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The scent of attractiveness: Levels of reproductive hormones explain individual differences in women's body odour
Abstract
Individuals are thought to have their own distinctive body odour which reportedly plays an important role in mate choice. In the present study we investigated individual differences in body odours of women and examined whether some women generally smell more attractive than others or whether odour preferences are a matter of individual taste. We then explored whether levels of reproductive hormones explain women's body odour attractiveness, to test the idea that body odour attractiveness may act as a chemosensory marker of reproductive fitness. Fifty-seven men rated body odours of 28 healthy, naturally cycling women of reproductive age. We collected all odours at peak fertility to control for menstrual cycle effects on body odour attractiveness. Women's salivary oestradiol, progesterone, testosterone and cortisol levels were assessed at the time of odour collection to test whether hormone levels explain body odour attractiveness. We found that the men highly agreed on how attractive they found women's body odours. Interestingly , women's body odour attractiveness was predicted by their oestradiol and progesterone levels: the higher a woman's levels of oestradiol and the lower her levels of progesterone, the more attractive her body odour was rated. In showing that women's body odour attractiveness is explained by levels of female reproductive hormones, but not by levels of cortisol or testosterone, we provide evidence that body odour acts as a valid cue to potential fertility.
... 1,2 However, use of contraception destroy cyclic attractiveness of body odors. 1 On the other hand, it is known that body odor plays an important role in the perception of physical attractiveness and as a regulator of desire, especially around ovulation time. [2][3][4][5] The use of perfumes has been rooted in the culture of various continents for millennia. 6,7 It seems that people are often dissatisfied with their own smell and try to mask it by using perfume. ...
... 1,2 Others, found comparable phenomenon for body odor alone by measuring the level of hormones in the subjects. 3,4 The human body is obviously able to send physiological olfactory signals acting as an attractant or information about the readiness to pair. [1][2][3][4][5] It is, therefore, a factor that plays an important role in reproduction. ...
... 3,4 The human body is obviously able to send physiological olfactory signals acting as an attractant or information about the readiness to pair. [1][2][3][4][5] It is, therefore, a factor that plays an important role in reproduction. However, work of Lenochova dealt with men, therefore, is not useful to compare with smell attractiveness during women menstrual cycle. ...
Introduction
Perfumes are the cosmetics applied to the skin. Body odor has been shown to be attractive in the fertile days in non-user of contraception. However, contraception pill intake destroy cyclic attractiveness of odors.
Aim
The aim was to test attractiveness and intensiveness of perfume applied to the female skin in course of menstrual cycle.
Material and methods
Diluted vanilla extract was applied on forearm of 18 women (9 women users of contraception and 9 non-users of contraception). Thirty minutes occlusion samples were collected and judged for its attractiveness and intensity by 25 men. Samples were collected at 1st, 8th, 14th, and 22nd day of cyclus.
Results
Attractiveness of smell of perfume in women, which use contraceptive was statistically significantly higher than in non-user. Furthermore, attractiveness of smell at 15th day of menstrual cycle was second best when perfume was applied in women, which use contraceptive.
Conclusions
Perfume on the skin of women, which apply contraceptive, smell better than on non-contraceptive-user skin. Moreover, women body odor together with perfume is highly attractive in contraceptive-user in the middle of the cyclus.
... These considerations suggest that endocrine predictors of odour attractiveness can provide important clues regarding whether and how human ovulation became concealed. One prior study collected an odour sample from women near ovulation and reported that, between-women, oestradiol was positively and progesterone negatively associated with ratings of odour attractiveness [23]. This between-women comparison does not directly assess whether elevated luteal phase progesterone suppresses odour attractiveness relative to other days within the same cycle, however, and in fact no prior studies appear to have tested the relationship between within-women shifts in ovarian hormones and within-women changes in odour attractiveness. ...
... above the grand-mean ratings (table 1), suggestive of a medium effect size. One prior study also reported a positive between-woman correlation between oestradiol and odour attractiveness when each was measured once per woman in the late follicular phase [23]. We suggest caution in the interpretation of this finding, however, for two reasons. ...
Odour cues associated with shifts in ovarian hormones indicate ovulatory timing in females of many nonhuman species. Although prior evidence supports women's body odours smelling more attractive on days when conception is possible, that research has left ambiguous how diagnostic of ovulatory timing odour cues are, as well as whether shifts in odour attractiveness are correlated with shifts in ovarian hormones. Here, 46 women each provided six overnight scent and corresponding day saliva samples spaced five days apart, and completed luteinizing hormone tests to determine ovulatory timing. Scent samples collected near ovulation were rated more attractive, on average, relative to samples from the same women collected on other days. Importantly, however, signal detection analyses showed that rater discrimination of fertile window timing from odour attractiveness ratings was very poor. Within-women shifts in salivary oestradiol and progesterone were not significantly associated with within-women shifts in odour attractiveness. Between-women, mean oestradiol was positively associated with mean odour attractiveness. Our findings suggest that raters cannot reliably detect women's ovulatory timing from their scent attractiveness. The between-women effect of oestradiol raises the possibility that women's scents provide information about overall cycle fecundity, though further research is necessary to rigorously investigate this possibility.
... Not only the voice, but also the scent of a potential partner might be used as a cue when it comes to partner choice (Havlíček et al., 2008;Mahmut & Croy, 2019;White & Cunningham, 2017). Importantly, humans use scent to extract an impressive amount of information relevant for mate choice, such as sex, dominance, fertility, health, and genetic compatibility (Groyecka et al., 2017;Lobmaier, Fischbacher, Wirthmüller, & Knoch, 2018;Roberts, Gosling, Carter, & Petrie, 2008). Interestingly, smell might be more important for women than for men (Havlíček et al., 2008). ...
... Interestingly, smell might be more important for women than for men (Havlíček et al., 2008). Previous research on olfactory preferences of men have mainly focused on genetic compatibility (e.g., Roberts et al., 2008) and ovulatory shift effects (e.g., Lobmaier et al., 2018), while the contribution of olfactory attractiveness in male mate choice has remained relatively unexplored. Altogether, these findings suggest that incorporating vocal and olfactory cues of attractiveness might explain a substantial amount of variance in mate choice. ...
When people meet a potential partner for the first time, they are confronted with multiple sources of information, encompassing different modalities, that they can use to determine whether this partner is suitable for them or not. While visual attractiveness has widely been studied with regard to partner choice, olfactory and auditory cues have received less attention, even though they might influence the attitudes that people have towards their partner. Therefore, in this study, we employed a combination of pre-date multimodal rating tasks followed by speed-date sessions. This offered a naturalistic setup to study partner choice and disentangle the relative effects of a priori attractiveness ratings of sight, scent and sound on date success. Visual attractiveness ratings showed a strong positive correlation with propensity to meet the partner again, while the effects of olfactory and auditory attractiveness were negligible or not robust. Furthermore, we found no robust sex differences in the importance of the three modalities. Our findings underscore the relative importance of visual attractiveness in initial mate choice, but do not corroborate the idea that static pre-date measures of auditory and olfactory attractiveness can predict first date outcomes.
... It is unknown whether oestradiol concentration mediates the perceived change in BO [19]. Male ratings of women's BO attractiveness is predicted by the women's oestradiol level [30]. ...
... This might be owing to either a strong resemblance between the pubertal daughter's BO and the mother's own BO with regard to oestradiol level or to the fact that it is unclear whether oestradiol affects BO perception in a similar way to testosterone [25]. Oestradiol level of the donor has been shown to predict male ratings of women's BO attractiveness [30], and this might apply for female evaluation likewise. However, this was in the context of mate choice, whereas our study focused on the motherchild relationship, which is why context-dependent differences have to be considered. ...
Mothers are able to identify the body odour (BO) of their own child and prefer this smell above other BOs. It has hence been assumed that the infantile BO functions as a chemosignal promoting targeted parental care. We tested this hypothesis and examined whether children's BOs signal genetic similarity and developmental status to mothers. In addition, we assessed whether BOs facilitate inbreeding avoidance (Westermarck effect). In a cross-sectional design, N = 164 mothers participated with their biological children ( N = 226 children, aged 0–18 years) and evaluated BO probes of their own and four other, sex-matched children. Those varied in age and in genetic similarity, which was assessed by human leucocyte antigen profiling. The study showed not only that mothers identified and preferred their own child's BO, but also that genetic similarity and developmental status are transcribed in BOs. Accordingly, maternal preference of their own child's odour changes throughout development. Our data partly supported the Westermarck effect: mothers' preference of pubertal boys' BOs was negatively related to testosterone for the own son, but not for unfamiliar children.
This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
... As mentioned briefly above, it is less clear from a theoretical viewpoint why one would predict an effect of partnership and/or parity on either E2 or P4 levels in women from the viewpoint of social endocrinology, especially given the complex and crucial roles of these hormones in regulating female reproductive capabilities. Although levels of E2 are implicated in mate attraction (Jasieńska et al., 2004), this may be due to an evolved ability of men to detect subtle cues of a woman's fecundity or ovulatory status (Gildersleeve et al., 2012;Lobmaier et al., 2018;Puts et al., 2013) and may bear little relationship to aspects of partnering or parity. Gettler et al. (2018) have suggested that studies in social endocrinology should analyze multiple hormones and the complex, dynamic relationships between them in order to understand more fully how they relate to parental and mating investments. ...
Recent studies in social endocrinology have explored the effects of social relationships on female reproductive steroid hormones—estradiol and progesterone—investigating whether they are suppressed in partnered and parous women. Results have been mixed for these hormones although evidence is more consistent that partnered women and women with young children have lower levels of testosterone. These studies were sequential to earlier research on men, based on Wingfield’s Challenge Hypothesis, which showed that men in committed relationships, or with young children, have lower levels of testosterone than unpartnered men or men with older or no children. The study described here explored associations between estradiol and progesterone with partnership and parity among women from two different ethnicities: South Asian and white British. We hypothesized that both steroid hormones would be lower among partnered and/or parous women with children ≤3 years old, regardless of ethnicity. In this study we analyzed data from 320 Bangladeshi and British women of European origin aged 18 to 50 who participated in two previous studies of reproductive ecology and health. Levels of estradiol and progesterone were assayed using saliva and/or serum samples and the body mass index calculated from anthropometric data. Questionnaires provided other covariates. Multiple linear regressions were used to analyze the data. The hypotheses were not supported. We argue here that, unlike links between testosterone and male social relationships, theoretical foundations for such relationships with female reproductive steroid hormones are lacking, especially given the primary role of these steroids in regulating female reproductive function. Further longitudinal studies are needed to explore the bases of independent relationships between social factors and female reproductive steroid hormones.
... Last, we want to note that attractiveness judgments are based on more than faces and voices. Odor cues (Havlicek et al., 2008;Lobmaier et al., 2018), visual perception of the body (Kościński, 2013), gaze direction (Ho et al., 2018;Kaisler et al., 2020), and emotional expression (Lindeberg et al., 2019;Kaisler et al., 2020) for example also play an important role and should be addressed in future studies. ...
Vocal and facial cues typically co-occur in natural settings, and multisensory processing of voice and face relies on their synchronous presentation. Psychological research has examined various facial and vocal cues to attractiveness as well as to judgements of sexual dimorphism, health, and age. However, few studies have investigated the interaction of vocal and facial cues in attractiveness judgments under naturalistic conditions using dynamic, ecologically valid stimuli. Here, we used short videos or audio tracks of females speaking full sentences and used a manipulation of voice pitch to investigate cross-modal interactions of voice pitch on facial attractiveness and related ratings. Male participants had to rate attractiveness, femininity, age, and health of synchronized audio-video recordings or voices only, with either original or modified voice pitch. We expected audio stimuli with increased voice pitch to be rated as more attractive, more feminine, healthier, and younger. If auditory judgements cross-modally influence judgements of facial attributes, we additionally expected the voice pitch manipulation to affect ratings of audiovisual stimulus material. We tested 106 male participants in a within-subject design in two sessions. Analyses revealed that voice recordings with increased voice pitch were perceived to be more feminine and younger, but not more attractive or healthier. When coupled with video recordings, increased pitch lowered perceived age of faces, but did not significantly influence perceived attractiveness, femininity, or health. Our results suggest that our manipulation of voice pitch has a measurable impact on judgements of femininity and age, but does not measurably influence vocal and facial attractiveness in naturalistic conditions.
... There's another advantage. With the female allowing, indeed encouraging him to be close, he is in a position to detect subtle indications of impending ovulation (eg, Lobmaier et al., 2018) and sexual arousal (Wiseman & Shrira, 2020), that a lower-mate-value male, who, in not being allowed close and instead positively distanced, could not. He will never be in a position to increase the probability of conception to sufficiently offset the likely costs, to render a bid for a sneak mating worth the risk. ...
Women's mate choice, given profoundly differential male genetic quality (specifically genomic integrity), is heavily skewed towards topmost-ranked males, producing polygyny with residual monogamy and bachelordom. Polygyny is ancestral, as in gorilla harems (apparently homologous with human female cliques): originally predation-avoidance grouping, male-interposed to obviate female-female stress depressing fertility to sub-replacement (Dunbar). Pair-bonding ensures successive highest-possible-quality offspring while offsetting age-related fertility decline, and dissuading low-mate-value social-sexual approach, thereby actually facilitating access by (or to) high-mate-value males for extra-pair conception. It's a female fertility platform and springboard for its enhancement. Failure properly to incorporate male heterogeneity and female discernment explains a longstanding theoretical impasse, with infanticide prevention a default mistaken hypothesis attempting to account for monogamy's chimerical opportunity costs.
... Axillary apocrine secretions contain various odoriferous volatile chemicals [20]. Some, such as the androstenes, are intermediate products in the metabolic conversion of cholesterol to the primary sex hormones and are variously aromatic [14,24]. Androstenes have been shown to act as chemosignals that can influence human behavior in multiple ways such as sexual interest, attraction, mood, emotions and possibly mate selection [25][26][27][28][29]. ...
Background and objective: Luteinizing hormone-releasing hormone
agonists (LHRHa) suppress gonadal hormone production and are commonly used to
treat prostate cancer (PC) in men and conditions ranging from uterine fibroids to
estrogen-sensitive cancers in women. They are also used to delay sexual
development in children considering gender reassignment or experiencing premature
puberty. As chemically castrating agents, LHRHa may affect cutaneous steroid
secretions, which, in turn, could alter body odor and influence the psycho-sexual
dynamics between individuals. The objectives of the present study were to
determine (1) if LHRHa indeed alter cutaneous skin secretions, and (2) whether this
leads to perceivable changes in body odor.
Material and methods: Axillary skin secretions were collected
on new cotton T-shirts worn by men undergoing androgen deprivation therapy with
an LHRHa to treat PC (n = 10), both before starting the LHRHa and 3 months later.
Healthy heterosexual university students (50 males, 50 females) were recruited to
smell and rate the shirts for their masculinity, attractiveness, and intensity of
odor. Liquid chromatography-mass spectrometry (LC-MS) was also used to analyze
steroids extracted from the shirt samples.
Results: LC-MS showed a statistically significant decline in
the concentration of the androgenic metabolites, androsterone and
5α-androstane-3,17-dione. This confirms that LHRHa drugs that suppress
gonadal hormone production markedly reduce cutaneous secretion of androgenic
metabolic intermediates in adult males. However, no differences in odor were
detected in the ratings of the shirts by male, female, nor male and female raters
combined for any of the three variables assessed. Possible reasons why the human
sniffers failed to perceive a change in odor are explored.
Conclusion: Our data document that LHRHa alter steroid skin
secretions in older men, but whether such changes alter the olfactory signals
that might influence psychosocial interactions remains unresolved.
... Bonding difficulties are associated with the inability to recognize the own baby's odour, and mothers with impaired bonding do not perceived their own child's odour as pleasant as healthy mothers (Croy, Mohr, Weidner, Hummel, and Junge-Hoffmeister (2019)). Mate choice and romantic relations are also influenced by olfactory cues (for a review, see (Mahmut and Croy 2019), as they impact attractiveness perception, presumably dependent on genetic (e.g., Sorokowska et al. (2018) or for review (Havlíček, Winternitz, and Roberts 2020)) or hormonal traits (Lobmaier, Fischbacher, Wirthmüller, and Knoch 2018). With regard to sexuality, olfaction contributes to quality and quantity of sexual behaviour (Bendas, Hummel, and Croy 2018) and the experience of sexual arousal is mediated by body odour perception (Cerda-Molina, Hernández-López, Claudio, Chavira-Ramírez, and Mondragón-Ceballos 2013). ...
The sense of smell essentially contributes to social communication, guides nutrition behaviour and elicits avoidance towards environmental hazards. Olfactory smell impairment may hence entail severe consequences for affected individuals. Compared with sensory loss in other modalities, reduced olfactory function is often unnoticed by those affected and diagnosed late. Those patients seeking help frequently suffer from long-term impairments resulting in reduced well-being and quality of life. The current review provides an overview of aetiology, prevalence and specifics of diagnostics in acquired and congenital olfactory loss and focusses on short- and long-term consequences. Compensation strategies are elaborated, and treatment options are mentioned. Individual characteristics associated with the development of serious mental health impairment are discussed in order to help practitioners identifying populations at risk.
... This, to our knowledge, is the first study to examine the effects of body odor of ovulating and pregnant women on male heterosexuals both in terms of behavior and brain activity. Previous studies have been mutually exclusive by focusing on either visual attractiveness during the menstrual cycle using photographs or body movements ( Miller et al., 2007 ;Puts et al., 2013 ;Roberts et al., 2004 ), or on the attractiveness of body odor over the entire cycle ( Cerda- Molina et al., 2013 ;Gildersleeve et al., 2012 ;Havlicek et al., 2006 ;Kuukasjarvi et al., 2004 ;Lobmaier et al., 2018 ;Probst et al., 2017 ). Our attempt is the first to combine the investigation of both the neural and behavioral effects of reproductive body odor on facial attractiveness and pregnancy ratings. ...
Female chemical signals underlie the advertising of sexual receptivity and fertility. Whether the body odor of a pregnant woman also has a signaling function with respect to male behavior is yet to be conclusively established. This study examines how the body odors of ovulating and pregnant women differentially affect the behavior of heterosexual men.
Body odor samples were collected from 5 pregnant women and 5 matched controls during ovulation. In a double-blind functional magnetic resonance imaging design, 18 heterosexual men were exposed to female body odors during ovulation (OV) and pregnancy (PRG) while being required to indicate the attractiveness of concurrently presented female portrait images. The participants were also required to indicate whether they assumed a depicted woman was pregnant.
While neither OV nor PRG altered the perceived attractiveness of a presented face, the men tended to identify the women as pregnant while exposed to a PRG body odor. On the neural level, OV activated a network of the frontotemporal and limbic regions, while PRG activated the superior medial frontal gyrus.
The results suggest that the detection of sexual availability activates the male brain regions associated with face processing and reward/motivation, whereas sensing pregnancy activates a region responsible for empathy and prosocial behavior. Thus, the female body odor during pregnancy likely helps foster circumstances conducive to the future care of offspring while the body odor advertising sexual availability promotes mating behavior. The brains of heterosexual men may be capable of unconsciously discriminating between these two types of olfactory stimuli.
... Women who were naturally cycling received significantly more tips when they were in their follicular phase compared to their luteal phase, whereas women who were using HCs did not report changes in tips. Laboratory research has also found that the attractiveness of women's faces, voices, and scents varies cross the menstrual cycle in ways that are specifically related to progesterone, estrogen, and testosterone levels (e.g., Gildersleeve et al. 2012;Havlíček et al. 2006;Kuukasjärvi et al. 2004;Lobmaier et al. 2018). Ratings of women's vocal attractiveness are positively related to conception risk (Pipitone and Gallup Jr 2008), and progesterone negatively predicts attractiveness ratings of both women's faces and voices by men and women raters (Puts et al. 2013;Roberts et al. 2004). ...
Objectives
Progestins (i.e., synthetic progesterone) used in hormonal contraceptives (HCs) have been developed to mimic endogenous progesterone to inhibit ovulation and prevent pregnancy. Although the physiological side effects of different progestin formulations and administrative routes (e.g., oral pill, injection, skin patch) are well understood, the potential affective and behavioral side effects of various progestins are relatively under-studied. Progestins vary in terms of their dosage, bioavailability, metabolism, and affinity for progesterone and other steroid hormone receptors. Yet, research investigating the effects of these compounds on women’s affect, sex drive, and mate preferences has not systematically accounted for these differences when considering their psychobehavioral side effects.Methods
Here, the biological differences between progesterone and progestins, as well as the differences between progestin types, are considered.ResultsResearch looking at the effects of progesterone and progestins on women’s affect, sex drive, and mating psychology is reviewed, with emphasis on work that has explored differences between progestin types. In this review, we argue that accounting for these unique aspects of progestins is necessary for a comprehensive understanding of the influence of HCs on women.ConclusionA better understanding of these differences may clarify previous research and inform future studies.
... The particular hormones that mediate this alteration in odor preference across the menstrual cycle are yet to be identified but steroid hormones may be a likely candidate. Steroid hormones seem to affect body odor perception -for example, higher estradiol concentration is associated with higher attractiveness of female body odor (Lobmaier et al., 2018), whereas male body odor contains more androgen-derived steroids and is perceived as more intense (Sergeant, 2010). The relation to actual testosterone levels has however been unclear (Rantala et al., 2006). ...
Mothers can recognize their own children by body odor. Besides signaling familiarity, children’s body odors may provide other information relevant to maternal caregiving behavior, such as the child’s developmental status. Thus, we explored whether mothers are able to classify body odors on pre- vs. postpubertal status above chance levels. In total, 164 mothers were presented with body odor samples of their own and four unfamiliar, sex-matched children who varied in age (range 0–18 years). Pubertal status was measured by (a) determining the child’s steroid hormone level and (b) parental assessment of the child’s developmental stage using the Pubertal Development Scale. Mothers classified developmental status with an accuracy of about 64%. Maternal assessments were biased toward pre-puberty. Classification was predicted by perceptual evaluation of the body odor (i.e. intensity and pleasantness) and by the child’s developmental stage, but not by hormones. In specific, mothers with pubertal-aged children classified body odors using the child’s developmental status, whereas mothers with younger children only classified body odors using perceptual information (i.e. intensity and pleasantness). Our data suggests that body odors convey developmental cues, but how this developmental information is manifested in body odor remains unclear.
... 41,42 Furthermore, the scent of a woman's body changes depending on the phase of the menstrual cycle and its attractiveness, as perceived by men, is connected with high levels of estradiol and low levels of progesterone. 43 A properly hydrated skin is perceived as healthier, and its ageing is definitely slower. 44 The positive effect after stabilized HA injections, i.e. healthier looking facial skin, can be sustained for over half a year. ...
Background:
Skin ageing is a physiological process, progressive and irreversible. Hyaluronic acid injection treatments are used to correct the signs of skin ageing.
Material and methods:
Hyaluronic acid was implanted in the area of the cheek and the forehead aesthetic units in 57 women, aged 35-55 years. Apart from the clinical observation, self-assessment of the therapeutic results was conducted. The "My skin" questionnaire was used for subjective evaluation of the treatment results.
Results:
Mean wrinkle score in the pre-menopausal group changed after the treatment, from 3.2±0.6 to 1.1±0.3 and from 3.2±0.6 to 0.8±0.6 for the forehead and the cheek esthetic units, respectively. In the post-menopausal group, the score decreased from 3.8±0.4 to 1.7± 0.7 and from 3.2±0.617 to 0.8± 0.6 for the forehead and the cheek esthetic units, respectively. The changes were age-dependent. Improved appearance of the facial skin - higher satisfaction with skin tone and scent - was reported after hyaluronic acid injections. Higher subjective perception of improvement corresponded to older age, irrespectively of the menopausal status. Correlations between age and the effect of the treatment on maintaining proper skin hydration as well as between improved appearance of the forehead area and feelings of autonomy and well-being were found.
Conclusion:
Hyaluronic acid injections significantly improved the subjective perception and overall assessment of the scent and appearance of the facial skin.
... There is increasing evidence that human body odor, a complex mixture of volatile compounds produced by bacterial transformation of sweat gland secretions, is involved in interpersonal communication. For instance, body odor provides information about genetic proximity through the major histocompatibility complex [1][2][3], about hormonal levels of male and female donors [4][5][6][7], about health condition [8][9][10], and about emotional state [11][12][13]. Such information is relevant for social interactions in general, and for mate choice and interpersonal attractiveness in particular [14]. ...
There is increasing evidence that human body odor is involved in interpersonal communication. However, among the wide variety of substances excreted by the human body that might act as chemosignals, much attention has been granted to androstenes to the detriment of other categories. Here, we focused on the acidic fraction of human body odor. We investigated men and women's perceptual descriptions and detection thresholds of the sexually dimorphic (male) compound 3-hydroxy-3-methylhexanoic acid (HMHA) in two contrasted cultures, France and Madagascar. Perceptual responses to HMHA in both countries were very similar. HMHA proved to be more typical of body odor than another chemically-related major compound of human body odor 3MHA (3-methylhex-2-enoic acid also known as 3M2H). A significant portion of the samples studied (between 8 and 19%) was likely to be anosmic to HMHA (and to 3MHA: 25%). Although differences would be expected between men and women's perceptual responses to HMHA, based on the assumption that this compound would have a function in human partner choice, no sex differences were found for any of the perceptual variables. However, in Malagasy women, perceived intensity of HMHA was higher in participants who were in the fertile phase of the menstrual cycle. Whether HMHA is relevant in the perception of a potential partner thus requires further explorations, with more implicit approaches for example and/or by investigating the repercussions of HMHA specific anosmia on interpersonal relationships.
... We note that, in our sample, two of the HC group were no longer using HC at the time of sample collection, and five women in the NHC group had begun to use HC by the time of sample collection. Changes in HC use during a relationship might present an interesting opportunity to further investigate levels of olfactory similarity and relationship satisfaction, as we know both that hormone levels have an influence on body odour [66,67,68] and that changes in HC use during the course of a relationship may alter attraction to, and satisfaction with, a partner [71]. However, as this was not something we set out to test, we do not have sufficient variation in the current sample to investigate this, and future researchers should take this into consideration. ...
There is substantial evidence for assortative partner preferences in humans based on physical characteristics. In contrast, evidence suggests that olfactory preferences tend to be disassortative, with people preferring body odour of potential partners who are dissimilar at key genetic loci, perhaps to gain fitness advantage through offspring heterozygosity. We compared ratings of perceived body odour similarity of real couples with those of randomly paired 'fake' couples. Contrary to prediction, we find that odours of real partners are perceived more, rather than less, similar to each other than fake couples. However, this applied only to natural odour samples: there were no differences in similarity levels of real and fake couples' samples which were collected while wearing artificial fragrances. Furthermore, in light of suggestions that hormonal contraception (HC) disrupts disassortative odour preferences in women, we compared odour similarity among real couples in which the female partner was using or not using HC at the time when the relationship began. We find that odours of HC-using couples are of intermediate similarity between non-using and fake couples, suggesting that HC use during partner choice could affect odour-influenced assortment. We also examined the association between relationship satisfaction and perceived similarity of unfragranced odours of real couples. We found that these are positively correlated in male partners but negatively correlated in the female partners, indicative of a sex difference in the relative favourability of odour similarity in partner preference. Finally, by comparing odour similarity ratings with those given by perfumers using a novel olfactory lexicon we found evidence that similarity judgements were based on the Spicy/Animalic aspects of individual odour profiles. Taken together, our results challenge the conventional view that odour-mediated partner preferences in humans are typically disassortative.
Background:
Body odor is an important aspect in interpersonal communication. For psychological and chemical research on body odors, suitable procedures for sampling and application, and analysis of body odors are essential. In this study, different textile fabrics (polyester, cotton, and Gazin gauze) were comparatively evaluated in view of their potential suitability for body odor sampling by determining recovery rates of selected body odor substances. In addition, the impact of sample preparation and storage conditions on the recovery rates was determined.
Results:
The recovery rates of dimethyl disulfide, (E)-non-2-enal, 5α-androst-16-en-3-one, 6-methylhept-5-en-2-one, heptanal and 3-sulfanylhexan-1-ol were determined under different conditions of storage (storage for 30 min at room temperature or storage for 30 min at room temperature followed by freezing at - 80 °C for 4 weeks) and sample work-up (solvent extraction with and without solvent-assisted flavour evaporation, in the following: SAFE). SAFE led to overall lower recovery rates with a significant effect for (E)-non-2-enal and 5α-androst-16-en-3-one. Nevertheless, the results showed that SAFE can be an essential step when working with a complex matrix. When comparing the different fabrics, except for (E)-non-2-enal no difference between the recovery rates obtained for cotton and polyester became evident. Gazin gauze showed lower recovery rates for all compounds. Finally, our results showed that the here investigated target compounds are stable during storage for four weeks at - 80 °C.
Significance and novelty:
The results show on the one hand that the here investigated compounds were stable during storage and that the fiber type had limited influence on overall recovery rates. On the other hand, they highlight the limitations of using textile materials for sampling of volatile substances, especially with regard to low recovery rates for certain substances and the necessity of material pre-treatment or distillation steps for enabling GC-MS analysis after solvent extraction.
Studies of mate choice from an evolutionary perspective often begin by investigating whether individuals of one sex share similar preferences for mates. Evidence for shared preferences is often interpreted as support for the hypothesis that preferences are adaptations that have evolved to select high-quality mates. To date, the importance of body odor in human mate choice is uncertain because fundamental questions, such as whether preferences for body odor are shared, have not yet been systematically explored. Here, we asked groups of heterosexual men and women from the University of Pennsylvania to rate the attractiveness of body odors, faces, and voices of opposite-sex individuals. We used our data to produce quantitative estimates of the amount of rater agreement for each of the three modalities of attractiveness, applying a uniform methodology that facilitates cross-modality comparisons. Overall, we found evidence of agreement within all three modalities. Yet, our data also suggest a larger component of attractiveness judgments that can be attributed to personal preferences and idiosyncratic noise. Importantly, our results provide no evidence that agreement regarding odor attractiveness is substantially quantitatively different from the amount of agreement found in other modalities that have been the focus of most previous work. To the extent that evidence exists of shared preferences for faces and voices, our results reveal evidence of shared preferences for body odors.
Findings on female sexual motivation across the ovulatory cycle are mixed. Some studies have reported increased female sexual desire on fertile days or midway through the ovulatory cycle, whereas others have reported increased sexual desire on nonfertile days. We postulated and tested the hypothesis that the pattern of the cyclical change of female sexual desire is associated with women's life history. Female participants completed life-history measures and rated their levels of sexual desire on the survey day and reported the first day of their current and subsequent cycle, respectively (Study 1), or recorded their sexual desire throughout an entire cycle by submitting daily reports (Study 2). Results indicate that women with a fast life history experienced peak sexual desire midcycle, whereas women with a slow life history experienced two peaks of sexual desire midcycle and around their menses. These findings suggest that, consistent with the underlying life history, cyclically differential peaking of sexual desire may serve different reproductive functions.
Background:
The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).
Methods:
Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.
Results:
The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.
Conclusion:
This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.
Androstenol has been reported to influence judgements of attractiveness and to affect participants’ mood. In the present study, participants were asked to sniff androstenol or a control odour (pure ethanol) unilaterally with the left or right nostril. Subsequently, they rated the attractiveness of photographs of the opposite sex and their own feelings on four mood scales. Participants rated the photographs as significantly more attractive after sniffing androstenol compared with the control odour. This did not depend upon androstenol being perceived as pleasant. Androstenol made male participants feel more lively, and both male and female participants more sexy, when sniffed through the right compared with the left nostril. Participants rated themselves as more irritable and aggressive when exposed to androstenol through the left nostril. The findings are discussed in relation to the effects of arousal on attraction and in the context of current theories of hemispheric differences in emotion.
Trust is essential in initiating social relationships. Due to the differential evolution of sex hormones as well as the fitness burdens of producing offspring, evaluations of a potential mating partner’s trustworthiness likely differ across sexes. Here, we explore unknown sex-specific effects of facial attractiveness and threat on trusting other-sex individuals. Ninety-three participants (singles; 46 women) attracted by the other sex performed an incentivized trust game. They had to decide whether to trust individuals of the other sex represented by a priori-created face stimuli gradually varying in the intensities of both attractiveness and threat. Male and female participants trusted attractive and unthreatening-looking individuals more often. However, whereas male participants’ trust behavior was affected equally by attractiveness and threat, female participants’ trust behavior was more strongly affected by threat than by attractiveness. This indicates that a partner’s high facial attractiveness might compensate for high facial threat in male but not female participants. Our findings suggest that men and women prioritize attractiveness and threat differentially, with women paying relatively more attention to threat cues inversely signaling parental investment than to attractiveness cues signaling reproductive fitness. This difference might be attributable to an evolutionary, biologically sex-specific decision regarding parental investment and reproduction behavior.
Body odours and their importance for human chemical communication, e.g., in the mother–child relationship, are an increasing focus of recent research. Precise examination of sampling methods considering physiology and feasibility aspects in order to obtain robust and informative odour samples is therefore necessary. Studies comparing body odour sampling at different body sites are still pending. Therefore, we sampled axilla, breast, and head odour from 28 mother–infant dyads and examined whether odour perception differs with regard to the body site. The participating mothers were asked to evaluate their own and their infant’s body odour samples, as well as odours of two unfamiliar mother–infant dyads. We tested whether maternal pleasantness and intensity evaluation, as well as recognition ability of the odours differed between the body sites. In infants, the head odour exhibited slightly lower pleasantness ratings than axilla and breast, and intensity ratings did not differ between body sites. In mothers, body site affected intensity ratings but not pleasantness ratings, as the breast odour was rated as less intense compared with head and axilla. Across all body sites, mothers rated the own and their infant’s odour as less intense when compared with unfamiliar samples. Recognition ability did not differ between body sites, and in line with previous studies, mothers were able to recognize their own and their own infant’s odour above chance. In sum, our study extends the previous methodological repertoire of body odour sampling and indicates that the axilla, breast, and head of adults as well as infants serve as informative odour sources.
Women’s mate choice, given profoundly differential male genetic quality (specifically genomic integrity), is heavily skewed towards topmost-ranked males, producing polygyny with residual monogamy and bachelordom. Polygyny is ancestral, as in gorilla harems (apparently homologous with human female cliques): originally predation-avoidance grouping, male-interposed to obviate female-female stress depressing fertility to sub-replacement (Dunbar). Pair-bonding ensures successive highest-possible-quality offspring while offsetting age-related fertility decline, and dissuading low-mate-value social-sexual approach, thereby actually facilitating access by (or to) high-mate-value males for extra-pair conception. It’s a female fertility platform and springboard for its enhancement. Failure properly to incorporate male heterogeneity and female discernment explains a longstanding theoretical impasse, with infanticide prevention a default mistaken hypothesis attempting to account for monogamy’s chimerical opportunity costs.
Body odours reportedly portray information about an individual’s genotype at the major histocompatibility complex (MHC, called human leucocyte antigen, HLA, in humans). While there is strong experimental support for MHCassociated mating behaviour in animals, the situation in humans is more complex. A lot of effort has been spent on testing HLA-associated odour preferences of women. To date, only very few studies have looked at HLA-linked olfactory preferences in men and these studies have revealed inconsistent results. Here, we investigate men’s HLA-associated preferences for women’s body odours. Importantly, and in contrast to previous studies, these odours were gathered at peak fertility (i.e. just before ovulation) when any HLA-associated odour preferences should be strongest. We scrutinized whether men’s preference for women’s body odours is influenced by (i) the number of shared HLA alleles between men and women, (ii) HLA heterozygosity, and (iii) the frequency of rare HLA alleles. We found that men could readily differentiate between odours they found attractive and odours they found less attractive, but that these preferences were not associated with HLA. Specifically, men did not prefer odours from women who are HLA dissimilar, HLA heterozygous, or who have rare HLA alleles. Together, these findings suggest that HLA has no effect on men’s odour preferences. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
Genes of the major histocompatibility complex (MHC) in vertebrates are integral for effective adaptive immune response and are associated with sexual selection. Evidence from a range of vertebrates supports MHC-based preference for diverse and dissimilar mating partners, but evidence from human mate choice studies has been disparate and controversial. Methodologies and sampling peculiarities specific to human studies make it difficult to know whether wide discrepancies in results among human populations are real or artifact. To better understand what processes may affect MHC-mediated mate choice across humans and non-human primates we performed phylogenetically controlled meta-analyses using 58 effect sizes from 30 studies across 7 primate species. Primates showed a general trend favoring more MHC-diverse mates, which was statistically significant for humans. In contrast, there was no tendency for MHC-dissimilar mate choice, and for humans, we observed effect sizes indicating selection of both MHC-dissimilar and MHC-similar mates. Focusing on MHC-similar effect sizes only, we found evidence that preference for MHC-similarity was an artifact of population ethnic heterogeneity in observational studies but not among experimental studies with more control over socio-cultural biases. This suggests that human assortative mating biases may be responsible for some patterns of MHC-based mate choice. Additionally, the overall effect sizes of primate MHC-based mating preferences are relatively weak (Fisher's Z correlation coefficient for dissimilarity Zr = 0.044, diversity Zr = 0.153), calling for careful sampling design in future studies. Overall, our results indicate that preference for more MHC diverse mates is significant for humans and likely conserved across primates. This article is protected by copyright. All rights reserved.
The consistency of physical attractiveness ratings across cultural groups was examined. In Study 1, recently arrived native Asian and Hispanic students and White Americans rated the attractiveness of Asian, Hispanic, Black, and White photographed women. The mean correlation between groups in attractiveness ratings was
r = .93. Asians, Hispanics, and Whites were equally influenced by many facial features, but Asians were less influenced by some sexual maturity and expressive features. In Study 2, Taiwanese attractiveness ratings correlated with prior Asian, Hispanic, and American ratings, mean
r = .91. Supporting Study 1, the Taiwanese also were less positively influenced by certain sexual maturity and expressive features. Exposure to Western media did not influence attractiveness ratings in either study. In Study 3, Black and White American men rated the attractiveness of Black female facial photos and body types. Mean facial attractiveness ratings were highly correlated (
r = .94), but as predicted Blacks and Whites varied in judging bodies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Does women’s body attractiveness predict indices of reproductive capacity? Prior research has provided evidence that large breast size and low waist-to-hip ratio (WHR) are positively associated with women’s estrogen and progesterone concentrations, but no previous studies appear to have directly tested whether ratings of women's body attractiveness are predicted by higher concentrations of ovarian hormones measured across broad regions of the menstrual cycle. Here, we collected daily saliva samples across 1–2 menstrual cycles from a sample of young women; assayed the samples for estradiol, progesterone, and testosterone; obtained anthropometric measurements of the women’s bodies; and also obtained attractiveness ratings of the women’s bodies from photographs of them taken in standardized clothing with faces obscured. Contrary to previous research, mean hormone concentrations were uncorrelated with breast size and WHR. Body mass index (BMI) was a very strong negative predictor of body attractiveness ratings, similar to previous findings. Zero-order associations between women’s mean hormone concentrations and mean attractiveness ratings were not significant; however, after controlling for BMI, attractiveness ratings were independently and positively associated with both estradiol and testosterone concentrations. Discussion focuses on the implications of these findings for whether attractiveness assessment mechanisms are specialized for the detection of cues of differential fecundity in young women’s bodies.
Several studies have shown that a woman's vaginal or axillary odors convey information on her attractivity. Yet, whether such scents induce psychoneuroendocrinological changes in perceivers is still controversial. We studied if smelling axillary and vulvar odors collected in the periovulatory and late luteal phases of young women modify salivary testosterone and cortisol levels, as well as sexual desire in men. Forty-five women and 115 men, all of them college students and unacquainted with each other, participated in the study. Female odors were collected on pads affixed to the axilla and on panty protectors both worn the entire night before experiments. Men provided five saliva samples, a basal one before the smelling procedure, and four more 15, 30, 60, and 75 min after exposure to odors. Immediately after smelling the odor source, men answered a questionnaire rating hedonic qualities of scents, and after providing the last saliva sample they answered questionnaire on sexual desire. We found that periovulatory axillary and vulvar odors increased testosterone and cortisol levels, with vulvar scents producing a more prolonged effect. Luteal axilla odors decreased testosterone and cortisol levels, while luteal vulva odors increased cortisol. Periovulatory axilla and vulva scents accounted for a general increase of interest in sex. These odors were also rated as more pleasant and familiar, while luteal vulvar odors were perceived as intense and unpleasant.
So many women who do everything right to stay healthy still wind up with breast cancer, heart disease, or osteoporosis. In The Fragile Wisdom, Grazyna Jasienska provides an evolutionary perspective on the puzzle of why disease prevention among women is so frustratingly difficult. Modern women, she shows, are the unlucky victims of their own bodies’ conflict of interest between reproductive fitness and life-long health.
The crux of the problem is that women’s physiology has evolved to facilitate reproduction, not to reduce disease risk. Any trait—no matter how detrimental to health in the post-reproductive period—is more likely to be preserved in the next generation if it increases the chance of giving birth to offspring who will themselves survive to reproductive age. To take just one example, genes that produce high levels of estrogen are a boon to fertility, even as they raise the risk of breast cancer in mothers and their daughters.
Jasienska argues that a mismatch between modern lifestyles and the Stone Age physiology that evolution has bequeathed to every woman exacerbates health problems. She looks at women’s mechanisms for coping with genetic inheritance and at the impact of environment on health. Warning against the false hope gene therapy inspires, Jasienska makes a compelling case that our only avenue to a healthy life is prevention programs informed by evolutionary understanding and custom-fitted to each woman’s developmental and reproductive history.
Scent-marking is a ubiquitous form of olfactory signaling in male mammals and both territorial males in resource-defense mating systems and dominant males in dominance mating systems scent-mark. A large body of evidence suggests a link between scent-marking by male mammals and intrasexual competition. Resource holders appear to mark to help establish and maintain their status. They may do this because scent marks allow potential opponents to assess the status or RHP of the signaler. Nonresource holding competitors benefit because they can adjust the level of escalation in relation to potential costs and benefits and avoid risky contests. Resource holders benefit through reduced costs because many nonresource holders withdraw to avoid escalated contests.
Scent communication plays a central role in the mating behavior of many nonhuman mammals but has often been overlooked in the study of human mating. However, a growing body of evidence suggests that men may perceive women's high-fertility body scents (collected near ovulation) as more attractive than their low-fertility body scents. The present study provides a methodologically rigorous replication of this finding, while also examining several novel questions. Women collected samples of their natural body scent twice--once on a low-fertility day and once on a high-fertility day of the ovulatory cycle. Tests of luteinizing hormone confirmed that women experienced ovulation within two days of their high-fertility session. Men smelled each woman's high- and low-fertility scent samples and completed discrimination and preference tasks. At above-chance levels, men accurately discriminated between women's high- and low-fertility scent samples (61%) and chose women's high-fertility scent samples as more attractive than their low-fertility scent samples (56%). Men also rated each scent sample on sexiness, pleasantness, and intensity, and estimated the physical attractiveness of the woman who had provided the sample. Multilevel modeling revealed that, when high- and low-fertility scent samples were easier to discriminate from each other, high-fertility scent samples received even more favorable ratings compared with low-fertility scent samples. This study builds on a growing body of evidence indicating that men are attracted to cues of impending ovulation in women and raises the intriguing question of whether women's cycling hormones influence men's attraction and sexual approach behavior.
Previous research indicates that the scent of developmental stability (low fluctuating asymmetry, FA) is attractive to women who are fertile (at high-conception risk points in their menstrual cycles), but not to other women or men. Prior research also indicates that the scent of dissimilarity in major histocompatibility complex (MHC) genes may play a role in human mate choice. We studied the scent attractiveness to the opposite sex of t-shirts worn for 2 nights' sleep. Our results indicate that the two olfactory systems are independent. We repeated previous results from studies of the scent of symmetry. We repeated previous results from MHC research in part; men, but not women, showed a preference for t-shirts with the scent of MHC dissimilarity. Women's scent ratings of t-shirts were uncorrelated with the wearer's MHC dissimilarity and allele frequency, but positively correlated with the wearer's MHC heterozygosity. Fertile women did not exhibit any MHC trait preferences. Women's preference for the scent of men who were heterozygous for MHC alleles may be stronger in women who are at infertile cycle points. Men preferred the scent of common MHC alleles, which may function to avoid mates with rare alleles that exhibit gestational drive. Men also preferred the scent of women at fertile cycle points. The scent of facially attractive women, but not men, was preferred. Neither FA nor facial attractiveness in either sex correlated with MHC dissimilarity to others, MHC heterozygosity, or MHC allelic rarity. Copyright 2003.
The characteristic human axillary odor is formed by bacterial action on odor precursors that originate from apocrine sweat glands. Caucasians and Africans possess a strong axillary odor ,whereas many Asians have only a faint acidic odor. In this study, we provide evidence that the gene ABCC11 (MRP8), which encodes an apical efflux pump, is crucial for the formation of the characteristic axillary odor and that a single-nucleotide polymorphism (SNP) 538G --> A, which is prominent among Asian people, leads to a nearly complete loss of the typical odor components in axillary sweat. The secretion of amino-acid conjugates of human-specific odorants is abolished in homozygotic carriers of the SNP, and steroidal odorants and their putative precursors are significantly reduced. Moreover, we show that ABCC11 is expressed and localized in apocrine sweat glands. These data point to a key function of ABCC11 in the secretion of odorants and their precursors from apocrine sweat glands. SNP 538G --> A, which also determines human earwax type, is present on an extended haplotype, which has reached >95% frequency in certain populations in recent human evolution. A strong positive selection in mate choice for low-odorant partners with a dysfunctional ABCC11 gene seems a plausible explanation for this striking frequency of a loss-of-function allele.
Alarm substances are airborne chemical signals, released by an individual into the environment, which communicate emotional stress between conspecifics. Here we tested whether humans, like other mammals, are able to detect emotional stress in others by chemosensory cues. Sweat samples collected from individuals undergoing an acute emotional stressor, with exercise as a control, were pooled and presented to a separate group of participants (blind to condition) during four experiments. In an fMRI experiment and its replication, we showed that scanned participants showed amygdala activation in response to samples obtained from donors undergoing an emotional, but not physical, stressor. An odor-discrimination experiment suggested the effect was primarily due to emotional, and not odor, differences between the two stimuli. A fourth experiment investigated behavioral effects, demonstrating that stress samples sharpened emotion-perception of ambiguous facial stimuli. Together, our findings suggest human chemosensory signaling of emotional stress, with neurobiological and behavioral effects.
Body odor sampling is an essential tool in human chemical ecology research. However, methodologies of individual studies vary widely in terms of sampling material, length of sampling, and sample processing. Although these differences might have a critical impact on results obtained, almost no studies test validity of current methods. Here, we focused on the effect of freezing samples between collection and use in experiments involving body odor perception. In 2 experiments, we tested whether axillary odors were perceived differently by raters when presented fresh or having been frozen and whether several freeze-thaw cycles affected sample quality. In the first experiment, samples were frozen for 2 weeks, 1 month, or 4 months. We found no differences in ratings of pleasantness, attractiveness, or masculinity between fresh and frozen samples. Similarly, almost no differences between repeatedly thawed and fresh samples were found. We found some variations in intensity; however, this was unrelated to length of storage. The second experiment tested differences between fresh samples and those frozen for 6 months. Again no differences in subjective ratings were observed. These results suggest that freezing has no significant effect on perceived odor hedonicity and that samples can be reliably used after storage for relatively long periods.
Previous studies in animals and humans show that genes in the major histocompatibility complex (MHC) influence individual odours and that females often prefer odour of MHC-dissimilar males, perhaps to increase offspring heterozygosity or reduce inbreeding. Women using oral hormonal contraceptives have been reported to have the opposite preference, raising the possibility that oral contraceptives alter female preference towards MHC similarity, with possible fertility costs. Here we test directly whether contraceptive pill use alters odour preferences using a longitudinal design in which women were tested before and after initiating pill use; a control group of non-users were tested with a comparable interval between test sessions. In contrast to some previous studies, there was no significant difference in ratings between odours of MHC-dissimilar and MHC-similar men among women during the follicular cycle phase. However, single women preferred odours of MHC-similar men, while women in relationships preferred odours of MHC-dissimilar men, a result consistent with studies in other species, suggesting that paired females may seek to improve offspring quality through extra-pair partnerships. Across tests, we found a significant preference shift towards MHC similarity associated with pill use, which was not evident in the control group. If odour plays a role in human mate choice, our results suggest that contraceptive pill use could disrupt disassortative mate preferences.
Evidence is presented showing that body fat distribution as measured by waist-to-hip ratio (WHR) is correlated with youthfulness, reproductive endocrinologic status, and long-term health risk in women. Three studies show that men judge women with low WHR as attractive. Study 1 documents that minor changes in WHRs of Miss America winners and Playboy playmates have occurred over the past 30-60 years. Study 2 shows that college-age men find female figures with low WHR more attractive, healthier, and of greater reproductive value than figures with a higher WHR. In Study 3, 25- to 85-year-old men were found to prefer female figures with lower WHR and assign them higher ratings of attractiveness and reproductive potential. It is suggested that WHR represents an important bodily feature associated with physical attractiveness as well as with health and reproductive potential. A hypothesis is proposed to explain how WHR influences female attractiveness and its role in mate selection.
We are entering one of the most exciting periods in the study of chemical communication since the first pheromones were identified some 40 years ago. This rapid progress is reflected in this book, the first to cover the whole animal kingdom at this level for 25 years. The importance of chemical communication is illustrated with examples from a diverse range of animals including humans, marine copepods, Drosophila, Caenorhabditis elegans, moths, snakes, goldfish, elephants and mice. It is designed to be advanced, but at the same time accessible to readers whatever their scientific background. For students of ecology, evolution and behaviour, this book gives an introduction to the rapid progress in our understanding of olfaction at the molecular and neurological level. In addition, it offers chemists, molecular and neurobiologists an insight into the ecological, evolutionary and behavioural context of olfactory communication.
Putative associations between sex hormones and attractive physical characteristics in women are central to many theories of human physical attractiveness and mate choice. Although such theories have become very influential, evidence that physically attractive and unattractive women have different hormonal profiles is equivocal. Consequently, we investigated hypothesized relationships between salivary estradiol and progesterone and two aspects of women’s physical attractiveness that are commonly assumed to be correlated with levels of these hormones: facial attractiveness (N=249) and waist-to-hip ratio (N=247). Our analyses revealed no compelling evidence that women with more attractive faces or lower (i.e., more attractive) waist-to-hip ratios had higher levels of estradiol or progesterone. One analysis did suggest that women with more attractive waist-to-hip ratios had significantly higher progesterone, but the relationship was weak and the relationship not significant in other analyses. These results do not support the influential hypothesis that between-women differences in physical attractiveness are related to estradiol and/or progesterone.
Putative associations between sex hormones and attractive physical characteristics in women are central to many theories of human physical attractiveness and mate choice. Although such theories have become very influential, evidence that physically attractive and unattractive women have different hormonal profiles is equivocal. Consequently, we investigated hypothesized relationships between salivary estradiol and progesterone and two aspects of women's physical attractiveness that are commonly assumed to be correlated with levels of these hormones: facial attractiveness (N = 249) and waist-to-hip ratio (N = 247). Our analyses revealed no compelling evidence that women with more attractive faces or lower (i.e., more attractive) waist-to-hip ratios had higher levels of estradiol or progesterone. One analysis did suggest that women with more attractive waist-to-hip ratios had significantly higher progesterone, but the relationship was weak and the relationship not significant in other analyses. These results do not support the influential hypothesis that between-women differences in physical attractiveness are related to estradiol and/or progesterone.
Evidence is presented showing that body fat distribution as measured by waist-to-hip ratio (WHR) is correlated with youthfulness, reproductive endocrinologic status, and long-term health risk in women. Three studies show that men judge women with low WHR as attractive. Study 1 documents that minor changes in WHRs of Miss America winners and Playboy playmates have occurred over the past 30-60 years. Study 2 shows that college-age men find female figures with low WHR more attractive, healthier, and of greater reproductive value than figures with a higher WHR. In Study 3, 25- to 85-year-old men were found to prefer female figures with lower WHR and assign them higher ratings of attractiveness and reproductive potential. It is suggested that WHR represents an important bodily feature associated with physical attractiveness as well as with health and reproductive potential. A hypothesis is proposed to explain how WHR influences female attractiveness and its role in mate selection.
Female reproductive hormones exert important non-reproductive influences on autonomic regulation of body temperature and blood pressure. Estradiol and progesterone influence thermoregulation both centrally and peripherally, where estradiol tends to promote heat dissipation, and progesterone tends to promote heat conservation and higher body temperatures. Changes in thermoregulation over the course of the menstrual cycle and with hot flashes at menopause are mediated by hormonal influences on neural control of skin blood flow and sweating. The influence of estradiol is to promote vasodilation, which, in the skin, results in greater heat dissipation. In the context of blood pressure regulation, both central and peripheral hormonal influences are important as well. Peripherally, the vasodilator influence of estradiol contributes to the lower blood pressures and smaller risk of hypertension seen in young women compared to young men. This is in part due to a mechanism by which estradiol augments beta-adrenergic receptor mediated vasodilation, offsetting alpha-adrenergic vasoconstriction, and resulting in a weak relationship between muscle sympathetic nerve activity and total peripheral resistance, and between muscle sympathetic nerve activity and blood pressure. After menopause, with the loss of reproductive hormones, sympathetic nerve activity, peripheral resistance and blood pressure become more strongly related, and sympathetic nerve activity (which increases with age) becomes a more important contributor to the prevailing level of blood pressure. Continuing to increase our understanding of sex hormone influences on body temperature and blood pressure regulation will provide important insight for optimization of individualized health care for future generations of women.
A large research literature indicates that men perceive women as more attractive when they are at high fertility than at low fertility within the ovulatory cycle. However, it remains unclear whether women also perceive women as more attractive at high fertility. This study examined women's ratings of samples of natural body odor collected from naturally-cycling women at high and low fertility within the cycle and from hormonal contraceptive-using women at mid-cycle. Like men, women rated naturally-cycling women's high-fertility scent samples as more attractive than their low-fertility samples. Women rated hormonal contraceptive users' scent samples as more attractive than naturally-cycling women's high- and low-fertility samples, though the difference between HC and high-fertility samples was statistically significant only when raters were treated as the unit of analysis. These findings reveal a potentially important role for scent communication in women's perceptions of other women and are consistent with the notion that the ovulatory cycle could influence human social behavior. The findings also highlight the need for rigorous investigations of the possible impacts of hormonal contraception on women's attractiveness and social relationships with other women.
The major histocompatibility complex (MHC, called HLA in humans) is an important genetic component of the immune system. Fish, birds and mammals prefer mates with different genetic MHC code compared to their own, which they determine using olfactory cues. This preference increases the chances of high MHC variety in the offspring, leading to enhanced resilience against a variety of pathogens. Humans are also able to discriminate HLA related olfactory stimuli, however, it is debated whether this mechanism is of behavioural relevance. We show on a large sample (N = 508), with high-resolution typing of HLA class I/II, that HLA dissimilarity correlates with partnership, sexuality and enhances the desire to procreate. We conclude that HLA mediates mate behaviour in humans.
Autonomic mechanisms are fundamental to human physiological thermoregulation, and female reproductive hormones have substantial influences on several aspects of these mechanisms. Of these, the best recognized are the thermoregulatory responses that occur at menopause (hot flushes) and the changes in body temperature within the menstrual cycle which may help couples predict ovulation. Our goal in this brief review is to summarize current knowledge regarding the influences of reproductive hormones on autonomic mechanisms in human thermoregulation. In general, estrogens tend to promote lower body temperatures via augmentation of heat dissipation responses, whereas progesterone tends to promote higher body temperatures. Recent evidence suggests specific influences of estrogens on central autonomic nuclei involved in control of skin blood flow and sweating. Estrogens also augment vasodilation by direct effects on peripheral blood vessels. Influences of progesterone are less well understood, but include both centrally regulated changes in thermoregulatory set-point as well as and peripheral effects, including augmented vasoconstriction in the skin. We conclude with a brief discussion of thermoregulatory adjustments associated with changing hormone levels during menopause, pregnancy and polycystic ovary syndrome.
This article is part of a Special Issue "Chemosignals and Reproduction" Across phyla, chemosensory communication is crucial for mediating a variety of social behaviors, which form the basis for ontogenetic and phylogenetic survival. In the present paper, evidence on chemosensory communication in humans, with special reference to reproduction and survival, will be presented. First, the impact of chemosignals on human reproduction will be reviewed. Work will be presented, showing how chemosensory signals are involved in mate choice and partnership formation by communicating attractiveness and facilitating a partner selection, which is of evolutionary advantage, and furthermore providing information about the level of sexual hormones. In addition to direct effects on phylogenetic survival, chemosignals indirectly aid reproductive success by fostering harm protection. Results will be presented, showing that chemosensory communication aids the emotional bond between mother and child, which in turn motivates parental caretaking and protection, leading to infant survival. Moreover, the likelihood of group survival can be increased through the use of stress-related chemosignals. Stress-related chemosignals induce a stress-related physiology in the perceiver, thereby priming a fight-flight-response, which is necessary for an optimum adaption to environmental harm. Finally, effects of sexual orientation on chemosensory communication will be discussed in terms of their putative role in stabilizing social groups, which might indirectly provide harm protection and foster survival. An integrative model of the presented data will be introduced. In conclusion, an outlook, focusing on the involvement of chemosensory communication in human social behavior and illustrating a novel approach to the significance of chemosensory signals in human survival, will be given.
Copyright © 2014 Elsevier Inc. All rights reserved.
Evidence has accumulated in recent years supporting the hypothesis that both facial and bodily physical attractiveness in humans are certifications of developmental and hormonal health. Such evidence indicates that physical attractiveness is an honest or Zahavian signal of phenotypic and genetic quality. The hypothesis that physical beauty connotes health was first proposed by Westermarck and was discussed later by Ellis and Symons. It has been suggested that facial attractiveness in women is a deceptive signal of youth, unrelated to phenotypic and genetic quality. This sensory-bias or super-stimulus hypothesis is not supported by this study of men’s ratings of the attractiveness of photographs of 92 nude women. Independent ratings of photographs of faces, fronts with faces covered, and backs of the same women are significantly, positively correlated. The correlation between the ratings of different photos implies that women’s faces and external bodies comprise a single ornament of honest mate value, apparently constructed during puberty by estrogen and also probably by developmental adaptations for symmetry. Thus, women’s physical attractiveness in face and body honestly signal hormonal and perhaps developmental health.
Evidence has accumulated in recent years supporting the hypothesis that both facial and bodily physical attractiveness in humans are certifications of developmental and hormonal health. Such evidence indicates that physical attractiveness is an honest or Zahavian signal of phenotypic and genetic quality. The hypothesis that physical beauty connotes health was first proposed by Westermarck and was discussed later by Ellis and Symons. It has been suggested that facial attractiveness in women is a deceptive signal of youth, unrelated to phenotypic and genetic quality. This sensory-bias or super-stimulus hypothesis is not supported by this study of men’s ratings of the attractiveness of photographs of 92 nude women. Independent ratings of photographs of faces, fronts with faces covered, and backs of the same women are significantly, positively correlated. The correlation between the ratings of different photos implies that women’s faces and external bodies comprise a single ornament of honest mate value, apparently constructed during puberty by estrogen and also probably by developmental adaptations for symmetry. Thus, women’s physical attractiveness in face and body honestly signal hormonal and perhaps developmental health.
The present review examines recent studies related to the ability of Homo sapiens to communicate basic conspecific biologic information via body odors. In addition to evaluating reports that humans can detect
individuality, gender, and reproductive state from olfactory cues, studies claiming that odors are involved in producing menstrual
synchrony and other phenomena are also critically examined. Although both anatomic and behavioral studies support the notion
that humans have the ability to communicate biologic information via odors, additional studies are needed to establish the
role of odors in influencing basic human behaviors. Appropriate controls using several types of odors and double-blind procedures
are sorely needed before a number of findings in this field can be adequately interpreted.
In many species, females are more sexually attractive to males near ovulation. Some evidence suggests a similar pattern in humans, but methodological limitations prohibit firm conclusions at present, and information on physiological mechanisms underlying any such pattern is lacking. In 202 normally-cycling women, we explored whether women's attractiveness changed over the cycle as a function of two likely candidates for mediating these changes: estradiol and progesterone. We scheduled women to attend one session during the late follicular phase and another during the mid-luteal phase. At each session, facial photographs, voice recordings and saliva samples were collected. All photographs and voice recordings were subsequently rated by men for attractiveness and by women for flirtatiousness and attractiveness to men. Saliva samples were assayed for estradiol and progesterone. We found that progesterone and its interaction with estradiol negatively predicted vocal attractiveness and overall (facial plus vocal) attractiveness to men. Progesterone also negatively predicted women's facial attractiveness to men and female-rated facial attractiveness, facial flirtatiousness and vocal attractiveness, but not female-rated vocal flirtatiousness. These results strongly suggest a pattern of increased attractiveness during peak fertility in the menstrual cycle and implicate estradiol and progesterone in driving these changes.
The axillary microflora of 229 subjects was characterized quantitatively and the results correlated with whether the odor was pungent body odor or instead a faint “acid odor.” The axillary flora was found to be a stable mixture of Micrococcaceac, aerobic diphtheroids and Propionibacteria. Significantly higher numbers of bacteria were recovered from the axillae of those with pungent axillary odor than in those with acid odor. Aerobic diphtheroids in high numbers were recovered in all subjects having typical body odor. These included lipophilic as well as large-colony diphtheroids.
When droplets of apocrine sweat placed on the forearm were inoculated with various bacteria which reside in the axilla, only diphtheroids generated typical body odor. Cocci produced a sweaty odor attributable to isovalerie acid.
It is generally accepted that short-chain (C2-C5) volatile fatty acids (VFAs) are among the causal molecules of axillary malodour. It is also widely acknowledged that malodour generation is attributable to the biotransformation of odourless natural secretions, into volatile odorous products, by axillary bacteria. However, little information is available on the biochemical origins of VFAs on axillary skin. In these studies, assay systems were developed to investigate the generation of VFAs from substrates readily available to the bacteria resident on axillary skin. Propionibacteria and staphylococci were shown to ferment glycerol and lactic acid to the short-chain (C2-C3) VFAs, acetic and propionic acid. Furthermore, staphylococci are capable of converting branched aliphatic amino acids, such as leucine, to highly odorous short-chain (C4-C5) methyl-branched VFAs, such as isovaleric acid, which are traditionally associated with the acidic note of axillary malodour. However, in vitro kinetic data indicates that these pathways contribute less to axillary VFA levels, than fatty acid biotransformations by a recently defined sub-group of the Corynebacterium genus, coryne-bacteria (A). The results of these studies provide new understanding on the biochemical origins of VFA-based axillary malodour which, in turn, should lead to the development of novel deodorant systems.
The axillary microflora of 163 male and 122 female subjects was examined. Subjects were found to have either a coryneform or coccal dominated flora. Three hundred and sixty coryneform isolates were identified to generic level by cell-wall type. Axillary coryneforms were found to comprise 83%Corynebacterium, 5%Brevibacterium and 12% other coryneforms. There was a significant correlation between coryneform-dominated floras and the occurrence of erythrasma, trichomycosis axillaris and pronounced axillary odour.
We have developed a method of estimating day of ovulation using urinary ovarian hormone data. The method identifies a day of luteal transition that occurs at the shift from production of follicular oestrogen to luteal progesterone. The algorithm for identifying this shift was evaluated and judged better than specified alternatives in that it resulted in (1) a high concordance between the day of luteal transition and peaks in urinary luteinizing hormone (LH) for cycles with well-defined peaks, (2) a low variance in the length of the luteal phase of the menstrual cycle, which presumably reflects a low measurement error in estimating day of ovulation, and (3) a high proportion of cycles for which an approximate day of ovulation could be determined. To validate the new algorithm, it was applied to an independent data set. The algorithm identified a day of luteal transition in 88 percent of these cycles, and the identified day occurred within two days of the urinary LH peak for all of the cycles with clear LH peaks. Determination of the day of luteal transition to estimate ovulation requires only first-morning urine specimens, requires no correction for day-to-day variations in urine concentration, and can be applied to a mid-ycle window of data.
Females of a number of primate species display their fertile period by behavioural and/or morphological changes. Traditionally, the fertile period in human females has been considered to be concealed. However, this presumption has rarely been tested. One of the possible mechanisms for assessing menstrual cycle phase is through the sense of smell. In this study possible changes in odour across the menstrual cycle were investigated. Samples of body odour were acquired from 12 women (aged 19–27 yr), none of whom were using hormonal contraceptives. Samples were collected using cotton pads worn in the armpit for 24 h, from the menstrual, follicular and luteal cycle phases. Our experimental sample of 42 males (age 19–34 yr) repeatedly rated these odour samples for their intensity, pleasantness, attractiveness and femininity. Raw subjective smell ratings from each man were transformed to z-scores. Subsequently, these z-scores were tested by the general linear mixed-model analysis (PROC MIXED, SAS) with the female's ID nested within the subject's ID as a random factor to account for the repeated measures of the subjects. Significant changes across the cycle were found for ratings of pleasantness [F(2,689) = 702; p = 0.001], attractiveness [F(2,546) = 6.35; p = 0.002] and intensity [F(2,530) = 3.57; p = 0.028]. Odour from women in the follicular (i.e. fertile) phase was rated as the least intense and the most attractive. Subsequent post hoc analysis revealed significant differences in intensity, pleasantness and attractiveness between the menstrual phase and the follicular phase, and in pleasantness and attractiveness between the menstrual and luteal phases. Significant difference between the follicular and the luteal phase was found only for attractiveness. Our results suggest that men can potentially use smell as a mechanism for monitoring menstrual cycle phase in current or prospective sexual partners. Therefore, the fertile period in humans should be considered non-advertized, rather than concealed.
Efforts to collect evidence of human pheromones have focused on three partly overlapping classes of possible human pheromones: (1) axillary steroids, (2) vaginal aliphatic acids, and (3) stimulators of the vomeronasal organ. Examples of each of these classes have been patented for commercial use, and in some cases aggressively marketed, but there is only incomplete evidence supporting any particular claim that a substance acts as a human pheromone. The large axillary scent glands found in humans appear to be well adapted for the production of pheromones, but may actually be used for non-pheromonal odor communication, such as the sharing of information about the immune system. Putative menstrual synchronization within social groups of women and putative acceleration of the menstrual cycle caused by men's odors may suggest the existence of human pheromone systems, but evidence in both cases is still inconclusive.
Humans in societies around the world discriminate between potential mates on the basis of attractiveness in ways that can dramatically affect their lives. From an evolutionary perspective, a reasonable working hypothesis is that the psychological mechanisms underlying attractiveness judgments are adaptations that have evolved in the service of choosing a mate so as to increase gene propagation throughout evolutionary history. The main hypothesis that has directed evolutionary psychology research into facial attractiveness is that these judgments reflect information about what can be broadly defined as an individual’s health. This has been investigated by examining whether attractiveness judgments show special design for detecting cues that allow us to make assessments of overall phenotypic condition. This review examines the three major lines of research that have been pursued in order to answer the question of whether attractiveness reflects non-obvious indicators of phenotypic condition. These are studies that have examined facial symmetry, averageness, and secondary sex characteristics as hormone markers.
Extremely high variability in genes of the major histocompatibility complex (MHC) in vertebrates is assumed to be a consequence of frequency-dependent parasite-driven selection and mate preferences based on promotion of offspring heterozygosity at MHC, or potentially, genome-wide inbreeding avoidance. Where effects have been found, mate choice studies on rodents and other species usually find preference for MHC-dissimilarity in potential partners. Here we critically review studies on MHC-associated mate choice in humans. These are based on three broadly different aspects: (1) odor preferences, (2) facial preferences and (3) actual mate choice surveys. As in animal studies, most odor-based studies demonstrate disassortative preferences, although there is variation in the strength and nature of the effects. In contrast, facial attractiveness research indicates a preference for MHC-similar individuals. Results concerning MHC in actual couples show a bias towards similarity in one study, dissimilarity in two studies and random distribution in several other studies. These vary greatly in sample size and heterogeneity of the sample population, both of which may significantly bias the results. This pattern of mixed results across studies may reflect context-dependent and/or life history sensitive preference expression, in addition to higher level effects arising out of population differences in genetic heterogeneity or cultural and ethnic restrictions on random mating patterns. Factors of special relevance in terms of individual preferences are reproductive status and long- vs. short-term mating context. We discuss the idea that olfactory and visual channels may work in a complementary way (i.e. odor preference for MHC-dissimilarity and visual preference for MHC-similarity) to achieve an optimal level of genetic variability, methodological issues and interesting avenues for further research.
In an in vitro test situation, human observers estimated the relative intensity and pleasantness of human axillary odors using the method of magnitude estimation. In addition, the likely gender of the donor of each odor was also estimated. Under these test conditions, only a small proportion of the observers predicted the sex of the odor donor above chance levels. The results support the following conclusions: (1) male and female responses to axillary odors are generally similar in both magnitude and direction (regardless of the sex from which the odors are sampled); (2) the assignment of a gender referent is closely related to the perceived intensity and pleasantness of axillary odors, with the stronger and less pleasant odors being more frequently assigned to a male gender category; and (3) the intensity and pleasantness of axillary odors, on the average, are inversely related.
Like poets and artists, psychoanalysts have appreciated the virtually limitless range that the body offers to sexualization; they have made it a crucial part of daily clinical experience, and via the libido theory have built it into psychoanalytic theory. With the possible exception of the eyeball every portion of the external human anatomy seems capable of eroticization, though obviously, for most people, some parts are more susceptible than others. Under these circumstances, it is strange that the sexual significance of the axillae has been almost ignored by psychoanalytic researchers. Grinsteins Index of Psychoanalytic Writings has only a few references, most of which consider the matter indirectly. Like the female genitals, the axillae are apertures covered by relatively coarse hair, produce secretions and an odor and are quite capable of dissociation in their sexual aspects. This paper reviews the existing material on the relationships between the axillae and sexuality, presents examples of the relationship from clinical practice, everyday life, art, anthropology, mythology, and literature, and considers the relevant human and primate physiological knowledge.
Axillary 5 alpha-androst-16-en-3-one (5 alpha-androstenone) levels were found to be significantly higher in men than in women but do not vary between left and right axillae, are not related to age, handedness or degree of hirsutism (in women) nor to anosmia to this steroid. In men (but not in women), levels are related linearly to axillary cholesterol concentrations but not to squalene. Olfactory thresholds for 5 alpha-androstenone varied widely, the lowest recorded being 0.2 ppb, but there was no difference in thresholds between men and women. Women (70%) found the smell 'repellant' but anosmia did not differ greatly between men and women (9-20%). Anosmia to the smell of 5 alpha-androst-16-en-3 alpha-ol was most marked in women (90%) rather than in men (45%). Axillary 5 alpha-androstenone values were generally consistent with the 'musky' or 'strong' smells of male axillary extracts, compared with the 'sweet' smell of those from female subjects.
The axillary microflora of 163 male and 122 female subjects was examined. Subjects were found to have either a coryneform or coccal dominated flora. Three hundred and sixty coryneform isolates were identified to generic level by cell-wall type. Axillary coryneforms were found to comprise 83% Corynebacterium, 5% Brevibacterium and 12% other coryneforms. There was a significant correlation between coryneform-dominated floras and the occurrence of erythrasma, trichomycosis axillaris and pronounced axillary odour.
The peripheral plasma levels of immunoreactive LH, FSH, oestradiol and progesterone were analyzed daily throughout the cycle in 68 normally menstruating women, exhibiting a cycle length of 25 to 36 days during the period of blood sampling. The (geometric) mean length of the follicular phase was 15 days, with an individual variation between 9 and 23 days. The mean length of the luteal phase was 13 days, with an individual variation between 8 and 17 days. The mean ratio of the length of the follicular to luteal phase (F/L ratio) was 1.13, and 62 of 68 subjects (91%) exhibited an F/L ratio between 0.75 and 1.80. In one-third of the cycles studied. the pre-ovulatory oestradiol and LH peaks occurred before the 12th, or after the 18th day of the cycle, and the length of the luteal phase was shorter than 12, or longer than 15 days.
The length of the follicular phase was positively correlated to the mean LH level of days LH-7 to LH-3 before the midcycle surge ( P < 0.001) and negatively correlated to the mean oestradiol level of the first 6 days of the cycle ( P < 0.001) and to the height of the preovulatory oestradiol peak ( P <0.01). There was also a positive correlation between the length of the entire cycle and the mean LH level throughout the cycle ( P < 0.01) or during days LH-7 to LH-3 ( P < 0.001), or the height of the midcycle LH surge ( P <0.01), and a negative correlation between cycle length and the mean oestradiol level of the first 6 cycle days ( P < 0.001), or of the entire follicular phase ( P < 0.001), or of the complete cycle ( P < 0.01). Hence a combination of high initial oestradiol levels with low LH levels is associated with relatively short cycles and the opposite combination with relatively long ones.
In agreement with previous findings in 32 normally menstruating women, 94%, or 64 of the 68 subjects of the present study had plasma progesterone levels higher than 16 nmol/1 for a minimum of 5 days. Hence, progesterone levels lower than this value or exceeding this value for a shorter period than 5 days are considered to reflect an insufficient or partially suppressed luteal function.
In addition, 62 of the 68 subjects studied (91%) fulfilled a series of criteria concerning the minimal and maximal levels of LH, FSH, oestradiol and also progesterone during different cycle phases. It is suggested that these criteria together with the progesterone levels indicated above are characteristic of a normal ovulatory cycle, at least in the local population. The acquisition of similar 'critical levels' in other populations may provide a useful approach towards the establishment of generally accepted criteria for distinguishing a normal from an abnormal cycle.
Oestradiol and progesterone profiles from naturally occurring conception and exposed non-conception cycles were compared to assess the impact of natural variation in concentrations of ovarian steroid hormones on female fecundity. In a prospective, longitudinal study, 24 women collected saliva samples twice daily and recorded intercourse for up to 1 year or until a pregnancy was clinically confirmed. Oestradiol and progesterone concentrations were measured by a salivary radioimmunoassay. Average mid-follicular oestradiol concentrations were significantly higher in conception than in non-conception cycles (12.6 +/- 1.7 versus 8.5 +/- 0.6 pmol/l, P < 0.01). A separate analysis, including only cycles from those women who contributed both conception and non-conception cycles, demonstrated an even more pronounced difference in mid-follicular oestradiol concentrations, not just for conception and non-conception cycles as groups (14.5 +/- 2.3 versus 6.5 +/- 0.7 pmol/l, P < 0.001), but also between the conception and average non-conception concentrations of individual women. Among these women, relative mid-follicular oestradiol concentration was highly correlated with the probability of successful conception. In addition, relative body weight was significantly positively correlated with mid-follicular oestradiol concentration. These findings indicate that variation in follicular development, reflected in variation in follicular oestradiol concentrations, is an important indicator of fecundity.
The purpose of this study was to test the hypothesis that regulated body temperature is decreased in the preovulatory phase in eumenorrheic women. Six women were studied in both the preovulatory phase (Preov-2; days 9-12), which was 1-2 days before predicted ovulation when 17beta-estradiol (E2) was estimated to peak, and in the follicular phase (F; days 2-6). The subjects walked on a treadmill ( approximately 225 W x m-2) in a warm chamber (ambient temperature = 30 degreesC; dew-point temperature = 11.5 degreesC) while heavily clothed. E2, esophageal temperature (Tes), local skin temperatures, and local sweating rate were measured. The estimate of when the E2 surge would occur was correct for four of six subjects. In these four subjects, E2 increased (P </= 0.05) from 42.0 +/- 24.5 pg/ml during F to 123.2 +/- 31.3 pg/ml during Preov-2. Resting Tes was 37.02 +/- 0.20 degreesC during F and 36.76 +/- 0.28 degreesC during Preov-2 (P </= 0.05). The Tes threshold for sweating was decreased (P </= 0.05) from 36.88 +/- 0.27 degreesC during F to 36. 64 +/- 0.35 degreesC during Preov-2. Both mean skin and mean body temperatures were decreased during rest in Preov-2 group. The hypothesis that regulated body temperature is decreased during the preovulatory phase is supported.