Zoology Notes on Zoology | Biology

Zoology Notes on zoology.  After reading this you will learn about:- 1. Humble Beginning of Zoology 2. Greek Origin of Zoology 3. Roman Origin 4. Dark Ages 5. History 6. Renaissance 7. Divisions 8. Practical Applications.

Contents:

1. Notes on the Humble Beginning of Zoology
2. Notes on  Paper on the Greek Origin of Zoology
3. Notes on Paper on the Roman Origin of Zoology
4. Notes on Paper on the Dark Ages of Zoology
5. Notes on Paper on the History of Zoology
6. Notes on Paper on the Renaissance of Zoology
7. Notes on Paper on the Divisions of Zoology
8. Notes on Paper on the Practical Applications of Zoology

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Zoology Notes # 1. Humble Beginning of Zoology:

From the very dawn of his appearance on earth, man has always been interested in animals. These interests were centered, chiefly, round his need to kill animals for food and also to escape from being killed. As a necessary corollary, primitive men had to know something about the habit and distribu­tion of the animals round him.

Thus the knowledge about the habit and distribu­tion of animals constitutes the dawn of the Science of Zoology and at the same time it may perhaps be regarded as the oldest of all sciences. Cro-Magnon men had drawn many pictures of animals in the caves they used to live (Fig. 6.1).

These pictures were that of Bison, Reindeer, hairy rhinoceros, mammoths, birds and fishes. The pictures are so vivid that it is possible to identify the animals up to the genus level. These drawings are certainly indicative of the types and distribution of animals of that age.

The next important record that is avail­able to us dates from about 5000 years ago and that from the fertile crescent of the Tigris and Euphrates. That was the age of Barbarism. Records show that men in those ages were engaged in some agricul­ture and animal husbandry. Both these practices demanded some preliminary knowledge of Biology.

As time passed on, the civilization of Babylon arose in the same geographic area and with it written language came into existence. A written language provided an opportunity in which observations could be recorded and read.

In 2000 B.C., the Babylonian ruler, Hummurabi made the existing laws, including medical laws codi­fied. He arranged to record the codes on clay tablets and kept the tablets in a special building which undoubtedly form­ed the first library.

In close parallel to the civilization in the fertile crescent of the Tigris and Euph­rates, the Egyptian civilization was emer­ging in the valley of the Nile. The ability of these people to make paper from the water plant, Papyrus, did a tremendous job to advance the recording of knowledge and, therefore, the advance of science.

The Ebers Papyrus is an encyclopedia of medi­cal information of that time and Smith Papyrus (both named after their discover­ers) was a text book on surgery.

The recent translation of these ancient documents shows that the treatises dated from the fifteenth century B.C. All these indicate to the fact that the science of medicine attain­ed a wonderfully high grade of develop­ment amongst those people.

As the formu­lation of a system of medicine in the early hours of mankind needs observation and practice of centuries, it is reasonable to believe that these manuscripts were the attempts at reducing medicine to a system. It is apparent that the system is built upon much scientific knowledge and must have been inspired by earlier writings on medi­cine and allied sciences.

The civilization of Egypt is divided into three periods. They are:

(i) Pre-dynastu period,

(ii) First dynasty and

(iii) New king­dom.

The New kingdom lasted till 600 B.C. Low relief carvings of animal figures of the pre-dynastic period have been dis­covered. During the first dynasty period step pyramids were erected. This period saw the evolution of a Polytheistic religion in which the Pharaohs were gods and kings at the same time.

At the fag end of this period there was a switch over to Monotheistic religion. Ihknaton was the king then. He encouraged realism in arts and the picture of animals drawn in his regime are so accurate that the animals drawn could be identified up to the species level.

All these advancements were, how­ever, temporary. During the period of New-kingdom a reversion to old poly­theism came and mythical god animals saturated the work of art. From this time onwards the civilization of Egypt under­went a decline.

Overlapping somewhat with the Egypttian civilization the Aegeans on the island of Crete, shores of Greece and parts of Asia minor adjacent to it arose. Picture of animals represented mostly by fishes and cattle of this age have been dis­covered. Pain killing drugs were known at this period. The serpent was considered as god. The Aegean civilization fell to in­vaders by 1100 B.C.

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Research Paper # 2. Greek Origin of Zoology:

The Greeks were a collec­tion of tribes of mixed origin that invaded the coasts and lands of the eastern ‘part of the Mediterranean. They used to call them­selves as Hellenes. They had settled there about the beginning of the second millen­nium before Christ. Before the coming of Greek-speaking people, the eastern coast of the Mediterranean was inhabited by peo­ple who were in a neolithic state of culture.

They were either displaced or absorbed by the Greeks. The Myceneans and their colonial offshoot Minoans in the island of Crete were the first Greek tribes to attain civilized state. Frequent warfare between the Myceneans and Minoans resulted in the fall and decay of both the civilizations round about 1400 B.C. From the ruin left by these warfares, a distinct Greek civiliza­tion arose gradually.

The first Greek tribes who have left any literary remains were the Ionians and the Dorians. The Ionians had greater inclina­tion towards philosophy, mathematics and astronomy. Theories concerning the struc­ture of the universe and attempts to classify substances as elements were offered by Thales.

The Dorians on the other hand were less civilized but more practical. In the island of Cos within the Dorian territory sprang up a medical school about 600 B.C. It is the earliest scientific institu­tion that is known to us. Knowledge for its own sake was sought and as a result science started rising to new height.

The germ of evolution ideas had its inception in the minds of the Greek philo­sophers during this period. The thoughts were speculative and often coloured with mythology. One of these Greek philoso­phers was Anaximander whose adult life spanned the first half of the sixth century B.C. According to him men were first formed as fishes.

Later on they cast off their fish skins and took up life on dry land. Xenophanes was a contemporary of Anaximander in part and lived on into the fifth century B.C. He was the first person to recognise fossils and to say that fossils re­present the remains of animals that once lived.

He also realised that the presence of fossils of marine animals on dry lands is suggestive of the fact that these fossil laden lands were once under the sea.

The centre of civilization gradually was shifted to southern Italy and Sicily, and this shifting became complete by 5th cen­tury B.C. Pythagoras migrated from Greece to Italy at about this time. He was a poli­tician, religious leader and scientist and attempted at realistic interpretations of natural phenomenon.

Alcameon was an­other man of letter of the same period who made dissections and performed many crude physiological experiments.

Alcameon for the first time saw the nerves of the eye and the eustachian tube. At about the same time in the island of Cos there lived the physician of all times—Hippo­crates (460-370 B.C.). The modern Hippocratic oath of doctors stems from his name.

He learnt medicine on his native island of Cos. He practised and taught it in Cos, various other islands and on the main land of Greece. He was a man of noble charac­ter, dignified bearing and humane feeling.

A good number of books bear the name of Hippocrates but all of them were not certainly written by him. Some of the best and most interesting of them are of about his date. Probably these were his work. The books reveal a good idea of what he knew and how he worked.

These early work of medicine contain no information whatsoever of the know­ledge that is now considered necessary for a doctor. No anatomical, physiological or chemical knowledge is portrayed in these work. Instruments were unknown.

Hippocrates had to work with his own sense. The real scientific value of his work lies in the careful record of what was seen. His work not only recorded things seen but also tell us how these observations were made. These help us to follow the physi­cian into the sickroom and watch him at work

Hippocrates advocated the doctrine of four humours. The ancients supposed that all matters were made up of four essential elements. They are earth, air, fire and water. It was further supposed that the elements work’ either in opposition or in alliance with each other.

Thus, water was opposed to fire but allied to earth. The oppositions and affinities were associated with the view that each element is compounded of a pair of primary qualities in the form of heat and cold, moisture and dryness.

Hippocrates sup­posed that all living bodies are made of four humours. They are sanguis (blood), cholera (yellow bile), melancholia (black bile) and Pituita (Phlegm). These four humours bear special relationship with the four ele­ments. Health depends upon the mixing of the humours in the right proportions. If one or the other is in excess the patient will suffer accordingly.

Though this belief is long abandoned still it finds a place in many expressions in current use. Besides these, Hippocratic work contains some striking and short sayings called Apromism.

Some of the Hippocratic apromisms which have passed into common speech and are eternal in use are given below:

(i) Art is long and life is short.

(ii) Desperate diseases need desperate remedies.

(iii) Sleeping -too much is as bad as walking too much.

(iv) One man’s meat is another man’s poison.

The fifth century B.C. had also to donate some ideas about evolution. It saw the man Empedocles who has been hailed by Osborn (1896) as ‘the father of evolution idea’. According to this philosopher, plants were the first to rise out of the earth, as did, subsequently, animals.

Unattached organs and parts of animal body were formed first and then these organs and parts started combining with each other in haphazard manner. Most of these combi­nations became monsters or freaks and could not survive.

But occasionally there had been happy combination of organs, i.e., right organ in the right place. Such ‘fit’ combinations survived and populated the earth. It is interesting to note that the idea of fit combination was reflected in the Darwinian idea of survival of the fittest after twenty-three century.

Another scientist of the Greek age was Socrates (469-399 B.C.). Socrates laid a good foundation for the development of future science but unfortunately he was against experimentation and was a believer of supernaturalism. Plato was another great philosopher of the Greek age.

Plato had a strong bias towards mathematics and according to him the world and nature were mere illusions. The Institution where Plato taught was called Academy. The meaning of the word was simply the name of a grove of trees. The word is much in use even today to indicate a place of learning.

The greatest of all scientists amongst the Greeks was Aristotle (284-322 B.C.). He was the son of the physician to the royal family of Phillip II of Macedonia and was trained in the Academy of Plato. Plato influenced Aristotle a great deal, but in certain philosophical matters there was much difference between them.

Aris­totle was essentially a biologist but re­mained attached to his teacher till Plato’s death in 347 B.C. Aristotle felt disappoint­ed when he was not made the head of Plato’s academy and established a rival academy which he called Lyceum. Here his bias towards biology and natural history had full play.

In addition to major contri­butions to the other sciences, he spent ten years observing marine life and wrote several books on Zoology. He devised the first system on taxonomy. He was the tea­cher of Alexander the Great.

After the Peloponnesian wars there came a decline of Greek civilization and was replaced by the Macedonian Empire centered in Alexandria on the north-coast of Africa. Two important investigators are worth mentioning of this era.

One was Herophilus (280 B.C.) who is considered as the ‘father of medical Anatomy’. He established the difference between artery, vein and nerves. He also recognised the brain as being the organ of thinking.

Fol­lowing him came up Erasistratus who is considered as ‘the father of medical phy­siology’. He could distinguish between sensory and motor nerves and did formu­late the primitive ideas about the function of the blood vessels.

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Research Paper # 3. Roman Origin of Zoology:

The Athenian scientific school virtually came to an end after the death of Alexander the Great in 323 B.C. His empire broke into fragments to be seized by his generals. Meanwhile, the Roman civilization began its rise about 500 B.C. and became the dominant centre of the civilized world within two hundred years. Alexandria at this time became the centre of scientific world.

A definite ‘Alexandrian period’ came up in the history of science. It covers the last three hundred years before the Christian era. The biolo­gical work of the Alexandrian school have perished save and except fragmentary writings of two biologists of that age, i.e., Herophilus and Erasistratus. As both of them were. Greeks, they have been dis­cussed earlier under the Greeks.

During the early phase of Roman civili­zation there had been little advance in Zoology. Varro during this period expressed the belief that diseases are caused by orga­nisms which cannot be seen—a concept that was proved to be true two thousand years later by Pasteur.

In the later period of Roman civilization there came Pliny (Pliny the Elder), the Roman naturalist. He was a man of an en­tirely different character and outlook. He was a man of immense industry with an enthusiasm for collection.

He put together a vast number of extracts known in his time about nature and compiled the book Historia Naturalis. The book consisted of tales of wonder, of travellers and sailors yarn and superstition. Thus there was more misinformation than information.

After Pliny the most important biologist investigator in antiquity was Galen (A.D. 130-200). He was a physician. He made frequent dissection of animals. He exa­mined the structure of sheep, oxen, pigs, dogs, bears and many other animals.

He could recognise the resemblances between man and monkey. He gave good descrip­tions of muscles, bones and joints. Galen did a good deal of work on the function of organs. In his role as a physiologist he in­vestigated the functions of spinal cord and also the purposes served by air breathing. He believed that air enters into heart directly from the lungs.

He believed in one God and developed a personal philoso­phy with the idea that every organ in the human body was created by God in per­fect form. This idea fitted in well with the Moslem and the Christian faith and as a result his ideas were incorporated into religious dogma. He commanded so much respect that no one dared to re-examine or question his work even 1500 years after his death.

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Research Paper # 4. Dark Ages of Zoology:

After Galen, there was no expansion of scientific knowledge for many centuries. It is believed that the ad­vent of Christianity is the root cause be­hind this dark phase. The early Christians were intolerant of the ideas of science that had been developed until this time.

The scientists who developed them had been the religious enemies of the Christians and little of their culture was acceptable to the Christians. The early Christians believed that the return of Messiah was in the offing and their attention was directed to this event. Science was of no interest to them.

When the knowledge and intelligence of men of the Western Europe were on the decline, the same were rising in Syria, Asia Minor and Constantinople. Greek scientific work was studied there.

In the seventh century the great move­ment of Islam came. It established Arabic as a literary language and by the ninth century the intellectual leadership went to the people of Arabic speech. It remained with them till the thirteenth century.

In the hands of the Moslem physicians great advances were made in medicine, mathe­matics and other sciences. Their science, however, was based on translation of the Greek work into Arabic.

These transla­tions were made in large number and ardently studied throughout the Islamic countries. Islam was a rapidly conquering religion and soon extended at the point of sword from Near East to North Africa. Spain, Portugal, Southern Italy, Sicily and many Mediterranean islands.

Thus when the Moslem civilization was dominating the stage, Europe was plunged into dark ages and the progress of European science came virtually to a standstill position. When the European people came to recognise their intellectual infer­iority they sprang up to secure retranslation of their past scientific work.

These were made from the Arabic to Latin with the help of the Jews. The heritage of science from the Greek and Roman periods would have been lost had it not been translated into Arabic.

The view that the rise of Christianity led to the destruction of science in Europe has been challenged recently. Two main reasons have been advocated against the view. The challenger historians advocate that science in Europe began its downward course long before the rise of Christianity.

Moreover at the end of the second century of the Christian era, when ancient science almost decomposed, the Christian formed a too little and insignificant sect to in­fluence the people who would study science. It cannot, however, be denied that too much spiritual interest of Christianity in the early centuries did nothing to pro­mote science and on die contrary, dis­couraged any revival of science in the later era.

Another important factor, according to this, was the mental make-up of the ruling class in the Roman Empire. The Romans were very much practical people. They were engaged very much in governing their empire.

They produced great mili­tary leaders, great lawyers alright but never cared or appreciated theoretical in­vestigations. Science can be applied to meet the practical needs of life but mere application is never in itself a science. Science will fail to flourish until theoretical investigations are undertaken for their own sake.

The Roman military organisation had certainly medical services. This service was well and carefully organised. Thus far the Roman rulers showed their practical bend of minds. But these leaders never thought of getting their medical officers trained on scientific lines.

They never established medical schools. Effective training in ana­tomy and physiology was totally lacking in the Roman Empire. Mere reading can­not sustain science. Science can only sus­tain by systematic observations and experiments. These two essentials of science were unheard of in the Roman regime.

The contempt for and aversion to science of the Roman leaders is significant because it teaches a lesson which is of value today and of value in all the de­partments of science.

Research Paper # 5. History of Zoology:

The association of man and animals dates back to the prehistoric period. The prehistoric men knew animals, they could distinguish them from one another, from different angles, primarily from their daily needs and safety. The early Egyptians knew quite a lot about animals, and domesticated cattle, sheep, pigs, cats and ducks.

Attempts were made by Greek philoso­phers of fifth and sixth century B.C. to ex­plain the origin of life. Aristotle (384-322 B.C.) wrote about animals of Greece and the nearby region of Asia Minor in his Historia animalism.

Greek physician Galen (131- 201 A.D.) the founder of experimental physi­ology, dissected pigs and monkeys and made notable discoveries on the functions of brain and nerves and demonstrated that arteries carry blood and not air, the idea held till then.

Belgian anatomist Andreas Vesalius, Professor in the University of Padua in Italy, published his observations based on the dissection of human body. ‘On the structure of the Human Body’ in 1543. Galen’s descrip­tion of human anatomy had many errors.

In spite of that, Vesalius’ challenge to unques­tioned authority of Galen for 1,300 years in­vited severe adverse criticism and he was finally forced to resign from Professorship. Since the domestication of animals by early Egyptians, our knowledge in zoology has been enriched from the contributions of a large number of workers, the names of the majority of whom are unheard to the average students of zoology.

From the time of Vesalius, till the appearance of Charles Darwin, the progress was not that fast. Darwin, a man of vision, brought the science of animals from the laboratories and libraries of a few people or organisations to the common man. The father of zoology helped people at large to get an idea about the vastness and diversity of the animal world.

The progress of zoology has been spec­tacular from the early twentieth century. Naturalists, systematics, anatomists, physi­ologists, cytologists and geneticists, embryologists, evolutionists, biophysicists and bio­chemists, ecologists, mathematicians and stat­isticians, all nurtured the giant tree of zoo­logy with utmost care and attention.

Today, molecular biology and genetics have developed to such an extent that different disciplines have been created for them.

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Research Paper # 6. Renaissance of Zoology:

Dust for centuries over the scientific discourses started to be washed out with the advent of the spring of Renaissance. It began in the twelfth century and with it scientific investigations again began to progress in Europe. Roger Bacon, a monk, studied optics, the tides of the ocean and human anatomy.

His reli­gious affiliation prevented him from dis­section of animals. Copernicus and Galileo, though non-biologists, were other two scientists of the early Renaissance period. The contributions made by them were in­dications of freedom of thought and at the same time the rising interest in science at that time.

The early part of Renaissance was fol­lowed by a period of unrest. The Magna Charta in 1215, the death of Joan of Arc in 1431 and the auto-da-fe of Gregory, IX¹ are all indicative of the unrest.

The fourteenth century began with a period of travel. Many information depict­ing rare and strange things, as a result, came in from overseas. Trade with the East became escalated and drugs started to be imported. Trade and commerce brought with them travellers tales. Some of the tales were true while majority were false. Those of Marco Polo (1254-1324) are true but those associated with the name of Mandeville are false.

In the year 1453 Constantinople (Istan­bul of modern times) was captured by Moslems. They cut off the trade route bet­ween Asia and Europe. The search for alternate route to the Orient was stimulat­ed.

Vasco-da-Gama, Diaz, Columbus and others went out in search of the routes. The exploration of the world soon reflected itself in biological literature. Voyages of exploration resulted in the recognition of many foreign plants and animals.

Renaissance period gave the world a number of scientists who contributed to Zoology in Europe. The most important of them was Leonardo-da-Vinci. He was a bio­logist of all times and enjoys the same fame in a number of other branches of science as well as in arts.

His knowledge of Anato­my and concept of Physiology was out­standing. Paraffin embedding of tissues and casting of body cavities were the tech­niques invented by him. These techniques have become extremely productive in the hands of later investigators.

Vesalius (1514-1564) was another impor­tant scientist of the Renaissance period. He threw a challenge to Galen’s anatomy and started dissecting animals. He, by publishing the first true atlas of anatomy has laid the foundation of the subject.

William Harvey in 1628 published a book on the function of heart and circula­tory system to become the father of experi­mental physiology. Harvey’s thought has undergone little change in modern phy­siology.

The advent of ‘Encyclopedists’ is another important feature of the Renaissance period. During the sixteenth century an acute need was felt for some orderly arrangement to the available knowledge in Biology and accordingly, a group of Ency­clopedists arose. They attempted to collect all known facts about living things. Conrad Gesner (1516-1565), the Swiss naturalist is the best representative of this school.

The other important events of the Renaissance period (later period) are the establishment of scientific societies and advent of scientific journals. These led to exchange of scientific information and views amongst the scientists of the world.

The story of the science of Biology forms the beginning of a story of continuity. It began in an humble way and was all mingled up with medicine in the initial phase.

The character of the progress of Biology shows that—

(a) It was a crusade against superstition.

(b) It was a battle to overthrow the authority.

(c) It was a gradual switch over from descriptive to comparative and then to experimental.

(d) Instrumentation has aided the progress to a great extent.

The germ of Biology was united with medicine for a long time. Its separation from medicine and its colossal rise as an independent subject is due mainly to the ‘steady growth of that zest for exploration into unknown fields which began with the new birth of science in the sixteenth cen­tury’.

The modern biology did not arise till the nature of the protoplasm was made known by Schultze in 1860. From that year onward the history of Zoology is necessarily the history of its individual disciplines. The growth of knowledge became so rapid and the number of significant contributions are so large that it is better to spell out the chronology of development of zoology in an abbreviated fashion.

Research Paper # 7. Divisions of Zoology:

i. Morphology or Anatomy:

The study of gross structures of organisms—both external and internal, and the relation of one organ with the other.

ii. Microanatomy:

The study of histological structures or tissues under magnification.

iii. Physiology:

It deals with the functions of organs in relation to structure.

iv. Cytology:

The study of structural details of the cells, their modifications and divisions.

v. Embryology:

The science of development of animals from zygote stage to fully formed young individual. Now-a-days it has been replaced by the term morphogenesis or embryogeny.

vi. Parasitology:

The structure, modification and the influence of parasitic life, both on parasite and host.

vii. Entomology:

Various aspects of insects including their influences on other animals.

viii. Taxonomy:

Nomenclature of animals and classification or assigning them proper posi­tion in the animal kingdom.

ix. Ecology:

Relation of animals with the environment and the influence of the latter on the former.

x. Zoogeography:

Distribution of animals on the surface of the earth.

xi. Evolution:

Descent with modifications or the appearance of new species from preex­isting species.

xii. Genetics:

Genetics is the science of inher­itance. It is concerned with the transmission of potentialities of characters from generation to generation.

xiii. Molecular Biology:

Quantitative studies of the molecular structures and the factors responsible for biological processes. It includes analysis of gene structures and functions and genetic control of synthesis of biological molecules and their regulatory processes in the cell.

Research Paper # 8. Practical Applications of Zoology:

Our ever-increasing knowledge in zool­ogy has enabled us to apply this science in human benefit, ranging from prevention of diseases to production of various items for our use, introduction and stabilisation of new hybrids, and in many other fields.

Medicine:

A knowledge of animals pro­ducing various diseases, viz. malaria, filaria, nagana, liver rot, etc., is essential for proper treatment. Further knowledge on anatomy and physiology of experiment animals like rabbit, monkey and others enables us not only to test the drugs but in the manufacture of hormones, enzymes, vaccines, etc.

Fibre:

The beautiful silk is really the secre­tion from the silk glands of the silkworm Bombyx mori and others. The larva builds a hard protective cocoon around it, within which it pupates. The silk thread is obtained from this cocoon.

Lac:

The lac is a resinous substance se­creted by the female lac insect Tachardia lacca to build their nests on the branches of food tree. The dye obtained in the processing of lac is used for colouring and the shellac in vari­ous industries, viz. pottery, varnish, toy, elec­tric insulation, shoe polish, etc.

Pearl:

The pearl is an important item of commerce. It is extensively used in the manu­facture of ornaments and decorative articles. Large scale pearl cultivation is carried out in a number of countries including India, of which Japan tops the list.

Food:

The animals themselves or their products are very important items in the list of our food. With increased demand for ani­mal and animal products for food—fishery, poultry, piggery and dairy have been started on commercial basis.

a. Fishery:

The knowledge on anatomy, physiology, breeding, growth, migration and behaviour of marine, estuarine and fresh water fishes is being utilised in fisheries and it has been possible to produce a number of high-yielding fishes. Sea is a vast reservoir of fish and sea fishing is encouraged by a num­ber of countries.

b. Dairy:

Healthy cattle and buffaloes are a good source of protein and milk. In dairy, in addition to maintaining proper health of the live-stock, efforts have been made with success to improve stock by hybridization.

c. Poultry:

Birds are a good source of most tasty meat and egg. Fowl and duck are the common animals of a poultry. The mainte­nance of the health of the birds and improve­ment of stock by hybridization and other means go side by side in an ideal poultry.