Historical perspective from Pheromones.com

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I founded the domain Pheromones.com in 1996, and will preserve some of the history of posts to that domain here. My focus on the links from cell type differentiation, which is controlled by the epigenetic effects of food odors and pheromones causes me to continue with accurate representations of biologically-based cause and effect at http://rna-mediated.com/

Scientific evidence continues to validate the concept of human pheromones as it was first portrayed for a general readership in The Scent of Eros: Mysteries of Odor in Human Sexuality (1995). The 2002 book revision updates what is known about human pheromones, and includes information available before July, 2002. The following information, including more recent works, which add to knowledge about human pheromones, is available for researchers or others who share an interest in the growing body of knowledge about the role of pheromones in behavior.

It has become clear that human pheromones affect us more than most people can imagine. Our knowledge of visual input, and of how vision might influence our sexual preferences, pales by comparison. During this decade, many more people will learn that our sexual preferences are driven in the same manner as it is in all mammals: directly via olfaction and pheromones, and only indirectly by pheromonal associations with visual input. This knowledge will help to predict/explain behaviors, and help to resolve problematic behaviors.

Applied Science:

People think that their first response to a physically attractive potential partner is due to visual input. This is not accurate. If we were not already conditioned by human pheromones to respond to physical attributes, we could not develop an appropriate response to what we see.

Even when the chemicals were transferred to you in the womb, your experience with food chemistry before birth set the stage for your adult food preferences. Just as food aroma cause changes in our physiology that are associated with hunger, ingestion, and satiety, human pheromones cause our physiology to change. With the human pheromone-induced changes in physiology come human pheromone-induced changes in behavior. The changes in physiology and behavior happen without thought; you don’t know that the changes are happening.

Pheromones are chemical signals from other people that condition you to respond to what you see. For example: which of these pictures do you find most attractive

These pictures are of a face that has been altered in appearance to show the difference between how high levels of testosterone change facial features (left) compared to how high levels of estrogen change facial features (right). The three faces between the most masculine face (on the right) and the most feminine face (on the left) represent variations in levels of hormones, like testosterone and estrogen, that are associated with attractive male and/or female facial features. (courtesy of Dr. Victor Johnston)

It’s even more difficult to comprehend how thoroughly human pheromones affect our behavior because we are not aware of their affects. We think about what we see, and — without thought — attribute attractive physical characteristics to our visual perception. In truth, however, we are very much like other animals. We know that they depend on their sense of smell for food choice and for mate choice. We are like other animals that don’t need to think about their choices. Neither do we –except that sometimes after-the-fact we may ask ourselves “What was I thinking?”

Pictures of food are visually appealing due to associations we make with the chemical appeal of the food. It wouldn’t look good if it didn’t smell good. Pictures of people are visually appealing due to unconscious associations we make with their chemical appeal.

Perhaps it’s easier to grasp this concept of odors and pheromones if you think about your food preferences. No matter how good it looks, if the aroma isn’t right, you’re not going to be interested in the food. And no matter how good someone looks, you’re not going to be interested in them if their scent signature is not right.

Scientific support

Scientific evidence continues to validate the concept of human pheromones as it was first portrayed for a general readership in The Scent of Eros: Mysteries of Odor in Human Sexuality (1995). The 2002 book revision updates what is known about human pheromones, and includes information available before July, 2002. The following information, including more recent works, which add to knowledge about human pheromones, is available for researchers or others who share an interest in the growing body of knowledge about the role of pheromones in behavior.

It has become clear that human pheromones affect us more than most people can imagine. Our knowledge of visual input, and of how vision might influence our sexual preferences, pales by comparison. During this decade, many more people will learn that our sexual preferences are driven in the same manner as it is in all mammals: directly via olfaction and pheromones, and only indirectly by phenomenal associations with visual input. This knowledge will help to predict/explain behaviors, and help to resolve problematic behaviors.

Documentation:

Heterosexual Pheromones (see Homosexual Pheromones below)

Human Pheromones: Integrating Neuroendocrinology and Ethology: a review by James V. Kohl, M. Atzmueller, B. Fink, & K. Grammer was published in Neuroendocrinology Letters 22(5), p. 309-321.

This award winning review is the first to link pheromones and olfactory conditioning of the human sexual response to personal preferences for symmetry, genetic diversity, hormone-mediated facial features, and hormone-mediated body types. It is an overview of how pheromones are involved in the development (organization and activation) of human sexual behavior.  Abstract HERE Full text HERE and also available as a .pdf.

Also see: Diamond M, Binstock T, & Kohl JV (1996) From fertilization to adult sexual behavior: Nonhormonal Influences on sexual behavior. Hormones and Behavior. 30: 333-353. Full text HERE.

Here is a short, technical, synopsis of The Scent of Eros written for other researchers: (1995) Precis–The Scent of Eros: Mysteries of Odor in Human Sexuality. Psycoloquy 6, 33 (Oct. 29)


The diagram Kohl uses to illustrate his presentations is available HERE. [Will open in a new MS Word doc]

HUMAN PHEROMONES AND A MAMMALIAN MODEL OF MATE PREFERENCE: a model for the pheromone-driven development of human sexuality was presented by JV Kohl at the Association for Chemoreception Sciences (AChemS), 2001. The abstracts from this conference were published in Chemical Senses Volume 26, Number 8 : October 2001.
KEY ISSUE: Pheromones and olfaction are more important to the development of human sexuality than are visual stimuli. Pheromone production/distribution, olfactory acuity/specificity, and hormone responses, especially the luteinizing hormone (LH) response, which is elicited by human pheromones, explain the development of human mate preferences, just as they explain mammalian mate choice and properly timed reproductive sexual behavior. The absence of a mammalian neuroendocrine model for sexual attraction that is primarily based on visual input suggests that olfactory input conditions visual aspects of human sexual attraction. Androsterone is offered as an example of a putative human pheromone.


Evidence that human pheromones activate the human hypothalamus.

Savic, I., Berglund, H., Gulyas, B., and Roland, P. (2001). Smelling of odorous sex hormone-like compounds causes sex differentiated hypothalamic activations in humans. Neuron 31, 661-668. Abstract HERE
KEY FINDING: Pheromones either from men or from women are processed in sexually dimorphic regions male and female brain. (see also Savic et al., 2005 cited below).

Comments on Savic et.al:
Sobel, N and  Brown, W.M. (2001) The Scented Brain: Pheromonal Responses in Humans Neuron 2001 31: 512-514.”A robust hypothalamic response is seldom seen with ordinary odorants, and such an extreme sex difference is never seen with ordinary odorants. Considering that the hypothalamus mediates pheromonal effects and that sex specificity is a hallmark of pheromonal effects, Savic’s groundbreaking work adds significant weight to the claim that these compounds are human pheromones.”


Evidence that human pheromones elicit change in hormone levels in other humans. This evidence (from 1996 forward) is essential to the concept of human pheromones. No conclusive proof that human pheromones altered hormone levels in other humans was available prior to 1996. However, in 1992, Kohl’s first scientific presentation: ” Luteinizing hormone (LH), the link between sex and the sense of smell” predicted recent findings.

Male axillary extracts effect pulsatile secretion of luteinizing hormone [LH] and mood  in female recipients. Preti G,  Wysocki CJ,  Barnhart K,  Sondheimer SJ and Leyden JJ. Biology of Reproduction 2003 Jun;68(6):2107-13.. Abstract HERE

The findings from this study were presented during the 23rd Annual Meeting of the Association for Chemoreception Sciences (2001). KEY FINDING: Application of male axillary extracts affects mood and LH pulsatility, which can be used as an assay to isolate the active components of axillary extracts. SIGNIFICANCE: Pheromones from men change hormone levels (physiology) and mood (behavior?) in women.This affective response could be expected to occur in heterosexual relationships. Futhermore, changes in LH pulsatility could be expected to result in increased estrogen levels, and increased oxytocin (a “bonding” hormone also linked to orgasm) levels.

Shinohara K, Morofushi M, Funabashi T, Kimura F. (2001)  Axillary pheromones modulate pulsatile LH secretion in humans. Neuroreport. Apr 17;12(5):893-5. Abstract HERE.

Shinohara K. et. al., (2000) Abstract HERE
KEY FINDING: “androstenol retards the growth and maturation of ovarian follicles and consequently delays the timing of ovulation.”

Stern, K., & McClintock, M. (1998). Regulation of ovulation by human pheromones. Nature. Mar 12;392(6672):177-9. Abstract HERE.
KEY FINDING: “By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.” SIGNIFICANCE: The pheromones of women change hormone levels (LH and FSH) in other women.

Monti-Bloch L, et. al., (1998) Abstract HERE. KEY FINDING: Humans have a functional VNO and respond to pheromones with hormonal change.

Berliner DL, Monti-Bloch L, Jennings-White C, & Diaz-Sanchez V (1996). Abstract HERE. KEY FINDING: existence of a human vomeronasal-hypothalamic-pituitary-
gonadal system.

Jacob S, Spencer NA, Bullivant SB, Sellergren SA, Mennella JA, McClintock MK. Effects of breastfeeding chemosignals on the human menstrual cycle. Hum Reprod. 2004 Feb;19(2):422-9. KEY FINDING: Because compounds from lactating women and their infants modulated the ovarian cycles of women, as is seen in other mammals, they have the potential to function as pheromones, regulating fertility within groups of women.”

Recent mammalian studies support Kohl’s concept: olfactory input conditions our visual response

Moncho-Bogani J, Lanuza E, Hernandez A, Novejarque A, Martinez-Garcia F. Attractive properties of sexual pheromones in mice: innate or learned? Physiol Behav. 2002 Sep;77(1):167-76. KEY INDICATION  Pavlovian-like associative learning (i.e., classical conditioning) in which previously neutral volatiles (very likely odorants) acquire attractive properties by association with the nonvolatile, innately attractive pheromone(s) is the likely basis for not only the sexual but also the ‘chemical’ experience (previous experience with sexual pheromones), which must be taken into account to interpret the role of chemicals as releaser or primer pheromones.

Gelez H, Archer E, Chesneau D, Campan R, Fabre-Nys C. Importance of learning in the response of ewes to male odor. Chem Senses. 2004 Sep;29(7):555-63. KEY ISSUES: Ram exposure activates the LH response in ewes; sexual experience is a factor. After pairing lavendar scent with ram exposure; the lavendar scent activated the LH response in ewes. Simply put, ewes can learn to associate an arbitrary odor with the affect of pheromones on their level of LH.

Del Punta K, Leinders-Zufall T, Rodriguez I, Jukam D, Wysocki CJ, Ogawa S,  Zufall F, Mombaerts P. Deficient pheromone responses in mice lacking a cluster of vomeronasal receptor genes. Nature. 2002 Sep 5;419(6902):70-4. Abstract HERE

Takami S.  Recent progress in the neurobiology of the vomeronasal organ.  Microsc Res Tech. 2002 Aug 1;58(3):228-50. Abstract HERE

Beckman M (2002) Pheromone reception. When in doubt, mice mate rather than hate. Science. 2002 Feb 1;295(5556):782. No abstract available.

Kippin TE, Pfaus JG (2001) The nature of the conditioned response mediating olfactory conditioned ejaculatory preference in the male rat. Behav Brain Res. Jul;122(1):11-24. Abstract HERE.

Kelliher KR, Baum MJ (2001). Nares occlusion eliminates heterosexual partner selection without disrupting coitus in ferrets of both sexes. J Neurosci.Aug 1;21(15):5832-40. Abstract HERE.

Kendrick KM, Haupt MA, Hinton MR, Broad KD, Skinner JD (2001)  Sex differences in the influence of mothers on the sociosexual preferences of their offspring. Horm Behav.Sep;40(2):322-38. Abstract HERE

In other mammals, pheromones influence the onset of puberty, and are also important in establishing nurturing behavior. Here are three articles that (despite no significant mention of pheromones) strongly suggest that human pheromones influence the onset of puberty:

Ellis & Garber (2000) Abstract HERE
“Stepfather presence, rather than biological father absence, best accounted for earlier pubertal maturation in girls living apart from their biological fathers.”

Ellis BJ et. al., (1999) Abstract HERE
“In total, the quality of fathers’ investment in the family emerged as the most important feature of the proximal family environment relative to daughters’ pubertal timing.”

In other mammals, pheromones from the female alter levels of testosterone in the male. Here are three studies that strongly suggest pheromones from women alter levels of testosterone in men.

Storey A et. al., (2000) Abstract HERE
Testosterone levels in men decreased as pregnancy in their mate progressed. “This pattern of hormonal change in men suggests that hormones may play a role in priming males to provide care for young.”

Gray, P. et al. (2002) Evolution and Human Behavior (vol 23, p 193)
KEY FINDING: Married men have lower testosterone levels than single men

Gray PB, Campbell BC, Marlowe FW, Lipson SF, Ellison PT.
Social variables predict between-subject but not day-to-day variation in the testosterone of US men. Psychoneuroendocrinology. 2004 Oct;29(9):1153-62.
KEY FINDING: Married men had lower evening T levels than unmarried men


Homosexual Pheromones

As first indicated in The Scent of Eros (1995), and in the award winning review by Kohl et. al, 2001, olfaction and pheromones can also explain sexual orientation (something that will never be explained by using a visual model of physical attraction.) The fact that there has never been a mammalian model for the development of visually perceived physical attraction may help others to understand why a mammalian model for olfactory conditioning of the human sexual response is required to explain many aspects of human sexuality. Kohl has prepared a cohesive and up-to-date detailed explanation of the role of pheromones in male homosexual orientation.

Kohl, JV (in press) The Mind’s Eyes: Human Pheromones, Neuroscience, and Male Sexual Preferences. Journal of Psychology & Human Sexuality, Vol 18, issues 3/4.

Kohl will present this review during a scheduled 2-hour workshop: Society for the Scientific Study of Sexuality 2006 Annual Meeting, Las Vegas, Nevada. November 9-12.

Many researchers have jumped on the neuroscientific approach to explaining sexual behavior. What other researchers often seem to miss, however, is knowledge of the means by which the neuroendocrinology (the genetic nature) of the brain (e.g., oxytocin, dopamine, serotonin) is altered when we come in social contact with other people (nurture). We are frequently informed that something “happens” in the brain, without being told what causes it to happen. Most researchers don’t even begin to mention why it happens differently in homosexuals than in heterosexuals. In this regard, homosexual orientation defies explanation via a visual approach to physical attraction. The question of why or how a man becomes physically attracted to another man is never addressed. If pheromonal conditioning of the visual response is what causes other mammals to become attracted to each other (and this is obvious), then someone needs to explain why this is not the case in humans, especially with regard to sexual orientation. Perhaps the link between human pheromones and homosexual orientation is too controversial a subject for today’s researchers to consider. When it is considered, you’ll find information here at www.pheromones.com.

Kohl, JV (2005) Human Pheromones, Neuroscience, and Male Homosexual Orientation. International Behavioral Development Symposium. Minot, ND, Aug 3-6.
to be linked from an introductory article in the Fall 2005/Winter 2006 issue of Entelechy: Mind and Culture. http://www.entelechyjournal.com/

An early draft of Homosexual Orientation in Males: Human Pheromones and Neuroscience (Part one): by James V. Kohl was published in Across-Species Comparisons and Psychopathology Bulletin 3 (2), 19-24. This article follows the biological logic presented in the 2001 Neuroendocrinology Letters review article, and extends the argument for olfactory conditioning of sexual orientation. Thereby, sex differences in hypothalamic activation by human pheromones make an overwhelming contribution to male sexual orientation. Part one focusses on neuroendocrinology. Part two focusses on neuroanatomical correlates of sexual orientation. Sexually Dimorphic Neuroanatomy and Sex Differences in Behavior. The Bulletin for Section #44 (Psychotherapy) of the World Psychiatric Association and the ASCAP Society 3 (4) 14-19.

Another researcher proposed a link between pheromones and sexual orientation: (Neuroendocinology Letters: Aug 2002, Vol. 23 No. 4: 287-288)
Mating types in yeast, vomeronasal organ in rodents, homosexuality in humans: does a guiding thread exist? by Dr. Daniele Oliva, Palermo, ITALY. HERE

Empirical data supporting the role of pheromones in homosexuality was presented at a conference in 2003. On May 9, 2005, more than two years after its first presentation, the above study was made known to the public. Preference for Human Body Odors is Influenced by Gender and Sexual Orientation by Yolanda Martins, George Preti, Christina R. Crabtree, and Charles J. Wysocki was published in the September 2005 issue of Psychological Science.

Martins Y, Preti G, Crabtree CR, Runyan T, Vainius AA, Wysocki CJ. Preference for human body odors is influenced by gender and sexual orientation. Psychol Sci. 2005 Sep;16(9):694-701.

Berglund H, Lindstrom P, Savic I. Brain response to putative pheromones in lesbian women. Proc Natl Acad Sci U S A. 2006

Earlier work “…findings show that our brain reacts differently to two
putative pheromones compared with common odors, and suggest a link between sexual orienatation and hypothalamic neuronal processes.”
Savic I, Berglund H, Lindstrom P. Brain response to putative pheromones in homosexual men. Proc Natl Acad Sci U S A. 2005 May 9

Of interest to some researchers will be the fact that these study findings correlate well with non-human animal studies. For example, recent research has demonstrated structural brain differences associated with naturally occurring variations in sexual partner preferences in rams. See: Roselli CE, Larkin K, Resko JA, Stellflug JN, Stormshak F. The volume of a sexually dimorphic nucleus in the ovine medial preoptic area/anterior hypothalamus varies with sexual partner preference. Endocrinology. 2004 Feb; 145(2): 478-83.
KEY INDICATION: A mammalian model linking pheromones and olfaction to neuroanatomy and neuroendocrinology may extend to encompass aspects of human sexual orientation.

In addition, it seems likely that aromatase activity is involved in the differences presented in the article above. See: Roselli CE, Resko JA, Stormshak F.  Estrogen synthesis in fetal sheep brain: effect of maternal treatment with an aromatase inhibitor. Biol Reprod. 2003 Feb; 68(2): 370-4.
KEY INDICATION: Aromatase activity might be linked to estradiol receptor content in the amygdala (an olfactory processing center) which varies with sexual orientation in rams. This fits well with what is known about sexual differentiation of the mammalian olfactory system(s).

Despite the dearth of information linking pheromones to homosexual orientation, the new information is coming from different scientific disciplines. This will continue to make the “big picture” difficult to detail, as few researchers have enough time to step outside their own discipline to examine and integrate reports from other disciplines. In addition, there appears to be some generalized avoidance by other researchers when it comes to linking results from studies of other mammals to results from studies of men and women.

In contrast, Kohl presented Human Pheromones, Neuroscience, and Male Homosexual Orientation during the prestigious International Behavioral Development Symposium. Minot, ND, Aug 3-6, 2005. Here is his presentation abstract.

Converging lines of independent evidence advance an olfactory/pheromonal explanation of male homosexual orientation. Homosexuals distinguish between the natural odor of heterosexuals and homosexuals, and homosexuals prefer the natural body odor of other homosexuals. Brain activation by putative human pheromones correlates with sexual orientation. A detailed mammalian model suggests that olfactory input from the social environment provides the biological basis of androphilic and gynephilic mate choice. In this mammalian model, pheromones elicit a neuroendocrine response that correlates with affective reactions and with the development of predictable sexual behavior. Some mammalian males have an atypical neuroendocrine response to pheromones and/or exhibit an androphilic response to other males. The neuroanatomical and neuroendocrine basis as well as the most likely psychophysiological basis for the atypical androphilic response is detailed. Human studies support extension of the mammalian model to human males by incorporating genetic predisposition and a learned sexuality paradigm in which sexually dimorphic pheromones from the social environment hormonally condition the visual response to attractive physical features. In contrast, there is no biological basis for a mammalian visual model that explains how a male develops a sexual preference for another male.

This presentation makes it clear that human studies fully support extension to humans of a mammalian model in which pheromones provide the basis for the development of our sexual response cycle.


For additional scientific evidence that is relevant to the concept of human pheromones see: Human studies and Animal studies (below)

Human studies

Winman A.
Do perfume additives termed human pheromones warrant being termed pheromones? Physiol Behav. 2004 Sep 30;82(4):697-701. KEY ISSUE: This article refutes study findings and claims made by authors, who may have an interest in marketing a pheromone product. Minimally, this is the second published refutation of claims made by Dr. Winnifred Cutler. See:  McCoy NL, Pitino L.

Spencer NA, McClintock MK, Sellergren SA, Bullivant S, Jacob S, Mennella JA.
Social chemosignals from breastfeeding women increase sexual motivation.
Horm Behav. 2004 Sep;46(3):362-70. KEY FINDING: “…natural compounds collected from lactating women and their breastfeeding infants increased the sexual motivation of other women, measured as sexual desire and fantasies.” No specific compound was isolated.   .

Kovacs G, Gulyas B, Savic I, Perrett DI, Cornwell RE, Little AC, Jones BC, Burt DM, Gal V, Vidnyanszky Z. Smelling human sex hormone-like compounds affects face gender judgment of men. Neuroreport. 2004 Jun 7;15(8):1275-7.  KEY FINDING: Odorous sex hormone-like steroids: 5-alpha-androgenst-16-en-3-one (androgen) or oestra-1, 3, 5 (10), 16-tetraen-3-ol (estrogen) bias  face gender discrimination. As a result of inhalation of androgen, men perceive faces to be more masculine as compared to when they are exposed to estrogen.

Cornwell RE, Boothroyd L, Burt DM, Feinberg DR, Jones BC, Little AC, Pitman R, Whiten S, Perrett DI. Concordant preferences for opposite-sex signals? Human pheromones and facial characteristics. Proc R Soc Lond B Biol Sci. 2004 Mar 22;271(1539):635-40.  KEY FINDING: “…putative sex pheromones and sexually dimorphic facial characteristics convey common information about the quality of potential mates.”

Herz RS, Eliassen J, Beland S, Souza T. Neuroimaging evidence for the emotional potency of odor-evoked memory. Neuropsychologia. 2004;42(3):371-8. KEY INDICATION “…the subjective experience of the emotional potency of odor-evoked memory is correlated with specific activation in the amygdala during recall and offers new insights into the affective organization of memory.

Lundstrom JN, Goncalves M, Esteves F, Olsson MJ. Psychological effects of subthreshold exposure to the putative human pheromone 4,16-androstadien-3-one.
Horm Behav. 2003 Dec;44(5):395-401. KEY FINDING “…this study corroborates earlier findings suggesting that androstadienone exposure yields effects on women’s mood; the feeling of being focused. The mood effects were not dependent on menstrual cycle phase. Further, these effects are replicable and occur also when androstadienone detection is rigorously controlled for across variation in menstrual cycle.”

Bensafi M, Brown WM, Tsutsui T, Mainland JD, Johnson BN, Bremner EA, Young N, Mauss I, Ray B, Gross J, Richards J, Stappen I, Levenson RW, Sobel N. Sex-steroid derived compounds induce sex-specific effects on autonomic nervous system function in humans. Behav Neurosci. 2003 Dec;117(6):1125-34. KEY INDICATION “…AND’s opposite effects on physiology in men and women further implicate this compound in chemical communication between humans.”

Knecht M, Lundstrom JN, Witt M, Huttenbrink KB, Heilmann S, Hummel T.
Assessment of olfactory function and androstenone odor thresholds in humans with or without functional occlusion of the vomeronasal duct. Behav Neurosci. 2003 Dec; 117(6): 1135-41. KEY INDICATION: The human vomeronasal duct, and therefore, the human VNO does not play a major role in sensitivity toward odorants or the perception of a putative human pheromone.

Lundstrom JN, Hummel T, Olsson MJ. Individual differences in sensitivity to the odor of 4,16-androstadien-3-one. Chem Senses. 2003 Sep;28(7):643-50. KEY FINDING Women tend to be more sensitive to the odor than men; “olfactory sensitivity to androstadienone is bimodally distributed in the population with a subgroup consisting of highly sensitive people.”

Chen D, Haviland-Jones J. Human olfactory communication of emotion. Percept Mot Skills. 2000 Dec;91(3 Pt 1):771-81. KEY FINDING Nonhuman animals communicate their emotional states through changes in body odor. Information in human body odors also is indicative of emotional state. This finding introduces new complexity in how humans perceive and interact.

Ackerl K, Atzmueller M, Grammer K. (2002)   ORIGINAL RESEARCH REPORT. The Scent of Fear. Neuroendocrinol Lett. 2002 Apr;23(2):79-84. Full text HERE.
KEY FINDING: Women are able to detect the scent of fear.

Woodson, JC  Including ‘learned sexuality’ in the organization of sexual behavior.Neurosci Biobehav Rev 2002 Jan;26(1):69-80  Abstract HERE
KEY CONCEPT: “…learning from experience plays a critical role in the organization of sexual motivation and psychosexual differentiation…[and] … provide[s] an essential link between biological predispositions and mature sexual preferences…”

Gangestad SW, Thornhill R, Garver CE.(2002)  Changes in women’s sexual interests and their partners’ mate-retention tactics across the menstrual cycle: evidence for shifting conflicts of interest. Proc R Soc Lond B Biol Sci. 2002 May 7;269 (1494):975-82. Abstract HERE. KEY FINDING: Men are able to perceive their partner’s hormonal state, and adjust their behavior accordingly.

Jacob, S., McClintock, M.K., Zelano, B., & Ober, C. Paternally  inherited HLA alleles are associated with women’s choice of  male odor. Nature Genetics, DOI: 10.1038/ng830 (2002). Abstract HERE  KEY FINDING: “Our data indicate that paternally inherited  HLA-associated odors influence odor preference and may serve as social cues.”

Jacob S, Hayreh DJ, McClintock MK. (2001) Context-dependent effects of steroid chemosignals on human physiology and mood.  Physiol Behav. 2001 Sep 1-15;74(1-2):15-27. Abstract HERE KEY FINDING: Autonomic nervous system (ANS) responsivity to the human chemosignals D4,16-androstadien-3-one and 1,3,5,(10),16-estratetraen-3-ol is context dependent (e.g.) modulated by the presence of a man or woman.

Jacob S, Kinnunen LH, Metz J, Cooper M, McClintock MK (2001) Sustained human chemosignal unconsciously alters brain function. Neuroreport. Aug 8;12(11):2391-4 Abstract HERE

Singh D, Bronstad PM. (2001)  Female body odour is a potential cue to ovulation. Proc R Soc Lond B Biol Sci 2001 Apr 22;268(1469):797-801 Abstract HERE
KEY FINDING: Fertile (i.e., ovulating) women produce the most pleasant odor: evidence against the “concealed ovulation,” which is a basic premise in evolutionary psychology.

Wysocki, CJ, Preti, G (2000). Human Body Odors and Their Perception. Japanese Journal of Taste and Smell Research 7:19-42. EXCELLENT REVIEW

(Note: since the link between human pheromones and human hormones, like LH, is now well-established, the somewhat more speculative link between human pheromones and behavior will become better accepted.)

Jacob, S. & McClintock, M. (2000). Abstract HERE
KEY FINDING: Putative human pheromones are ” psychologically potent, mandating future work delineating their function-i.e., whether these steroids are communicative chemosignals, context specific, or related to unconscious associations.”

Lundstrom JN, Goncalves M, Esteves F, Olsson MJ.
Psychological effects of subthreshold exposure to the putative human pheromone 4,16-androstadien-3-one. Horm Behav. 2003 Dec; 44(5): 395-401.

Grosser BI, Monti-Bloch L, Jennings-White C, Berliner DL. (2000) Abstract HERE
KEY FINDING: ” administration of this steroid [androstadienone] under these conditions results in a significant reduction of nervousness, tension and other negative feeling states. Concordant changes were observed in autonomic physiology.

Morofushi M et.al., (2000) Abstract HERE
KEY FINDING: Women whose menstrual cycles synchronized with room-mates had higher olfactory acuity for androstenol.

MHC and Behavior (see the pertinent abstracts)

ANIMAL STUDIES

Gelez H, Fabre-Nys C. The “male effect” in sheep and goats: a review of the respective roles of the two olfactory systems. Horm Behav. 2004 Sep;46(3):257-71. Review. KEY FINDING: The VNO is not required for rams to elicit an LH response from ewes.

Johnson BN, Mainland JD, Sobel N. Rapid olfactory processing implicates subcortical control of an olfactomotor system. J Neurophysiol. 2003 Aug;90(2):1084-94. Epub 2003 Apr 23. KEY INDICATION The time course of sniffing appears to be more rapid than  a response that requires cortical control. “Considering that odorant transduction takes around 150 ms and odorant-induced cortical evoked potentials have latencies of around 300 ms, the rapid motor adjustments measured here suggest that olfactomotor sniff feedback control is subcortical and may rely on neural mechanisms similar to those that modulate eye movements to accommodate vision and ear movements to accommodate audition.”

Westberry J, Meredith M. The influence of chemosensory input and gonadotropin releasing hormone on mating behavior circuits in male hamsters. Brain Res. 2003 Jun 6;974(1-2):1-16. KEY FINDING “…the combination of pheromone exposure and intracerebrally-injected GnRH increases Fos expression in the MPOA above the increase seen in pheromone-exposed males, or in males given only the exogenous GnRH. In males with vomeronasal organs removed (VNX), there was an also an increment in Fos expression in the MPOA when these pheromone exposed males were injected with GnRH, provided they had previous sexual experience. Males with vomeronasal organs removed and without sexual experience showed increased Fos expression in the medial amygdala when pheromone exposure and GnRH injection were combined, but not in the medial preoptic area.”

Keverne EB.
Pheromones, vomeronasal function, and gender-specific behavior.
Cell. 2002 Mar 22; 108(6): 735-8. Review.

Westberry JM, Meredith M. Pre-exposure to female chemosignals or intracerebral GnRH restores mating behavior in naive male hamsters with vomeronasal organ lesions. Chem Senses. 2003 Mar;28(3):191-6.  RATIONALE: Hamster vaginal fluid and  intracerebroventricular injections of GnRH eliminate mating deficits normally seen in naive male hamsters with vomeronasal organs removed. KEY FINDING The action of  female pheromones on GnRH  is the most likely link to restoration of  naive males who have had their vomeronasal organs removed.

Brennan PA, Schellinck HM, de la Riva C, Kendrick KM, Keverne EB.
Changes in neurotransmitter release in the main olfactory bulb following an olfactory conditioning procedure in mice. Neuroscience. 1998 Dec; 87(3): 583-90. KEY INDICATION: Changes in synaptic connectivity occur in response to odors during classically conditioned behavior; which may be a general feature of olfactory learning.
COMMENT: If the above is true, it becomes more important for others to realize that pheromones cause changes in hormone levels during development, and these changes cause changes in synaptic connectivity that varies in males and females..

Katz LS, Price EO, Wallach SJ, Zenchak JJ.
Sexual performance of rams reared with or without females after weaning.
J Anim Sci. 1988 May; 66(5): 1166-73. KEY INDICATION: Pheromone exposure during development might play an important role in adult  sexual orientation and in sexual behavior.

Pertinent quotes from –or links to– additional articles of interest:

Rodriguez I, Greer CA, Mok MY, Mombaerts P (2000) A putative pheromone receptor gene expressed in human olfactory mucosa. Nat Genet; 26:18-9 Abstract HERE

Sobel N, et. al., (2000) “These findings localize human brain activation that was induced by an undetectable air-borne chemical (the low concentration compound). Abstract HERE

Porter RH and Winberg J (1999) “Early odor-based recognition may be an important factor in the development of the infant-mother bond. Abstract HERE

Winberg J, and Porter RH (1998) “New knowledge about human odour physiology may have diagnostic and therapeutic implications–” Abstract HERE

McClintock MK (1998) A review article of the next four articles (below). Abstract HERE

Wood RI (1998) “According to our current model, hormones may act as a gating signal to strengthen synaptic contacts along the chemosensory pathway, thereby permitting or enhancing transmission of chemosensory cues.” Abstract HERE

Monti-Bloch L, Jennings-White C, Berliner DL (1998) “These findings present new information supportive of a functional vomeronasal system in adult humans.” Abstract HERE

Johnston RE (1998) “In sum, it is important to maintain a broad, balanced view and to avoid oversimplifications if we are to advance our understanding of the sensory mechanisms underlying responses to chemical signals and other odors.” Abstract HERE

Meredith M (1998) “Despite evidence [in hamsters] that the release of LHRH in response to female chemosignals is dependent on vomeronasal input, no activation of LHRH neurons has been demonstrated in males exposed to such chemosignals.” Abstract HERE

Gangestad, S.W., & Thornhill, R. (1998). Menstrual cycle variation in women’s preferences for the scent of symmetrical men. Proceedings of the Royal Society of London B. 265, (1399) May 22, 927-933. KEY FINDING: Women use olfactory cues as honest signals about certain qualities of men, especially when conception is possible. Abstract HERE.

Thornhill, R & Gangestad, Sw (1999) The Scent of Symmetry: A Human Sex Pheromone that Signals Fitness? Evolution and Human Behavior 20, 175-201.
Full text HERE

Grammer K, Jutte A (1997) A reference to an article (in German): Abstract HERE
KEY CONCEPT: Female pheromones (copulins), which are present in vaginal secretions, influence male perception of females and may induce hormonal changes in males.

Ober C, et.al. (1997) Abstract HERE
Key finding: “These results are consistent with the conclusion that Hutterite mate choice is influenced by HLA haplotypes, with an avoidance of spouses with haplotypes that are the same as one’s own.”

Atzmueller, M.
Androstenone causes a change in the physiology and behavior of men. This change in physiology is expected to be a change in testosterone levels. Since testosterone seems to be linked with status and dominance in men it is suggested that men with high testosterone levels should be less willing to cooperate with others than men with lower testosterone levels.

Ackerl, K. Atzmueller, A., Grammer, K. (2002)
The Scent of Fear: Results show that subjects were able to discriminate between fear and non-fear axillary pads, suggesting that women are indeed able to detect ‘the scent of fear’.

Rikowski, A., (1997)
Human Body Odour, Symmetry, and Attractiveness.
Key finding: “This study supports the hypothesis that human body odour reveals information about general mate quality.”

Juette A., (1995)
Female pheromones and male physiology. Weibliche Pheromone – Wirkung und Rolle von synthetischen “Kopulinen” bei der versteckten Ovulation des Menshchen. Diplomarbeit an der Universitat Wien. September 1995. Key finding: ovulatory vaginal copulins appear to increase testosterone in men.

Poran, N.S. (1995) Cyclic attractivity of human female odors. Advances in the Biosciences 93: 555-560.

Wedekind C, Seebeck T, & Paepke AJ (1995). MHC-dependent mate preferences in humans. Proceedings of the Royal Society of London 260: 245. Abstract HERE

Fan, W., Liu, Y-C., Parimoo, S., & Weissman, S.M. (1995) Olfactory receptor-like genes are located in the human major histocompatibility complex. Genomics 27: 119-123. Abstract HERE

Jennings-White, C. (1995) Perfumery and the sixth sense. Perfumer & Flavorist 20:

Moran, D.T., Monti-Block, L., Stensaas, L.J., & Berliner, D.L. (1995) Structure and function of the human vomeronasal organ. In Handbook of Olfaction and Gustation. R.L. Doty (Ed.) Marcel Dekker, New York. p. 793-820.

Monti-Block, L., Jennings-White, C., Dolberg, D.S., & Berliner, D (1994) The human vomeronasal system. Psychoneuroendocrinology 19: 673-86. Abstract HERE

Foidart, A., Legros, J.J., & Balthazart, J. (1994) [Human pheromones: animal trace or unrecognized reality?] Les pheromones humaines: vestige animal ou realite non reconnue. Revue Medicale De Liege 49, 12:662-80 (Published in French)

Mammalian, including human, pheromones influence GnRH. For more information about the role of GnRH (“the biological core of mammalian reproduction in reproductive physiology”), see: Hormones of the Hypothalamus

Yoon H, Enquist LW, Dulac C. Olfactory Inputs to Hypothalamic Neurons Controlling Reproduction and Fertility. Cell. 2005 Nov 9; [Epub ahead of print]
KEY FINDING: “…chemosensory modulation of LHRH neuronal activity and mating behavior … appear unaffected in mouse mutants lacking vomeronasal signaling.”

Baxi KN, Dorries KM, Eisthen HL. Is the vomeronasal system really specialized for detecting pheromones? Trends Neurosci. 2005 Nov 2; [Epub ahead of print]
REVIEW: We review the abundant data concerning the roles of both the olfactory and the vomeronasal systems in the processing of both pheromones and other odorants, demonstrating that this ‘equivalency hypothesis’ is untenable.

Boehm U, Zou Z, Buck LB.Feedback Loops Link Odor and Pheromone Signaling with Reproduction. Cell. 2005 Nov 9; [Epub ahead of print]
KEY FINDING:  “…GnRH neurons appear to integrate information from multiple sources and modulate a variety of brain functions.”

You may also wish to search “NCBI PubMed” for the most recent scientific journal articles about pheromones, the vomeronasal organ, GnRH, or other topics mentioned on this site.

Junk science

Cutler WB, Friedmann E, McCoy NL (1998) “These initial data need replication but suggest that human male pheromones affected the sexual attractiveness of men to
women.” Abstract HERE Results refuted Abstract HERE Wysocki CJ, Preti G (1998) A reference for a critique of the Cutler et al. (1998) claim.

McCoy NL, Pitino L. (2002)  “Three or more sociosexual behaviors increased over baseline for 74% of pheromone users compared with 23% of placebo users.” Unanswered questions on this study: What putative human pheromone was tested; who did this pheromone affect and how? Abstract HERE Results refuted Winman A. Do perfume additives termed human pheromones warrant being termed pheromones? Physiol Behav. 2004 Sep 30;82(4):697-701.

Rako, S, Friebely, J (2004) Pheromonal Influences on Sociosexual Behavior in Postmenopausal Women. Journal of Sex Research 41; 372-380. “These results suggest that the pheromone formulation worn with perfume for a period of 6 weeks has sex-attractant effects for postmenopausal women.” WB Cutler’s proprietary “pheromone formulation” was used, which ensures the study’s “junk science” categorization because non-disclosure of the pheromone formulation means the study cannot be replicated by independent research.


Here is information about AChemS conference presentations that continue to fully support Kohl’s conceptualization of how human pheromones drive the development of human sexuality. 2004 abstracts should be available in November 2004.

From PRESENTATION ABSTRACTS of the 25th Annual Meeting of the Association for Chemoreception Sciences  April 9-13, 2003.

Symposium : Interplay of Olfaction & Emotion Systems EMOTIONAL OLFACTORY STIMULI: FROM UNCONSCIOUS TO CONSCIOUS PROCESSING McClintock M.K.
Olfactory chemosignals function at different levels of consciousness. Consciously detected odors or scents, elicit emotions and associations. Pheromones elicit neuroendocrine responses or modulate behavior. We propose the term “vasana” for olfactory chemosignals that affect human emotions, yet are not available for direct conscious scrutiny. We anticipate that different brain mechanisms process the different classes of olfactory chemosignals. Specific examples will be discussed.

MULTIPLE CHEMICAL SUPERSENSITIVITY – THE MECHANISMS OF ACTION Savic I., Berglund H., Hillert l. Multiple chemical supersensitivity (MCS) is a rapidly increasing condition, yet with unknown pathophysiology.  Our results do not support the notion that MCS is associated with neuronal sensitisation.  We propose that this
condition may be a consequence of aversive odor-conditioning leading to harm avoidance, and top-down regulation of odor-response, and suggest odour counter-conditioning as a suitable treatment strategy.

VOMEROPHERINS PRODUCE LOW-FREQUENCY CALCIUM
OSCILLATIONS IN HUMAN VOMERONASAL NEURONS
Winegar B., Monti-Bloch L.  Intracellular Ca was measured during perfusion with a series of pregnanes, norpregnanes and androstanes. Vomeropherins that we tested typically increased intracellular calcium ~100 – 200 nM. A number of vomeropherins also produced reversible increases in low-frequency calcium fluctuations. Calcium oscillations may be related to the molecular mechanisms of sensory transduction.

HUMAN VOMERONASAL ORGAN CHANGES DURING THE MENSTRUAL CYCLE Monti-Bloch L., Linder C., Allen D. Gonadotropins have been shown to influence mammalian VNO growth. In premenopausal women the VNO pit changed size during
the menstrual cycle. We found significantly increased VNO pits in the periovulatory phase of the cycle as compared to the other phases. These changes coincided with increased serum levels of gonadotropins. The changes in human VNO size reported here are interpreted as a result of the tropic effect of gonadotropic hormones on
VNO tissue.

ADULT HUMAN VOMERONASAL EPITHELIUM EXPRESS MOLECULAR MARKERS OF NEURON-LIKE ACTIVITY Diaz V., Morales A., Castell A. The epithelium lining of the VNO is in a continuous cell replacement, during the adult life span, similar to other sensory epithelia and cell proliferation is under the control of trophic factors.

SPECIES-SPECIFICITY IN PHEROMONE RECEPTOR LOCI? Lane R.P., Cutforth T., Axel R., Hood L., Trask B.J. V1R expansions may have contributed to species divergence.

PHEROMONE CODING BY THE MAMMALIAN MAIN OLFACTORY EPITHELIUM Leinders-Zufall T., Ziesmann J., Puche A.C., Bock R., Ma W., Novotny M.V., Zufall F.
Pheromones that are high potency ligands for neurons in the VNO are also detected by the MOE. Thus, in mammals the VNO is not the exclusive site of pheromone detection.

ACCURATE ODOR DISCRIMINATION IN THE ABSENCE OF ODOR PREFERENCE IN MALE VASOPRESSIN 1B RECEPTOR-KO MICE INDICATES ALTERED SOCIAL
MOTIVATION Kelliher K.R., Zufall F., Wersinger S.R., Young W.S. Vasopressin 1b receptor knockout (V1bRKO) mice are less aggressive  wild-type (WT) littermates and also differ from WT mice in a socially motivated bedding preference test, despite the
fact that V1bRKO mice have no difficulty in discriminating between male and female chemosensory cues during an operant testing paradigm.  We propose that the role of the vasopressin 1b receptor is in the subsequent evaluation of chemosensory cues, rather than their detection.

RESPONSES OF FEMALE MOOSE TO FRACTIONATED SOCIALLY-RELEVANT CHEMOSENSORY STIMULI SELECTIVELY ACTIVATE POSTERIOR MEDIAL
AMYGDALA Westberry J., Meredith M. The amygdala receives chemosensory input from olfactory and vomeronasal systems and is involved in  discriminatoty social/sexual and emotional responses. Chemosensory activation in posterior medial amygdala matches this discrimination in male hamsters and our recent evidence implicates intra-amygdaloid inhibition. Both anterior and posterior medial amygdala (MeA/MeP) are activated (Fos, FRA expression) by conspecific, socially relevant,
chemosensory stimuli from females and from males.  We hypothesize that indirect inhibition of MeP results from some patterns of input to MeA. Activation of such cells in MeA does not vary with differences in MeP response and those in MeP are positively not negatively correlated with overall MeP response.

CHEMOSENSORY STIMULATION OF FOS IN MEDIAL AMYGDALA REFLECTS NEURAL ACTIVATION NOT SYNAPTIC ENHANCEMENT. Blake C., Westberry J., Sirpal S., Weinburg D., Meredith M. Immediate-early genes (IEGs) can be activated in neurons by depolarization, probably via calcium influx.  We compared Fos-protein expression following the first or third stimulation with a socially relevant chemosensory stimulus. Differences in Fos expression between, for example, sexually naive and experienced animals, could not be interpreted simply as an increase in sensory system sensitivity with stimulus repetition.

OLFACTORY SENSITIVITY FOR ANDROSTENONE IN THREE SPECIES OF NONHUMAN PRIMATES Laska M., Wieser A., Hernandez Salazar L.
Three species of nonhuman primates are able to detect androstenone at concentrations lower than those reported in pigs and humans. These results suggest that androstenone may be involved in olfactory communication in nonhuman primates and that the specific anosmia for this odorant found in ~30% of human subjects
may be due to the reduced number of functional olfactory receptor
genes compared to nonhuman primates.

EFFECTS OF ANDROSTADIENONE ON MOOD AND PHYSIOLOGY INCREASE IN EMOTIONAL CONTEXTS Bensafi M., Tsutsui T., Sobel N. Androstadienone (AND) and estratetraenol (EST) are two human sex-steroid derivates that affect mood and physiology in a sex-specific way. During a non-arousing video, AND, but not EST, maintained positive mood in women, but not in men. During an arousing videos, AND, but not EST maintained positive mood (happy) in women  and increased
negative mood (sad) in men.  AND decreased memory of the “sad” film in both sexes. During the “erotic” video AND decreased respiration rate specifically in men. This indicates that the sex-specific effects of AND, the most prevalent androstene in
human secretions, are more salient in emotional contexts.

WHAT THE NOSE KNOWS: PREFERENCE FOR HUMAN BODY ODORS AS A FUNCTION OF GENDER AND GENDER PREFERENCE Martins Y. Preti G. Wysocki C.J. Results suggested a difference in the production of odor profile based upon gender preference and, at least for homosexuals, a preference for the odor from other homosexuals.

ANDOSTRADIENONE´S IMPACT ON EMOTIONAL EXPERIENCE THROUGH MOOD INDUCTION Freyberg R., Wilson P., Haviland-Jones J. Previous research has demonstrated the modulating effect of androstadienone (AND) on “naturally” occurring negative mood. These findings extend previous research, which found a decrease in negative mood states. AND´s ability to affect induced mood adds support to its growing role as a modulator of emotion. Given our findings, putative pheromones are
clearly taking their place among the many factors that both influence and play a part in emotion.

INDIVIDUAL DIFFERENCES (IDS) IN THE DETECTION OF HUMAN MOOD FROM AXILLARY ODOR McGuire T.R., Brahms J., Morris C., Haviland-Jones J.
Previous research demonstrated a low but significant probability that
human axillary odors can be correctly labeled with the donors’ mood.
Increasing the number of trials and providing feedback provides a larger group of detectors and substantially improves reliable identification of IDs.

OLFACTORY PROCESSING: EFFECTS OF NOSTRIL AND REPETITION Jonsson F.U., Olsson M.J., Broman D.A. Men, but not women showed significantly higher identification performance as an effect of previous presentation when tested via the left nostril. The present results suggest that in order to understand olfactory lateralization,
effects of repetition as well as sex are important factors.


From PRESENTATION ABSTRACTS of the 24th Annual Meeting of the Association for Chemoreception Sciences  April 24-28, 2002. Listed by first author only:

Windy BROWN: Physiological and psychological effects of two putative human pheromones. KEY FINDING: The sex steroid derivatives: androstadienone and estratetraenol are present in human sweat, and they affected several psychological and physiological measures in a sex-specific manner that reflects brain activation.

Patricia WILSON: Androstadienone affects courtship-like behaviors in women. KEY FINDING: “While AND  [Androstadienone] may affect the likelihood of signaling a partner, it does not affect attraction to a specific partner.”

Mats J OLSSON: Detection thresholds for 4,16-androstadien-3-one. KEY FINDING:
” When supersmellers were excluded, the group-mean threshold approximated 300 micromolar and men and women did not differ in thresholds.”

Rachel S HERZ: A Test of Associative Odor Learning. KEY FINDING: This finding gives strong support to the notion that hedonic responses to odors are acquired via learned emotional associations.

Charles J. WYSOCKI:  Sex Differences in Olfactory Cross-Adaptation of Human Sweat Odor. KEY FINDING: ” These results reveal unexpected sex differences in the production of  axillary odors and, importantly, sex differences in the perception of these  odors, especially in the presence of other, competing odorants. It is as if the biologically relevant odor from the opposite sex appears to break  through.”

George PRETI: Human Axillary Odors Formed by Endogenous Bacteria. KEY FINDING  “Little or no androstenol or androstenone were found, which is consistent with previous results demonstrating that volatile steroids play a minor role in axillary odor.” “Our data suggest that axillary organic acids are likely involved in pheromonal affects.”

Jenne M. WESTBERRY: Selective response to chemosensory stimulation in medial amygdala. KEY FINDING: ” These data are  consistent with anatomical evidence indicating convergence of rostral and  caudal AOB input at the level of the medial amygdala [in hamsters] but they suggest that the amygdala may sort and process chemosensory information according  to different criteria than the AOB. The MeP has abundant steroid receptors and many social behaviors are dependent on an adequate steroid level.

Joel D MAINLAND:  Plasticity Underlying Androstenone Learning may be Mediated Centrally rather than Peripherally. KEY FINDING: “Ö this plasticity may involve central, rather than peripheral components of the olfactory system.” “These preliminary data indicate that plasticity involves components of the olfactory system receiving birhinal input.”

Noam SOBEL:  Olfactory coding of pleasantness and intensity in the human amygdaloid Complex.  “Activity in the AC [amygdaloid complex] was significantly correlated with individual intensity rating (r = .35, p = .001) but not with  pleasantness rating (r = .04, p = .7). These findings suggest that the AC may be encoding more of the immediate physical dimensions of odor  (intensity) rather than the later ìpsychological dimensionsî (pleasantness).

Jianli WANG: Different Reaction of Human Brain to the Invigorating and Relaxing Odors. Though brain activation patterns were similar in certain  respects, lavender and peppermint elicited different profiles of neural reactivity, indicating that olfactory stimuli can have diverse and profound effects on emotion-processing, motor, sensory, and cognitive systems.”

Pamela DALTON: Hormonal gating of exposure-induced sensitivity to odors in women WOMEN. KEY FINDING: “There was a significant interaction between group and time (p<0.02), with women using HRT [hormone replacement therapy] showing  significantly greater sensitization to benzaldehyde than women not on HRT. No comparable changes were observed for the control odor among either group, confirming the relative specificity of the enhanced sensitivity.”

Bensafi M, Brown WM, Khan R, Levenson B, Sobel N. Sniffing human sex-steroid derived compounds modulates mood, memory and autonomic nervous system function in specific behavioral contexts. Behav Brain Res. 2004 Jun 4;152(1):11-22.
KEY FINDING: “These results suggest that sex-steroidal compounds modulate mood, memory and autonomic nervous system responses and increase their significance within specific behavioral contexts. These findings lend support to a specific role for these compounds in chemical communication between humans.”

Bensafi M, Tsutsui T, Khan R, Levenson RW, Sobel N.Sniffing a human sex-steroid derived compound affects mood and autonomic arousal in a dose-dependent manner. Psychoneuroendocrinology. 2004 Nov;29(10):1290-9. KEY ISSUE: “These findings further implicate AND in chemical communication between humans, but pose questions as to the path by which AND is transduced, whether through chemical sensing or transdermal diffusion.”

Meredith M, Westberry JM. Distinctive responses in the medial amygdala to same-species and different-species pheromones. J Neurosci. 2004 Jun 23;24(25):5719-25. “This is the first evidence for an important role of the amygdala, a limbic structure known to be involved in social and emotional behavior, in discrimination of species specificity in chemosignals.”

Kovacs G, Gulyas B, Savic I, Perrett DI, Cornwell RE, Little AC, Jones BC, Burt DM, Gal V, Vidnyanszky Z. Smelling human sex hormone-like compounds affects face gender judgment of men. Neuroreport. 2004 Jun 7;15(8):1275-7. “Our results provide evidence for specific cross-sensory effects of the gender-specific chemosensory cues on the categorization of visual face gender.”

Wilcox AJ, Baird DD, Dunson DB, McConnaughey DR, Kesner JS, Weinberg CR. On the frequency of intercourse around ovulation: evidence for biological influences.
Hum Reprod. 2004 Jul;19(7):1539-43. KEY FINDING: “There apparently are biological factors that promote intercourse during a woman’s 6 fertile days.” COMMENT: The most important biological factor in mammalian female copulation during the fertile period is olfaction/pheromones.

Reyes R, Mendoza J, Ballesteros J, Moffatt C. Male chemosignals inhibit the neural responses of male mice to female chemosignals. Brain Res Bull. 2004 May 30;63(4):301-8. KEY FINDING: “…male urine inhibited the responses of cells within the MOS and AOS to female urine.”

Roberts SC, Havlicek J, Flegr J, Hruskova M, Little AC, Jones BC, Perrett DI, Petrie M. Female facial attractiveness increases during the fertile phase of the menstrual cycle. Proc R Soc Lond B Biol Sci. 2004 Aug 7;271 Suppl 5:S270-2.  KEY FINDING: “This indicates the existence of visible cues to ovulation in the human face, and is consistent with similar cyclical changes observed for preferences of female body odour.”

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