ANIMAL BEHAVIOUR (Part 1 of 3)   Leave a comment

Man has always been fascinated by the amazingly varied behaviour of animals. Ancient man observed the habits of animals, partly out of curiosity but primarily in order to hunt and to domesticate some animals. Most people today have a less practical interest in animal behaviour They simply enjoy the antics and activities of pets, of animals in zoos, and of wildlife. But in modern times animal behaviour has also become a scientific speciality The biologists and psychologists who study animal behaviour try to find out why animals act in the specific ways they do and how their behaviour helps them and their offspring survive. Some of them feel that the behaviour of animals provides clues to the behaviour of man.

Anthropomorphism, the ascribing of human form or qualities to gods or things, as when ancient people attributed powers to fire, stones, and trees, and as animals in fables have the gift of speech.

A great deal of fanciful “animal lore” has arisen over the years in the mistaken belief that animals behave for the same reasons as man. The view that non-human things have human attributes is called anthropomorphism. An example of anthropomorphism is found in the following passage written by the 1st century AD Roman author Pliny the Elder:

The largest land animal is the elephant. It is the nearest to man in intelligence; it understands the language of its country and obeys orders, remembers duties that it has been taught, is pleased by affection and by marks of honour, nay more it possesses virtues rare even for man, honesty, wisdom, justice, also respect for the stars and reverence for the sun and moon.

Undeniably, the elephant can be taught to perform certain tasks, but no one today seriously believes that it reveres the sun and the moon.

Animal behaviour can be studied in natural settings or in the laboratory. Often, laboratory experiments are designed to test notions based on outdoor observation. The study of animal behaviour from the viewpoint of observing instinctive behaviour in the animal’s natural habitat is called ethology. (The ways in which animals solve their common problems for example, eating, drinking, protecting themselves and their offspring from predators, reproducing, and grooming are all the concerns of an ethologist, a scientist who studies animal behaviour) A contrasting viewpoint on behaviour, practised in the United States particularly, has concentrated mainly on learning processes, behavioural development, and the influence of behaviour on an animal’s internal workings the action of nerve impulses and hormones, for example. Both approaches are important.

What Is Behaviour?

Simply defined, animal behaviour is anything an animal does its feeding habits, its reproductive actions, the way it rears its young, and a host of other activities. Behaviour is always an organized action. It is the whole animal’s adjustment to changes inside its body or in its surroundings.

The group activities of animals are an important aspect of animal behaviour Bees, for example, communicate with each other about food, and birds may flock during migratory flights. Group activities are often adaptations to a new set of circumstances. Without adaptation, a species could not survive in an ever-changing environment.

Behaviour can also be thought of as a response to a stimulus some change in the body or in the environment. All animals, even those too small to be seen without a microscope, respond to stimuli.

How an Animal Reacts to a Stimulus

A stimulus is a signal from the animal’s body or its environment. It is a form of energy light waves or sound vibrations, for example. All but the simplest animals receive a stimulus light, sound, taste, touch, or smell through special cells called receptors, located in many places on or in the body. For example, fish have taste buds over much of their body, sometimes even on the tail. These buds enable fish to taste the water they swim through and thus to detect nearby food. Cats, which prowl the dark, rely on sensitive touch organs associated with their whiskers.

At the receptors the incoming energy is changed into nerve impulses. In complex animals these impulses may travel either to the brain or through reflex arcs to trigger the hormone or muscle actions of a response.

Conditioning – A Way of Modifying Behaviour

The behaviour of many, perhaps all, animals can be modified by a kind of training called conditioning. Two types of conditioning have been studied classical conditioning and operand conditioning. The first type was discovered by the Russian physiologist Ivan Pavlov; the second, by the American psychologist B.F. Skinner.

In classical conditioning, an animal can be made to respond to a stimulus in an unorthodox manner. For example, a sea anemone can be conditioned to open its mouth when its tentacles are touched a response that it does not ordinarily make to this stimulus. When undergoing such conditioning, an animal is repeatedly offered two different stimuli in timed sequences. The first, called the neutral, or conditioned, stimulus, does not usually cause the animal to respond in the desired way. In the sea anemone experiment, touch is the neutral stimulus. The second, called the unconditioned stimulus, does cause the desired behaviour Squid juice is the unconditioned stimulus because it will cause the sea anemone to open its mouth. In classical conditioning, the neutral stimulus is followed by the unconditioned stimulus. The unconditioned stimulus may be given while the neutral stimulus is being delivered or afterwards The sea anemone was touched first, then given squid juice. After hundreds of such trials, it opened its mouth when touched even though no squid juice was offered.

In operand conditioning, an animal is given some type of reward or punishment whenever it behaves in a certain way for example, whenever it pushes a lever, presses a bar, or moves from one place to another. The reward or punishment, called a reinforcement, follows the action. Food or water may be used as rewards; an electric shock, as a punishment. Rewarding the animal increases the probability that it will repeat the action; punishment decreases the probability. Operand conditioning has been used not only with animals but also in programmed instruction and teaching machines.

Role of the Nervous System in Behaviour

An important relationship exists between an animal’s nervous system and its ability to respond to environmental changes. Animals with a fairly simple nervous system, such as ants, respond in a relatively fixed, or stereotyped, fashion as compared with animals that have a more highly developed and specialized nervous system, such as rats. A rat can link up, or integrate, different stimuli from the environment and can store and use the information from past experience to solve simple and complex problems far better than an ant can. However, the rat does not do as well as a higher mammal, such as a chimpanzee.

For example, a rat, an ant, and a chimpanzee can each learn a complicated pattern of responses to reach food. The rat is trained to run a maze a number of pathways toward a goal, all but one of which end in blind alleys to find food. Then the rat begins at the end of the maze and must learn to run the course backward in order to reach food placed at the starting point. The rat takes less trials to learn the maze backward than forward. An ant given the same training cannot benefit from its past experience. It must learn the backward path as though it were a new one. The chimpanzee shows the greatest learning ability of the three. When the chimpanzee solves a problem, such as discriminating between two geometric shapes, it can do so by generalizing from a “set to learn.” That is, after it has learned that it can obtain food by making the correct choice between the two shapes, it easily makes the correct response on the next try. A rat requires a number of trials before it can associate “shape” with “food.”

The Evolution of Behaviour

Behavioural scientists arrange living things according to the complexity of their behaviour and the extent to which it can be modified. They have found that animals with more complex body and nervous systems have more complex and more modifiable behaviour In addition, however, the behavioural patterns that have evolved among living things are particular ways of adapting to their environments the places where they develop and reproduce. For example, though all animals feed, there are evident differences in the way they feed. Marine worms sift sand for edible organisms. An army ant stings a beetle and brings it back to the colony’s bivouac, where it is dismembered by other members of the colony. A chimpanzee peels a banana before eating it.

It is possible to observe living animals and find out why they act as they do, but can anyone know how extinct animals behaved? There are fossil remains of extinct animals, but behavioural patterns cannot be left as fossils. Yet, equipped only with such fossil remains, scientists can get inklings about the behaviour of extinct species. They achieve this by studying living species in the laboratory or in their natural habitats to determine their behavioural similarities and differences. Then they try to uncover the relationship between the structure of the body parts of these species and the particular function of each body part. Thus, if particular characteristics of the structure of a wing or a leg, for example, can be identified with a particular activity of a living animal, a scientist studying the evolution of behaviour can make plausible guesses about the possible function of fossil bones. He can then develop notions about the possible behaviour of extinct species that were ancestors of certain living animals.

For example, by studying the different groups of passerine, or perching birds, researchers have identified the evolutionary relationships among them. One way is to use tail flick as a taxonomic character a structural trait employed in analysing the relationships among different species. Perching birds flick their tails in a particular way as they move through trees. By analysis of the extent of tail-feather spread during a tail flick and the direction and amount of tail movement, evolutionary relationships can be seen among such passerines as cardinals, buntings, weaver birds, wax bills, and finches.

Evolutionary relationships among species may also be studied by analysing different behavioural patterns. Among the most important behavioural patterns are orientation, social organization, and communication. All species exhibit each of these. However, within species considerable variation exists in the stimuli to which individuals respond, the age at which they respond, and the patterns of their response.


Posted 2011/12/20 by Stelios in Education

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