Modelo de Diseño

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The Biological Basis of Aesthetics

Although this book is primarily concerned with creative perfumery, in this chapter we will be looking briefly at the function of smell in nature and the implications that this can have for the work of the perfumer. Smell is the most primitive of the senses, and our response to certain odors is deeply embedded in the subconscious mind. Much of what we know to be true, from our experience as perfumers, can be related to the origins of our olfactory sense and the part that it has played in the evolution of our species.

Smell, or the process of olfaction, is a chemical sense. Unlike the senses of hearing and vision which are stimulated by energetic phenomena, it depends upon the detection of airborne molecules coming in contact with specialized chemoreceptive cells.

Although evolution has taken place over many millions of years, nature has been surprisingly conservative in the development of the olfactory mechanism. The basic type of receptor cell found in primitive animals has changed very little during the course of evolution, remaining much the same in groups of animals as diverse as insects, birds, fish, and mammals. What has evolved, however, is the ability of the brain to make use of the incoming information from the environment: through the innate recognition and preference for certain types of smell, and through the ability to learn and to associate them with successful behavior patterns such as the sourcing of food or the escape from danger.

shows that the development of the olfactory tissue is closely linked to that of the pituitary gland which lies at the base of the brain. Among other functions the pituitary plays a key role in the coordination of sexual activity and reproduction. This ancient association between the sense of smell and the reproductive process is one that has important implications for work of the perfumer.

From the receptor cells nerves pass through the olfactory lobes at the front end of the brain direct to the central basal region, the part known as the ''limbic system." This forms part of our deep-seated unconscious mind, being associated with the control of emotion and sexual activity, as well as with feelings of pleasure. In evolutionary terms it is also the oldest part of the brain, providing evidence of the early and continuing importance of the sense of smell in animal behavior.

Only after entering the limbic system does the olfactory message pass to the cerebral hemispheres, which form the major part of the human brain, where cognitive recognition occurs and the ability to associate the smell with its name. By this sequence of events our full awareness of a smell takes place only after the deepest parts of the unconscious have been activated. As a result, even without conscious recognition, smell can be the most evocative of our senses, linking us to past experiences and stirring our emotions at a level that we find hard to explain.

Compared with other mammals and even with our closest relatives, the apes, the sense of smell in humans is exceptionally poor. Nevertheless, it continues to play a significant role not only in our conscious lives but also, as we will see later, in our subconscious awareness.

If we define a smell as being any material or group of materials that is capable of being detected by the process of olfaction, then we may divide the smells that occur in nature into two groups: those that are produced by the general processes of the environment and those that are used as a form of communication between living organisms, both between individual animals, either of the same or of different species, and between plants and animals. The first group consists of simply chemicals that exist whether or not there is an animal with a sense of smell capable of detecting them; the second is the result of millions of years of natural selection and evolution. The results of evolution are there because they have a clear adaptive advantage to the organism

mechanism, and to convey a message to which there will be a behavioral response. They are nature's perfumes, the structure of which may be a guide to the perfumer.

The chemical sense as a means of communication between separate organisms first assumed biological importance with the evolution of sexual reproduction. Aquatic organisms, long before the development of sight or hearing, needed to locate and correctly identify members of their own species for pairing. This was achieved by the release of specific chemical materials by one individual which directly affected the behavior of another, resulting in the synchronized release of gametes and fertilization. Such chemical messengers, or

pheromones, occur in almost all animals, from unicellular organisms to insects and higher mammals, and play an important part in the mating process along with visual and vocal displays. They have a direct influence on the nervous system of the individuals at which they are directed, affecting their behavior and leading to successful mating. They are either single materials or simple mixtures to which the animal's response is genetically predetermined.

There is no process of learning involved. They are for the animal concerned quite literally

"what turns it on."

Apart from chemicals that act directly as pheromones in the reproductive activity of higher animals, there are many other associated materials, sometimes coming from animal

excrement, that cause an arousal of interest and act as innate recognition factors between animals within a species, or as a warning to others. Some of these, as we will see later, have an important function in perfumery.

This link between the sense of smell and reproductive activity not only goes back to the most primitive organisms but is also deeply embedded in the unconscious mind of all higher

animals including humans. Research into human biology has shown that if the neural link between the nasal receptor cells and the pituitary is broken, sexual interest and function may be greatly impaired.

However, at some stage in our evolution the sense of smell became greatly diminished. This may have come about partly because of the adoption of an upright bipedal position which distanced the human nose from many of the sources of smell. At the same time pheromones ceased to be the irresistible sexual turn-ons that they were to our prehuman ancestors. In his book The Scented Ape, Michael Stoddart (1990) regards the desensitization of the olfactory system that occurred in humans as having played a key role in our evolution, protecting the

Pheromones are still produced and undoubtedly play some part in our unconscious behavior patterns. It is possible, for example, that our "gut reaction" to the people we meet, whether we like them or not, has something to do with our subconscious awareness of the

pheromones they produce.

Despite this switching off of the importance of pheromones other types of human odor continue to play an important role in the bonding between individuals: between mother and child, between man and woman, and between members of a family. Although our ability to recognize people by their odor is very much less than, say, that of a dog, it is clear that each of us has his or her own unique smell.

The olfactory desensitization that took place in our evolution coincided with the development of the higher brain, the neocortex. Behavior patterns and preferences, including those linked to our sense of smell, became increasingly learned by experience rather than being based on a circuitry of nerves hard-wired at birth.

Newborn humans have few olfactory preferences; most of the wiring has to be put in place during the early years of development, though we continue to learn and acquire odor

preferences throughout our lives. The cultural implications of this and its relation to perfumery are of course immense, since each of us is able to learn and respond to an enormous range of odorous materials rather than only to those dictated by a genetically predetermined system of behavioral responses.

The Importance of Animal Smells in Perfumery

Although human odor forms a natural part of our social environment, it has become a fundamental principle of civilized society that human beings should not smell of human beings. Much of this has come about through social development and the conditioning that we receive as children, based on hygiene and sexual modesty. But the neural pathways connecting the sense of smell to our deepest centers of pleasure remain, and humans have from the earliest times delighted in the use of perfumes rich in products of animal origin—of any animal, that is, except the human being. In ancient times, and through to the Middle Ages, natural civet and musk were used in their own right as perfumes, employed not only for their supposedly aphrodisiac properties but also

at levels where the mental associations induced by them remain in the unconscious mind.

Intensely animalic materials of natural origin, as well as their synthetic counterparts, fecal notes such as indol and scatol, are widely used at acceptably low levels in perfume

compositions of every type. Many plant products also have associations with animal notes and probably have an unconscious erotic effect. Costus has a smell associated with the

sebacious glands of the hair, cumin has an intense smell of sweat, ambrette seed and angelica contain powerful musk like constituents. The recent introduction of cassis bourgeons into many modern perfumes may be connected to its resemblance to the sexually related odor of the male cat. The consumer must of course be quite unaware of this association.

However, there are also many synthetic materials, and materials of plant origin, that resemble natural animal odors such as musk and ambergris without having the intense fecal or urinous overtones that require them to be hidden within a composition at a level where their presence cannot be consciously recognized. These materials may be quite different chemically to the natural product, but to us their odor and effect are similar. Included in this category are the amber notes derived from labdanum and clary sage, as well as the numerous synthetic musk materials such as galaxolide and musk ketone.

The use of a great variety of musk and ambergris notes in the composition of perfumes is of great significance in perfumery. When smelled as part of a perfume they are capable of producing a sense of pleasure associated with ancient neural pathways without the perceiver being aware of the true nature of the stimulus. They form an important part of nearly every successful perfume.

The Olfactory Relationship Between Plants and Animals

Floral notes are also among the most widely used in perfumery. To the human psyche they are the most beautiful of smells and a constant source of inspiration to the perfumer.

The sense of smell in animals and their behavioral response to the presence of certain types of molecule has been exploited by plants in the evolution of their own reproductive

processes. Many plants produce smells that mimic either the pheromones of insects or olfactory

muguet, and lilac. Although most of the animals that pollinate flowers are insects, some small animals including rodents and bats are similarly used by plants, attracted by the means of odors which to the animal concerned have a genuinely erotic association.

Even in fungi the exploitation of animals for the purpose of spore dispersal has produced some remarkable relationships. Pigs have for centuries been used in the search for truffles, toward which they have an insatiable curiosity. The fungus that produces its fruiting body underground is now known to contain substantial quantities of a pheromone produced by the male boars for attracting sows. By digging up the truffle and breaking it into pieces, the pig is actually aiding in the dispersal of its spores. The fact that we also regard the truffle as so great a delicacy is no doubt linked to our own unconscious awareness of its link with animal pheromones.

But many plants went on from this relationship based on the mimicking of single erogenic materials to evolve vastly more complicated fragrances in order to advertise their presence to animals such as bees and other insects. Flowers were evolved that offered a reward of food to a visiting insect in return for a service to the plant, that of transferring pollen from one flower to another. Plants are in effect using the wings of insects to carry pollen from one flower to another, providing them with fuel by way of nectar.

This coevolution between plants and animals for their mutual benefit has not only resulted in the complex and individual fragrances that they produce but in the wonderful color and structure of flowers themselves. We do not know whether insects such as bees can smell precisely the same range of materials as ourselves or whether their olfactory world differs from ours in the same way as does their vision. Bees are able to "see" ultraviolet, and the patterns of flowers that guide the bee toward the source of food appear quite different to the bee than they do to us. But, since we are able to smell most constituents of essential oils, it is probably fair to assume that our range of smell is quite similar. Perhaps bees have a much clearer idea of the smell of benzyl alcohol, which occurs in many flowers, than do most perfumers. How it would actually smell to them we cannot imagine any more than we can imagine the color of ultraviolet.

But let us consider the development of this relationship between insects and flowers in a little more detail, since there are some

distribution of pollen by insects had been established within the plant world the evolutionary pressure to achieve the maximum efficiency became enormous. Plants competed with each other in advertising their presence to insects by the evolution of more and more wonderfully specialized floral structures and scents; insects in their turn became increasingly specialized for the feeding on nectar and pollen. Not only were the plants dependent on insects, but insects became dependent on plants. Each had a vested interest in the survival of the other.

The greatest efficiency was to be achieved by ensuring that an insect should feed only on one species of flower at a time, so avoiding the wasteful distribution of pollen to other flowers.

Some insects developed an innate ability to memorize a particular odor as being associated with a ready supply of food. Bees returning to the hive are able to pass on to their coworkers information as to the direction and distance at which a source of nectar is to be found

together with its associated scent. Programmed in this way, the bee will then visit only this particular type of flower.

What is interesting from the point of view of the perfumer is that this coevolution between animal and plant has resulted in the synthesis by plants of complex fragrances, often made up of many hundreds of materials, rather than being based on just one or two materials as in the case of pheromones.

Distantly related plants, such as rose, jasmin, and lavender have quite independently gone down this road of complexity, based on different groups of chemical constituents. We may conclude, therefore, that complexity of odor has evolved as being the most effective way of evoking a desired response from an animal with the ability to smell and the ability to

memorize odor. What is remarkable is that the particular combinations of materials that individual flowers produce to make up their fragrance have, to our own sense of smell, an identity far greater than a random mixture of as many ill-assorted chemicals. Perhaps we may infer from this, in view of the similarity of our receptor cells, that the balance of materials is as important to the olfactory mechanism of the bee as it is to our own in producing a sense of identity and aesthetic pleasure.

If we look further into the chemical makeup of fragrances produced by flowers, taking rose as a typical example, we find that the oil is usually made up of perhaps no more than four of five materials that represent the main bulk of the product, with frequently hundreds of other materials making up the balance. If we mix together in the

results in the fragrance that is uniquely rose.

This balance between simplicity and complexity also plays an important part of the structure of a well-made perfume, and is a subject to which we will return in the next chapter.

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