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psych/​smell directory


“I Cloned My Dog—They Have Completely Different Personalities”, Spelliscy 2022

“I Cloned My Dog—They Have Completely Different Personalities”⁠, Shaun Spelliscy (2022-01-30; ; backlinks; similar):

Sydney’s always been a ball-crazy dog, too. From a very young age, she just loved chasing a ball. But it wasn’t until she was 6 years old that something really remarkable happened. I was taking her for a midnight walk on Granville Island in Vancouver when she smelt the scent of a ball underground and just went after it. She spent 30 minutes digging a hole and retrieved that ball. It dawned on me then that if I could replace the scent of a ball with a sulfide scent, we could train her to be a prospector.

…As a mineral prospecting company, we will typically visit a location after an aerial geophysical survey has taken place. A plane will have mapped the area and if that survey has shown some geophysical anomaly, something that could indicate a sulfidic mineral; say nickel, copper or gold, we will then hike through to investigate further. After I trained Sydney to detect sulfide scents, she would join us. If there is cover on the ground that obscures our view, she is able to detect any sulfidic minerals beneath. Provided it’s a reasonable depth of course, she can’t detect minerals buried 100 meters underground! Her method is to dig away at the ground, and then she’ll make a little nest on what she finds and go to sleep on it. She’s done her job at that stage and then she’s so happy she just has a nap. But it’s not like dogs hunting a scent across the countryside, it’s quite a calm procedure.

…very few dogs can detect mineral sulfides and report back on them in the way she can. We tried to see if Border Collies could do it, and they only could, but only to a degree. We then spent about 6 months with an Australian Cattle dog called Jake but he still didn’t have Sydney’s capability…Over the years we tried various other dogs but none had the capacity for detection that Sydney has.

…Then, in 2019, I discovered a place in Texas that clones pets, called ViaGen⁠, and they were very easy to deal with. A local veterinarian completed a biopsy so we could provide tissue samples for the cloning process, those samples were sent to ViaGen for further processing and placed in storage until we pulled the trigger to clone Sydney in 2021. I have no real understanding of the specifics of the cloning process, other than what I had to be involved in and provide in terms of tissue samples, but I have always been an advocate for animal welfare locally and in Mexico. Cloning Sydney cost us $50,000 and we thought that meant we were getting one puppy in the fall of 2021. Then, on July 9, I got a call saying, “Your puppies have arrived.”

…Both [cloned puppies, Olivia and Fiona] are also completely ball crazy and very agile…I have found it takes around 400 training sessions, each around 15 minutes long, for a dog to develop confidence to hunt a particular scent, but our training is incredibly kind to the dogs and we see lack of praise as a punishment. Olivia and Fiona’s official training is in its early stages, but both show incredible aptitude for one or two scents related to copper, nickel, gold and diamond. They really do have Sydney’s instinct when it comes to scenting, but they go about it differently. My first indication of the puppies’ ability to detect scents happened with Fiona, I was leash training her with a harness when she was 100 days old. As we walked through the yard, she put on the brakes, started digging, and found a buried bone that was about 3 inches under the soil. She has been introduced to bones before, but she instinctively smelt this bone that had probably been buried there for more than a year.

People have different reactions to cloning, some think it’s OK and others think it’s wrong because there are so many dogs in shelters already. I can understand that perspective, but in our particular situation there really wasn’t any other option than to reproduce Sydney in the way we did…in my work circles, people know all about Sydney, so they are really enchanted by the puppies. Anyone familiar with Sydney is excited that there are 2 more of her around to continue her legacy of mineral detection.

“Eau De Cleopatra: Mendesian Perfume and Tell Timai”, Littman et al 2021

2021-littman.pdf: “Eau de Cleopatra: Mendesian Perfume and Tell Timai”⁠, Robert J. Littman, Jay Silverstein, Dora Goldsmith, Sean Coughlin, Hamedy Mashaly (2021-09-01; ):

A combination of Classics, Egyptology, and experimental archaeology were utilized to recreate the (in)famous perfume used by Queen Cleopatra VII.

Especially important was the use of classical sources and paleobotany to determine the identity of the Egyptian sacred oils such as camphor and balanos⁠. Excavations at the site of Tell Timai revealed a perfumery that contributed to our ability to recreate the process of perfume manufacture.

…One constellation of variables produced a scent that was extremely pleasant, with a spicy base note of freshly ground myrrh and cinnamon and accompanied by sweetness. It has remained potent for nearly 2 years, a quality associated with Egyptian perfumes already in Theophrastus’s time [On Odours]…Mendesian reproduced (counterclockwise from bottom left): mortar and pestle⁠, myrrh⁠, pine resin⁠, desert date oil, cassia and cinnamon quills, completed perfume.

This ancient “Mendesian” perfume has since been recreated in the lab, exhibited at the Smithsonian, and worn again for the first time in millennia.

“Large-scale Genome-wide Association Study of Food Liking Reveals Genetic Determinants and Genetic Correlations With Distinct Neurophysiological Traits”, May-Wilson et al 2021

“Large-scale genome-wide association study of food liking reveals genetic determinants and genetic correlations with distinct neurophysiological traits”⁠, Sebastian May-Wilson, Nana Matoba, Kaitlin Wade, Jouke-Jan Hottenga, Maria Pina Concas, Massimo Mangino et al (2021-07-28; similar):

Variable preferences for different foods are among the main determinants of their intake and are influenced by many factors, including genetics. Despite considerable twins’ heritability, studies aimed at uncovering food-liking genetics have focused mostly on taste receptors. Here, we present the first results of a large-scale genome-wide association study of food liking conducted on 161,625 participants from UK Biobank⁠. Liking was assessed over 139 specific foods using a 9-point hedonic scale. After performing GWAS⁠, we used genetic correlations coupled with structural equation modelling to create a multi-level hierarchical map of food liking. We identified three main dimensions: high caloric foods defined as “Highly palatable”, strong-tasting foods ranging from alcohol to pungent vegetables, defined as “Learned” and finally “Low caloric” foods such as fruit and vegetables. The “Highly palatable” dimension was genetically uncorrelated from the other two, suggesting that two independent processes underlie liking high reward foods and the Learned/​Low caloric ones. Genetic correlation analysis with the corresponding food consumption traits revealed a high correlation, while liking showed twice the heritability compared to consumption. For example, fresh fruit liking and consumption showed a genetic correlation of 0.7 with heritabilities of 0.1 and 0.05, respectively. GWAS analysis identified 1401 significant food-liking associations located in 173 genomic loci, with only 11 near taste or olfactory receptors. Genetic correlation with morphological and functional brain data (33,224 UKB participants) uncovers associations of the three food-liking dimensions with non-overlapping, distinct brain areas and networks, suggestive of separate neural mechanisms underlying the liking dimensions. In conclusion, we created a comprehensive and data-driven map of the genetic determinants and associated neurophysiological factors of food liking beyond taste receptor genes.

“Sniffing Out New Friends: Similarity in Body-Odor Predicts the Quality of Same-Sex Non-Romantic Dyadic Interactions”, Ravreby et al 2021

“Sniffing Out New Friends: Similarity in Body-Odor Predicts the Quality of Same-Sex Non-Romantic Dyadic Interactions”⁠, Inbal Ravreby, Kobi Snitz, Noam Sobel (2021-06-17; ; similar):

Most are familiar with the notion of socially “clicking” with someone, namely sensing an immediate bond that can lead to strong and often long-lasting friendships. The mechanisms underlying such rapid bonding remain unclear. Given that body-odor similarity is a critical cue for social interaction in non-human mammals, we tested the hypothesis that body-odor similarly contributes to bonding in same-sex non-romantic human dyads. We observed that objective ratings obtained with an electronic nose, and subjective ratings obtained from human smellers, converged to suggest that click-friends smell more similar to each other than random dyads. Remarkably, we then found that we could use the electronic nose to predict which strangers would later form better dyadic interactions. Thus, humans may literally sniff-out new friends based on similarities in body-odor.

“Consequences of Gaining Olfactory Function After Lifelong Anosmia”, Pellegrino et al 2021

2021-pellegrino.pdf: “Consequences of gaining olfactory function after lifelong anosmia”⁠, Robert Pellegrino, Coralie Mignot, Charalampos Georgiopoulos, Antje Haehner, Thomas Hummel (2021-05-18; similar):

We present a rare case in which a patient has gained her smell after lifelong anosmia⁠.

The patient was objectively tested and diagnosed with functional anosmia at age 13 and reported they were experiencing a new sensation of smell at age 22.

Our results show an electrophysiological signal for 2 unimodal odorants. The patient had a retronasal score in the hyposmic range and self-reported the ability to smell non-trigeminal odors, but reported being disturbed by the presence of the new sense and co-occurrence of phantosmia⁠.

We discuss our case in routes of neurogenesis and non-forming memory association with odors.

[Keywords: Anosmia, olfactory recovery, neurogenesis, congenital, new sense, memory, phantosmia]

…As typical with congenital loss, the patient was diagnosed in her early teenage years, most likely after it was brought to her attention that others smell…However, in her mid-20s, she started to perceive odors. From then on, she also perceived an occasional odor phantom, i.e., phantosmia, following an odorous sensation, elicited by an odorous stimulus, which could not be switched off. Hence, she experiences an olfactory percept, and then the sensation lingers from that previous exposure even with no airflow. To our knowledge, this is the first report on a patient recovering from lifelong anosmia.

…From an age of 24 years she was able to perceive more and more fragrances with occasional new smell impressions every few weeks. During an interview process, she emphasized that her “new sense” is an annoyance to her with most odor sensations being unpleasant. Only a few fragrances are perceived as pleasant (eg. lavender or curry). To the former, she has experienced more and more unpleasant smells (eg. manure, onion, garlic) than pleasant ones which has increased her anxiety. During the last months, she fainted and connected this collapse to the olfactory stress. Additionally, during the recent olfactory recovery period (~18 months), there have been a few olfactory phantoms (phantosmia II°: intense [8⁄10], unpleasant [−2 on a scale from −5 to +5], lasting minutes to hours, not daily but constant frequency, extremely annoyed by the odor phantom (Hummel et al 2013)). From a follow-up interview (10 days after November visit), the patient reported on the odor phantoms “I often cannot tell whether the smell is real or not. It usually feels just as strong and real as when I actually smell something” and “smells stay in the nose for hours which is stressful”. On a third interview (4 months after November visit), following an odor presentation, a pinch of the nose did not make the smell disappear. Gustatory function has remained unchanged over the years although retronasal aromas have mostly become more pleasant.

…The patient claimed that she could smell half (16) of these odors which included mostly trigeminal (eg. peppermint, clove), but also nontrigeminal odorants (eg. coffee, lilac). Many pleasant ratings for spices were lower than what is commonly found (eg. clove, anise, ginger; (Dravnieks et al 1984)) and some similar odors were given opposite ratings of liking (low peppermint, but high mint). Supra-threshold taste sprays showed normal taste function (eg. normogeusia) for sweet, bitter, sour, and salty (4⁄4 correct; (Hummel et al 2013)).

…More obvious questions are how it should be possible that (1) somebody without olfactory bulbs should have olfactory percepts, and that (2) a person without a sense of smell from birth should develop olfactory function. At least the former question has been discussed in depth previously (Weiss et al 2020). Among the major ideas were (1) that, although unlikely given the resolution of present MR scans, OBs might have been too small to be detected, (2) that the olfactory sensations are mediated by the trigeminal nerve, which would be astonishing given the many subtle, unimodal odors the patient was able to detect and the electrophysiological response to pure unimodal odorants. In addition, a hypothesis could be that portions of the coding of olfactory information are different from that in other mammals so that some olfactory sensations are possible even without an olfactory bulb.

“It’s Trust or Risk? Chemosensory Anxiety Signals Affect Bargaining in Women”, Meister & Pause 2021

2021-meister.pdf: “It’s trust or risk? Chemosensory anxiety signals affect bargaining in women”⁠, Lukas Meister, Bettina M. Pause (2021-05-01; ⁠, ; similar):

  • Chemosensory anxiety signals seem to act contagiously.
  • Chemosensory anxiety signals reduce trust as well as risk behavior.
  • Chemosensory anxiety signals predominantly affect women.
  • Chemosensory anxiety signals act independent of odor concentration.

It is well documented how chemosensory anxiety signals affect the perceiver’s physiology, however, much less is known about effects on overt social behavior. The aim of the present study was to investigate the effects of chemosensory anxiety signals on trust and risk behavior in men and women.

Axillary sweat samples were collected from 22 men during the experience of social anxiety, and during a sport control condition. In a series of 5 studies, the chemosensory stimuli were presented via an olfactometer to 214 participants acting as investors in a bargaining task either in interaction with a fictitious human co-player (trust condition) or with a computer program (risk condition).

It could be shown that chemosensory anxiety signals reduce trust and risk behavior in women. In men, no effects were observed.

Chemosensory anxiety is discussed to be transmitted contagiously, preferentially in women.

[Keywords: chemosensory communication, trust, risk, bargaining, TSST-G, anxiety]

“Dog Savior: Immediate Scent-Detection of SARS-COV-2 by Trained Dogs”, Vesga et al 2020

“Dog Savior: Immediate Scent-Detection of SARS-COV-2 by Trained Dogs”⁠, Omar Vesga, Andres F. Valencia, Alejandro Mira, Felipe Ossa, Esteban Ocampo, Maria Agudelo, Karl Čiuoderis et al (2020-06-19; ; similar):

Molecular tests for viral diagnostics are essential to confront the COVID-19 pandemic, but their production and distribution cannot satisfy the current high demand. Early identification of infected people and their contacts is the key to being able to isolate them and prevent the dissemination of the pathogen; unfortunately, most countries are unable to do this due to the lack of diagnostic tools. Dogs can identify, with a high rate of precision, unique odors of volatile organic compounds generated during an infection; as a result, dogs can diagnose infectious agents by smelling specimens and, sometimes, the body of an infected individual. We trained six dogs of three different breeds to detect SARS-CoV-2 in respiratory secretions of infected patients and evaluated their performance experimentally, comparing it against the gold standard (rRT-PCR). Here we show that viral detection takes one second per specimen. After scent-interrogating 9,200 samples, our six dogs achieved independently and as a group very high sensitivity, specificity, predictive values, accuracy, and likelihood ratio, with very narrow confidence intervals⁠. The highest metric was the negative predictive value, indicating that with a disease prevalence of 7.6%, 99.9% of the specimens indicated as negative by the dogs did not carry the virus. These findings demonstrate that dogs could be useful to track viral infection in humans, allowing COVID-19 free people to return to work safely.

“Speed-accuracy Trade-off in Plants”, Ceccarini et al 2020

“Speed-accuracy trade-off in plants”⁠, Francesco Ceccarini, Silvia Guerra, Alessandro Peressotti, Francesca Peressotti, Maria Bulgheroni, Walter Baccinelli et al (2020-06-15; ⁠, ; similar):

Speed-accuracy trade-off (SAT) is the tendency for decision speed to covary with decision accuracy. SAT is an inescapable property of aimed movements being present in a wide range of species, from insects to primates. An aspect that remains unsolved is whether SAT extends to plants’ movement.

Here, we tested this possibility by examining the swaying in circles of the tips of shoots exhibited by climbing plants (Pisum sativum L.) as they approach to grasp a potential support. In particular, by means of 3-dimensional kinematical analysis, we investigated whether climbing plants scale movement velocity as a function of the difficulty to coil a support.

Results showed that plants are able to process the properties of the support before contact and, similarly to animal species, strategically modulate movement velocity according to task difficulty.

…To date, a great absent in the Fitts’s law literature is the “green kingdom.” At first glance, plants seem relatively immobile, stuck to the ground in rigid structures and, unlike animals, unable to escape stressful environments. But, although markedly different from those of animals, movement pervades all aspects of plant behavior (Darwin & Darwin 1880). As observed by Darwin 1875⁠, the tendrils of climbing plants undergo subtle movements around their axes of elongation. This elliptical movement, known as circumnutation⁠, allows plants to explore their immediate surroundings in search, for instance, of a physical support to enhance light acquisition (Larson 2000). Also, Darwin (1875; see also Trewavas 2017) observed that the tendrils tend to assume the shape of whatever surface before they come into contact with. Implicitly this might signify that they “see” the support and plan the movement accordingly. In this view, climbing plants might be able to plan the course of an action ahead of time and program the tendrils’ choreography according to the “to-be-grasped” object.

Support for this contention comes from both theoretical and empirical studies suggesting that plant movement is not a simple product of cause-effect mechanisms but rather seems to be driven by processes that are anticipatory in nature (eg. Calvo & Friston 2017⁠; Guerra et al 2019). For instance, a recent study shows that a climbing plant (Pisum sativum L.) not only is able to perceive a potential support, but it also scales the kinematics of tendrils’ aperture according to its size well ahead they touch the stimulus (Guerra et al 2019). This has been taken as the demonstration that plants plan the movement purposefully and in ways that are flexible and anticipatory.

With this in mind, one of the empirical predictions stemming from Fitts’s law can be well-suited to model the 3-dimensional circumnutation of plants. Precisely, we refer to the evidence that movement time scales as a function of the target’s size: When the distance is constant, thinner targets are reached more slowly than thicker ones (see Murata & Iwase 2001). We test this prediction in Pisum sativum L. by assessing the change of velocity of the tendrils during their approach-to-grasp a thin or to a thicker support.

Results…The analysis of movement time confirms this evidence, showing that movement time was shorter for the thinner than for the thicker stimulus (β < 0) with a probability of 79.3%. This evidence suggests that plants are able to process the properties of the support and are endowed with a form of perception underwriting a goal-directed and anticipatory behavior (Guerra et al 2019). However, in contrast with previous human and animal literature (eg. Beggs & Howarth 1972⁠; Fitts 1954⁠; Heitz & Schall 2012), our results indicate an opposite pattern of what Fitts’s law predicts. Remember that according to Fitts’s law, the velocity of the movement is inversely proportional to ID (2D/​W). In other words, our results seem to suggest that plants exhibit more difficulty grasping a thicker than a thinner support. These findings are line with previous reports showing a lower success rate of attachment for thick supports (Peñalosa 1982), and a preference for plants to climb supports with a smaller diameter (Darwin 1875; Putz 1984⁠; Putz & Holbrook 1992 [The Biology of Vines]). Furthermore, by using the curvature of tendrils during the twining phase, Goriely & Neukirch 2006 demonstrate that for thinner supports, the contact angle (ie.t, the angle between the tip of the tendril and the tangent of the support) is a near-zero value. Instead, with thicker supports, the contact angle tends to increase as tendrils must curl into the support’s surface to maintain an efficient grip. When the support is too thick, the contact angle increases to an extent that the tendril curls back on itself, losing grip. Interestingly, field studies in rainforests showed that the presence of climbing plants tends to decrease in areas in which there is a prevalence of thicker supports (Carrasco-Urra & Gianoli 2009).

A possible explanation for this phenomenon may reside in the fact that, for plants, reaching to grasp thick supports is a more energy consuming process than grasping for thinner ones. Indeed, the grasping of a thick support implies that plants have to increase the tendril length in order to efficiently coil the support (Rowe et al 2006), and to strengthen the tensional forces to resist gravity (Gianoli 2015)

“Are Humans Constantly but Subconsciously Smelling Themselves?”, Perl et al 2020

“Are humans constantly but subconsciously smelling themselves?”⁠, Ofer Perl, Eva Mishor, Aharon Ravia, Inbal Ravreby, Noam Sobel (2020-04-20; backlinks; similar):

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 statistically-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, ~94% of ~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.

“Developmentally Regulated Volatiles Geosmin and 2-methylisoborneol Attract a Soil Arthropod to Streptomyces Bacteria Promoting Spore Dispersal”, Becher et al 2020

2020-becher.pdf: “Developmentally regulated volatiles geosmin and 2-methylisoborneol attract a soil arthropod to Streptomyces bacteria promoting spore dispersal”⁠, Paul G. Becher, Vasiliki Verschut, Maureen J. Bibb, Matthew J. Bush, Béla P. Molnár, Elisabeth Barane et al (2020-04-06; ; similar):

Volatile compounds emitted by bacteria are often sensed by other organisms as odours, but their ecological roles are poorly understood. Well-known examples are the soil-smelling terpenoids geosmin and 2-methylisoborneol (2-MIB), which humans and various animals sense at extremely low concentrations. The conservation of geosmin biosynthesis genes among virtually all species of Streptomyces bacteria (and genes for the biosynthesis of 2-MIB in about 50%), suggests that the volatiles provide a selective advantage for these soil microbes.

We show, in the present study, that these volatiles mediate interactions of apparent mutual benefit between streptomycetes and springtails (Collembola).

In field experiments, springtails were attracted to odours emitted by Streptomyces colonies. Geosmin and 2-MIB in these odours induce electrophysiological responses in the antennae of the model springtail Folsomia candida, which is also attracted to both compounds. Moreover, the genes for geosmin and 2-MIB synthases are under the direct control of sporulation-specific transcription factors, constraining emission of the odorants to sporulating colonies. F. candida feeds on the Streptomyces colonies and disseminates spores both via faecal pellets and through adherence to its hydrophobic cuticle.

The results indicate that geosmin and 2-MIB production is an integral part of the sporulation process, completing the Streptomyces life cycle by facilitating dispersal of spores by soil arthropods.

“An Unmet Need: Patients With Smell and Taste Disorders”, Erskine & Philpott 2019

2019-erskine.pdf: “An unmet need: Patients with smell and taste disorders”⁠, Sally E. Erskine, Carl M. Philpott (2019-12-19; similar):

Objectives: There are large numbers of patients with olfactory disturbance in the UK and shortfalls in assessment and support amongst mainstream practice in both primary and secondary care leading to substantial quality-of-life impairment and potential missed diagnoses. The aim of this study was to determine the key themes which can be identified from the accounts of anosmia sufferers and to identify important areas to target for future research or service development.

Design: Qualitative analysis of written patient accounts from patients corresponding with a tertiary smell and taste clinic in the UK. This qualitative study utilised unstructured written patient accounts from consenting patients experiencing olfactory disturbances received by the smell and taste clinic. Framework analysis was performed using Nvivo 10 software.

Setting: Tertiary smell and taste clinic.

Participants: Consenting patients who contacted the smell and taste clinic with accounts of their experiences.

Main Outcome Measures: Themes generated by qualitative analysis with Nvivo software.

Results: Accounts submitted by 71 participants were included in the analysis; age range 31–80 years, 45 females, 26 males. Themes identified include negative emotional impact, feelings of isolation, impaired relationships and daily functioning, impact on physical health and the difficulty and financial burden of seeking help.

Conclusions: Olfactory disturbances have a wide-ranging impact on the lives of sufferers, compounded by a lack of knowledge of the disorder amongst clinicians. There is a role for further support and education both for sufferers and for clinicians, as well as a need to improve our understanding of olfactory disturbance.

“Human Olfaction without Apparent Olfactory Bulbs”, Weiss et al 2019

“Human Olfaction without Apparent Olfactory Bulbs”⁠, Tali Weiss, Timna Soroka, Lior Gorodisky, Sagit Shushan, Kobi Snitz, Reut Weissgross, Edna Furman-Haran et al (2019-11-06; similar):

  • Humans can have normal olfaction without apparent olfactory bulbs
  • Olfaction without apparent bulbs is seen in 0.6% of women, but not in men
  • Olfaction without apparent bulbs is associated with left-handedness

The olfactory bulbs (OBs) are the first site of odor representation in the mammalian brain, and their unique ultrastructure is considered a necessary substrate for spatiotemporal coding of smell.

Given this, we were struck by the serendipitous observation at MRI of 2 otherwise healthy young left-handed women, yet with no apparent OBs. Standardized tests revealed normal odor awareness, detection, discrimination, identification, and representation. Functional MRI of these women’s brains revealed that odorant-induced activity in the piriform cortex⁠, the primary OB target, was similar in its extent to that of intact controls. Finally, review of a public brain-MRI database with 1,113 participants (606 women) also tested for olfactory performance, uncovered olfaction without anatomically defined OBs in ~0.6% of women and ~4.25% of left-handed women.

Thus, humans can perform the basic facets of olfaction without canonical OBs, implying extreme plasticity in the functional neuroanatomy of this sensory system.

[Keywords:, olfaction, olfactory bulb, olfactory perception, odor coding, structural brain imaging, functional brain imaging, anosmia, left-handedness, brain plasticity]

“Machine Learning for Scent: Learning Generalizable Perceptual Representations of Small Molecules”, Sanchez-Lengeling et al 2019

“Machine Learning for Scent: Learning Generalizable Perceptual Representations of Small Molecules”⁠, Benjamin Sanchez-Lengeling, Jennifer N. Wei, Brian K. Lee, Richard C. Gerkin, Alán Aspuru-Guzik, Alexander B. Wiltschko et al (2019-10-23; ; similar):

Predicting the relationship between a molecule’s structure and its odor remains a difficult, decades-old task. This problem, termed quantitative structure-odor relationship (QSOR) modeling, is an important challenge in chemistry, impacting human nutrition, manufacture of synthetic fragrance, the environment, and sensory neuroscience.

We propose the use of graph neural networks for QSOR, and show they significantly out-perform prior methods on a novel data set labeled by olfactory experts. Additional analysis shows that the learned embeddings from graph neural networks capture a meaningful odor space representation of the underlying relationship between structure and odor, as demonstrated by strong performance on two challenging transfer learning tasks.

Machine learning has already had a large impact on the senses of sight and sound. Based on these early results with graph neural networks for molecular properties, we hope machine learning can eventually do for olfaction what it has already done for vision and hearing.

“Genetic Variation across the Human Olfactory Receptor Repertoire Alters Odor Perception”, Trimmer et al 2019

2019-trimmer.pdf: “Genetic variation across the human olfactory receptor repertoire alters odor perception”⁠, C. Trimmer, A. Keller, N. R. Murphy, L. L. Snyder, J. R. Willer, M. H. Nagai, N. Katsanis, L. B. Vosshall et al (2019-05-07; ; similar):

A persistent mystery in olfaction is how the combinatorial activation of a family of 400 olfactory receptors (ORs) encodes odor perception. We take advantage of the high frequency of natural OR knockouts in the human genome to tackle a major bottleneck in the field—namely, how an odor is transduced into perceptual characteristics. We demonstrate that loss of function of an individual OR correlates with changes in perceived intensity and pleasantness. This study demonstrates how natural variation can provide important clues to the normal translation of OR activation to odor information and places a constraint on the amount of redundancy in the olfactory code.

Humans use a family of more than 400 olfactory receptors (ORs) to detect odors, but there is currently no model that can predict olfactory perception from receptor activity patterns. Genetic variation in human ORs is abundant and alters receptor function, allowing us to examine the relationship between receptor function and perception.

We sequenced the OR repertoire in 332 individuals and examined how genetic variation affected 276 olfactory phenotypes, including the perceived intensity and pleasantness of 68 odorants at 2 concentrations, detection thresholds of 3 odorants, and general olfactory acuity.

Genetic variation in a single OR was frequently associated with changes in odorant perception, and we validated 10 cases in which in vitro OR function correlated with in vivo odorant perception using a functional assay. In 8 of these 10 cases, reduced receptor function was associated with reduced intensity perception. In addition, we used participant genotypes to quantify genetic ancestry and found that, in combination with single OR genotype, age, and gender, we can explain between 10% and 20% of the perceptual variation in 15 olfactory phenotypes, highlighting the importance of single OR genotype, ancestry, and demographic factors in the variation of olfactory perception.

[Keywords: olfaction, genetic variation, human genome, odor intensity, ancestry]

“Discovery of Volatile Biomarkers of Parkinson’s Disease from Sebum”, Trivedi et al 2018

“Discovery of volatile biomarkers of Parkinson’s disease from sebum”⁠, Drupad K. Trivedi, Eleanor Sinclair, Yun Xu, Depanjan Sarkar, Camilla Liscio, Phine Banks, Joy Milne et al (2018-11-15; backlinks; similar):

Parkinson’s disease (PD) is a progressive, neurodegenerative disease that presents with significant motor symptoms, for which there is no diagnostic test (1–3). We have serendipitously identified a hyperosmic individual, a ‘Super Smeller’ that can detect PD by odor alone, and our early pilot studies have indicated that the odor was present in the sebum from the skin of PD subjects(4). Here, we have employed an unbiased approach to investigate the volatile metabolites of sebum samples obtained non-invasively from the upper back of 64 participants in total (21 controls and 43 PD subjects). Our results, validated by an independent cohort, identified a distinct volatiles-associated signature of PD, including altered levels of perillic aldehyde and eicosane, the smell of which was then described as being highly similar to the scent of PD by our ‘Super Smeller’.

1 sentence summary

Metabolomics identifies volatile odorous compounds from patient sebum that associate with the smell of Parkinson’s.

“The Odor Value Concept in the Formal Analysis of Olfactory Art”, Kraft 2018

2019-kraft.pdf: “The Odor Value Concept in the Formal Analysis of Olfactory Art”⁠, Philip Kraft (2018-11-12; similar):

In the past 15 years, there has been a tremendous increase in the emergence of olfactory artworks despite the traditional skepticism with respect to scents as subjects of art. This essay submits that this skepticism lacks aesthetic justification; art is what is accepted as such, and olfactory art is in fact already well accepted as an art form by the general public. However, there exists no methodological tool for the formal analysis of olfactory artworks. The essay suggests such a method, based on odor values; this is elaborated using the fragrance ‘Dune’ (Dior, 1991), and is compared with a purely visual approach to the same subject. This new concept allows for the derivation of simple compositional sketches and is then exemplified by the formal analysis of three more recent olfactory artworks: Elodie Pong/​Roman Kaiser, ‘White’ (2016), Martynka Wawrzyniak/​Yann Vasnier, ‘Tears (T6)’ (2012), and Christophe Laudamiel, ‘heat’ (2003).

…When the fragrance materials mentioned above are combined to give a rough preliminary sketch of ‘Dune’ (Dior, 1991), that is, a basic outline of the fragrance, analogous to the initial sketch of an artist outlining the basic idea for a painting, drawing or sculpture, it becomes apparent that the somewhat green-leafy seaweed contrast of the original is missing, which would seem to require the further addition of an ingredient providing a natural green-leafy note such as Stemone (d2) in the compositional sketch. Of course, the genuine perfume ‘Dune’ (Dior, 1991) consists of many more materials, likely around 40 ingredients; yet, with these 12 compositional cornerstones one can already well sketch out, study and contemplate about the fragrance.

This provides the basis of a method for assessment of fragrances as objets d’art. After having identified the key elements of a scent, the individual odorants are arranged according to their evaporation profile (vapor pressures) from volatile to substantive. We can then outline each one as a block, the width of which corresponds to the perceived intensity of the ingredient, while the height indicates the duration of its perception moving along the evaporation curve of the scent from top to middle to base note. The y-axis will thus be a measure of the percentage amount of a given material in the formula, while the x-axis will correspond to the common logarithm of the odor value (OV) as a measure of intensity…To account for the fact that the sensory perception of potency is not linear but exponential, the common logarithm is used to correlate our perception with the mathematical data, and both correlate astonishingly well. Thus, after adjusting and equilibrating the individual odor blocks in different trials for ‘Dune’ (Dior, 1991), the schematic representation delineated in Figure 2 was obtained in the fourth trial.

Figure 2: Schematic representation of ‘Dune’ (Dior, 1991) with the common logarithm of the odor value (x-axis) plotted against the amounts (y-axis) to derive the sketch of Table 1 (d1 in the table corresponds to ② in this figure, etc.).

…‘Tears (T6)’ is the most interesting work of the ‘Smell Me’ series as it is the lightest, brightest, most uplifting and cheerful scent, although or quite possibly because the underlying tears weren’t anything but tears of joy (Figure 6). Wawrzyniak collected her tears in crying sessions by listening to songs from her childhood, including for instance those from the Polish movie ‘Akademia Pana Kleska’ (1983), and a tape recording with her parents when she was four years of age (Figure 7). Interestingly, she observed in her crying sessions that the smell of her tears changed according to the trigger of her sadness.

“Effects of Latent Toxoplasmosis on Olfactory Functions of Men and Women”, Flegr et al 2017

“Effects of latent Toxoplasmosis on olfactory functions of men and women”⁠, Jaroslav Flegr, Manfred Milinski, Šárka Kaňková, Martin Hůla, Jana Hlaváčová, Kateřina Sýkorová (2017-12-10; ⁠, ; similar):

The prevalence of Toxoplasmosis is higher in schizophrenics than in the general population. It has been suggested that certain symptoms of schizophrenia, including changes in olfactory functions, are in fact symptoms of Toxoplasmosis that can be easily detected in schizophrenics only due to the increased prevalence of Toxoplasmosis in this population. Schizophrenics have impaired identification of odors and lower sensitivity of odor detection. Here we searched for differences in olfactory functions between 62 infected and 61 non infected non-schizophrenic subjects. The infected men scored better in the standard odor-identification test. The infected women rated all smells as more intensive while the infected men rated nearly all smells as less intensive. Infected women rated the pleasantness of the smell of undiluted cat urine as higher than the non-infected women and the opposite was true for the men (the opposite direction shifts in men and women were described earlier for highly diluted cat urine). Toxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli. Our results suggest that latent Toxoplasmosis is associated with changes in the olfactory functions in humans; however, the observed changes differ from those observed in schizophrenics.

Key findings

Infected men but not women show better odor identification ability than the non-infected controls.

The infected women rated all smells as more and men as less intensive than the controls.

The infected women rated smell of cat urine as more and men as less pleasurable than the controls.

Toxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli.

We found no new evidence for the Toxoplasmosis hypothesis of schizophrenia.

“The Sense of Smell Impacts Metabolic Health and Obesity”, Riera et al 2017

“The Sense of Smell Impacts Metabolic Health and Obesity”⁠, Celine E. Riera, Eva Tsaousidou, Jonathan Halloran, Patricia Follett, Oliver Hahn, Mafalda M. A. Pereira et al (2017-07-05; ; similar):

  • Loss of adult olfactory neurons protects against diet-induced obesity
  • Loss of smell after obesity also reduces fat mass and insulin resistance
  • Loss of IGF1 receptors in olfactory sensory neurons (OSNs) improves olfaction
  • Loss of IGF1R in OSNs increases adiposity and insulin resistance

Olfactory inputs help coordinate food appreciation and selection, but their role in systemic physiology and energy balance is poorly understood. Here we demonstrate that mice upon conditional ablation of mature olfactory sensory neurons (OSNs) are resistant to diet-induced obesity accompanied by increased thermogenesis in brown and inguinal fat depots. Acute loss of smell perception after obesity onset not only abrogated further weight gain but also improved fat mass and insulin resistance. Reduced olfactory input stimulates sympathetic nerve activity, resulting in activation of β-adrenergic receptors on white and brown adipocytes to promote lipolysis. Conversely, conditional ablation of the IGF1 receptor in OSNs enhances olfactory performance in mice and leads to increased adiposity and insulin resistance. These findings unravel a new bidirectional function for the olfactory system in controlling energy homeostasis in response to sensory and hormonal signals.

[Keywords: olfactory sensory neuron, hyposmia, hyperosmia, diet-induced obesity, energy balance, thermogenesis, lipolysis, insulin-like growth factor 1 receptor, insulin resistance]

Our sense of smell is key to the enjoyment of food, so it may be no surprise that in experiments at the University of California, Berkeley, obese mice who lost their sense of smell also lost weight.

What’s weird, however, is that these slimmed-down but smell-deficient mice ate the same amount of fatty food as mice that retained their sense of smell and ballooned to twice their normal weight.

In addition, mice with a boosted sense of smell—super-smellers—got even fatter on a high-fat diet than did mice with normal smell.

The findings suggest that the odor of what we eat may play an important role in how the body deals with calories. If you can’t smell your food, you may burn it rather than store it.

These results point to a key connection between the olfactory or smell system and regions of the brain that regulate metabolism, in particular the hypothalamus, though the neural circuits are still unknown.

“This paper is one of the first studies that really shows if we manipulate olfactory inputs we can actually alter how the brain perceives energy balance, and how the brain regulates energy balance”, said Céline Riera, a former UC Berkeley postdoctoral fellow now at Cedars-Sinai Medical Center in Los Angeles.

…“Sensory systems play a role in metabolism. Weight gain isn’t purely a measure of the calories taken in; it’s also related to how those calories are perceived”, said senior author Andrew Dillin, the Thomas and Stacey Siebel Distinguished Chair in Stem Cell Research, professor of molecular and cell biology and Howard Hughes Medical Institute Investigator. “If we can validate this in humans, perhaps we can actually make a drug that doesn’t interfere with smell but still blocks that metabolic circuitry. That would be amazing.”

“Poor Human Olfaction Is a 19th-century Myth”, McGann 2017

“Poor human olfaction is a 19th-century myth”⁠, John P. McGann (2017-05-12; ; similar):

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.

“Body Odor Based Personality Judgments: The Effect of Fragranced Cosmetics”, Sorokowska et al 2016

“Body Odor Based Personality Judgments: The Effect of Fragranced Cosmetics”⁠, Agnieszka Sorokowska, Piotr Sorokowski, Jan Havlíček (2016-04-18; ; similar):

People can accurately assess various personality traits of others based on body odor (BO) alone. Previous studies have shown that correlations between odor ratings and self-assessed personality dimensions are evident for assessments of neuroticism and dominance. Here, we tested differences between assessments based on natural body odor alone, without the use of cosmetics and assessments based on the body odor of people who were allowed to use cosmetics following their daily routine.

67 observers assessed samples of odors from 113 odor donors (each odor donor provided 2 samples—one with and one without cosmetic use); the donors provided their personality ratings, and the raters judged personality characteristics of the donors based on the provided odor samples.

Correlations between observers’ ratings and self-rated neuroticism were stronger when raters assessed body odor in the natural body odor condition (natural BO condition; rs = 0.20) than in the cosmetics use condition (BO+cosmetics condition; rs = 0.15). Ratings of dominance statistically-significantly predicted self-assessed dominance in both conditions (rs = 0.34 for natural BO and rs = 0.21 for BO+cosmetics), whereas ratings of extraversion did not predict self-assessed extraversion in either condition. In addition, ratings of body odor attractiveness and pleasantness were statistically-significantly lower in natural BO condition than in BO+cosmetics condition, although the intensity of donors’ body odors was similar under both conditions.

Our findings suggest that although olfaction seems to contribute to accurate first impression judgments of certain personality traits, cosmetic use can affect assessments of others based on body odor.

“A Social Chemosignaling Function for Human Handshaking”, Frumin et al 2015

“A social chemosignaling function for human handshaking”⁠, Idan Frumin, Ofer Perl, Yaara Endevelt-Shapira, Ami Eisen, Neetai Eshel, Iris Heller, Maya Shemesh, Aharon Ravia et al (2015-03-03; similar):

Social chemosignaling is a part of human behavior, but how chemosignals transfer from one individual to another is unknown. In turn, humans greet each other with handshakes, but the functional antecedents of this behavior remain unclear.

To ask whether handshakes are used to sample conspecific social chemosignals, we covertly filmed 271 subjects within a structured greeting event either with or without a handshake.

We found that humans often sniff their own hands, and selectively increase this behavior after handshake. After handshakes within gender, subjects increased sniffing of their own right shaking hand by more than 100%. In contrast, after handshakes across gender, subjects increased sniffing of their own left non-shaking hand by more than 100%. Tainting participants with unnoticed odors statistically-significantly altered the effects, thus verifying their olfactory nature.

Thus, handshaking may functionally serve active yet subliminal social chemosignaling, which likely plays a large role in ongoing human behavior.

Animals often sniff each other as a form of greeting to communicate with each other through chemical signals in their body odors. However, in humans this form of behavior is considered taboo, especially between strangers.

Scientists argue that, in spite of our efforts to avoid being ‘smelly’, we may actually smell each other without being aware that we do so. Here, Frumin et al 2015 first put on latex gloves and then shook hands with volunteers to collect samples of their odor. Chemical analysis of the gloves found that a handshake alone was sufficient to transfer the volunteers’ odor. These odors were made of chemicals that are similar to ones that animals smell when sniffing each other.

Therefore, when we shake hands with a stranger, it is possible that we may inadvertently smell the stranger’s chemical signals. To address this possibility, Frumin et al 2015 investigated how humans behave after shaking hands with a stranger. Volunteers were asked to wait in a room alone before they were greeted by one of the researchers. Some of these volunteers were greeted with a handshake and others were greeted without a handshake. Afterwards, all the volunteers spent some time in a room by themselves where their behavior was covertly monitored.

Frumin et al 2015 found that volunteers who shook hands were more likely to sniff their hand, for example, by touching their nose when they were in the room on their own, than those who did not shake hands. After the volunteers shook hands with someone of their own gender, they spent more time sniffing their right hand (the one they had used for the handshake). However, after the volunteers shook hands with someone of the opposite gender, they spent more time sniffing their left hand instead.

Next, the body odor of some of the experimenters was tainted by perfumes or gender-specific odors. Volunteers who shook hands with these tainted individuals behaved differently; when the experimenter was tainted with perfume the volunteers spent more time sniffing their own hands, but when the experimenter was tainted with a gender-specific odor they spent less time sniffing of their own hands. This shows that different smells influenced the hand sniffing behavior of the volunteers.

Frumin et al 2015’s findings suggest that a simple handshake may help us to detect chemical signals from other people. Depending on the person’s gender, we may respond by sniffing our right hand to check out the person’s odor, or our left hand to smell ourselves in comparison. Future studies will involve finding out how this sniffing behavior could work as an unconscious form of human communication.

“Scent of the Familiar: An FMRI Study of Canine Brain Responses to Familiar and Unfamiliar Human and Dog Odors”, Berns et al 2015

“Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors”⁠, Gregory S. Berns, Andrew M. Brooks, Mark Spivak (2015-01; ⁠, ; similar):

  • fMRI in 12 awake, unrestrained dogs.
  • Presented 5 scents: (1) familiar human; (2) strange human; (3) familiar dog; (4) strange dog; (5) self.
  • On average, all scents activated olfactory bulb.
  • Only “familiar human” activated caudate nucleus.
  • Suggests reward-response is reserved for familiar humans over conspecifics.

Understanding dogs’ perceptual experience of both conspecifics and humans is important to understand how dogs evolved and the nature of their relationships with humans and other dogs. Olfaction is believed to be dogs’ most powerful and perhaps important sense and an obvious place to begin for the study of social cognition of conspecifics and humans.

We used fMRI in a cohort of dogs (n = 12) that had been trained to remain motionless while unsedated and unrestrained in the MRI. By presenting scents from humans and conspecifics, we aimed to identify the dimensions of dogs’ responses to salient biological odors—whether they are based on species (dog or human), familiarity, or a specific combination of factors. We focused our analysis on the dog’s caudate nucleus because of its well-known association with positive expectations and because of its clearly defined anatomical location. We hypothesized that if dogs’ primary association to reward, whether it is based on food or social bonds, is to humans, then the human scents would activate the caudate more than the conspecific scents. Conversely, if the smell of conspecifics activated the caudate more than the smell of humans, dogs’ association to reward would be stronger to their fellow canines. 5 scents were presented (self, familiar human, strange human, familiar dog, strange dog).

While the olfactory bulb/​peduncle was activated to a similar degree by all the scents, the caudate was activated maximally to the familiar human. Importantly, the scent of the familiar human was not the handler, meaning that the caudate response differentiated the scent in the absence of the person being present. The caudate activation suggested that not only did the dogs discriminate that scent from the others, they had a positive association with it.

This speaks to the power of the dog’s sense of smell, and it provides important clues about the importance of humans in dogs’ lives.

[Keywords: fMRI, canine, olfaction, social cognition, reward]

“Comparative Analysis of the Domestic Cat Genome Reveals Genetic Signatures Underlying Feline Biology and Domestication”, Montague et al 2014

2014-montague.pdf: “Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication”⁠, Michael J. Montague, Gang Li, Barbara Gandolfi, Razib Khan, Bronwen L. Aken, Steven M. J. Searle, Patrick Minx et al (2014-10-03; ⁠, ⁠, ; backlinks; similar):

Little is known about the genetic changes that distinguish domestic cat populations from their wild progenitors. Here we describe a high-quality domestic cat reference genome assembly and comparative inferences made with other cat breeds, wildcats, and other mammals. Based upon these comparisons, we identified positively selected genes enriched for genes involved in lipid metabolism that underpin adaptations to a hypercarnivorous diet. We also found positive selection signals within genes underlying sensory processes, especially those affecting vision and hearing in the carnivore lineage. We observed an evolutionary tradeoff between functional olfactory and vomeronasal receptor gene repertoires in the cat and dog genomes, with an expansion of the feline chemosensory system for detecting pheromones at the expense of odorant detection. Genomic regions harboring signatures of natural selection that distinguish domestic cats from their wild congeners are enriched in neural crest-related genes associated with behavior and reward in mouse models, as predicted by the domestication syndrome hypothesis. Our description of a previously unidentified allele for the gloving pigmentation pattern found in the Birman breed supports the hypothesis that cat breeds experienced strong selection on specific mutations drawn from random bred populations. Collectively, these findings provide insight into how the process of domestication altered the ancestral wildcat genome and build a resource for future disease mapping and phylogenomic studies across all members of the Felidae.

“Perceptual Convergence of Multi-component Mixtures in Olfaction Implies an Olfactory White”, Weiss et al 2012

“Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white”⁠, Tali Weiss, Kobi Snitz, Adi Yablonka, Rehan M. Khan, Danyel Gafsou, Elad Schneidman, Noam Sobel (2012-12-04; backlinks; similar):

In vision, two mixtures, each containing an independent set of many different wavelengths, may produce a common color percept termed “white.” In audition, two mixtures, each containing an independent set of many different frequencies, may produce a common perceptual hum termed “white noise.” Visual and auditory whites emerge upon two conditions: when the mixture components span stimulus space, and when they are of equal intensity. We hypothesized that if we apply these same conditions to odorant mixtures, “whiteness” may emerge in olfaction as well. We selected 86 molecules that span olfactory stimulus space and individually diluted them to a point of about equal intensity. We then prepared various odorant mixtures, each containing various numbers of molecular components, and asked human participants to rate the perceptual similarity of such mixture pairs. We found that as we increased the number of non-overlapping, equal-intensity components in odorant mixtures, the mixtures became more similar to each other, despite not having a single component in common. With ~30 components, most mixtures smelled alike. After participants were acquainted with a novel, arbitrarily named mixture of ~30 equal-intensity components, they later applied this name more readily to other novel mixtures of ~30 equal-intensity components spanning stimulus space, but not to mixtures containing fewer components or to mixtures that did not span stimulus space. We conclude that a common olfactory percept, “olfactory white”, is associated with mixtures of ~30 or more equal-intensity components that span stimulus space, implying that olfactory representations are of features of molecules rather than of molecular identity.

“Nature's Spoils: The Underground Food Movement Ferments Revolution”, Bilger 2010

“Nature's Spoils: The underground food movement ferments revolution”⁠, Burkhard Bilger (2010-11-22; ; similar):

[Discussion of food subcultures: dumpster divers, raw food enthusiasts, fermenters, roadkill, and ‘high’ (fully rotten meat) food advocates, with visits to gay commune Hickory Knoll and raw milk dairies. The author ultimately draws the line at trying high game, however.]

When Torma unclamped his jar, a sickly-sweet miasma filled the air—an odor as natural as it was repellent. Decaying meat produces its own peculiar scent molecules, I later learned, with names like putrescine and cadaverine. I could still smell them on my clothes hours later. Torma stuck two fingers down the jar and fished out a long, wet sliver. “Want a taste?” he said.

It was the end of a long day. I’d spent most of it consuming everything set before me: ants, acorns, raw milk, dumpster stew, and seven kinds of mead, among other delicacies. But even Katz took a pass on high meat. While Torma threw back his head and dropped in his portion, like a seal swallowing a mackerel, we quietly took our leave. “You have to trust your senses”, Katz said, as we were driving away. “To me, that smelled like death.”

“Predators Are Attracted to the Olfactory Signals of Prey”, Hughes et al 2010

“Predators Are Attracted to the Olfactory Signals of Prey”⁠, Nelika K. Hughes, Catherine J. Price, Peter B. Banks (2010-09-04; ; backlinks; similar):


Predator attraction to prey social signals can force prey to trade-off the social imperatives to communicate against the profound effect of predation on their future fitness. These tradeoffs underlie theories on the design and evolution of conspecific signalling systems and have received much attention in visual and acoustic signalling modes. Yet while most territorial mammals communicate using olfactory signals and olfactory hunting is widespread in predators, evidence for the attraction of predators to prey olfactory signals under field conditions is lacking.

Methodology/​Principal Findings:

To redress this fundamental issue, we examined the attraction of free-roaming predators to discrete patches of scents collected from groups of two and six adult, male house mice, Mus domesticus, which primarily communicate through olfaction. Olfactorily-hunting predators were rapidly attracted to mouse scent signals, visiting mouse scented locations sooner, and in greater number, than control locations. There were no effects of signal concentration on predator attraction to their prey’s signals.


This implies that communication will be costly if conspecific receivers and eavesdropping predators are simultaneously attracted to a signal. Significantly, our results also suggest that receivers may be at greater risk of predation when communicating than signalers, as receivers must visit risky patches of scent to perform their half of the communication equation, while signalers need not.

“Material Degradomics: On the Smell of Old Books”, Strlič et al 2009

2009-strlic.pdf: “Material Degradomics: On the Smell of Old Books”⁠, Matija Strlič, Jacob Thomas, Tanja Trafela, Linda Cséfalvayová, Irena Kralj Cigić, Jana Kolar, May Cassar et al (2009-09-17; similar):

We successfully transferred and applied ✱-omics concepts to the study of material degradation, in particular historic paper.

The main volatile degradation products of paper, constituting the particular “smell of old books”, were determined using headspace analysis after a 24 h predegradation procedure.

Using supervised and unsupervised methods of multivariate data analysis, we were able to quantitatively correlate volatile degradation products with properties important for the preservation of historic paper: rosin⁠, lignin and carbonyl group content, degree of polymerization of cellulose⁠, and paper acidity. On the basis of volatile degradic footprinting, we identified degradation markers for rosin and lignin in paper and investigated their effect on degradation. Apart from the known volatile paper degradation products acetic acid and furfural⁠, we also put forward a number of other compounds of potential interest, most notably lipid peroxidation products.

The nondestructive approach can be used for rapid identification of degraded historic objects on the basis of the volatile degradation products emitted by degrading paper.

[Keywords: degradation, organic polymers, biopolymers, materials, volatile organic compounds]

[Analytical Chemistry: …“Ordinarily, traditional analytical methods like [LC] are used to test paper samples that have been ripped out”, Strlič says. “The advantage of our method is that it’s nondestructive.”

Strlič calls the method “material degradomics”. Like other ✱-omic methods in research, he explains, material degradomics correlates phenotype—i.e., a book’s condition—to metabolic byproducts: in this case, VOC emissions from degrading paper.

The team analyzed 72 well-characterized historical papers from the 19th and 20th centuries. These documents included papers made with rosin (a pine tar resin), bleached pulp, groundweed, and rag fiber. VOCs from these papers were measured using GC/​MS. The 15 most abundant VOCs were then related statistically to key constituents in paper, including lignin, reducing carbonyl content, rosin, ash, pH, degree of polymerization, and protein content. The scientists used partial least squares (PLS) multivariate regression models to relate VOC peaks to their underlying chemical sources in paper, Strlič says. The team took this approach because different chemical constituents can emit the same VOCs, he explains. PLS is better suited to co-correlated data than classical regression models, which resolve more independent data sets.

From a degradation standpoint, the 2 most problematic constituents in paper are lignin and rosin, Strlič explains. Lignin—a natural component in wood fiber, which replaced the more durable rag paper made before 1850—yellows with age. And rosin, which is a hydrophobic compound added to paper to make it suitable for writing, eventually breaks down into corrosive, acidic byproducts. As these 2 constituents degrade, they emit characteristic patterns of VOC emissions at predictive levels, Strlič and his colleagues found. Lignin releases acetic acid, hexanol, and furfural, whereas rosin gives off various aldehydes and ketones, in addition to 2-ethylhexanol⁠. Some constituents—notably ash and protein content—could not be correlated with any VOC emissions.

Strlič hopes material degradomics methods will one day be used to evaluate culturally-significant, historical papers. Ideally, a hand-held analytical device could “sniff” valuable holdings on a book-by-book basis, he says. Gerrit de Bruin, head of conservation at the National Archives in the Hague (The Netherlands), agrees. “We need more nondestructive tools for cultural forensics”, he says. “As an end-user of this technology, I find the concept promising.”

De Bruin and other specialists in the field worry especially about books, newspapers, and other documents made from 1850 to 1990. Paper products made during this period were “sized”, or saturated, with rosin precipitated into fiber. The acidic byproducts released by rosin cause paper to degrade nearly 10× faster than earlier papers, which were sized with gelatin⁠, a more neutral additive, Strlič explains. In the U.S. and elsewhere, rosin sizing was phased out for environmental reasons (rosin-containing pulp and paper effluents are toxic) and because the U.S. Permanent Paper Law⁠, passed in 1990, gave paper mills incentives to convert to more alkaline processes. Meanwhile, papers made from 1850 to 1990 could degrade within one to 2 centuries after their production, posing a crisis for archives around the world.]

“The Aesthetics of Smelly Art”, Shiner & Kriskovets 2007

2007-shiner.pdf: “The Aesthetics of Smelly Art”⁠, Larry Shiner, Yulia Kriskovets (2007-08-06; similar):

The remarkable increase in the number of artworks that foreground scents and odors during recent years suggests the need for an assessment of the aesthetic and artistic possibilities of smell. Because there has been so little olfactory art in the past, it is hardly surprising that this area has been largely neglected by philosophical aesthetics.

This essay is intended as a survey of theoretical issues raised by olfactory art and as a defense of its practice against traditional skepticism about the aesthetic and artistic relevance of scents. Although the complexity of some of the individual issues would be worthy of an entire article, we have chosen to offer an overview in the hope of attracting other philosophers, as well as critics and curators, to consider this fascinating new area for reflection. As interesting as it would be to explore the aesthetic aspects of the everyday experience of smells or the use of odors in cultural ceremonies such as Japanese Kodo or even the use of odors to accompany plays and films, we focus on contemporary olfactory art meant to be presented in galleries, museums, or as public installations/​performances.2

Because much of this art may be unfamiliar, we begin with several examples of artworks based on odors. Then we examine some traditional objections to smell as a legitimate object of aesthetic attention, and finally, we discuss the art status of olfactory artworks, closing with the complex issue of whether or in what sense perfume is art.

…An artist who has made impressive use of natural scents to create olfactory environments intended to transport the audience into a different world is the Brazilian fabric sculptor, Ernesto Neto, who once packed long, diagonal legs of women’s sheer nylon stockings with the scents of spices such as cloves, cumin, and turmeric as part of the exhibition Wonderland at the St. Louis Art Museum in 2000. Some of the stockings stretched from floor to ceiling, others simply lay on the floor like sacks of colored powders. These nettings spread their scents throughout the museum space, creating a dreamy atmosphere that varied for each visitor depending on his or her associations with the odors.

…Other artists use scents in a more confrontational way, often to illustrate political or social ideas. In the project Actual Odor, the artist Angela Ellsworth wore a jersey cocktail dress soaked in her own urine for the duration of the opening reception for the Token City installation (a subway simulation) by artist Muriel Magenta at the Arizona State University Art Museum (1997). Ellsworth wanted to demonstrate how smell destroys any social boundaries existent in a subway, as it permeates the space and transcends visual barriers or experiences. While wearing the smelly dress, the artist was fanning herself and spreading the odor with a hand fan, one side of which was lettered with the word ‘actual’ and the other side with the word ‘odor.’ Ellsworth mingled with other museum visitors and for continuous periods of time sat in the projection space of Token City. Most of the visitors could smell the unpleasant odor, yet did not associate the nicely dressed woman with the smell, nor could they find the source of the scent. Ellsworth’s work can be grouped with a number of artists who have created site-specific installations involving smells or have taken their performance into the streets.

…One of the most prolific olfactory artists today is the Belgian, Peter de Cupere, whose scent sculptures, scent installations, perfumes, and olfactory performances seek to engage audiences through all the senses, but primarily through scent. Among his scent sculptures is Earthcar (2002), a small car covered with earth and fake green plants, emitting the smells of thyme, anise⁠, pine, olive, and grape. Installations have included Blue Skies (1999) consisting of a blue-painted room with a thousand yards of fishnet and dried fish along with synthetic fish and coconut smells. A work even more focused on odors was his Black Beauty Smell Happening (1999), which teased gallery visitors with a perfume he called “Black Beauty.” During the exhibition, attractive male and female models dressed in black cat suits with cutout patches mingled with the audiences. De Cupere sprayed his perfume, that itself left black traces, on the bare skin showing through the cutouts. For spectators to smell the perfume, they needed to draw their noses close to the “smell zones.”

…Our last example is a work by Helgard Haug, a young performance artist who won a prize in support of a public art piece at the subway station Berlin Alexanderplatz⁠, once the social center of East Berlin. Haug commissioned a distillation of the scents of Berlin Alexanderplatz and put it into little souvenir glass vials that were dispensed in the station during the year 2000. The artist collaborated with Karl-Heinz Burk, a professional from the industrial aroma-producing factory H and R in Braunschweig, to produce her U-deur. The perfumer designed the scent based on his own perception of the station without chemical analysis. U-deur included the smell of bread as one of the primary odors (because there was once a bakery stand in the subway) along with the smells of cleaning agents, oil, and electricity. The public response to the project was extraordinary. People wrote that the little sniff-bottle brought to mind memories and associations with the smells of a divided Berlin, for instance, the “dead” stations that West Berlin subway trains went through after passing the Wall, as well as thoughts about the Stasi archive with its items saturated with the body odor of East German criminals and dissidents.8 Other olfactory artists have done installations evoking the smell of places, such as Sissel Tolaas’s simulation of the odors of Paris, including among other things, the scents of dog droppings, ashtrays, and a slaughterhouse.9Our last example is a work by Helgard Haug, a young performance artist who won a prize in support of a public art piece at the subway station Berlin Alexanderplatz, once the social center of East Berlin. Haug commissioned a distillation of the scents of Berlin Alexanderplatz and put it into little souvenir glass vials that were dispensed in the station during the year 2000. The artist collaborated with Karl-Heinz Burk, a professional from the industrial aroma-producing factory H and R in Braunschweig, to produce her U-deur. The perfumer designed the scent based on his own perception of the station without chemical analysis. U-deur included the smell of bread as one of the primary odors (because there was once a bakery stand in the subway) along with the smells of cleaning agents, oil, and electricity. The public response to the project was extraordinary. People wrote that the little sniff-bottle brought to mind memories and associations with the smells of a divided Berlin, for instance, the “dead” stations that West Berlin subway trains went through after passing the Wall, as well as thoughts about the Stasi archive with its items saturated with the body odor of East German criminals and dissidents.8

Other olfactory artists have done installations evoking the smell of places, such as Sissel Tolaas’s simulation of the odors of Paris, including among other things, the scents of dog droppings, ashtrays, and a slaughterhouse.9

…Although most olfactory artists work with natural odors, the invention of the gas chromatograph and mass spectrometer (GC⁠/​MS), which together can chart the hundreds of chemical components of any odor, has meant that artists can either use the GC/​MS themselves or hire a perfumer or chemist to analyze and reproduce or reshape an existing smell in concentrate. One artist who has taken the latter route is Clara Ursitti, whose electronically dispensed Eau Claire was based on her own body odor and was released when gallery visitors closed the door of a special booth containing it.42 In another work, Bill, the reconstituted scent was dispensed from a small burner in the center of an empty room. The lack of ancillary media make these two works more or less “pure” olfactory art, but like most installations and performances, or even painting and sculpture these days, Ursitti’s works were accompanied by an “artist’s statement” that explained her interest in exploring people’s reactions to scents, and noting, in the case of Eau Claire, that the scent was vaginal, and in the case of Bill, that it was sperm (one should add that Bill was first presented during the Bill Clinton-Monica Lewinsky affair). Thus, both these works required the artist’s statement in order to be understood and interpreted. Without the artist’s statement, many gallery visitors may not have been able to identify even the type of smells offered and mistaken it for a weird perfume.43

“Mechanisms of Scent-tracking in Humans”, Porter et al 2006

2006-porter.pdf: “Mechanisms of scent-tracking in humans”⁠, Jess Porter, Brent Craven, Rehan M. Khan, Shao-Ju Chang, Irene Kang, Benjamin Judkewitz, Jason Volpe et al (2006-12-17; similar):

Whether mammalian scent-tracking is aided by inter-nostril comparisons is unknown. We assessed this in humans and found that (1) humans can scent-track, (2) they improve with practice, (3) the human nostrils sample spatially distinct regions separated by ~3.5 cm and, critically, (4) scent-tracking is aided by inter-nostril comparisons. These findings reveal fundamental mechanisms of scent-tracking and suggest that the poor reputation of human olfaction may reflect, in part, behavioral demands rather than ultimate abilities.

“History of Combinatorial Generation (The Art of Computer Programming: Volume 4: Pre-Fascicle 4B: Section § Pg22”, Knuth 2005-page-22

2005-knuth-taocp-v4-prefascicle4b.pdf#page=22: “History of Combinatorial Generation (The Art of Computer Programming: Volume 4: Pre-Fascicle 4B: Section § pg22”⁠, Donald E. Knuth (2005-10-28; ⁠, )

“The Scent of the Nile: Jean-Claude Ellena Creates a New Perfume”, Burr 2005

“The Scent of the Nile: Jean-Claude Ellena creates a new perfume”⁠, Chandler Burr (2005-03-14; similar):

[Profile of French perfumer Jean-Claude Ellena⁠. One of several high-profile perfumers, he is hired by the luxury brand Hermès to develop a new perfume that can compete with their envied competitors, Chanel⁠. Ellena is charged with creating a new perfume embodying the concepts ‘Egypt’ and ‘the Nile’, somehow.

The process of prototyping perfume candidates is long and involved, requiring many back and forth exchanges, and changes of ingredients to economize or work with suppliers: how a perfume smells straight from the bottle is not how it will smell when being worn and gradually evaporating from body heat, and tweaks in combinations can lead to an entirely different psychologically-perceived smell. The Hermès executives only know it when they smell it. A visit to Egypt itself eventually turns up some candidate ideas, like mangoes. Then the process of iteration begins.]

A master perfumer like Ellena has memorized hundreds, if not thousands, of recipes for manufacturing smells. Many complex natural scents can be conjured with only a few ingredients. The scent of freesia, he explained, is created by combining two simple molecules: beta-ionone and linalool, both synthetics. (To give freesia a cold, metallic edge, a touch of allyl amyl glycolate is added.) The smell of orange blossom is made by combining linalool and methyl anthranilate, which smells like Concord grapes.

In my presence, Ellena once dipped a touche [paper strip] into a molecule called isobutyl phenal acetate, which has a purely chemical smell, and another touche into vanillin, a synthetic version of vanilla. He placed the two paper strips together, waved them, and chocolate appeared in the air. “My métier is to find shortcuts to express as strongly as possible a smell”, he explained. “For chocolate, nature uses eight hundred molecules. I use two.” He handed me four touches—vanillin plus the natural essences of cinnamon, orange, and lime. The combined smell was a precise simulation of Coca-Cola. “With me, one plus one equals three”, Ellena said. “When I add two things, you get much more than two things.”

…Ellena is proud to be an illusionist. “Picasso said, ‘Art is a lie that tells the truth’”, he told me. “That’s perfume for me. I lie. I create an illusion that is actually stronger than reality. Sketch a tree: it’s completely false, yet everyone understands it.” The point of Un Jardin sur le Nil, he said, was not to reproduce the scent of a green mango but, rather, to create a fantasy version of green mango.

…Ellena was now finishing work on a luxurious new collection of scents that would be called the Hermèssences. In Paris, Dubrule had told me that wearing an Hermèssence would be like dining with Pierre Gagnaire or Guy Savoy—“great French chefs who are going to search out unexpected contrasts. We will be able to use some very Hermès materials.” By this, she meant expensive. Her culinary description was metaphorical, but, in fact, Ellena was creating a scent called Ambre Narguilé—a narguilé is a water pipe—which smells of sliced apples wrapped in leaves of blond tobacco and drizzled with caramel, cinnamon, banana, and rum. And on his desk was a vial that contained the beginning of the next Hermèssence. It smelled, he said, like a leather bathing suit emerging from a swimming pool. He was working on a scent that smelled like leather sprinkled with sugar. His goal at Hermès, he said, was “to show that the perfume is not the result of chance but a reflection of a reasoned process.” He made a series of stepping motions with his hand, squinting at a target ahead. “When you start out, it’s more about your passions. At the end, it’s intellectual.”

“The Sense of Smell in the Neuroses and Psychoses”, Brill 1932

1932-brill.pdf: “The Sense of Smell in the Neuroses and Psychoses”⁠, A. A. Brill (1932-01-01; )

“Arithmetic By Smell”, Galton 1894

1894-galton.pdf: “Arithmetic By Smell”⁠, Francis Galton (1894; similar):

It seems worth while to put a few simple experiments on record, which I made for my own satisfaction a few months ago, in order to assure myself that arithmetic may be performed by the sole medium of imaginary smells, just as by imaginary figures or sounds…Whenever the tubing is grasped by the hand, a whiff of scented air is forced through the nozzle; when the grasp is relaxed, fresh air enters through the nozzle and passing through the wool becomes quickly impregnated with scent. The apparatus is then ready to be used again. Whiffs of scented air may thus be sent out 4 or 3 times in moderately quick succession and be almost equally odorous throughout.

…Subtraction succeeded as well as addition. I did not go so far as to associate separate scents with the attitudes of mind severally appropriate to subtraction and addition, but determined by my ordinary mental processes which attitude to assume, before isolating myself in the world of scents…There was not the slightest difficulty in banishing all visual and auditory images from the mind, leaving nothing in the consciousness besides real or imaginary scents.

…A few experiments were made with taste. Salt, sugar, citric acid, and quinine seemed suitable for the purpose, and there appeared to be little difficulty in carrying on the experiments to a sufficient extent to show that arithmetic by taste was as feasible as arithmetic by smell.

[See also: “Multiplying 10-digit numbers using Flickr: The power of recognition memory”⁠, Drucker 2010, “Harnessing vision for computation”⁠, Changizi 2008.]

Truffle § Extraction




Space food








Olfactory white




Dishwasher salmon




Ōoka Tadasuke § Famous cases