Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Although anthropologists frequently report the centrality of odours in the daily lives and cultural beliefs of many small-scale communities, Western scholars have historically considered the sense of smell as minimally involved in human communication. Here, we suggest that the origin and persistence of this latter view might be a consequence of the fact that most research is conducted on participants from Western societies who, collectively, were rather old (adults), deodorized and desensitized (ODD) to various aspects of olfactory perception. The view is rapidly changing, however, and this themed issue provides a timely overview of the current state-of-the-art on human chemocommunication. Based on evolutionary models of communication, the papers cover both general mechanisms of odour production by ‘senders’ and odour perception by ‘receivers’. Focus on specific functional contexts includes reciprocal impact of odours between infants and mothers, the role of odour in mate choice and how odours communicate emotion and disease. Finally, a position paper outlines pitfalls and opportunities for the future, against the context of the replication crisis in psychology. We believe a more nuanced view of human chemical communication is within our grasp if we can continue to develop inter-disciplinary insights and expand research activities beyond ODD people. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Over the past decades, in the scientific literature on the physiology and genetics of smell, objections have been repeatedly expressed to the classical concepts of attributing humans to the group of microsmatics, i.e. mammals with a poorly developed olfactory analyzer and an insignificant role of odors in everyday life (Schaal, 1988;Shepherd, 2004;McGann, 2017;Roberts et al., 2020). Numerous comparative behavioral studies performed on various mammalian species and in humans have shown that sensitivity to odors is not directly related to the size of the receptor pool and BIOLOGY BULLETIN REVIEWS Vol. ...
... The reception of intraspecific chemical signals in humans may well be mediated by receptors located in the main olfactory epithelium. According to Roberts et al. (2020), the downplaying of the role of smell in human communi-cation and, as a consequence, the inhibition of research in this area, was also facilitated by the fact that most of the research was carried out by Western scientists and on adult representatives of Western societies, "deodorized and desensitized," and the response to odors can be culturally determined, classifying them as unimportant or repulsive regardless of biological significance. The study of the releaser pheromones in humans is extremely difficult for ethical reasons, and strict control over the experiment is not always possible. ...
... Currently, the only scientifically substantiated work on the search for pheromone releasers in humans is a study by Benoit Schaal's group from France (Doucet et al., 2009;Schaal and Al Aïn, 2014), which shows a stereotypical species-specific behavioral response of infants to secretions of Montgomery glands of a nursing woman; infant response was independent of postnatal olfactory experience and whether the nursing mother was his own. Well-reproducible and controlled test reaction opens up opportunities for searching for candidates for the role of pheromones (Schaal and Al Aïn, 2014;Roberts et al., 2020). Studies of the same group described the pheromone of rabbit milk 2-methylbut-2-enal (Schaal et al., 2003). ...
... In our everyday lives, smells have a "communicative" function, informing us about the quality of food and warning us for environmental hazards (e.g., gas leaks) (Stevenson, 2010). An even less well-known function of smell is social communication (de Groot et al., 2017;Parma et al., 2017;Pause, 2017;Roberts et al., 2020); the topic of this article. Studies have shown that our smells provide others with cues about our identity and gender (Penn et al., 2007), age (Mitro et al., 2012), health (Olsson et al., 2014), and emotions (de Groot et al., 2015;Pause et al., 2020). ...
... Social smells are markedly complex: body odor contains thousands of molecules (de Lacy Costello et al., 2014), and massive variability is caused by factors including genotype, hormonal status, mood, skin bacteria, diet, smoking, hygiene habits, clothing, and use of fragranced products (e.g., Natsch and Emter, 2020;Roberts et al., 2020). Past studies have generally sidestepped this challenge by performing small-scale psychological experiments under carefully controlled, sterile conditions (for a meta-analysis: de Groot and Smeets, 2017; for a critical view: Wyatt, 2020). ...
... The current science of non-verbal communication via smell is rooted in a longstanding tradition of strictly controlled laboratory experiments focusing on the empirical testing of hypotheses addressing cause-effect relations, using reliable and validated methods and carefully calibrated instruments (for empirical demonstrations, see e.g., Chen and Haviland-Jones, 2000;Regenbogen et al., 2017;Endevelt-Shapira et al., 2018;Quintana et al., 2019;de Groot et al., 2020b;Gomes et al., 2020;Pause et al., 2020 (for recent narrative overviews, see e.g., Loos et al., 2019;Ferdenzi et al., 2020;Havlíček et al., 2020(for meta-analyses, see e.g., Gildersleeve et al., 2014de Groot and Smeets, 2017). This approach, with a preference for intrinsic over extrinsic validity, has been the method of choice to build our (psychological) science for decades. ...
... За последние десятилетия в научной литературе, посвященной физиологии и генетике обоняния, неоднократно высказывались возражения классическим представлениям об отнесении человека к группе микросматиков, т.е. млекопитающих со слабо развитым обонятельным анализатором и ничтожной ролью запахов в повседневной жизни (Schaal, 1988;Shepherd, 2004;McGann, 2017;Roberts et al., 2020). Многочисленные сравнительные поведенческие исследования, выполненные на различных видах млекопитающих и человеке, показали, что чувствительность к запахам напрямую не связана с объемами рецепторного пула и нейроанатомического субстрата (например, Laska et al., 2005;Niimura, Nei, 2005). ...
... Рецепция внутривидовых химических сигналов у человека вполне может быть опосредована рецепторами, расположенными в основной обонятельной выстилке. По мнению Робертс с соавторами (Roberts et al., 2020), преуменьшению роли обоняния в коммуникации человека и, как следствие, торможению исследований в этой области также способствовал тот факт, что большинство исследований выполнялось западными учеными и на взрослых представителях западных обществ, "деодорированных" и "десенситизированных", а реакция на запахи может быть культурно обусловленной, относя их к неважным или отталкивающим независимо от биологической значимости. Исследование релизер-феромонов человека крайне затруднено по причинам этического характера, а также далеко не всегда возможен строгий контроль за проведением эксперимента. ...
... В настоящее время единственной научно обоснованной работой по поиску феромонов-релизеров у человека является исследование группы Бенуа Шааля из Франции (Doucet et al., 2009;Schaal, Al Aïn, 2014), в котором показан стереотипный видоспецифический поведенческий ответ младенцев на секрет желез Монтгомери кормящей матери, который не зависел от постнатального обонятельного опыта и от того, является ли кормящая мать его родной. Наличие хорошо воспроизводимой и контролируемой тест-реакции открывает возможности поиска кандидатов на роль феромонов (Schaal, Al Aïn, 2014;Roberts et al., 2020). Исследованиями той же самой группы в свое время был выделен феромон молока кроликов 2-метилбут-2-еналь (Schaal et al., 2003). ...
Article
Full-text available
Chemical communication is the most ancient way of information exchange between organisms. For majority of mammals, the analysis of olfactory stimuli is crucial for organization of complex behaviors. The review is devoted to the analysis of the role of pheromones in the organization of mammalian behavior in the evolutionary aspect. The discussion about the existence of human pheromones has drawn attention of scientific community in recent decades: a separate section covers this topic. Special attention is paid to the patterns of changes in the neuroanatomical substrate and the pool of functional genes encoding the olfactory and vomeronasal receptors in mammals, including humans. The future perspectives of research in this area are discussed
... Odor awareness is relevant not only for the examples described before but also for odors, especially body odors, conveying socially relevant messages. Indeed, as in other species [3], increasing evidence suggests that the chemicals produced by the human body are essential in interpersonal relationships [4,5]. Essentially, each individual presents a typical body odor that, as for physical appearance, reflects personal stable characteristics or transient events (e.g., personality, sex, age, health, and even transient emotional states; [6,7]). ...
... Despite the growing body of literature documenting the importance of human social odors on everyday social interactions [4] as well as the presence of alteration of social odor perception in neuropsychiatry diseases [67,68] and neurodevelopmental disorders [69,70], the attention humans pay to social odors has been largely neglected in the available measurements of odor awareness. Having a proper scale developed to assess social odor awareness is thus extremely relevant for the understanding of social odor processing and the social related behavior. ...
Preprint
The degree of attention individuals pay to olfactory cues (called odor awareness) influence the role of odors in everyday life. Particularly, odors produced by the human body (i.e., social odors) are able to carry a wide variety of information and to elicit a broad spectrum of emotional reactions, making them essential in interpersonal relationships. Hence, despite the assessment of awareness toward social odors is crucial, a proper tool is still lacking. Here, we designed and validated the Social Odor Scale (SOS), a measure to assess the individual differences in awareness towards different social odors. In Study 1, an exploratory factor analysis (EFA) supports the initially developed four factor structure of the Italian version of the scale. In Study 2, EFA was performed in the German version of the scale confirming the validity of scale structure. Finally, a confirmatory factor analysis (Study 4) corroborates the construct validity of the SOS and its subscales. Hence, the final version of SOS is composed of 16 items, four for each subscale: own, familiar, romantic partner, and stranger social odors. Study 3 and 4 revealed that SOS total score and its subscales were positively correlated with other validated olfactory scales, but not with olfactory abilities. Moreover, SOS was found to reflect the inter-individual variability that characterize social odor processing: SOS was related to age, gender and reproductive state of the participants. Overall, the results indicated that SOS is a valid and reliable instrument to assess awareness toward social odors in everyday life.
... Robot smell was rarely studied in the past few years, even though human olfactory communication is vital during interpersonal communication [127]. The paper [127] endowed the social robot with an olfactory display system that can emit the smell to decorate the robot movement. ...
... Robot smell was rarely studied in the past few years, even though human olfactory communication is vital during interpersonal communication [127]. The paper [127] endowed the social robot with an olfactory display system that can emit the smell to decorate the robot movement. The paper completed the synchronization between the controllable smell presentation and the robot movements in human-robot interaction. ...
Thesis
Having a natural interaction makes a significant difference in a successful human-robot interaction (HRI). The natural HRI refers to both human multimodal behavior understanding and robot verbal or non-verbal behavior generation. Humans can naturally communicate through spoken dialogue and non-verbal behaviors. Hence, a robot should perceive and understand human behaviors so as to be capable of producing a natural multimodal and spontaneous behavior that matches the social context. In this thesis, we explore human behavior understanding and robot behavior generation for natural HRI. This includes multimodal human emotion recognition with visual information extracted from RGB-D and thermal cameras and non-verbal multimodal robot behavior synthesis.Emotion recognition based on multimodal human behaviors during HRI can help robots understand user states and exhibit a natural social interaction. In this thesis, we explored multimodal emotion recognition with thermal facial information and 3D gait data in HRI scene when the emotion cues from thermal face and gait data are difficult to disguise. A multimodal database with thermal face images and 3D gait data was built through the HRI experiments. We tested the various unimodal emotion classifiers (i.e., CNN, HMM, Random Forest model, SVM) and one decision-based hybrid emotion classifier on the database for offline emotion recognition. We also explored an online emotion recognition system with limited capability in the real-time HRI setting. Interaction plays a critical role in skills learning for natural communication. Robots can get feedback during the interaction to improve their social abilities in HRI.To improve our online emotion recognition system, we developed an interactive robot learning (IRL) model with the human in the loop. The IRL model can apply the human verbal feedback to label or relabel the data for retraining the emotion recognition model in a long-term interaction situation. After using the interactive robot learning model, the robot could obtain a better emotion recognition accuracy in real-time HRI.The human non-verbal behaviors such as gestures and face action occur spontaneously with speech, which leads to a natural and expressive interaction. Speech-driven gesture and face action generation are vital to enable a social robot to exhibit social cues and conduct a successful HRI. This thesis proposes a new temporal GAN (Generative Adversarial Network) architecture for a one-to-many mapping from acoustic speech representation to the humanoid robot's corresponding gestures. We also developed an audio-visual database to train the speaking gesture generation model. The database includes the speech audio data extracted directly from the videos and the associated 3D human pose data extracted from 2D RGB images. The generated gestures from the trained co-speech gesture synthesizer can be applied to social robots with arms. The evaluation result shows the effectiveness of our generative model for speech-driven robot gesture generation. Moreover, we developed an effective speech-driven facial action synthesizer based on GAN, i.e., given an acoustic speech, a synchronous and realistic 3D facial action sequence is generated. A mapping between the 3D human facial actions to real robot facial actions that regulate the Zeno robot facial expression is completed. The application of co-speech non-verbal robot behaviors (gesture and face action) synthesis for the social robot can make a friendly and natural human-robot interaction.
... Odor awareness is relevant not only for the examples described before but also for odors, especially body odors, conveying socially relevant messages. Indeed, as in other species [3], increasing evidence suggests that the chemicals produced by the human body are essential in interpersonal relationships [4,5]. Essentially, each individual presents a typical body odor that, as for physical appearance, reflects personal stable characteristics or transient events (e.g., personality, sex, age, health, and even transient emotional states; [6,7]). ...
... Despite the growing body of literature documenting the importance of human social odors on everyday social interactions [4] as well as the presence of alteration of social odor perception in neuropsychiatry diseases [67,68] and neurodevelopmental disorders [69,70], the attention humans pay to social odors has been largely neglected in the available measurements of odor awareness. Having a proper scale developed to assess social odor awareness is thus extremely relevant for the understanding of social odor processing and the social related behavior. ...
Article
Full-text available
The degree of attention individuals pay to olfactory cues (called odor awareness) influences the role of odors in everyday life. Particularly, odors produced by the human body (i.e., social odors) are able to carry a wide variety of information and to elicit a broad spectrum of emotional reactions, making them essential in interpersonal relationships. Hence, despite the assessment of awareness toward social odors is crucial, a proper tool is still lacking. Here, we designed and initially validated the Social Odor Scale (SOS), a 12-item scale designed to measure the individual differences in awareness towards different social odors. In Study 1, an exploratory factor analysis (EFA; KMO test: MSA = 0.78; Bartlett’s test: χ ² (78) = 631.34, p < 0.001; Chi-squared test: χ ² (42) = 71.84, p = 0.003) suggests that the three factors structure was the model that best fit with the Italian version of the scale. The confirmatory factor analysis (CFA) supports a second-order model with one higher-order factor representing social odor awareness in general and three lower-order factors representing familiar, romantic partner, and stranger social odors. The final version of the scale presented a good fit (RMSEA = 0.012, SRMR = 0.069, CFI = 0.998, TLI = 0.997). In Study 2, CFA was performed in the German version of the scale confirming the validity of scale structure. Study 3 and 4 revealed that SOS total score and its subscales were positively correlated with other validated olfactory scales, but not with olfactory abilities. Moreover, SOS was found to be related to the gender of the participants: women reported to be more aware to social odors and, specifically, to familiar social odors than men. Overall, the results indicated that SOS is a valid and reliable instrument to assess awareness toward social odors in everyday life.
... It necessitates less training than the phenomenological approach on the subjects' part. Although some scientists continue to claim the incompatibility of introspection with experimental science, many now acknowledge that this is one of the only ways to obtain valuable data on higherorder cognitive processes 26,27 , and use it to help understand physiological or imaging recordings, as we will see further in Chapter 4. ...
Thesis
Full-text available
Odor perception is an essential function in humans, allowing for hazard prevention, food detection and social communication. However, this sense is often underestimated, especially regarding the ability to identify and describe odors through language. In this PhD, we aimed to better understand the subjective experience of smell, its diversity, and its neural correlates. To this end, we first introduced olfaction with its specificities and the importance of hedonics in odor perception. Then, we investigated interindividual variability in olfaction through a series of studies and showed that olfactory perception comprises both a shared and a diverse component depending on the odorants, with little effect of common factors of variation like age or sex. Also, we showed that the relation between chemical structure, receptors and perception of odors is influenced by the degree of interindividual variability, a finding important for the ongoing stimulus-percept issue in olfactory research. Through this bibliographic and experimental work, we show that there is a lack of reflection on the way we measure perception, and that its subjective nature has been under considered in contemporary research. We thus discuss the place of subjectivity in science and several methodologies that were proposed to better integrate first-person reports in experimental protocols. From these approaches, we set up a new study collecting unbiased subjective reports of odors, to construct a descriptive model of olfactory experience. We found that contrary to common belief, people can talk about odors, using references to diverse categories, including associated memories, qualitative description, source, impact, use and difficulty. With data mining, we were also able to get a fine-grained characterization a few perceptual profiles for the odors. Next, we considered the ongoing debate around the neural basis of consciousness, and the proposed methodologies to relate first-person data with cerebral activity measurements. Another study thus attempted to relate the subjective experience of odors with the evoked brain activity. The results open new ways to construct imaging protocols with a better inclusion of first-person accounts. In conclusion, we argue that subjective data has an important place in experimental research that it must be rigorously collected to fully understand human perception. We also emphasize the importance of integrating different disciplinary approaches to get a global picture of our objects of study.
... This ability is present in micro-organisms as well as in complex species such as mammals. However, during evolution, human beings' increasing reliance of other senses, such as vision, has decreased our sense of smell [2]. Nevertheless, the OS is the designated machinery for recognizing and elaborating conscious olfactory stimuli allowing humans to discriminate more than a trillion odorant stimuli [3,4]. ...
Article
Full-text available
To date, little is known about the role of olfactory receptor (OR) genes on smell performance. Thanks to the availability of whole-genome sequencing data of 802 samples, we identified 41 knockout (KO) OR genes (i.e., carriers of Loss of Function variants) and evaluated their effect on odor discrimination in 218 Italian individuals through recursive partitioning analysis. Furthermore, we checked the expression of these genes in human and mouse tissues using publicly available data and the presence of organ-related diseases in human KO (HKO) individuals for OR expressed in non-olfactory tissues (Fisher test). The recursive partitioning analysis showed that age and the high number (burden) of OR-KO genes impact the worsening of odor discrimination (p-value < 0.05). Human expression data showed that 33/41 OR genes are expressed in the olfactory system (OS) and 27 in other tissues. Sixty putative mouse homologs of the 41 humans ORs have been identified, 58 of which are expressed in the OS and 37 in other tissues. No association between OR-KO individuals and pathologies has been detected. In conclusion, our work highlights the role of the burden of OR-KO genes in worse odor discrimination.
... To answer all these questions will involve a substantial collective research effort, requiring attention from researchers with diverse areas of expertise who, ideally, will collect data from diverse segments of the human population (Roberts, Havlíček, & Schaal, 2020). This kind of research is rarely cheap or easy, which can pose a practical barrier to researchers with limited resources (and, even when resources are available, may be a disincentive within a scientific community that prizes large sample sizes). ...
Article
People readily perceive and react to the body odors of other people, which creates a wide range of implications for affective, cognitive, and behavioral responses. In this article, we provide an overview of recent research in this area. We summarize the process by which people associate body odors with different kinds of interpersonally relevant information, briefly review two lines of research on responses to strangers’ body odors (research on olfactory cues and emotions, research on olfactory cues and impression formation), and review new research on the psychological consequences of smelling loved ones’ odors—including consequences for stress reduction and sleep enhancement. We conclude with a discussion of emerging research questions and methodological considerations that may help guide future inquiry into the various ways that the odors of other people influence one’s emotions, cognitions, relationships, and health.
... Humans exchange various kinds of social information via chemosensory communication, related to the status of the genetic, neuronal, endocrine, and immune systems [1][2][3]. Hereby, social volatiles convey messages about age, gender, health, personality, basic drives, and emotions, fostering reproductive success and harm avoidance in humans. ...
Article
Full-text available
The current study examines neural responses to satiety- and fasting-related volatiles and their effect on the processing of body shapes. Axillary sweat was sampled with cotton pads from 10 individuals after 12 h of fasting, and after having consumed a standard breakfast. Pure cotton pads served as the control. The chemosensory stimuli were presented to 20 participants (via a constant-flow olfactometer) exclusively, and additionally as context to images of overweight and underweight avatars. EEG was recorded (61 electrodes), and chemosensory (CSERPs; P1, N1, P2, P3) and visual event-related potentials (VERPs; N1, P2, P3a, P3b) were analyzed. The amplitudes of all positive CSERP components differed more strongly from cotton in response to chemosensory satiety cues as compared to fasting cues (P1: p = 0.023, P2: p = 0.083, P3: p = 0.031), paralleled by activity within the middle frontal and temporal gyrus. Overweight compared to underweight body shapes tended to elicit larger VERP P2 amplitudes (p = 0.068), and chemosensory satiety cues amplified the VERP amplitudes in response to any body shape (P2, P3a, P3b; all ps < 0.017) as compared to the cotton control. The results indicate that chemosensory satiety cues transmit complex social information, overriding the processing of analogous visual input.
... The sense of smell is also involved in the non-verbal social communication of humans; in fact, through smell, humans can involuntarily convey personal information (de Groot et al., 2017;Parma et al., 2017;Pause, 2017;Roberts et al., 2020). ...
... Thus, the current study has provided further evidence that olfactory-assisted communication can be implicitly facilitated and can occur in applied, real-world environments. Prominent researchers encourage the completion of more ecologically valid human body odour research (Roberts et al. 2020), yet the authors recognise that there are some costs present in trading a controlled odour donation and presentation methodology for the methods used in this study, which are grounded in greater ecological realism. For instance, odour signals were not manipulated or measured and therefore the role of body odour in the identified within-dyad emotional convergence cannot be confirmed and an alternative factor may have affected the mediated relationship. ...
Article
Full-text available
Introduction Research has provided evidence for the transfer of single emotions including anger, anxiety and happiness through olfactory chemosignals, yet no work has examined the role of odour function in the aggregation of more complex emotional states or in the emotional contagion process. The aim of the present study was to ascertain whether an individual’s tendency to experience emotional aggregation was affected by objective measures of their olfactory function and subjective self-assessments of the importance of their own olfactory system. Methods In this study (N = 70), participant pairs were first assessed individually for olfactory threshold and odour identification, then completed the Importance of Olfaction Questionnaire. Each pair subsequently took part in two collaborative tasks. Individual emotion measures were taken before, during and after the completion of the two tasks. Results Multilevel structural equation modelling revealed that individuals’ within-dyad positive emotional agreement scores were associated with both their ‘importance of olfaction’ scores and their olfactory function. A significant association was also found between olfactory performance and the Importance of Olfaction scores. Conclusions These results provide evidence that the subjective importance an individual assigns to their sense of smell can predict their susceptibility to experience emotional aggregation during active, collaborative tasks. Implications The findings suggest that individuals’ tendency and capability to detect and respond to emotional chemosignals, a process required for olfactory-facilitated emotional contagion, may be affected by individual differences in olfactory function and subjective attitudes toward olfaction.
... This led some researchers to consider olfaction as a "muted sense" (Olofsson and Gottfried, 2015). Humans as a species appear, however, surprisingly good at detecting and discriminating odors, although they struggle to identify them, especially in decontextualized laboratory experiments studying participants pertaining to WEIRD (western, educated, industrialized, rich, and democratic) and ODD (old, deodorized, and desensitized) societies (Henrich et al., 2010;Roberts et al., 2020). However, ethnographic and ethnolinguistic studies report elaborated ways to conceptualize and lexicalize everyday odor impressions in traditional societies, including those related to the human body, (e.g., Majid and Burenhult, 2014;Barkat-defradas and Motteflorac, 2016;, showing that the human sense of smell is far from being muted, especially in cultures where it bears everyday survival value (Majid and Kruspe, 2018;Majid, 2021). ...
Article
Full-text available
A recent body of research has emerged regarding the interactions between olfaction and other sensory channels to process social information. The current review examines the influence of body odors on face perception, a core component of human social cognition. First, we review studies reporting how body odors interact with the perception of invariant facial information (i.e., identity, sex, attractiveness, trustworthiness, and dominance). Although we mainly focus on the influence of body odors based on axillary odor, we also review findings about specific steroids present in axillary sweat (i.e., androstenone, androstenol, androstadienone, and estratetraenol). We next survey the literature showing body odor influences on the perception of transient face properties, notably in discussing the role of body odors in facilitating or hindering the perception of emotional facial expression, in relation to competing frameworks of emotions. Finally, we discuss the developmental origins of these olfaction-to-vision influences, as an emerging literature indicates that odor cues strongly influence face perception in infants. Body odors with a high social relevance such as the odor emanating from the mother have a widespread influence on various aspects of face perception in infancy, including categorization of faces among other objects, face scanning behavior, or facial expression perception. We conclude by suggesting that the weight of olfaction might be especially strong in infancy, shaping social perception, especially in slow-maturing senses such as vision, and that this early tutoring function of olfaction spans all developmental stages to disambiguate a complex social environment by conveying key information for social interactions until adulthood.
... Studies show that smelling in humans is not just an individual act, but an interactional one [15]. There have been numerous developments in odor biometrics [16], electronic noses [17], and olfactory marketing [14]. Loss of the sense of The human sense of smell is far more acute than previously thought, yet it is still commonly believed that there is no language of smell. ...
Article
Full-text available
The human sense of smell can accomplish astonishing feats, yet there remains a prevailing belief that olfactory language is deficient. Numerous studies with English speakers support this view: there are few terms for odors, odor talk is infrequent, and naming odors is difficult. However, this is not true across the world. Many languages have sizeable smell lexicons — smell is even grammaticalized. In addition, for some cultures smell talk is more frequent and odor naming easier. This linguistic variation is as yet unexplained but could be the result of ecological, cultural, or genetic factors or a combination thereof. Different ways of talking about smells may shape aspects of olfactory cognition too. Critically, this variation sheds new light on this important sensory modality.
... Consequently, human olfaction must play a role in the maintenance of good health. The roles of human olfaction in nutrition, avoidance of potentially dangerous substances and mating have been studied in detail (Roberts et al., 2020). The role of human olfaction in preserving good health warrants additional research. ...
Chapter
Full-text available
The chapter explores the role of plant volatile compounds in communication between plants and other plants, insects and microbes. It also examines how plant volatiles, in the form of essential oils elicit responses in the human brain.
... Odors are ancient, species-general signals that trigger complex neural changes that function to consolidate social bonds with conspecifics, augment the salience of contextual cues, and signify mother and habitat (6); odors are the only sensory cues that can represent the mother in her absence. While the role of olfaction in humans has received less attention compared with vision and audition, anthropological studies describe the reliance on odors for group living in non-Western societies, the recognition of group odor by its members, ceremonies by which a father's smell is "transferred" to his infant, or the rubbing of body odors (BOs) by axilla sweat, suggesting that children integrate into social groups through the detection of familiar odors introduced to infants by their mother (7)(8)(9). Furthermore, studies have shown that human neonates rely on olfactory cues to recognize their mothers (10,11), and maternal chemosignals reduce pain in newborns (12), increase infant attention to face and eyes (13), shape face categorization (14), and attenuate neural response to fearful faces (15), underscoring the importance of maternal odors for orienting infants to species-critical social cues. Still, the mechanisms by which maternal BOs support maturation of the infant's social brain are largely unknown. ...
Article
Maternal body odors serve as important safety-promoting and social recognition signals, but their role in human brain maturation is largely unknown. Utilizing ecological paradigms and dual- electroencephalography recording, we examined the effects of maternal chemosignals on brain-to-brain synchrony during infant-mother and infant-stranger interactions with and without the presence of maternal body odors. Neural connectivity of right-to-right brain theta synchrony emerged across conditions, sensitizing key nodes of the infant’s social brain during its maturational period. Infant-mother interaction elicited greater brain-to-brain synchrony; however, maternal chemosignals attenuated this difference. Infants exhibited more social attention, positive arousal, and safety/approach behaviors in the maternal chemosignals condition, which augmented infant-stranger neural synchrony. Human mothers use interbrain mechanisms to tune the infant’s social brain, and chemosignals may sustain the transfer of infant sociality from the mother-infant bond to life within social groups.
... Les travaux de E. T. Hall ont popularisé ce courant de recherche, qui implique également des travaux portant sur la distance sociale et l'espace personnel (Bogardus, 1959) (Baldassare & Feller, 1975) (Rapp & Gutzmann, 2000) (Sommer, 2002) (Beaulieu, 2004) (Sorokowska, et al., 2017) ou le comportement dans les espaces publics (Goffman, 1963) (Mazur, 1977) (Evans, Lepore, & Allen, 2000). Les travaux consacrés à la proxémique sont souvent liés aux études de la communication tactile axées autour de leurs différentes fonctions et interprétations parmi les contextes, les genres et les cultures (Frank, Lawrence, 1958) (Burgoon, 1991) (Remland, Jones, & Brinkman, 1995) (Doty, 1981) (Vettraino-Soulard, 1992) (Olsson, et al., 2014) (Maille, 2001) (Roberts, Havlíček, & Schaal, 2020 (Birdwhistell, 1969), jusqu'aux outils numériques avancés (Ekman, Friesen, & Hager, 2002) (Cohn & Ekman, 2005) (Cohn & Kanade, 2007). ...
Thesis
L'analyse scientifique des unités non-verbales occupe une place encore marginale au sein des études d'interprétation. Or, le contexte éminemment interculturel des interactions exolingues interprétées exige de reconnaître le caractère multimodal des énoncés-sources pour en analyser les paramètres d'influence. Interdisciplinaire, le présent travail se propose d'examiner les modalités de prise en compte de la gestualité co-verbale dans la pratique professionnelle des interprètes en service public (ISP). Sur le plan théorique, cette recherche se donne pour objectif de tracer le chemin d'évolution du paradigme d'interprète allant d'un être transparent, jusqu'au médiateur interculturel. Elle s'articule par ailleurs autour de l'analyse du non-verbal au travers du prisme des modèles de la communication et de celui des études des propriétés sémiotiques des unités de sens du système visuel. Ces opérations mènent à élaborer une typologie des gestes observables en ISP, inspirée des classements avancés par des gestualistes tels que D. McNeill, J. Cosnier et F. Poyatos. La méthode adoptée repose sur une triangulation de données, impliquant d'abord une enquête menée auprès de 60 interprètes professionnels, des entretiens individuels ensuite, et enfin un corpus multimodal. L'analyse qui en découle permet de révéler des différences fondamentales entre la production d'une part et les perspectives de la perception des gestes co-verbaux d'autre part. Le corpus audiovisuel réunit ici des interactions authentiques et d'autres semi-contrôlées, en contexte médical, social et policier, impliquant 16 langues de travail différentes. L'analyse des séquences vidéo d'une durée totale de 13015 secondes, annotées à l'aide du logiciel ELAN, permet d'établir les profils gestuels des acteurs et d'examiner les schémas et les contextes de reproduction des gestes par les interprètes, pour en déduire des récurrences. Les résultats de l'étude suggèrent ainsi que la gestualité co-verbale participe aux processus de co-construction et de négociation du sens, facilite la médiation interculturelle et contribue à l'élaboration des relations de confiance dans des situations d'asymétrie de pouvoir. C'est pourquoi, la sensibilisation à la place inhérente du non-verbal dans les interactions en service public devrait faire partie de la formation des interprètes dont la mission essentielle consiste à assurer une médiation efficace, non seulement entre des systèmes linguistiques différents mais aussi entre des univers culturels distincts.
... Although initially useful, this gender uniformity adds a constraint on generality, and the same goes for the almost exclusive reliance on participants that are Western, Educated, Industrialized, Rich, Democratic (WEIRD; Henrich et al., 2010) (cf. de Groot et al., 2018;Roberts et al., 2020). Generalizing research findings from WEIRD samples to other populations is a major problem in science in general, and a particularly pressing issue when one examines the breadth and scale of the non-verbal language of smells (Box 2). ...
Article
Full-text available
Communication constitutes the core of human life. A large portion of our everyday social interactions is nonverbal. Of the sensory modalities we use for nonverbal communication, olfaction (i.e., the sense of smell) is often considered the most enigmatic medium. Outside of our awareness, smells provide information about our identity, emotions, gender, mate compatibility, illness, and potentially more. Yet, body odors are astonishingly complex, with their composition being influenced by various factors. Is there a chemical basis of olfactory communication? Can we identify molecules predictive of psychological states and traits? We propose that answering these questions requires integrating two disciplines: psychology and chemistry. This new field, coined sociochemistry, faces new challenges emerging from the sheer amount of factors causing variability in chemical composition of body odorants on the one hand (e.g., diet, hygiene, skin bacteria, hormones, genes), and variability in psychological states and traits on the other (e.g., genes, culture, hormones, internal state, context). In past research, the reality of these high-dimensional data has been reduced in an attempt to isolate unidimensional factors in small, homogenous samples under tightly controlled settings. Here, we propose big data approaches to establish novel links between chemical and psychological data on a large scale from heterogeneous samples in ecologically valid settings. This approach would increase our grip on the way chemical signals nonverbally and subconsciously affect our social lives across contexts. Part of a special issue, see: https://www.frontiersin.org/research-topics/11360/advances-and-obstacles-in-contemporary-nonverbal-communication-research#articles
... Indeed, as Valentova et al. point out, there is comparatively less research on non-visual forms of selfpresentation enhancement in general, which has been mentioned by others (see Groyecka et al., 2017). However, there is an increasing amount of research regarding the modulation of olfactory signals via certain fragranced cosmetics (e.g., perfumes; Allen et al., 2019;Roberts et al., 2020). Different kinds of self-presentation enhancement that target olfactory, vocal, tactile, gustatory, and/or behavioral components are fruitful areas for future investigators to pursue. ...
Article
Nonhuman terrestrial mammals sniff themselves and each other to decide who is friend or foe. Humans also sniff themselves and each other, but the function of this is unknown. Because humans seek friends who are similar to themselves, we hypothesized that humans may smell themselves and others to subconsciously estimate body odor similarity, which, in turn, may promote friendship. To test this, we recruited nonromantic same-sex friend dyads and harvested their body odor. We found that objective ratings obtained with an electronic nose, and subjective ratings obtained from independent human smellers converged to suggest that friends smell more similar to each other than random dyads. Last, we recruited complete strangers, smelled them with an electronic nose, and engaged them in nonverbal same-sex dyadic interactions. We observed that dyads who smelled more similar had more positive dyadic interactions. In other words, we could predict social bonding with an electronic nose. We conclude that there is indeed chemistry in social chemistry.
Article
Full-text available
Olfactory impairment is one of the more unique symptoms of COVID-19 infection, and has therefore enjoyed increased public attention in recent months. Olfactory impairment has various implications and consequences ranging from difficulty detecting dangerous pathogens to hindering social functioning and social behaviours. We provide an overview of how olfactory impairment can impact three types of close social relationships; family relationships, friendships and romantic relationships. Evidence is divided into several categories representing potential mechanisms by which olfactory impairment can impact close social relationships: bonding disruptions, decreased social support, missed group-eating experiences, hygiene concerns, and altered sexual behaviours. We conclude with a discussion of emerging future research questions.
Article
Olfaction plays an important role in social interaction. This study examined the influence of chemosensory and cognitive abilities on conscious odor sniffing behaviors in humans. Participants (N = 349) were surveyed using a questionnaire for the frequency of behaviors in terms of odor exploration from intrinsic and external sources. Chemosensory functions (e.g., odor identification, trigeminal sensitivity, taste functions, and nasal patency), self-reported olfactory function, and the subjective importance of olfaction were assessed. Hierarchical regression analyses demonstrate a strong impact of olfactory importance on odor exploration behavior. Both female gender and chemosensory function (odor identification ability and trigeminal sensitivity) had a positive impact on odor exploration behavior from individuals' own body and from external sources. Moreover, participants with dysosmia compared to those with normosmia showed less frequent odor exploration behaviors, while their behaviors were partly predicted by nasal patency. In conclusion, conscious olfactory exploration behaviors reflect the interest in the sense of smell and is strongly modulated by chemosensory function. In turn, individuals with lower olfactory sensitivity invest less in olfactory explorations.
Article
Full-text available
It is well accepted that emotional intensity scales with stimulus strength. Here, we used physiological and neuroimaging techniques to ask whether human body odor – which can convey salient social information – also induces dose-dependent effects on behavior, physiology, and neural responses. To test this, we first collected sweat from 36 males classified as low, medium, and high fear responders. Next, in a double-blind, within-subjects fMRI design, 31 females were exposed to three doses of fear-associated human chemosignals (vs. neutral sweat) while viewing face morphs varying between expressions of fear and disgust. Behaviorally we found that all doses of fear sweat volatiles biased subjects towards perceiving fear in ambiguous morphs, a dose-invariant effect generally repeated across physiological and neural measures. Bayesian dose-response analysis indicated moderate evidence for the null (except left amygdala), tentatively suggesting that the human olfactory system above all engages an all-or-none mechanism for tagging fear above a minimal threshold.
Article
Full-text available
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’.
Article
Full-text available
Human body odour is dominated by the scent of specific odourants emanating from specialized glands in the axillary region. These specific odourants are produced by an intricate interplay between biochemical pathways in the host and odour-releasing enzymes present in commensal microorganisms of the axillary microbiome. Key biochemical steps for the release of highly odouriferous carboxylic acids and sulfur compounds have been elucidated over the past 15 years. Based on the profound molecular understanding and specific analytical methods developed, evolutionary questions could be asked for the first time with small population studies: (i) a genetic basis for body odour could be shown with a twin study, (ii) no effect of genes in the human leukocyte antigen complex on the pattern of odourant carboxylic acid was found, and (iii) loss of odour precursor secretion by a mutation in the ABCC11 gene could explain why a large fraction of the population in the Far East lack body odour formation. This review summarizes what is currently known at the molecular level on the biochemistry of the formation of key odourants in the human axilla. At the same time, we present for the first time the crystal structure of the N α -acyl-aminoacylase, a key human odour-releasing enzyme, thus describing at the molecular level how bacteria on the skin surface have adapted their enzyme to the specific substrates secreted by the human host. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
Dominance hierarchy is often established via repeated agonistic encounters where consistent winners are considered dominant. Human body odour contains cues to psychological dominance and competition, but it is not known whether competition outcome (a marker of a change in dominance hierarchy) affects the hedonic quality of human axillary odour. Therefore, we investigated the effect of winning and losing on odour quality. We collected odour samples from Mixed Martial Arts fighters approximately 1 h before and immediately after a match. Raters then assessed samples for pleasantness, attractiveness, masculinity and intensity. We also obtained data on donors' affective state and cortisol and testosterone levels, since these are known to be associated with competition and body odour quality. Perceived body odour pleasantness, attractiveness and intensity significantly decreased while masculinity increased after a match irrespective of the outcome. Nonetheless, losing a match affected the pleasantness of body odour more profoundly, though bordering formal level of significance. Moreover, a path analysis revealed that match loss led to a decrease in odour attractiveness, which was mediated by participants’ negative affective states. Our study suggests that physical competition and to some extent also its outcome affect the perceived quality of human body odour in specific real-life settings, thus providing cues to dominance-related characteristics. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
Despite the lack of evidence that the ‘putative human pheromones' androstadienone and estratetraenol ever were pheromones, almost 60 studies have claimed ‘significant' results. These are quite possibly false positives and can be best seen as potential examples of the ‘reproducibility crisis', sadly common in the rest of the life and biomedical sciences, which has many instances of whole fields based on false positives. Experiments on the effects of olfactory cues on human behaviour are also at risk of false positives because they look for subtle effects but use small sample sizes. Research on human chemical communication, much of it falling within psychology, would benefit from vigorously adopting the proposals made by psychologists to enable better, more reliable science, with an emphasis on enhancing reproducibility. A key change is the adoption of study pre-registration and/or Registered Reports which will also reduce publication bias. As we are mammals, and chemical communication is important to other mammals, it is likely that chemical cues are important in our behaviour and that humans may have pheromones, but new approaches will be needed to reliably demonstrate them. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
All primates, including humans, engage in self-face-touching at very high frequency. The functional purpose or antecedents of this behaviour remain unclear. In this hybrid review , we put forth the hypothesis that self-face-touching subserves self-smelling. We first review data implying that humans touch their faces at very high frequency. We then detail evidence from the one study that implicated an olfactory origin for this behaviour: This evidence consists of significantly increased nasal inhalation concurrent with self-face-touching, and predictable increases or decreases in self-face-touching as a function of subliminal odourant tainting. Although we speculate that self-smelling through self-face-touching is largely an unconscious act, we note that in addition, humans also consciously smell themselves at high frequency. To verify this added statement, we administered an online self-report questionnaire. Upon being asked, approximately 94% of approximately 400 respondents acknowledged engaging in smelling themselves. Paradoxically, we observe that although this very prevalent behaviour of self-smelling is of concern to individuals, especially to parents of children overtly exhibiting self-smelling, the behaviour has nearly no traction in the medical or psychological literature. We suggest psychological and cultural explanations for this paradox, and end in suggesting that human self-smelling become a formal topic of investigation in the study of human social olfaction. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
Odours can have a significant influence on the outcome of social interactions. However, we have yet to characterize the chemical signature of any specific social cue in human body odour, and we know little about how changes in social context influence odour chemistry. Here, we argue that adoption of emerging analytical techniques from other disciplines, such as atmospheric chemistry, might become game-changing tools in this endeavour. First, we describe the use of online chemical ionization time-of-flight mass spectrometry to sensitively measure many hundreds of gas-phase volatile organic compounds in real time. By analysing ambient air emanating from undisturbed individuals or groups, the technique enables a continuous recording of an instantaneous odour change in response to external stimuli and changing social context. This has considerable advantages over the traditional approach of periodic sampling for analysis by gas chromatography. We also discuss multivariate statistical approaches, such as positive matrix factorization, that can effectively sift through this complex datastream to identify linked groups of compounds that probably underpin functional chemosignals. In combination, these innovations offer new avenues for addressing outstanding questions concerning olfactory communication in humans and other species, as well as in related fields using odour, such as biometrics and disease diagnostics. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
The study of human chemical communication benefits from comparative perspectives that relate humans, conceptually and empirically, to other primates. All major primate groups rely on intraspecific chemosignals, but strepsirrhines present the greatest diversity and specialization, providing a rich framework for examining design, delivery and perception. Strepsirrhines actively scent mark, possess a functional vomeronasal organ, investigate scents via olfactory and gustatory means, and are exquisitely sensitive to chemically encoded messages. Variation in delivery, scent mixing and multimodality alters signal detection, longevity and intended audience. Based on an integrative, 19-species review, the main scent source used (excretory versus glandular) differentiates nocturnal from diurnal or cathemeral species, reflecting differing socioecological demands and evolutionary trajectories. Condition-dependent signals reflect immutable (species, sex, identity, genetic diversity, immunity and kinship) and transient (health, social status, reproductive state and breeding history) traits, consistent with socio-reproductive functions. Sex reversals in glandular elaboration, marking rates or chemical richness in female-dominant species implicate sexual selection of olfactory ornaments in both sexes. Whereas some compounds may be endogenously produced and modified (e.g. via hormones), microbial analyses of different odorants support the fermentation hypothesis of bacterial contribution. The intimate contexts of information transfer and varied functions provide important parallels applicable to olfactory communication in humans. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
The major histocompatibility complex (MHC) is a core part of the adaptive immune system. As in other vertebrate taxa, it may also affect human chemical communication via odour-based mate preferences, with greater attraction towards MHC-dissimilar partners. However, despite some well-known findings, the available evidence is equivocal and made complicated by varied approaches to quantifying human mate choice. To address this, we here conduct comprehensive meta-analyses focusing on studies assessing: (i) genomic mate selection, (ii) relationship satisfaction, (iii) odour preference, and (iv) all studies combined. Analysis of genomic studies reveals no association between MHC-dissimilarity and mate choice in actual couples; however, MHC effects appear to be independent of the genomic background. The effect of MHC-dissimilarity on relationship satisfaction was not significant, and we found evidence for publication bias in studies on this area. There was also no significant association between MHC-dissimilarity and odour preferences. Finally, combining effect sizes from all genomic, relationship satisfaction, odour preference and previous mate choice studies into an overall estimate showed no overall significant effect of MHC-similarity on human mate selection. Based on these findings, we make a set of recommendations for future studies, focusing both on aspects that should be implemented immediately and those that lurk on the far horizon. We need larger samples with greater geographical and cultural diversity that control for genome-wide similarity. We also need more focus on mechanisms of MHC-associated odour preferences and on MHC-associated pregnancy loss. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
The impact of the olfactory sense is regularly apparent across development. The fetus is bathed in amniotic fluid (AF) that conveys the mother’s chemical ecology. Transnatal olfactory continuity between the odours of AF and milk assists in the transition to nursing. At the same time, odours emanating from the mammary areas provoke appetitive responses in newborns. Odours experienced from the mother’s diet during breastfeeding, and from practices such as pre-mastication, may assist in the dietary transition at weaning. In parallel, infants are attracted to and recognize their mother’s odours; later, children are able to recognize other kin and peers based on their odours. Familiar odours, such as those of the mother, regulate the child’s emotions, and scaffold perception and learning through non-olfactory senses. During juvenility and adolescence, individuals become more sensitive to some bodily odours, while the timing of adolescence itself has been speculated to draw from the chemical ecology of the family unit. Odours learnt early in life and within the family niche continue to influence preferences as mate choice becomes relevant. Olfaction thus appears significant in turning on, sustaining and, in cases when mother odour is altered, disturbing adaptive reciprocity between offspring and carer during the multiple transitions of development between birth and adolescence. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
Humans, like other animals, have an excellent sense of smell that can serve social communication. Although ample research has shown that body odours can convey transient emotions like fear, these studies have exclusively treated emotions as categorical , neglecting the question whether emotion quantity can be expressed chemically. Using a unique combination of methods and techniques, we explored a dose–response function: Can experienced fear intensity be encoded in fear sweat? Specifically, fear experience was quantified using multivariate pattern classification (combining physiological data and subjective feelings with partial least-squares-discriminant analysis), whereas a photo-ionization detector quantified volatile molecules in sweat. Thirty-six male participants donated sweat while watching scary film clips and control (calming) film clips. Both traditional univariate and novel multivariate analysis (100% classification accuracy; Q ² : 0.76; R ² : 0.79) underlined effective fear induction. Using their regression-weighted scores, participants were assigned significantly above chance (83% > 33%) to fear intensity categories (low–medium–high). Notably, the high fear group ( n = 12) produced higher doses of armpit sweat, and greater doses of fear sweat emitted more volatile molecules ( n = 3). This study brings new evidence to show that fear intensity is encoded in sweat (dose–response function), opening a field that examines intensity coding and decoding of other chemically communicable states/traits. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Full-text available
Background: Although conflicting findings abound, gender-related differences in olfactory identification have received continuous attention. To our best knowledge, no systematic and quantitative research has examined gender differences in olfaction identification at various stages of life. The present study aimed to find out if there is gender difference in human olfaction identification in different life stages. Methodology: Studies cited in the PubMed database were searched from its inception to August 2017 using the terms "olfact*" or "smell" and "gender" or "sex". The effect size of each comparison was calculated. 24 studies were included in this meta-analysis. Results: In this meta-analysis, we used Cohen's d to determine the effects sizes for the comparisons between women versus men among different groups. Its value was 0.18 (95% CI: -0.13 to 0.49) in Group A (age less than 18 years), 0.62 (95% CI: 0.43 to 0.81) in Group B (age 18-50 years), and 0.33 (95% CI: -0.01 to 0.66) in Group C. The effect was considered relatively small in Group A (age less than 18 years) and Group C (age more than 50 years), and a medium effect in Group B (age 18-50 years). Moreover, a significant difference was only present in Group B (age 18-50 years). Summarizing, the gender effect was only present in the group aged 18-50 years, in which women outperformed men significantly in odor identification. Conclusions: This meta-analytic review indicated that the gender differences only exist in young adults (age 18-50 years), while absent in juveniles (age less than 18 years) or an aged cohort (age more than 50 years). Females outperformed males in the young adults.
Article
Full-text available
Historically, antagonistic interactions have been a crucial determinant of access to various fitness-affecting resources. In many vertebrate species, information about relative fighting ability is conveyed, among other things, by vocalization. Previous research found that men's upper-body strength can be assessed from voice. In the present study, we tested formidability perception of intimidating vocalization (roars) and a short utterance produced by amateur male MMA fighters attending the amateur European Championships in relation to their physical fitness indicators and fighting success. We also tested acoustic predictors of the perceived formidability. We found that body height, weight, and physical fitness failed to predict perceived formidability either from speech or from the roars. Similarly, there was no significant association between formidability of the roars and utterances and actual fighting success. Perceived formidability was predicted mainly by roars' and utterances' intensity and roars' harmonics-to-noise ratio and duration. Interestingly, fundamental frequency (F 0) predicted formidability ratings in both roars and utterances but in an opposite manner, so that low F 0 utterances but high F 0 roars were rated as more formidable. Our results suggest that formidability perception is primarily driven by intensity and duration of the vocalizations.
Article
Full-text available
(Z)-4-undecenal (Z4-11Al) is the volatile pheromone produced by females of the vinegar fly Drosophila melanogaster. Female flies emit Z4-11Al for species-specific communication and mate-finding. A sensory panel finds that synthetic Z4-11Al has a characteristic flavour, which can be perceived even at the small amounts produced by a single female fly. Since only females produce Z4-11Al, and not males, we can reliably distinguish between single D. melanogaster males and females, according to their scent. Females release Z4-11Al at 2.4 ng/h and we readily sense 1 ng synthetic Z4-11Al in a glass of wine (0.03 nmol/L), while a tenfold concentration is perceived as a loud off-flavour. This corroborates the observation that a glass of wine is spoilt by a single D. melanogaster fly falling into it, which we here show is caused by Z4-11Al. The biological role of Z4-11Al or structurally related aldehydes in humans and the basis for this semiochemical convergence remains yet unclear.
Article
Full-text available
Modern lifestyles are disrupting the human senses-primarily sight, sound, and smell. Noise-induced hearing loss has been noted for centuries and increasing over time following the industrial era. From the mid-20thcentury, the numbers of individuals with myopia (the leading visual impairment) have been increasing globally. Historical evidence for olfactory dysfunction is not known but its etiological links to pollution suggest it increased following industrialization. Clinical interventions for sight and sound loss include preventative and corrective measures but none exist for olfactory dysfunction. Further, olfactory loss is linked to multiple negative health outcomes across physical, mental, and social domains. Due to the global rates of exposure to pollution, olfaction is a global health concern. The environmental injustice inherent in human society (locally and globally) results in inequitable risk for sensory loss by the most vulnerable populations and creates an even deeper gradient in health disparity. Situated within the environmental justice and health disparity literature, this paper introduces the termsensory inequityto describe variation in sensory environments based on socio-economic status (which is often entwined with race and education). A key challenge to risk management is awareness of sensory inequity experienced by vulnerable populations and incorporating that awareness into basic research and policy.
Article
Full-text available
People struggle to name odors [1-4]. This has been attributed to a diminution of olfaction in trade-off to vision [5-10]. This presumption has been challenged recently by data from the hunter-gatherer Jahai who, unlike English speakers, find odors as easy to name as colors [4]. Is the superior olfactory performance among the Jahai because of their ecology (tropical rainforest), their language family (Aslian), or because of their subsistence (they are hunter-gatherers)? We provide novel evidence from the hunter-gatherer Semaq Beri and the non-hunter-gatherer (swidden-horticulturalist) Semelai that subsistence is the critical factor. Semaq Beri and Semelai speakers-who speak closely related languages and live in the tropical rainforest of the Malay Peninsula-took part in a controlled odor- and color-naming experiment. The swidden-horticulturalist Semelai found odors much more difficult to name than colors, replicating the typical Western finding. But for the hunter-gatherer Semaq Beri odor naming was as easy as color naming, suggesting that hunter-gatherer olfactory cognition is special.
Chapter
Full-text available
Humans are traditionally considered to have a poorly developed sense of smell that is clearly inferior to that of nonhuman animals. This view, however, is mainly based on an interpretation of neuroanatomical and recent genetic findings, and not on physiological or behavioral evidence. An increasing number of studies now suggest that the human sense of smell is much better than previously thought and that olfaction plays a significant role in regulating a wide variety of human behaviors. This chapter, therefore, aims at summarizing the current knowledge about human olfactory capabilities and compares them to those of animals.
Article
Full-text available
Parental caregiving is critical for the survival of our young and continuation of our species. In humans, visual and auditory signals from offspring have been shown to be potent facilitators of parenting. However, whether odors emitted by our young also influence human parenting remains unclear. To explore this, we conducted a series of questionnaire surveys targeting parents with children under 6 years old. First, we collected episodes on experiencing odors/sniffing various parts of a child’s body (n = 507). The prevalence of experiencing events described in those episodes was examined in a separate survey (n = 384). Based on those results, the Child Odor in Parenting scale (COPs) was developed, and subsequently used in the main survey (n = 888). We found COPs to have adequate content validity, concurrent validity, and reliability. Responses to the COPs demonstrated that parents, especially mothers with infants, are aware of odors from their offspring, and actively seek them in daily child-rearing. The factor structure and content of the COPs items indicated that child odors have both affective and instrumental roles. Affective experiences induce loving feeling and affectionate sniffing, while instrumental experiences pertain to specific hygienic needs. The head was the most frequent source of affective experiences, and the child’s bottom of instrumental. Each was experienced by more than 90% of the mothers with a child below 1 year of age. Affective experiences significantly declined as the child grew older, possibly associated with the decline of physical proximity between parents and child. This age-related decline was not prominent for instrumental experiences, except for the bottom, which significantly declined after 3 years of age. The present findings suggest that child odors play roles in human parenting, and that their nature and significance change during the course of a child’s development.
Poster
Full-text available
Cross-culturally, people use fragrances which may affect the outcomes of social interactions. It has been suggested that fragrances might mask body odours or interact with them in an idiosyncratic fashion. To test these competing hypotheses we performed a series of experiments involving: i) individual body odour discrimination, ii) attribution of personality characteristics and iii) possible kin advantage in perfume selection. In each study, we compared judgements of the body odours alone and fragrance-body odour blends. In study I, odour donors used either no fragrance, assigned fragrance or self-selected fragrances. Discrimination rates were highest in the “no fragrance” condition, followed by ”own fragrance” and lowest (but significant) in the “assigned fragrance” condition. In study II, the odour donors completed the Big Five questionnaire and provided ”no fragrance“ odour samples and body odours blended with their own fragrance, which were then rated for personality characteristics. We found a significant association between self-reported and odour-based judgements of neuroticism and dominance in the “no fragrance“ condition; while only dominance showed this association in the “own fragrance“ condition. In study III, we tested whether a fragrance selected by kin (sisters) or non-kin (girlfriends) was perceived as more pleasant compared with a selection made by target men. We found that the body odour blended with fragrances selected by girlfriends or sisters were rated as more pleasant than those selected by the target men. Together, our results support the interaction hypothesis and suggest that the perfume-body odour complex is a potentially insightful model for culture-gene coevolution.
Article
Full-text available
Previous research suggests that artificial fragrances may be chosen to complement or enhance an individual’s body odor, rather than simply masking it, and that this may create an odor blend with an emergent quality that is perceptually distinguishable from body odor or fragrance alone. From this, it can be predicted that a new emergent odor might be more easily identified than an individual’s body odor in isolation. We used a triangle test paradigm to assess whether fragrance affects people’s ability to distinguish between individual odors. Six male and six female donors provided axillary odor samples in three conditions (without fragrance, wearing their own fragrance, and wearing an assigned fragrance). In total, 296 female and 131 male participants selected the odd one from three odor samples (two from one donor, one from another; both of the same sex). We found that participants could discriminate between the odors at above chance levels in all three odor conditions. Olfactory identification ability (measured using Sniffin’ Sticks) positively predicted discrimination performance, and sex differences in performance were also observed, with female raters being correct more often than men. Success rates were also higher for odors of male donors. Additionally, while performance was above chance in all conditions, individual odor discrimination varied across the three conditions. Discrimination rate was significantly higher in the “no fragrance” condition than either of the fragranced conditions. Importantly, however, discrimination rate was also significantly higher in the “own fragrance” condition than the “assigned fragrance” condition, suggesting that naturally occurring variance in body odor is more preserved when blended with fragrances that people choose for themselves, compared with other fragrances. Our data are consistent with the idea that fragrance choices are influenced by fragrance interactions with an individual’s own body odor.
Chapter
Full-text available
Olfaction is involved in various human social interactions, ranging from mother-offspring attachment to mate choice; as in other species, such chemical ­signalling is thought to be shaped by evolution. However, across many human ­cultures, individuals manipulate their body odour by means of various fragrances and these may significantly affect the outcome of social encounters in a context-specific fashion. Here we employ the framework of dual-inheritance theory, which advocates that cultural practices should be incorporated into the analysis of ­evolution of human behaviour, to explore cultural means of olfactory signalling such as ethnic and status markers. Further, we review studies showing that perfumes interact with body odour in an individual fashion and that people tend to choose perfumes according to their genetic make-up. This indicates that biologically evolved chemical ­signalling might operate in concert with cultural human practices. Finally, we propose two scenarios: (1) how culturally based preferences and use of perfume might impact gene frequencies in individual populations, and (2) how evolved cognitive biases might affect selection of scents that are appropriate for body adornments. This, in our view, makes the perfume-body odour complex a potentially insightful model for culture–gene coevolution.
Article
Full-text available
Olfactory responsiveness was assessed in 24 neonates born to mothers who had or had not consumed anise flavour during pregnancy. Both groups of infants were followed-up for behavioural markers of attraction and aversion when exposed to anise odour and a control odour immediately after birth and on day 4. Infants born to anise-consuming mothers evinced a stable preference for anise odour over this period, whereas those born to anise non-consuming mothers displayed aversion or neutral responses. This study provides the first clear evidence that through their diet human mothers influence the hedonic polarity of their neonates' initial olfactory responses. The findings have potential implications for the early mother-to-infant transmission of chemosensory information relative to food and addictive products.
Article
Full-text available
Le statut épistémique des odeurs occupe une place à part dans la littérature scientifique, en particulier en psychologie cognitive et au sein de l’anthropologie des sens. À partir d’une enquête ethnographique conduite en France et en Belgique francophone, nous montrons les limites d’une conception dominante de ces travaux qui consiste à trier les expériences olfactives dans le cadre d’un clivage hédonique, bonnes et mauvaises odeurs s’opposant d’un point de vue affectif, cognitif et normatif. Prenant appui sur une démarche d’ethnographie cognitive des perceptions consistant à étudier les odeurs en tant que résultat d’un processus de jugement dont on peut étudier le déploiement en tant qu’activité mentale située, nous montrons dans un premier temps la place qu’occupent les « mauvaises odeurs » corporelles dans l’intimité de nos informateurs. Puis nous présentons les odeurs oxymorons qui sont jugées à la fois bonnes et mauvaises. Ces deux cas illustrent les limites d’une analyse des odeurs en termes de clivage hédonique. Au-delà de cette question spécifique, nous proposons une analyse ethnographique des jugements cognitifs au coeur de l’intime comme cadre pour le développement de l’anthropologie des sens, et un rapprochement vis-à-vis des travaux de la psychologie cognitive dans ce domaine.
Article
Full-text available
Humans and most of our closest extant relatives, the anthropoids, are notable for their reduced “snout.” The striking reduction in facial projection is only a superficial similarity. All anthropoids, including those with long faces (e.g., baboons), have lost numerous internal projections (turbinals) and spaces (recesses). In sum, this equates to the loss of certain regions of olfactory mucosa in anthropoids. In addition, an accessory olfactory organ, the vomeronasal organ, is non-functional or even absent in all catarrhine primates (humans, apes, monkeys). In this commentary, we revisit the concept of anatomical reductions as it pertains to the anthropoid nasal region. Certain nasal structures and spaces in anthropoids exhibit well-known attributes of other known vestiges, such as variability in form or number. The cupular recess (a vestige of the olfactory recess) and some rudimentary ethmoturbinals constitute reduced structures that presumably were fully functional in our ancestors. Humans and at least some apes retain a vestige that is bereft of chemosensory function (while in catarrhine monkeys it is completely absent). However, the function of the vomeronasal system also includes prenatal roles, which may be common to most or all mammals. Notably, neurons migrate to the brain along vomeronasal and terminal nerve axons during embryogenesis. The time-specific role of the VNO raises the possibility that our concept of functional reduction is too static. The vomeronasal system of humans and other catarrhine primates appears to qualify as a “chronological” vestige, one which fulfills part of its function during ontogeny, and then becomes lost or vestigial. Anat Rec, 297:2196–2204, 2014. © 2014 Wiley Periodicals, Inc.
Article
Olfactory perception has implications for human chemosensory communication and in a broader context, it affects well-being. However, most of the studies investigating the consequences of olfactory loss have recruited patients who have already been categorized as having a dysfunctional sense of smell and sought help in an ENT clinic. We revisit these findings by distinguishing subjects with olfactory impairment from a group of subjects who all declared a normal sense of smell when enrolling for this study. In the initial sample of 203 individuals, we found 59 to have impaired olfaction and four with marginal olfactory performance, not useful in daily life. Interestingly, we found a significant between-group difference in cognitive functioning, further supporting the notion of the relationship between cognition and olfactory performance. However, their chemosensory communication and well-being appeared not to be different from subjects with normosmia. Impaired olfactory function certainly has a severe impact on daily life but more so in individuals who are bothered with it and decide to seek treatment. The limited-to-no olfactory perception in the fraction of subjects who neither complain about it nor seek help in ENT clinics does not seem to have a major effect on their social, cognitive, emotional and health functioning. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Interactions relating to human chemical signalling, although widely acknowledged, are relatively poorly characterized chemically, except for human axillary odour. However, the extensive chemical ecology of insects, involving countless pheromone and other semiochemical identifications, may offer insights into overcoming problems of characterizing human-derived semiochemicals more widely. Current techniques for acquiring insect semiochemicals are discussed, particularly in relation to the need for samples to relate, as closely as possible, to the ecological situation in which they are naturally deployed. Analysis is facilitated by chromatography coupled to electrophysiological preparations from the olfactory organs of insects in vivo . This is not feasible with human olfaction, but there are now potential approaches using molecular genetically reconstructed olfactory preparations already in use with insect systems. There are specific insights of value for characterizing human semiochemicals from advanced studies on semiochemicals of haematophagous insects, which include those involving human hosts, in addition to wider studies on farm and companion animals. The characterization of the precise molecular properties recognized in olfaction could lead to new advances in analogue design and a range of novel semiochemicals for human benefit. There are insights from successful synthetic biology studies on insect semiochemicals using novel biosynthetic precursors. Already, wider opportunities in olfaction emerging from in silico studies, involving a range of theoretical and computational approaches to molecular design and understanding olfactory systems at the molecular level, are showing promise for studying human semiochemistry. This article is part of the Theo Murphy meeting issue ‘ Olfactory communication in humans ’.
Article
The current study is the first to examine the central nervous processing of aggression chemosignals within men and women by means of chemosensory event-related potential (CSERP) analysis. Axillary sweat was collected from 17 men and 17 women participating in a competitive computer game (aggression condition) and playing a construction game (control condition). Sweat samples were pooled with reference to donor gender and condition, and presented to 23 men and 25 women via a constant flow olfactometer. Ongoing electroencephalogram was recorded from 61 scalp locations, CSERPs (P2, P3-1, P3-2) were analysed and neuronal sources calculated (low-resolution electromagnetic tomography, LORETA). Women, especially, showed larger P3-1 and P3-2 amplitudes in response to male as compared with female aggression signals (all p values < 0.01). The peak activation of this effect was related to activity within the dorsomedial prefrontal cortex (Brodmann area 8). As male aggression commonly targets physical harm, the competence of the human brain to sensitively detect male aggression signals is considered to be highly adaptive. The detection of male aggression signals seems to be of higher importance for women than for men. It is suggested that the processing of male aggression signals in women induces an immediate response selection. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
In this study, the odour thresholds (OT) and atmospheric lifetimes (AL) were compared for a suite of volatile organic compounds. It was found that odour threshold, as determined by the triangle bag method, correlated surprisingly well with atmospheric lifetime for a given chemical family. Molecules with short atmospheric lifetimes with respect to the primary atmospheric oxidant OH tend to be more sensitively detected by the human nose. Overall the correlation of odour threshold with atmospheric lifetime was better than with mass and vapour pressure. Several outliers from the correlations for particular chemical families were examined in detail. For example, diacetyl was an outlier in the ketone dataset that fitted the trend when its more important photolysis lifetime was included; and similarly, the relatively low odour threshold of carbonyl sulfide (OCS) was interpreted in terms of uptake by vegetation. The OT/AL relationship suggests that OH rate constants can be used as a first-order estimate for odour thresholds (and vice versa ). We speculate that the nose's high sensitivity to chemicals that are reactive in the air is likely an evolved rather than a learned condition. This is based on the lack of dependence on ozone in the aliphatics, that the anthropogenically emitted aromatic compounds had the worst correlation, and that OCS had a much lower than predicted OT. Finally, we use the OT/AL relationships derived to predict odour thresholds and rate constants that have not yet been determined in order to provide a test to this hypothesis. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Across diverse lineages, animals communicate using chemosignals, but only humans communicate about chemical signals. Many studies have observed that compared with other sensory modalities, communication about smells is relatively rare and not always reliable. Recent cross-cultural studies, on the other hand, suggest some communities are more olfactorily oriented than previously supposed. Nevertheless, across the globe a general trend emerges where olfactory communication is relatively hard. We suggest here that this is in part because olfactory representations are different in kind: they have a low degree of embodiment, and are not easily expressed as primitives, thereby limiting the mental manipulations that can be performed with them. New exploratory data from Dutch children (9–12 year-olds) and adults support that mental imagery from olfaction is weak in comparison with vision and audition, and critically this is not affected by language development. Specifically, while visual and auditory imagery becomes more vivid with age, olfactory imagery shows no such development. This is consistent with the idea that olfactory representations are different in kind from representations from the other senses. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
For humans, like other social animals, behaviour acts as a first line of defence against pathogens. A key component is the ability to detect subtle perceptual cues of sick conspecifics. The present study assessed the effects of endotoxin-induced olfactory and visual sickness cues on liking, as well as potential involved mechanisms. Seventy-seven participants were exposed to sick and healthy facial pictures and body odours from the same individual in a 2 × 2 factorial design while disgust-related facial electromyography (EMG) was recorded. Following exposure, participants rated their liking of the person presented. In another session, participants also answered questionnaires on perceived vulnerability to disease, disgust sensitivity and health anxiety. Lower ratings of liking were linked to both facial and body odour disease cues as main effects. Disgust, as measured by EMG, did not seem to be the mediating mechanism, but participants who perceived themselves as more prone to disgust, and as more vulnerable to disease, liked presented persons less irrespectively of their health status. Concluding, olfactory and visual sickness cues that appear already a few hours after the experimental induction of systemic inflammation have implications for human sociality and may as such be a part of a behavioural defence against disease. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Article
Many species use chemicals to communicate. In humans, there is increasing evidence that chemicals conveyed by the body are extremely important in interpersonal relationships. However, many aspects of chemical communication remain to be explored to fully understand this function in humans. The aim of this article is to identify relevant challenges in this field, with a focus on human attractiveness in the context of reproduction, and to put forward roadmaps for future studies that will hopefully extend to a wider range of social interactions. The first challenge consists in not being limited to body (mal)odours from the axilla. Preliminary data on how the odour of the face and head is perceived are presented. Second, there is a crucial need to increase our knowledge of the chemical bases of human chemical communication. Third, cross-cultural approaches must not be overlooked, because they have a major input in understanding the universal and culture-specific aspects of chemical communication. Fourth, the influence of specific cultural practices such as contraceptive and fragrance use is likely to be prominent and, therefore, needs to be well described. The fifth and last challenge for research projects in this field is the integration of different disciplines such as behavioural sciences, social sciences, neurosciences and microbiology. This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
Chapter
Humans were once considered to be microsmatic, but recent research suggests that we can use our sense of smell to detect important, socially relevant information about conspecifics. However, much of the research conducted todate has investigated natural, fragrance free human body odours. While this is important in order to understand the evolution of olfactory communication in humans, it fails to account for the current (and historical) widespread use of artificial fragrances. In this chapter, we outline ways in which extraneous artificial fragrances may augment the underlying body odour, or ‘odour space’ of an individual, and how this might influence the perception of socially relevant information. In doing so, we describe some specific mechanisms for the interaction between body odours and artificial fragrances (blending and masking) and we discuss some recent work which has attempted to distinguish between these mechanisms.
Article
Training and repeated exposure to odorants leads to enhanced olfactory sensitivity. So far, the efficacy of intensive olfactory training on olfactory function in a healthy population and its underlying neurobiological basis remain poorly known. This study investigated the effects of a 6-week intensive and well-controlled olfactory training on olfactory function and brain structure/neuroplasticity. Thirty-six healthy young individuals were recruited and randomly distributed in three groups: (1) 12 participants underwent daily intensive olfactory training of at least 20 min that included an (a) odor intensity classification task, an (b) odor quality classification task and an (c) target odor detection task, (2) 12 participants underwent an equivalent visual control training, and (3) 12 control individuals did not participate in any training. Before and after the training period, all participants performed a series of olfactory tests and those from groups 1 and 2 underwent structural magnetic resonance (MR) imaging, from which we obtained measures such as cortical thickness and tissue density. Participants improved in the respectively trained tasks throughout the 6-weeks training period. Those who underwent olfactory training improved general olfactory function compared to control participants, especially in odor identification, thus showing intramodal transfer. Further, MR imaging analysis revealed that olfactory training led to increased cortical thickness in the right inferior frontal gyrus, the bilateral fusiform gyrus and the right entorhinal cortex. This research shows that intensive olfactory training can generally improve olfactory function and that this improvement is associated with changes in the structure of olfactory processing areas of the brain.
Article
Human axillary (armpit) odors are highly diverse and have potential to reveal a wide range of individual information. This is echoed in gas chromatography findings, which show that axillary odors are comprised of many volatile compounds. Despite this, only a small number of verbal descriptors are used when investigating the perceptual qualities of body odors. We set out to develop a lexicon that would capture these perceptual qualities in more detail, working alongside perfumers and fragrance evaluators in order to benefit from their expertise in olfactory perception and semantic labeling of odors. Four experts developed a list of 15 verbal descriptors based on an exemplar set of male and female axillary samples, and then rated 62 samples (31 men and 31 women) using these. We explored the predictive value of these ratings, finding that subsets of descriptors distinguished male from female samples, appearing to be more reliable than explicit judgments of odor sex.
Article
It is commonly believed that humans have a poor sense of smell compared to other mammalian species. However, this idea derives not from empirical studies of human olfaction but from a famous 19th-century anatomist’s hypothesis that the evolution of human free will required a reduction in the proportional size of the brain’s olfactory bulb. The human olfactory bulb is actually quite large in absolute terms and contains a similar number of neurons to that of other mammals. Moreover, humans have excellent olfactory abilities. We can detect and discriminate an extraordinary range of odors, we are more sensitive than rodents and dogs for some odors, we are capable of tracking odor trails, and our behavioral and affective states are influenced by our sense of smell.
Article
The sense of smell has widely been viewed as inferior to the other senses. This is reflected in the lack of treatment of olfaction in ethnographies and linguistic descriptions. We present novel data from the olfactory lexicon of Seri, a language isolate of Mexico, which sheds new light onto the possibilities for olfactory terminologies. We also present the Seri smellscape, highlighting the cultural significance of odors in Seri culture that, along with the olfactory language, is now under threat as globalization takes hold and traditional ways of life are transformed. © 2016, Indiana University Anthropological Linguistics. All rights reserved.
Article
(Special Issue: Chemosensory Perception) As previously suggested, preference for kin body odour might undergo an adaptive change over the course of puberty in order to avoid potential inbreeding, resulting in aversion to body odour of the opposite-gender kin as individuals mature sexually. However, studies based on mutual body odour aversion have been rather inconclusive. We therefore investigated whether children's reports of individuals smelling good or bad differed as a function of age and pubertal status. We asked 219 children (94 M) aged 10-15 years to self-assess their pubertal development using a standardized measure and to name individuals they thought smelled good or bad. Results of the present study show that the older the girls were, the more likely they were to name males than females among nice-smelling people. Further, in both girls and boys alike, children with higher puberty scores were more likely to name children than adults. Neither in girls nor in boys did we observe any concurrent effect of age or pubertal status on children's reports of persons thought to smell bad. Irrespective of whether these changes are driven by age itself or age-related phenomena such as sexual maturation, these results suggest a shift towards a more general positive attitude to peers rather than active kin avoidance.
Article
The neural plasticity of the olfactory system offers possibilities of treatment in terms of stimulation of the sense of smell, and different studies have suggested effectiveness of smell training, i.e., daily exposition to certain odors. To obtain reliable and precise estimates of overall treatment benefit on the olfactory function, we meta-analyzed the effects of smell training reported in 13 previous studies. We analyzed the smell training effectiveness across three different olfactory abilities, smell identification, discrimination and threshold for odor detection. We found a significant, positive effect of olfactory training for all olfactory abilities, with large effects of training on identification, discrimination and TDI-score and small-to-moderate effect in the case of threshold for odor detection. Interestingly, the pattern of results differed across Sniffin Sticks subtests depending on the origin of participants smell disorder, and the smell training duration influenced its effectiveness in the case of identification and the TDI score. Although the exact mechanism of olfactory recovery following the smell training still requires further investigation, our meta-analysis showed that such training should be considered an addition or alternative to existing smell treatment methods.
Article
[ open access paper - you can download it from the URL below ] http://rspb.royalsocietypublishing.org/content/282/1804/20142994 As humans are mammals, it is possible, perhaps even probable, that we have pheromones. However, there is no robust bioassay-led evidence for the widely published claims that four steroid molecules are human pheromones: androstenone, androstenol, androstadienone and estratetraenol. In the absence of sound reasons to test the molecules, positive results in studies need to be treated with scepticism as these are highly likely to be false positives. Common problems include small sample sizes, an overestimate of effect size (as no effect can be expected), positive publication bias and lack of replication. Instead, if we are to find human pheromones, we need to treat ourselves as if we were a newly discovered mammal, and use the rigorous methods already proven successful in pheromone research on other species. Establishing a pheromone relies on demonstration of an odour-mediated behavioural or physiological response, identification and synthesis of the bioactive molecule(s), followed by bioassay confirmation of activity. Likely sources include our sebaceous glands. Comparison of secretions from adult and pre-pubertal humans may highlight potential molecules involved in sexual behaviour. One of the most promising human pheromone leads is a nipple secretion from the areola glands produced by all lactating mothers, which stimulates suckling by any baby not just their own. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
Article
Acknowledgements Introduction: The Meaning and Power of Smell Part I: In Search of Lost Scents 1. The Aromas of Antiquity 2. Following the Scent: From the Middle Ages to Modernity Part II: Explorations in Olfactory Difference 3. Universes of Odour 4. The Rites of Smell Part III: Odour, Power and Society 5. Odour and Power: The Politics of Smell 6. The Aroma of the Commodity: The Commercialization of Smell Bibliography