Body Odours Sampled at Different Body Sites in Infants and Mothers—A Comparison of Olfactory Perception

Body odours and their importance for human chemical communication, e.g., in the mother–child relationship, are an increasing focus of recent research. Precise examination of sampling methods considering physiology and feasibility aspects in order to obtain robust and informative odour samples is therefore necessary. Studies comparing body odour sampling at different body sites are still pending. Therefore, we sampled axilla, breast, and head odour from 28 mother–infant dyads and examined whether odour perception differs with regard to the body site. The participating mothers were asked to evaluate their own and their infant’s body odour samples, as well as odours of two unfamiliar mother–infant dyads. We tested whether maternal pleasantness and intensity evaluation, as well as recognition ability of the odours differed between the body sites. In infants, the head odour exhibited slightly lower pleasantness ratings than axilla and breast, and intensity ratings did not differ between body sites. In mothers, body site affected intensity ratings but not pleasantness ratings, as the breast odour was rated as less intense compared with head and axilla. Across all body sites, mothers rated the own and their infant’s odour as less intense when compared with unfamiliar samples. Recognition ability did not differ between body sites, and in line with previous studies, mothers were able to recognize their own and their own infant’s odour above chance. In sum, our study extends the previous methodological repertoire of body odour sampling and indicates that the axilla, breast, and head of adults as well as infants serve as informative odour sources.

Dogs display owner-specific expectations based on olfaction

Most current knowledge about dogs’ understanding of, and reacting to, their environment is limited to the visual or auditory modality, but it remains unclear how olfaction and cognition are linked together. Here we investigate how domestic dogs search for their owners using their excellent olfactory sense. We raise the question whether dogs have a representation of someone when they smell their track. The question is what they expect when they follow a trail or whether they perceive an odour as a relevant or non-relevant stimulus. We adopted a classical violation-of-expectation paradigm—and as targets we used two persons that were both important to the dog, usually the owners. In the critical condition subjects could track the odour trail of one target, but at the end of the trail they find another target. Dogs showed an increased activity when the person did not correspond with the trail compared to a control condition. Moreover, we found huge individual differences in searching behaviour supporting the assumption that dogs are only able to smell when they really sniff, and that the temperature has an influence on dogs performance. Results are discussed in the light of how cognitive abilities, motivation and odour perception influence each other.

Effect of dietary Thais coronata shell on odour reduction and nitrogen output in rabbit farm

This work investigated the effect of integrated forage-concentrate diets with Thais coronate as additive on reducing odour and nitrogen output in rabbit production. Thais coronate shells were thoroughly washed, dried and ground to 2mm particle size. Forty-five growing rabbits were fed diets comprising 25% forage and 75% concentrate with 0%, 0.25%, 0.50%, 0.75% or 1.0% ofthe shells for two weeks in a completely randomized design (CRD) experiment. The treatments were designated T1, T2, T3, T4 and T5, respectively with 9 rabbits per dietary treatment and replicated thrice with 3 rabbits per replicate. Faeces and urine were collected and odour perception scored by 10-member panel on a 5-point scale. The mean odour perception scores of T1 (urine =4.02, faeces=3.55) represented the strongest (P< 0.05) degree of pungency while T4 (urine=3.05, faeces=2.76) gave the least (P<0.05) pungent odour. Average total nitrogen yield from treatment 1 (2.93g/day) was significantly higher than those from treatments 3 (2.53g/day) and 4 (2.31g/day) but similar to those from treatments 2 (2.74g/day) and 5 (2.70g/day). Inclusion of T. coronata shell at0.75% in a forage-concentrate (T4) diet of rabbit reduces odour in rabbit production and elicits the least yield of nitrogen.

Human olfactory communication: current challenges and future prospects

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

Odorant-Binding Proteins as Sensing Elements for Odour Monitoring

Odour perception has been the object of fast growing research interest in the last three decades. Parallel to the study of the corresponding biological systems, attempts are being made to model the olfactory system with electronic devices. Such projects range from the fabrication of individual sensors, tuned to specific chemicals of interest, to the design of multipurpose smell detectors using arrays of sensors assembled in a sort of artificial nose. Recently, proteins have attracted increasing interest as sensing elements. In particular, soluble olfaction proteins, including odorant-binding proteins (OBPs) of vertebrates and insects, chemosensory proteins (CSPs) and Niemann-Pick type C2 (NPC2) proteins possess interesting characteristics for their use in sensing devices for odours. In fact, thanks to their compact structure, their soluble nature and small size, they are extremely stable to high temperature, refractory to proteolysis and resistant to organic solvents. Moreover, thanks to the availability of many structures solved both as apo-proteins and in complexes with some ligands, it is feasible to design mutants by replacing residues in the binding sites with the aim of synthesising proteins with better selectivity and improved physical properties, as demonstrated in a number of cases.

ODOUR STUDY WITH QUALITATIVE AND QUANTITATIVE RESEARCH METHODS IN VARIOUS DISTRICTS OF RIGA

Different emission sources of odours become increasingly important environmental problem which may have a negative impact on human health and quality of life. Human odour perception may be subjective, however on odour perception threshold is considered to be the odorant concentration where at least half of odour assessor’s group members confirm the existence of odour, and then it is 1 OUE /m3. Nowadays more and more advanced technologies are used to measure odour concentration. Olfactometer Scentroid SM100 allows users to accurately quantify ambient odour concentration in field. Also this equipment allows to collect source samples and analyze odour in a laboratory. Odour study in 2016 and 2017 with field olfactometer Scentroid SM100 and gas analyzer Gasmet DX-4030 in districts of Riga indicates that the highest concentrations of odour are in Bolderaja, Sarkandaugava, Kundzinsala, Mangalsala, Milgravis and Vecmilgravis. Study indicates that the highest odour concentrations, especially among producing companies can reach up to 6-7 odour units (OUE/m3), however gas analyzer Gasmet DX-4030 indicates oil products or carbon dioxide.