Is the perception of odour pleasantness shared across cultures and ecological conditions? Evidence from Amazonia, East Africa, New Guinea, Malaysia and Poland.

What makes an odour pleasant or unpleasant? The inherent properties of the constituent chemical compounds, or the nose of the beholder, driven by idiosyncratic differences and culture-specific learning? Here, 582 individuals, including Tanzanian Hadza hunter-gatherers, Amazonian Tsimane' horticulturalists, Yali from the Papuan highlands and two industrialized populations (Poles, Malaysians), rated the pleasantness of 15 odour samples. We find considerable similarities in odour assessments across cultures, but our data do not fully support a claim regarding the universality of smell preferences. Despite cross-cultural similarities in olfactory assessments, probably driven by odour properties, we suggest that odour availability in ecological and cultural niches bears an undeniable effect on human odour preferences.

Typical diet and type of economy do not predict food-sharing behaviors in three Tanzanian societies.

Food sharing behavior is a widely observed phenomenon, and it draws attention of scholars interested in finding both proximate and ultimate explanations of such practices. In the current study, we focused on possible socio-economic and environmental food-sharing predictors: type of economy (i.e., immediate-return vs. delayed-return) and typical diet composition (i.e., proportion of proteins and carbohydrates in typical daily caloric intake). We investigated whether members of three societies from Tanzania (N = 177), namely hunter-gatherers (Hadza), pastoralists (Datoga), and agriculturalists (Iraqw) differ with regard to food-sharing patterns in the Dictator Game and reactions to violations of the food-sharing norms in the Ultimatum Game. We found that neither the type of economy nor the typical diet influenced our outcomes. The results indicated, however, that food sharing behavior was positively predicted by certain individual-level characteristics: people of higher strength and lower body fat shared more food, and women were more willing to share food than men.

Odor-based context-dependent memory: influence of olfactory cues on declarative and nondeclarative memory indices.

Reinstating the olfactory learning context can increase access to memory information, but it is not fully clear which memory functions are subject to an enhancing odor context reinstatement effect. Here, we tested whether congruent odor context during encoding and recall positively affected declarative and nondeclarative memory scores using a novel method for manipulation of an odorous environment; namely, intranasal Nosa plugs. Recall of a text and a complex figure as well as performance in a priming task were assessed immediately and 1 wk after encoding. We found that congruent odor exposure at encoding and recall aided free retrieval of a story at delayed testing but had no significant effect on a complex figure recall or a word completion task. Differences between the assessed memory indices suggest that olfactory environmental cues may be primarily efficient in free verbal recall tasks.

Sex differences in human mate preferences vary across sex ratios.

A wide range of literature connects sex ratio and mating behaviours in non-human animals. However, research examining sex ratio and human mating is limited in scope. Prior work has examined the relationship between sex ratio and desire for short-term, uncommitted mating as well as outcomes such as marriage and divorce rates. Less empirical attention has been directed towards the relationship between sex ratio and mate preferences, despite the importance of mate preferences in the human mating literature. To address this gap, we examined sex ratio's relationship to the variation in preferences for attractiveness, resources, kindness, intelligence and health in a long-term mate across 45 countries (n = 14 487). We predicted that mate preferences would vary according to relative power of choice on the mating market, with increased power derived from having relatively few competitors and numerous potential mates. We found that each sex tended to report more demanding preferences for attractiveness and resources where the opposite sex was abundant, compared to where the opposite sex was scarce. This pattern dovetails with those found for mating strategies in humans and mate preferences across species, highlighting the importance of sex ratio for understanding variation in human mate preferences.

Sex Differences in Mate Preferences Across 45 Countries: A Large-Scale Replication.

Considerable research has examined human mate preferences across cultures, finding universal sex differences in preferences for attractiveness and resources as well as sources of systematic cultural variation. Two competing perspectives-an evolutionary psychological perspective and a biosocial role perspective-offer alternative explanations for these findings. However, the original data on which each perspective relies are decades old, and the literature is fraught with conflicting methods, analyses, results, and conclusions. Using a new 45-country sample (N = 14,399), we attempted to replicate classic studies and test both the evolutionary and biosocial role perspectives. Support for universal sex differences in preferences remains robust: Men, more than women, prefer attractive, young mates, and women, more than men, prefer older mates with financial prospects. Cross-culturally, both sexes have mates closer to their own ages as gender equality increases. Beyond age of partner, neither pathogen prevalence nor gender equality robustly predicted sex differences or preferences across countries.

Human height preferences as a function of population size in the Cook Islands and Norway.

OBJECTIVES: Height preferences and mating patterns related to body size vary across cultures yet it remains unclear why such between-population differences exist. Here, we test a hypothesis that nonrandom assortative mating is negative (mating with nonsimilar partners) in small isolated populations, and positive (mating with similar partners) in larger populations. METHODS: We compared preferences for sexual dimorphism in stature (SDS, male height/female height) among men and women living in small isolated communities (as few as 60 inhabitants) vs larger urban areas (as many as 70 000 inhabitants). To increase generalizability, data were collected from heterogeneous populations in the South Pacific (Rarotonga vs Palmerston, Cook Islands) and Northern Europe (capital city of Tromsø vs villages in the Troms County of Norway). RESULTS: Norwegians preferred a significantly larger difference in height between partners (median SDS ratio of 1.14) than did Cook Islanders (median SDS ratios of 1-1.04). Indeed, while 30% of Cook Island men and women preferred a partner of the exact same height, this preference was observed among less than 3% of Norwegian men and 7% of Norwegian women. Critically, distributions in SDS preferences did not differ by sex or population size. Thus, rural and urban dwellers within both countries showed similar positive assortative preferences for height, wherein own height explained up to 62% of the variability in preferred partner height. CONCLUSIONS: Our results do not support negative assortative preferences in small-scale communities, and further indicate that the "male-taller norm," while weaker among Cook Islanders than Europeans, is observed to some extent in the South Pacific.

Olfactory perception and blindness: a systematic review and meta-analysis.

Anecdotal reports suggest that blind people might develop supra-normal olfactory abilities. However, scientific evidence shows a mixed pattern of findings. Inconsistent observations are reported for both sensory-driven olfactory tasks (e.g., odor threshold) and higher-order olfactory functions (e.g., odor identification). To quantify the evidence systematically, we conducted a review and meta-analysis. Studies were included if they examined olfactory function (i.e., odor threshold, odor discrimination, free odor identification, or cued odor identification) in blind compared with a sighted control group. Articles were identified through computerized literature search. A total of 18 studies focused on olfactory threshold (n = 1227: 590 blind and 637 sighted individuals), 14 studies targeted discrimination (n = 940: 455 blind and 485 sighted), 14 studies measured cued identification (n = 968: 468 blind and 500 sighted), and 7 studies (n = 443: 224 blind and 219 sighted individuals) assessed free identification. Overall, there were no differences in effect sizes between the blind and sighted individuals after correcting the results for publication bias. We additionally conducted an exploratory analysis targeting the role played by three moderators of interests: participants' age, the proportion of women versus men in each of the studies included into meta-analysis and onset of blindness (early blind vs. late-blind). However, none of the moderators affected the observed results. To conclude, blindness seems not to affect cued/free odor identification, odor discrimination or odor thresholds.

Fast Screening of Olfactory Function Using the Q-Sticks Test.

OBJECTIVES: Classical, longer olfactory tests are associated with difficulties in everyday practice. The aim of this study was to investigate the clinical utility of the Q-Sticks test within the context of a multicenter study. METHODS: A total of 333 subjects, aged between 12 and 88 years, completed a 3-item Q-Sticks test and a longer Sniffin' Sticks identification test. We analyzed the sensitivity and specificity of the test results for different cutoffs for anosmia and hyposmia. RESULTS: Our study showed that the test can be used on subjects aged 12 years and older, regardless of their sex. The data indicated a test sensitivity and specificity of 91.8 and 92%, respectively, with a score of 2 taken as a cutoff for olfactory dysfunction. Conversely, normal olfactory function can be declared with high probability with a score of 3 in the Q-Sticks test. CONCLUSION: We reconfirmed that the Q-Sticks test is a good screening tool for everyday medical practice and in laboratory settings, although it has to be kept in mind that the test can produce false-negative results at a score of 3. The test was relatively sensitive to anosmia and differences between normosmic and hyposmic/anosmic patients.

Development of an International Odor Identification Test for Children: The Universal Sniff Test.

OBJECTIVE: To assess olfactory function in children and to create and validate an odor identification test to diagnose olfactory dysfunction in children, which we called the Universal Sniff (U-Sniff) test. STUDY DESIGN: This is a multicenter study involving 19 countries. The U-Sniff test was developed in 3 phases including 1760 children age 5-7 years. Phase 1: identification of potentially recognizable odors; phase 2: selection of odorants for the odor identification test; and phase 3: evaluation of the test and acquisition of normative data. Test-retest reliability was evaluated in a subgroup of children (n = 27), and the test was validated using children with congenital anosmia (n = 14). RESULTS: Twelve odors were familiar to children and, therefore, included in the U-Sniff test. Children scored a mean ± SD of 9.88 ± 1.80 points out of 12. Normative data was obtained and reported for each country. The U-Sniff test demonstrated a high test-retest reliability (r27 = 0.83, P < .001) and enabled discrimination between normosmia and children with congenital anosmia with a sensitivity of 100% and specificity of 86%. CONCLUSIONS: The U-Sniff is a valid and reliable method of testing olfaction in children and can be used internationally.

Global Study of Social Odor Awareness.

Olfaction plays an important role in human social communication, including multiple domains in which people often rely on their sense of smell in the social context. The importance of the sense of smell and its role can however vary inter-individually and culturally. Despite the growing body of literature on differences in olfactory performance or hedonic preferences across the globe, the aspects of a given culture as well as culturally universal individual differences affecting odor awareness in human social life remain unknown. Here, we conducted a large-scale analysis of data collected from 10 794 participants from 52 study sites from 44 countries all over the world. The aim of our research was to explore the potential individual and country-level correlates of odor awareness in the social context. The results show that the individual characteristics were more strongly related than country-level factors to self-reported odor awareness in different social contexts. A model including individual-level predictors (gender, age, material situation, education, and preferred social distance) provided a relatively good fit to the data, but adding country-level predictors (Human Development Index, population density, and average temperature) did not improve model parameters. Although there were some cross-cultural differences in social odor awareness, the main differentiating role was played by the individual differences. This suggests that people living in different cultures and different climate conditions may still share some similar patterns of odor awareness if they share other individual-level characteristics.

Human Leukocyte Antigen similarity decreases partners' and strangers' body odor attractiveness for women not using hormonal contraception.

The Human Leukocyte Antigen (HLA) is a gene complex that encodes important elements of the human immune system. HLA profile is communicated via olfaction and interindividual diversity is assumed to be advantageous for mate choice. Additionally, HLA diversity appears to enhance satisfaction and sexual attraction in existing romantic partnerships. However, whether this effect is transmitted via body odors and whether it results in an attraction towards HLA-dissimilar individuals and/or an avoidance of HLA-similar ones remains unclear. In the present study, we genotyped couples and asked each participant to rate a body odor sample from their partner and from three strangers of the opposite sex who expressed a similar or dissimilar HLA-B and HLA-C genotype. We found no statistically significant preference for HLA similarity or dissimilarity in men. Among women, the observed effects differed depending on hormonal contraception status. Like men, women on hormonal contraception did not exhibit significant HLA-related preferences. However, for women not using hormonal contraceptives, odors from HLA-B and HLA-C similar donors were significantly less attractive than those from HLA-dissimilar donors, regardless of whether the samples were from a partner or a stranger. Our findings support the hypothesis that HLA similarity is perceived via body odors and that such similarity affects human attraction. This mechanism may serve an evolutionarily adaptive function in preventing prospective offspring from having decreased immunocompetence, or decreasing the chance of kin mating.

A Compensatory Effect on Mate Selection? Importance of Auditory, Olfactory, and Tactile Cues in Partner Choice among Blind and Sighted Individuals.

Human attractiveness is a potent social variable, and people assess their potential partners based on input from a range of sensory modalities. Among all sensory cues, visual signals are typically considered to be the most important and most salient source of information. However, it remains unclear how people without sight assess others. In the current study, we explored the relative importance of sensory modalities other than vision (smell, touch, and audition) in the assessment of same- and opposite-sex strangers. We specifically focused on possible sensory compensation in mate selection, defined as enhanced importance of modalities other than vision among blind individuals in their choice of potential partners. Data were obtained from a total of 119 participants, of whom 78 were blind people aged between 16 and 65 years (M = 42.4, SD = 12.6; 38 females) and a control sample of 41 sighted people aged between 20 and 64. As hypothesized, we observed a compensatory effect of blindness on auditory perception. Our data indicate that visual impairment increases the importance of audition in different types of social assessments for both sexes and in mate choice for blind men.

No sex difference in digit ratios (2D:4D) in the traditional Yali of Papua and its meaning for the previous hypotheses on the inter-populational variability in 2D:4D.

OBJECTIVES: The ratio between the 2nd and 4th digit (2D:4D) is considered to be a sexually dimorphic trait in humans, with males having on average lower 2D:4D values than females. However, significant inter- and intra-sexual differences in digit ratios across populations have been reported. In order to further explore factors influencing the variability of 2D:4D, we performed a study among the Yali, a traditional population from Papua. METHODS: We measured digit ratios of 79 adults (47 males) from the traditional Yali society, a polygamous group who inhabit a harsh high-mountain environment almost directly on the equator. RESULTS: Statistical analysis of the data show no significant inter-sexual difference in digit ratios in our sample. CONCLUSIONS: We discuss the results in light of various factors that putatively shape the differences in digit ratios. We conclude that the results of our study contribute to the existing evidence suggesting that digit ratio might not be universally sexually dimorphic in humans.

Similarities in smell and taste preferences in couples increase with relationship duration.

Numerous studies point to partners' congruence in various domains and note an increase in their compatibility over time. However, none have explored a shift in chemosensory perception related to relationship duration. Here, we examined the relationship between the time heterosexual couples have spent together and the degree to which they share their gustatory and olfactory preferences. Additionally, we investigated whether these preferences are associated with relationship satisfaction. One-hundred couples aged from 18 to 68 years being together for a period between 3 and 540 months rated the pleasantness of a wide variety of olfactory and gustatory stimuli. We showed that both taste and smell preferences are more similar the longer couples have been in a relationship. We also observed a very interesting trend in terms of smell preferences, with relationship satisfaction being negatively related to congruence in smell preferences between partners. We discuss these results from the perspective of evolutionary psychology.

Body Odor Trait Disgust Sensitivity Predicts Perception of Sweat Biosamples.

Body odors are potent triggers of disgust and regulate social behaviors in many species. The role of olfaction in disgust-associated behaviors has received scant attention in the research literature, in part because olfactory disgust assessments have required laboratory testing with odors. We have devised the "Body Odor Disgust Scale" (BODS) to facilitate research on olfactory disgust. In this study, we evaluated whether individual differences in BODS scores would be associated with the perception of disgust for sweat samples in a laboratory setting. Results show that BODS was a strong predictor of disgust ratings of sweat samples even when controlling for general disgust sensitivity. In contrast, odor intensity ratings were unrelated to BODS scores. Our findings suggest that the BODS scores reflect body odor disgust perception. The BODS scale might facilitate research on olfactory disgust responses and associated behaviors.

Dietary customs and food availability shape the preferences for basic tastes: A cross-cultural study among Polish, Tsimane' and Hadza societies.

Biological significance of food components suggests that preferences for basic tastes should be similar across cultures. On the other hand, cultural factors play an important role in diet and can consequently influence individual preference for food. To date, very few studies have compared basic tastes preferences among populations of very diverse environmental and cultural conditions, and research rather did not involve traditional populations for whom the biological significance of different food components might be the most pronounced. Hence, our study focused on basic taste preferences in three populations, covering a broad difference in diet due to environmental and cultural conditions, market availability, dietary habits and food acquirement: 1) a modern society (Poles, n = 200), 2) forager-horticulturalists from Amazon/Bolivia (Tsimane', n = 138), and 3) hunter-gatherers from Tanzania (Hadza, n = 85). The preferences for basic tastes were measured with sprays containing supra-threshold levels of sweet, sour, bitter, salty, and umami taste solutions. We observed several interesting differences between participating societies. We found that Tsimane' and Polish participants liked the sweet taste more than other tastes, while Hadza participants liked salty and sour tastes more than the remaining tastes. Further, Polish people found bitter taste particularly aversive, which was not observed in the traditional societies. Interestingly, no cross-cultural differences were observed for relative liking of umami taste - it was rated closely to neutral by members of all participating societies. Additionally, Hadza showed a pattern to like basic tastes that are more common to their current diet than societies with access to different food sources. These findings demonstrate the impact of diet and market availability on preference for basic tastes.

Olfactory Performance in a Large Sample of Early-Blind and Late-Blind Individuals.

Previous examinations of olfactory sensitivity in blind people have produced contradictory findings. Thus, whether visual impairment is associated with increased olfactory abilities is unclear. In the present investigation, I aimed to resolve the existing questions via a relatively large-scale study comprising early-blind (N = 43), and late-blind (N = 41) and sighted (N = 84) individuals matched in terms of gender and age. To compare the results with those of previous studies, I combined data from a free odor identification test, extensive psychophysical testing (Sniffin' Sticks test), and self-assessed olfactory performance. The analyses revealed no significant effects of sight on olfactory threshold, odor discrimination, cued identification, or free identification scores; neither was the performance of the early-blind and late-blind participants significantly different. Additionally, the self-assessed olfactory abilities of the blind people were no different than those of the sighted people. These results suggest that sensory compensation in visually impaired is not pronounced with regards to olfactory abilities as measured by standardized smell tests.

Can blind persons accurately assess body size from the voice?

Vocal tract resonances provide reliable information about a speaker's body size that human listeners use for biosocial judgements as well as speech recognition. Although humans can accurately assess men's relative body size from the voice alone, how this ability is acquired remains unknown. In this study, we test the prediction that accurate voice-based size estimation is possible without prior audiovisual experience linking low frequencies to large bodies. Ninety-one healthy congenitally or early blind, late blind and sighted adults (aged 20-65) participated in the study. On the basis of vowel sounds alone, participants assessed the relative body sizes of male pairs of varying heights. Accuracy of voice-based body size assessments significantly exceeded chance and did not differ among participants who were sighted, or congenitally blind or who had lost their sight later in life. Accuracy increased significantly with relative differences in physical height between men, suggesting that both blind and sighted participants used reliable vocal cues to size (i.e. vocal tract resonances). Our findings demonstrate that prior visual experience is not necessary for accurate body size estimation. This capacity, integral to both nonverbal communication and speech perception, may be present at birth or may generalize from broader cross-modal correspondences.