Animal communication
Communication between animals can be defined, as in humans, as any action on the part of an organism that influences the behavior of another. It can be seen as an exchange of information (or symbols that carry information). The term 'signals' is used for the symbols implicated in animal communication, as they range from the emission of chemical substances to complicate bird songs. The discovery of instances of animal communications has been difficult because the response may be internal or postponed, or may consist in not carrying out certain action.
From the point of view of its purpose, communication can be seen as the process that enables the coordination of the activities of two or more individuals of a species. This coordination may refer to mating, getting food, parenting, fighting enemies, etc. The function of a signal may be inferred from the context in which it is given and the reaction of other animals. Different contexts and different receivers may produce dissimilar responses. For example, the same bird song may affect males and females in opposed ways.
The information that a signal makes available can be about characteristics of the sender (like age, sex, and breeding condition), or about the environment (like the availability of food, or the appearance of predators). It is only by analyzing the response that the signal's function can be thoroughly understood.
The most used types of animal signals are chemical, visual, and acoustic. Chemical signals, called 'pheromones,' are the most primitive ones and used by all kind of animals, from the elementary as the paramecium to the most complex as the mammals. Across all the animal range pheromones are utilized to trail-marking like in ants, or attracting mates and stimulating courtship like in fishes and mammals. The silk moth produces a male attracting odor that may act as far off as three kilometers. The dog territory marking is another class of chemical signal.
Visual messages may involve the movements or the appearance of the animal. Butterflies and Siamese fish execute courtship dances in the air and in the water. Apes show brilliant colors in their genital parts. Certain species of fish change the color of their bodies when are ready for mating, thus attracting individuals of the opposite sex. Because they limit communication to the range of vision, these signals are normally employed by species whose individuals live together.
Acoustic signals, instead, are suitable for communication where animals cannot see each other, as in a forest. It is also to the advantage of some species to remain occult, thus avoiding predators. Birds and crickets are common examples of animals that communicate by sounds. In both cases, their songs serve to indicate readiness to breed, aggression, alarm, or accomplish purposes of courtship or territory marking.
The development of communication means in animals seems to have some kind of correlation with the complexity of the message that the means can bring. Low-level forms such as pheromone emission seem to not depend on the contact of the young with other members of the species. On the contrary, birds and monkeys need that contact to learn the typical forms of communication of the species. Many birds do not learn the birdsong of the species when reared apart from other birds.
However, monkeys raised by humans can learn intricate forms of communication that can be considered as making up a language. In the 1960s, the Washoe project researchers succeeded in teaching a chimpanzee to communicate using the gesture language of the deaf, being the first time when a non-human primate was taught to use symbols in communicating. As well as bringing animals among men, researchers are sending human emissaries among animals. In the late 1980s, a computerized robot bee was introduced into a hive and used to communicate messages to the hive's bees using their dance language.
The ways that animals use to communicate are not limited to those studied so far. Recent discoveries about monkeys that can tell what is happening to their infants by their screams, and of whales than emit sounds under the range of human hearing, lead to think that animals may use advanced communication systems that we are not aware of.
Previous | Contents | Next
