A chemical message that one body can send to another body, conveying physiological information across the air. In insects and rodents, the mechanism is well-characterised and the molecular structures are precisely-identified. In humans, the situation is less clear, with sustained academic debate about whether the same mechanism operates and, if so, with what magnitude of effect on actual behaviour.

Pheromone (Japanese: フェロモン, feromon; English: pheromone) is a chemical signal substance secreted externally by an animal that produces specific physiological, behavioural, or psychological response in conspecific individuals. The term is a 1959 coinage combining Greek phero (“to carry”) and hormone (“to excite”), introduced by Karlson and Lüscher in the context of insect-research.

Distinction in vocabulary

The English-language vocabulary for the concept uses pheromone as the standard scientific term across all research contexts. Sub-categories include sex pheromone, alarm pheromone, territorial pheromone, and aggregation pheromone, with the principal context distinguishing the sub-type. Sexual attractant operates as a slightly-broader related term covering chemical-attractant signals more generally.

The Japanese-language feromon is a direct loan from the English / German scientific term and operates across the same registers. The Japanese term has additionally acquired a stronger everyday-vocabulary register than the English term: feromon ga deteiru (“pheromones are emanating”) functions as a common figurative description of perceived sexual attractiveness, in a usage substantially-divorced from the strict scientific meaning. The English-language colloquial use of “pheromone” in this figurative sense exists but is less established than the Japanese vernacular use.

Biology of pheromones

Multiple animal species use pheromones for diverse functions: mating-behaviour induction, territorial marking, alarm-signalling, and mother-infant communication, among others. The molecular structures of insect (silkworm bombykol, etc.) and rodent (mouse major-urinary-protein and others) sex pheromones have been precisely characterised. The pioneering 1959 silkworm bombykol identification by Karlson and Butenandt established the methodological foundation for pheromone research.

Pheromone reception in most animals is mediated by the vomeronasal organ (Jacobson’s organ), a specialised chemosensory structure separate from the main olfactory system. The structure exists in foetal humans but is degenerated in adult humans, with the question of remaining functionality remaining academically contested.

The debate around human pheromones

Whether functionally-active sex pheromones exist in humans remains without scientific consensus, with sustained debate.

Pheromone-candidate substances investigated in human research include androstenone (a steroid present in male sweat), androstadienone, and estratetraenol. Exposure to these substances has been reported in published research to affect mood, arousal, and hormonal secretion, though replication and effect-size remain debated.

The well-known Sweaty T-shirt experiment (Wedekind et al., 1995) had female subjects sniff T-shirts worn for several days by male subjects, with the finding that women preferred T-shirts from males with greater MHC-genetic-immune-system divergence from themselves. The result was interpreted as suggesting that olfactory cues might support preference for genetically-diverse offspring partners. Subsequent replication efforts have produced mixed results, and the debate continues.

Tristram Wyatt’s recent reviews (including the 2020 Science commentary) argue that no single human-pheromone candidate substance has been definitively demonstrated to function as a true pheromone in the strict biological sense, while acknowledging that diffuse-and-multi-component olfactory cues may nonetheless influence human behaviour and physiology.

General-vocabulary use

Separate from scientific rigour, “pheromones” is widely used as a general figurative term for “sexual-attractant force / sexual charisma”. Expressions like “she has pheromones” or “pheromones in the air” function as rhetorical devices for the difficult-to-verbalise quality of sexual attractiveness, expressed in body-odour-and-atmosphere terms.

In adult-content contexts, “body-odour fetish (nioi-fechi)” frames sexual attraction to natural body-odours (sweat, sebum, genital odours). This overlaps partly with the scientific pheromone concept, though the larger component is “personal-and-individual attraction to a specific person’s body-odour” rather than a chemically-defined pheromone effect.

Commercial pheromone products

“Pheromone perfumes” and “pheromone-effect body-odour supplements” circulate as commercial products, but the efficacy claims lack robust scientific basis. With no human sex pheromone yet definitively identified-and-confirmed, the marketing use of “pheromone” in these products lacks scientific support. Consumer-protection commentary and scientific-literacy critique consistently flags these products’ efficacy claims as unsupported.

Adjacent concepts

The McClintock effect (menstrual cycle synchrony among co-habiting women, reported by Martha McClintock in 1971) has been historically cited as suggestive of human chemical-communication. Subsequent reanalysis has questioned the original statistical analysis, with the effect’s robustness now contested. The example serves as a methodologically-instructive case for the broader human-pheromone research field: even initially-celebrated findings may not survive replication-and-reanalysis scrutiny.

The kissing-and-attraction olfactory research continues independently of the strict pheromone-debate. Body-odour-mediated partner-preference and partner-selection appears to be a real phenomenon, even if the underlying chemistry does not strictly meet the pheromone definition. Body-odour research thus has substantive standing as a behavioural-and-physiological research category independent of the contested pheromone-strict-definition status.

Related Terms

• Libido
• Sex hormones
• Body-odour fetish (nioi)
• Sweat (ase)
• Saliva (daeki)