964.

Rogers, J. and G. Beauchamp, in Mammalian Olfaction, Reproductive Processes and Behavior, R.L. Doty, Ed. (Academic Press, New York, 1974).

Stinkin' Synchin'

The menstrual cycle not only produces odors, rumored to serve as attractive cues, but reacts to external odors as well. One often hears of females living in close proximity undergoing the synchronization of their menstruation onset times. In an article published by Russell et al. (1980), it was stated that “menstrual synchrony is not due to changes in food, awareness of menstrual timing or lunar cycles, and [it is] suggested that the only significant factors seem to be the amount of time the women spend together and the lengths of their cycles.” They conducted a really cool experiment in an attempt to demonstrate if the olfactory cues of one very “regular” woman could influence the timing of menstrual onset in other women.

Eleven women, with mean age was 28.5 years, none of whom were lesbians or were taking oral contraceptives, volunteered to have an odor placed on their upper lip three times a week during a four month period. The odor was extracted from the axillary region (the armpit!) of a female donor with a history of a very regular menstrual cycle. She did not use underarm deodorant or perfumed soap, nor was she allowed to wash under her arms during the odor gathering period. Odor collection involved having the donor wear 4X4 cotton pads under her arms for 24 hours. The subjects had the pads rubbed on their upper lips and asked not to wash their faces for six hours. The group of control subjects received the same treatment, with the exception that they did not receive the odor. Test subjects and control subjects had no knowledge as to which group they belonged.

The results indicated with statistical significance of p < 0.01 that ododrs from one woman can influence the the mensrtual cycle of another. The mean difference in days between the menstrual onset of tested subjects and the donor at the beginning of the experiment was 9.2 days. This average decreased to 3.4 days by the end of the experiment with four of the five subjects synchronizing to within one day of the donor’s onset. The control group avearged 8.0 days from the donor’s onset in the pre-treatment month and 9.2 days in the post-treatment month.

Difference (in Days) Between Menstrual Onset of Donor and Subjects

Insert graphs Russell (1980) p 738 Fig 1

Figure 1: Recreated by extrapolation from Russell et al. (1980), these graphs represent the difference (in days) between each subject’s onset of menstruation with that of the donor. Each line represents one individual.

The possibility was noted that “the mechanism of [odor] transfer did not involve the nose at all, but diffusion of chemical compounds through the skin which may occur when the sample was placed on the subject’s upper lip.” If compounds placed under the nose were volatile and the subject unaware of their presence, then can one properly use the term “odor” anyway?

The olfactory influences on the menstrual cycle of crab-eating monkeys (Macaca fascicularis) have been studied along the same lines as human synch experiments. Wallis et al. (1986) placed twelve female monkeys in adjacent cages allowing for the occurrence of physical contact. Only one of the females had a history of regularly-timed menstruation. A control set was established in the same manner with the exception that cages were situated far enough apart so no physical contact was possible. Within the course of the six month study, the experimental subjects with irregular flow tended to normalize, although cycle synchronization was not observed as a trend. In the control group, irregular subjects continued to experience abnormally long cycles. The authors suggested, “Close physical contact may serve to transmit chemical and/or hormonal cues that can normalize the menstrual cycle of crab-eating monkeys.”

References

Russell, M.J., G.M. Switz, and K. Thompson. 1980. Olfactory influences on the human menstrual cycle. Pharmacol, Biochem., & Behav. 13: 737-738.

Wallis, J. 1986. The effest of female proximity and social interaction on the menstrual cycle of crab-eating monkeys (Macaca fascicularis). Primates 27(1): 83-94.

Doty, R.L. 1981. Olfactory communication in humans. Chem. Senses 6(4): 351-376.

see also:
McClintock, M.K. 1971. Menstrual synchrony and suppression. Nature 229: 244-245.