The following points highlight the top five outstanding makers of life science. The outstanding makers are: 1. Aristotle (384-322 B.C.) 2. Pliny the Elder (23-78 A.D.) 3. Galen (130-200 A.D.) 4. Vesalius (1514—1564) 5. Harvey (1578-1657).
1. Aristotle (384-322 B.C.):
Aristotle was born in 384 B.C. at Stagira. Stagira was a small town lay far away from Athens which was the centre of learning.
Aristotle’s father was a physician to the King of Macedon. In all probabilities Aristotle got his taste for biological investigation from his father. At the age of seventeen, Aristotle was sent to Athens to become a student of the great philosopher— Plato.
Plato influenced his pupil Aristotle a great deal. But they had profound differences between themselves. Plato had a strong bias for mathematics while Aristotle was essentially a biologist.
Aristotle (Fig. 6.3) expected to become the head of the academy after the death of his teacher, Plato in 347 B.C. He was no: made the head and in disappointment he left Athens to reside in a small Greek state on the coast of Asia Minor opposite to the island of Lesbos. Here his bias for natural history was in the full cry. He had ample leisure and he spent these time making investigations on marine life.
King Philip of Macedon invitee him to become the tutor of Alexander. He accepted the invitation and came to Macedon in the year 342 B.C. and stayed there for seven years teaching Alexander. King Philip was assassinated in that year and Alexander became the King. Aristotle now left Macedon and came back to Athens.
Aristotle never returned to Plato’s Academy but set up his own institution called Lyceum. He soon gathered round him an able band of students. He taught there for thirteen years and died in the year 322 B.C.
Biological work of Aristotle:
Of the biological work of Aristotle, four major treatises are surviving in a fairly complete form.
a. On Psyche.
b. Histories about animals.
c. On the generation of animals.
d. On the parts of animals.
Aristotle was interested in watching animals and their ways of life. He used to keep notes of what he saw. From his notes the following remarkable accounts can be cited.
i. On the Habits of Fish:
Aristotle gave a good account of the breeding habits of cat-fishes and pointed for the first time the ability of these fishes to emit an articulate sound. Of the marine fishes, Torpedo and Angler fishes drew his attention. According to him, “In marine creatures one may observe many ingenious devices adapted to the circumstances of their lives.” His accounts on Torpedo and Angler fish are perfectly true.
ii. On Octopuses and their Allies:
Aristotle has given a perfect and delightful description of the development of Octopus and Sepia.
iii. On Whales, Porpoises and Dolphins:
Aristotle had a clear idea about the important anatomical, physiological and embryo- logical differences between a man and fish. Thus he knew that man has lungs, it is warm-blooded and brings forth its young alive, i.e., viviparity. These characters are absent in fishes. From these differences he could separate the group of mammals that includes whales, porpoises and dolphins from the fishes.
iv. On Placental Dog Fishes:
Aristotle knew well that the fishes differ from mammals in being oviparous. But he could find out a group of fishes in which the youngs are born alive.
Aristotle tells us that a shark like fish called Galeos lays eggs within itself. These eggs during development acquire an attachment with the womb much like the placenta of mammal.
v. As Bee-Master:
The diversities present in the methods of working and general habits of bees is usually printed in Aristotle’s Historia animalium. Indications of observation and recording of the habits of animals are present here. But in all probabilities the habits of bees were not written by Aristotle himself. It might so happen that a practical bee-master under the influence of Aristotle has written the part.
vi. Aristotelian Classification:
Aristotle never made a formal classification. His work contain many terms. Though scattered, if these terms are arranged sequentially, it certainly will speak of a classification scheme or arrangement which was in Aristotle’s mind. The scheme is given below.
I. Enaima=Vertebrates (With red blood and either viviparous or oviparous)
(c) Viviparous quadrupeds:
(i) Ruminants with cutting teeth on the lower jaw, hoofs cloven— sheep, oxen, etc.
(ii) Solid hoofed animals—Horses, asses, etc.
(iii) Other viviparous quadrupeds.
Oviparous though at times externally viviparous:
(i) Cartilagenous except Galeos.
(ii) Other fishes.
II. Anaima = Invertebrates:
(No red blood and viviparous, vermiparous, budding or spontaneous)
With perfect eggs:
With eggs of special type:
(c) Insects, spiders, scorpions.
With generative slime, buds or spontaneous generation:
(d) Molluscs (except cephalopods).
With spontaneous generation:
(e) Sponges, coelenterates.
vii. Aristotle on the Nature of Life:
Aristotle was not only a practical biologist but also a theoretician. The most fundamental division among biologists has been between the schools known as Vitalists and Mechanists. According to vitalists living things are endowed with some principles of a quite peculiar nature and they are quite different from non-living matters.
This principle of the living objects not only exists but also is expressed in some manner. The mechanists on the other hand denied the truth of both these beliefs of the vitalists and claimed that all actions, movements, etc., of living things can be expressed as the outcome of forces and can be investigated in non-living matters. Aristotle belonged to the vitalist group.
Aristotle embarked upon die word Psyche to indicate soul. According to him there are vegetative soul and animal soul. The first or lowest was the vegetative soul and as such plants were regarded by him as the lowest Jiving form.
The qualities of life essential for this lowest form of soul were nutrition, growth and the power of reproduction. The animals had all these qualities plus the power of movements. Animals thus possessed, he thought, a second order of soul that includes sensitiveness and motive powers.
viii. Aristotle on Evolution:
He maintained that there is a gradation in nature. The lowest grade is inorganic, from which arose the higher grade of organic by a process of metamorphosis. He conceived that organic world exists in three states-—-Plants, Plant-animals and Animals.
Plant-animals are transitional groups and include sponge and sea anemone. Aristotle failed altogether to appreciate the true significance of fossils. His towering intellect wars a failure here.
Aristotle’s Role in the Development of Science:
Aristotle lived at a time when science was at its infancy and errors and crudities were the rules. So die measurement of the height of Aristotelian achievements in the yard stick of present day standard will not be justified. He had extensive knowledge of animals and specially the life histories of animals. He was the founder of classificatory schemes though it was incidental.
He was extremely interested in the problems of how creatures came into existence and he can very well be called the “father of embryology”. His observations of the structure, development and his anticipation of the idea of organic evolution, are the ones on which his fame rests.
The work of Aristotle place him as one amongst the greatest biologists. He was centuries ahead of his time. He was an original thinker and had an unrivalled capacity for arranging his own and others materials. Last but not the least is that his influence guided biologists to the right direction.
2. Pliny the Elder (23-78 A.D.):
Pliny was a Roman naturalist of the first century A.D. Pliny was a well-born gentleman and was an able and efficient civil servant. By profession he was a General.
Pliny (Fig. 6.4) was a man of immense industry and had a special aptitude for collection. These collections were not of natural history objects but, of information about them. He was a good collector— “collector of antedotes—who forsaking observation indiscriminately, mixed fable, fact and fancy taken from the writing of others”.
The book he had compiled was known as “Natural History”. It was written in thirty seven volumes and has been preserved with greater completeness.
Pliny was more an illusion and his work did nothing to extend the horizon of knowledge. The misinformation compiled by him retrograded the advancement of science as his work of low quality was widely read during the ages which followed.
He recasts Aristotle’s plan of classification and formulated a higher artificial one in its’ place. His scheme was based on incidental circumstances of abode of animals, i.e., air, water and land.
3. Galen (130-200 A.D.):
After Pliny there remained only one biological investigator in antiquity. He was Galen.
Galen (Fig. 6.5) was born in Pergamon in Asia Minor. Pergamon and Alexandria were the two important but rival centres of learning. At the beginning, Galen was a student of philosophy, but at the age of sixteen he switched over to medicine. According to the custom of those days Galen went travelling for studies at the age of twenty.
He learned anatomy at Alexandria medical school and came back to his native land at the age of twenty- eight and remained there for four years. He worked as surgeon to the Gladiators during these years. Fig. 6.6 demonstrates the dissection of human body in earlier days.
After that he migrated to Rome to seek a career. At Rome he became the physician to the emperor. His fame and eminence as a good physician, anatomist and physiologist soon became established.
Galen dissected animals like sheep, oxen, dogs, pigs, etc. He never dissected a human body at least publicly. He could recognise’ the resemblance between human anatomy and that of monkey.
Galen did a good deal of Work on the functioning of organs. In his role as a physiologist he made investigations on the function of spinal cord and tried to find out the purposes behind breathing and heart movement. He, however, could not discover the function of blood and was of the opinion that air enters from lungs directly to heart.
Galen established himself as an author at the age of twenty and remained anindustrious writer throughout his life. His work are enormous and cover all departments of medicine.
Galen had a tremendous influence over the men of his time and even for centuries his works have not been challenged. Thus the errors he made were passed on to the succeeding ages that followed him. The extraordinary respect that Galen commanded was due to his religion.
He was a pagan and believed in one God. He was able to develop the idea that every organ in the human body was created by God in the most perfect possible form. This fitted in well with the concept of Christianity of his time. This explains why the name and work of Galen were held for long fifteen hundred years.
4. Vesalius (1514—1564):
Vesalius was one of the founders of biology who believed in observation and reason. He was born in Brussels on 31st December, 1514. His leaning towards scientific pursuit was inherited from an ancestry of physicians and learned men. From his early life he had a passion for anatomy.
After his early training at Brussels and at the University of Louvain he went to Paris at the age of eighteen to study medicine. He was there for three years and when wars broke out in Belgium he had to go back to Louvain without the medical degree.
After earning some experience as surgeon on the field of battle he went to Padua being lured by the reports that he will have the opportunity of making practical dissections there. His talents were recognised at Padua. After receiving the degree of Doctor of Medicine in 1537 he joined the university as a surgeon.
Vesalius (Fig. 6.7), as a great teacher of anatomy used to teach in his own new way. He never allowed unskilled and ignorant barbers to make dissection of human for demonstration before his students. He used to do such dissections by his own hands.
His book on the “Fabrics of Human Body” is a biological masterpiece. The book opens with a description of bones and joints, the general classification of which forms Galen’s work. The skull has been considered as the first bone.
Skulls have been systematically measured and individuals and races have been classified as broad headed, round headed and Jong headed. Such classifications are of much importance to Anthropologists. A comparison between the skull of man and dog is also found in his book.
Vesalius was most successful with his work on muscles. He was successful in describing and drawing these muscles with much accuracy. Fig. 6.8. portrays the anatomical sketch of man.
He gave a fair description of the structure of heart but his account of the septum between the ventricles was not correct.
Vesalius was the first man to do battle against tradition. He believed in Galen rather than his own eyes but gradually lost his faith in Galen and at the end he casts Galen and his writings into the wind. Thus at the age of thirty the idol of authority was made shattered by him.
He used to teach only what he himself had seen and what he could make his students see. He brought into anatomy the new wave of the time and the men of the time specially the young answered the new wave. His great book with its illustrations has certainly laid the foundation of modern biological sciences.
The importance of Vesalius lies in the fact that he overthrew the adherence to authority as a method for ascertaining the truth and introduced observation and reason in science. He saw new truth with clearness and had the bravery to force his thoughts on an unsympathetic public.
5. Harvey (1578-1657):
As the sixteenth century was closing, there came William Harvey (Fig. 6.9) an Englishman with a new and hitherto unknown vision about comparative anatomy, physiology and embryology. He was born at Folkstone, on the south coast of England in 1578.
He belonged to a family of wealthy yeoman. He had his schooling in the King’s School at Canterbury and at the age of sixteen he entered Cains College. He was endowed with a power for observation upon organisation of animals but could not cultivate it at this university. Here he studied Latin and Greek to become a graduate with the Arts degree.
In 1598 he came to the great University of Padua in search of best medical instruction. He was fortunate in receiving his instruction in Anatomy and Physiology from Fabricius. Fabricius was the most learned and honoured teacher in Italy during that time.
A fast friendship grew between the young medical student and the mature anatomists. Harvey had his first familiarity with the circulatory system under the stimulus from his teacher. The knowledge of circulatory system was further amplified and geared up by Harvey.
Harvey was a student of originality and force and after graduating in Arts, studied for four or five years in scientific and medical lines to obtain the degree of Doctor of Physics. He came back to England in 1602 and obtained the degree of M.D. from Cambridge.
In 1615 he was called to lecture on anatomy at the Royal College of Physicians in London. He was also appointed physician to King James I. He continued, however, to lecture regularly at the Royal College.
Harvey’s book on the circulation of blood or “Anatomical Dissertation concerning the motion of the heart and blood” is still considered as one of the greatest monuments along the high-road of biology. The first edition of the book came out in 1628. It contained 72 pages in miserably printed little Latin quarto. The action of heart in forty species including worms, insects, crustaceans and fishes was recorded in it.
In his book he showed for the first time ever in print, that all the blood in the body moves in a circuit and that the heart beat is the propelling force behind circulation. His demonstration of the movement of blood in a circuit was based on careful observations, experiments and cogent reasonings.
The central point of Harvey’s reasoning was that the quantity of blood which leaves the left cavity of heart in a given span of time comes back again to heart after some lapse (30 minutes or less) of time.
Thus Harvey’s idea of movement of heart was new, his notion about circulation was new and his method of demonstration was new. His lectures at the Royal College embodied the most revolutionary doctrine ever delivered.
It is said that he worked also on comparative anatomy and the development of insects. The manuscripts and drawings of these work were lost due to war.
Vesalius undoubtedly revealed in a splendid way the construction of human body and Harvey went one step further by introducing experiment to determine the purpose of the structures. The work of Harvey are complemental to that of Vesalius. Their joint work directed and influenced the path of biological investigations in the right way.
The versatility of Harvey is beyond any question. He was the first amongst the biologists to give a really reasonable explanation, in physical terms, of any bodily process. His investigations on the anatomy of about sixty animals and embryology of insects and vertebrates had a tremendous influence in promoting future biological investigations.
Harvey initiated a total change in the attitude towards living processes. Biological investigations before his time had been full of vague terms intended to explain living activities. Innate heat, animal spirit, pneumatic force, etc., are some of the vague vocabularies. Harvey’s book rang the death knell of a whole vocabulary of such mysterious phrases.