pheromonal interaction between partners

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Choice of partner based on specific values of histocompatibility antigens.

Physical anthropologists, although they have long been aware of the extent to which skin odour varies within different social agglomerates and characterises certain human populations, have recently become interested in the olfactive perception of Homo sapiens. Aiming to prove the existence of various pheromonal phenomena in mankind, already partly proving in an experimental way in animals, and to explain prosimian behaviour - difficult to put down to cultural reasons alone - in biological terms, Pr of. Franca Ligabue Stricker, lecturer in Human Ecology at the Faculty of Science of the University in Turin, and her team, has, since 1990, been carrying on a complex series of multidisciplinary investigations on human pheromones.

Showing the investigations notable difficulties at the data acquiring stage, and since no adequate scientific measuring instruments are available the theme was tackled from different angles. As an introduction, the verification of social interaction of the female cycle was studied, a task undertaken by women. The observations concerning 29 young women (9 small groups of 3-4 students aged 18-23 years) interacting with each other on a daily basis of a minimum of 7 hours, for at least 8 months, for re asons of schooling, were compared with those of 29 control students chosen at random within the same social class (same diet) confirmed the findings of Mc Clintock regarding the synchronization tendency of the cycles of women who spend a lot of time toget her (Ligabue Stricker, F., 1991). Bearing in mind that the biological re-evaluation of olfactive communication in man is only possible by applying olfactive research to the study of physiological parameters, an attempt was then made to find a relation bet ween man’s physiological and his olfactive development. With this aim, a study of the olfactive perception of pheromone-like substances was carried out on 1400 subjects aged 3-14 years inclusive. This study highlighted how the perception of biologica lly significant odours (Osmopherone® and Osmopherine®) starts with a phase of very high olfactive neutrality (56% give an equal evaluation of the two pheromones), which coincides with reproductive neutrality and with a certain neutrality in the production of odours, which then gradually develops with age, from childhood to puberty (in a more distinct way, and earlier, in the female) (Ligabue Stricker, F. and Chiarelli, B., 1992; Ligabue Stricker, F. and Tua, N., 1993). Since puberty and development of gonadotropins go hand in hand, these results provide the proof that there is a relationship between endocrine and olfactive systems (relationship which forms the basis of pheromonal communication in animals) - states Prof. Ligabue Stricker in order to underline

this hypothesis, the team from the University in Turin continued its investigations with a further verification on adults, comparing the olfactive perception of healthy persons with that of a group of 160 patients presenting hormonal problems relating to reproduction, characterised by abnormal variations in hematic concentrations of gonadotropins and of sexual hormones which are normally used as indicators of patients’ reproductive function (FSH, LH, oestradiol, progesterone, testosterone, trl). Thei r olfactive perception concerning biologically significant substances was evaluated using substitutes for natural pheromones: Osmopherone and Osmopherine. The results obtained were presented at the X Congress of Italian Anthropologists, in Pisa, September 8-10, 1993, and showed that a deviation from the standard in hormonal concentrations corresponded to a deviation in the olfactive perception of pheromonal substances. The most revealing olfactive phenomenon in subjects with altered hormone levels, whethe r male or female, is the remarkable presence of cases of anosmia either for both or for one of the two odours, which did not occur in the healthy group. These data confirm the hypothesis of a close relationship between the olfactive, endocrine and reprodu ctive systems. Since personal odour is considered, by several authors, to be a stimulus capable of inducing unconscious responses on the level of non-verbal communication, another series of tests was made to try to establish whether there indeed exists a pheromonal interaction between partners, in man too. With this goal, the team from the University of Turin had already made tests to evaluate the effect of superposing artificial pheromones (widely used in modern cosmetic products to “renatura lise” perfumes!) in couples whose relationship was stable and perfectly balanced (Ligabue Stricker, F., 1991). Samples of synthetic substitutes of human male and female pheromones (Osmopherone and Osmopherine) opportunely diluted in their usual perf ume or deodorant were administered respectively to the males and females of established couples, alternating them randomly each month with “placebo” products. The results show that the substances used had a definite effect on the frequency of sexual intercourses only when administered to both partners, whilst if only one of the two was overloaded with the homologous “pheromone”, certain character-based problems arose. On the other hand, the positive effect of the balanced overload shows that well-balanced c ouples are normally in pheromonal harmony. Still with couples, Ligabue Stricker et al. attempted to show the relation, in man, between olfactive and immune systems, with a particular reference: the choice of partner based upon determined values of histoco mpatibility antigens, reflecting in olfactive complementarity. Research carried out on 80 stable couples typified by the HLA (Human Leukocyte Antigens) system and subjected to the olfactive test using Osmopherone and Osmopherine showed that between establ ished couples, antigenic frequence and olfactive behaviour, with regard to the two pheromone-like substances, differs from those of a control population of males and females chosen at random. From an evolutive point of view, “optimal” couples would be those wh ere the partners do not present antigenic condivisions and can consequently generate a progeniture with heterozygosis for loci of MHC (Major Histocompatibility Complex), which possess a greater selective advantage as compared to homozygotes. Such couples showed different olfactive behaviour compared to couples presenting an antigenic condivision. This would explain, by extrapolation, a common genetic basis between the most important system, which controls the mechanism of recognition of the “self 8;, and the olfactive perception of essential, natural pheromonal substances in the choice of an ideal partner from a biological point of view.

Recent experiments on mice have quite by chance led to the discovery that, in these animals, histocompatibility antigenes can act as an olfactive mark of recognition in the choice of the most suitable partner. Choosing a carrier of various antigenes woul d pass on to descendants, heterozygote for the most part, greater immunity and, consequently, a greater selective advantage. Ligabue Stricker et al. have shown that in Man too there may be a relationship between histocompatibility antigenes and olfactive perception, and in order to establish the extent to which, in our species too, biological factors of a histochemical nature may influence the choice of a partner, they are currently carrying out studies on couples having the same or different HLA antigene s. The research team wanted to find out whether there is an antigenic difference between coupled partners and singles, and have thus compared the frequency of class I HLA antigenes found in 1454 persons in couples (727 couples) with those found in the 1767 persons making up the control group. The partners of 80 couples were successively subjected to olfactive tests with pheromono-like substances and were then compared with a control group consisting of 133 singles, whose fitness had been previou sly evaluated basen on their fertility.

The results have shown that when comparing couples and singles, apart from varying antigenic frequency, there exists a differing evaluation of pheromonal substances, which is even more accentuated in couples where the partners do not share the same types of HLA and which, all in all, showed a greater fitness. Because of this, the preferential choice of a partner with different HLA factors, which is essential if a heterozygote descendancy is to be assured, might, in Man too, be determined by a pheromonal c ommunication system which would allow for the olfactive recognition of genetic individuality.


glycoproteins coded by MHC genes and individual odour

Some scientists have tried to determine which molecules are responsible for the olfactive signals generated by MHC. The observation that rats and mice are unable to recognise the specificity of MHC through blood samples, and that glycoproteins coded by th e MHC gene are heavy, essentially non-volatile molecules, has led us to think that the olfactive signal is not made up of whole gene products, but by fragments of these glycoproteins. In particular, it seems that the peptide portion contained in the pocke t of these molecules is the most significant for recognition of MHC genetic individuality; it has been found in animal urine, in a broken down form, that is to say, isolated from its cellular membrane and no longer linked to the glycoprotein complex.

Of particular interest is the observed presence of break down products of class I MHC molecules in human perspiration. It is consequently conceivable to suppose that MHC plays a role in the determination of personal odour in man too. One very controversia l theory on the source of odour being correlated to the most important histocompatibility system has been advanced by Howard (1977): “The association of olfactive signals with the H-2 complex may be indirect; metabolites produced by the bacterial flo ra, characteristic of the skin or the intestinal and urogenital tracts, whose presence is controlled by the immune system via MHC, may combine with the production of the odorous signal”. This theory was developed by Singh who, after having repeated Beauchamp’s experiments on mice and rats (Rattus norvegicus) in a sterile environment, revealed that while the absence of micro-organisms in the mouse did not appear to have an influence on the recognition of MHCs through the urine, a total inability to distinguish H-2 identical individuals from H-2 non-identical ones could be observed in rats.

BEHAVIOUR biological odour, desire and availability

Man may not be macrosmatic, but his sense of smell still plays an important role in his interpersonal relations. Mother and child recognise each other already at a very early stage by their individual smells, and in experimental situations too, a certain proportion of adults is able to recognise its own sexual partner or the sex of other people, by the smell of the clothes they are wearing (Eibl-Eibesfeldt, I.). Certain distinct pheromones render both men and women receptive to contact (androstenol has be en suggested), while other sexual pheromones encourage contact from women only (androstenone has been suggested) (Eibl-Eibesfeldt, I.). Human smells constitute signals of a stimulating nature (Schleidt, W. M.) which in some cases attract and in other repe l. In our mass society they are camouflaged by deodorants, which, in particular, eliminate the differences between sexes (Schleidt, W.M.); this represents a strategy of mimicry (Eibl-Eibesfeldt, I.) which, in final analysis, could be considered an error of today's culture of appearance by being harmful to natural interpersonal communications. Hence the advisibility that products used in personal hygiene be endowed with a note of biological odour [e.g. by pheromonic copulines of Osmopherone ( male) and Osmopherine (female)]. Biological odours are far more complex than the elementary notes of questionable experimental derivation obtained from simple chemical substances, such as androstenol and/or androstenone. When Claus and Hoppen discovered a significant amount of D16-type steroid hormones in celery, similar to the sexual pheromones used in zootechny as olfactory encouragement to sexual reproduction (androstanone), the popular reputation of celery as an aphrodisiac was confirmed. But neither the smell of celery, nor that of isolated androsteroids can determine the complex phenomena of biological and social behaviour. Fewer chemical and pheromonal comparisons have been made between honey and the lotus flower, as quoted in the Indian art of lov ing (Ananga Ranga by Kalyana Malla). As much has been said about the peptide sequence of the luteinizing hormone-releasing hormone (LH-RH) with which it is not possible to conjugate the verb “to love”, even though the presence of fibres with olfacti ve functions capable of influencing, precisely through the intervention of hypothalamic relaxant factors, gonadotropic secretion of the pituitary gland, itself a regulator of male and female genital function, has been frequently highlighted. But a person can ignore an object, a smell or a sound occuring in his surroundings if, simultaneously, his central state does not provide him with a particular valence (Vincent, J.J.). If behaviour is regulated by a myriad of interacting genes, each of which also has other responsabilities within the organism, one of which is processing of olfactive signals (Greenspan, R.J.), desire is not only the product of the body conjugating with its environment; it is also the result of occurrences which can be explained by the brain and its plasticity, and moods and the way they change (Vincent, J.J.). It follows that the natural biological odour, or the one implanted with selected pheromonic copulines (Osmophero-ne, Osmopherine), does not induce others to behave in a certain manner, but provides a unequivocal signal of availability to whomsoever, at that particular moment, is able selectively to perceive it (Rialdi, G.).

Discriminating sexually

An examination of the brain of the Drosophila (Greenspan, R.J., NY Univ.; Ferveur, J.F., Paris Univ.; Klemens, K.F., Störtkuhl, R.F., Fribourg Univ.) revealed the ability to discriminate sexually when either the lobe of its feeler or the fungiform element of the brain comprised, following experimental manipulation, female cells. Both these regions, the second of which is situated close to the area which induces “courtship” to take place, participate in the preparation of olfactive signals . If at least one of these centres of odour analysis contains female cells, the Drosophila loses its ability to differentiate males from females, and shows an equal sexual interest for every individual.

Communication through pheromones

The neuronic circuits which deal with simple forms of intraspecific communication may become remarkably complex. In communication by pheromones, cells which are receptive to odour will act, for example, in a very particular way; their information is produ ced in specialised macromolecular complexes in the lobe of the feeler (Reichert, H.). This information is then transfered, via these complexes, to a whole series of other centres in the brain (Boeckh). Exposing male Drosophila to anti-aphrodisiac p heromones while they are courting already paired females stimulates sensorial systems which send signals to the region of the brain responsible for the “courtship” mechanism. This accumulation then activates the CaMKII (calcium/calmodu-line-depe ndant proteinokinase II), which phosphoralyses EAG protein (component consisting of a number of channels which pass through the entire cellular membrane and regulate the flow of potassium ions towards the outside of the neurones) in the potassium channels . Following this modification, the channels open up and allow the potassium ions to leave the neurons, by reducing their activity and their ability to release neurotransmitters. When the neurons become silent, all interest in mating is lost (Greenspan, R.J.).

The book by Patrick Süskind

The book entitled “The Perfume” (Das Parfüm) by the German author Patrick Süskind represents a singular literary achievement. The main character, Jean-Baptiste Grenouille, must be interpreted in a pheromone key. We would again suggest our reader s to read it, for the lucidity of its theme of the sociobiological implication of olfaction and of the regulation, in a subliminal olfactive way, of the attitude of the human consortium, a theme about which we have already aired our views in 1978 (Relata Technica n. 15-16). The obsessive search for a human perfume by the main character in the book is centred upon this biological reality, padded out, naturally, with all the amplifications (but not inventions) to which the author resorts freely and consciou sly. Today we can certainly affirm the importance of the role played by biological odour in the dynamics of human inter-relations. This also conditions the formulation of products, to the detriment of their artificiality and in favour of an ever greater naturalisation or “humanisation”. If it is true that the widespread use of deodorants represents a strategy of mimicry on the one hand, while, on the other hand, the use of perfumes is intended to bring out personal odour in a less disagreeable manner than it would have in its own biological state, it is just as true that the biological signal of availability is destroyed, unless it is reconstructed by selected pheromonic copulines. The first is found in Osmopherone (the male copuline), the sec ond is in Osmopherine (the female copuline). Both having initially been osmosteniant steroids (1978), they have been successively integrated with osmosteniant elements identified in specific human acidophile microflora cultures, and reconstituted. Both confirm the complexity of the olfacto-genital axe, that some imagined being able to reduce to just a few molecules. The majority of authors today agree on the essentiality of the olfactive function in the interactions between partners and in the dialogue with their bodies. Among the masses, the evidence that indiscriminate use of chemical deodorant or perfuming ingredients which change bodily emissions simultaneously alter the equilibrium of relations between individuals is gaining more and more weight. It sh ould be strongly pointed out that this equilibrium of the interrelationship also has its complement in the olfactive channels. It is, indeed, as we have already said, the result of a complex story that the brain can express, thanks to its plasticity. In c onclusion, the olfactive ingredient is an important instrument for the orientation of our social, sexual and individual behaviour, for which reason it should always be highly valued in all hygiene, sanitary and cosmetic measures we take with the aim to co rroborate to an optimal degree not only our biological life, but also our psychic one. Consequently, in the composition of both male and female deodorants, the interrelational significance of the olfacto-genital correlation must be taken into consideration. Osmopherine and Osmopherone are the answer to this problem.

(See Issues, Articles 1996)