History of Biology: Names to
remember
Module 1: Why and how?
Aristotle Aristotle (384-322 BC) classified around 500 species, did embryo studies of eggs
and performed animal dissections. He was in search of the essence of organisms as
explanation to its functions. He was the tutor of Alexander the Great.
Aristotle also developed a guiding principle for taxonomy: determine the essential
attribute of a class of individuals and the number of variations on that attribute;
divide the class into that number of subclasses. Do the same for each subgroup.
Difficulties arise from the fact that you are supposed to determine in advance.
Hypatia Hypatia was a scientist-philosopher in Alexandria who studied e.g. mathematics,
astronomy and literature. She was one of the few women scientist during that
period. She was accused of witchcraft and killed by a Christian mob.
Galen Galen of Pergamum (130-200x) wrote more than 300 treatises on philosophy,
(Galenus) religion, pathology, etc. Galen understood that, despite his life-long search for the
truth, he would never be able to discover everything. Pergamum (were Galen was
born) saw itself as a cultural rival of Alexandria, and the Ptolemies tried to arrest
the intellectual growth in Pergamum. When Galen’s father Nikon died, he left
Pergamum to study in Alexandria, but a couple of years later he returned and
became a physician. Galen delivered anatomical lectures. Like Plato and Aristotle,
Galen believed that a form of divine intelligence had created the universe and
living beings. For Galen, the body was the instrument of the soul and proof of the
existence and the wisdom of God. Galen understood that most practioners needed
anatomical knowledge, and he was sure that his findings in animals could be
applied to humans.
Galen was the ultimate authority on medical and biological questions for hundreds
of years: his anatomical studies were not challenged until the 16th c. and his
physiological concepts remained unquestioned until the 17th c. Galen’s anatomy
had the defect that he had based he researches on animal models.
Despite Galen’s reputation and the fact that he gave public lectures and
demonstrations, he left no school of disciples. Galenic ideas became the
foundation of Islamic and Christian medical studies.
Galen’s concept: concept of the three spirits. He supported a worldview called
anthropomorphic teleology.
Galen was a doctor of gladiators and later became a Roman army doctor. His
problem was that dissection was unacceptable, so he learned anatomy through
wounded gladiators. Galen followed the Greek theory of the four humours:
imbalances were seen as the root of many afflictions.
Leonardo Da Leonardo Da Vinci (1452-1519) was apprenticed to Andra del Verrochio (the
Vinci foremost art teacher in Florence) when he was 14. Verrochio insisted that all his
pupils learned anatomy. Da Vinci thought about the movement of the earth, the
nature of sound and light, the use of rings to determine the age of trees, and the
nature of fossil shells. Studies of the superficial anatomy of the human body led to
an exploration of anatomy and physiological experiments. In addition to attending
public anatomies, he also dissected bodies himself. He also was the first anatomist
to wax casts the ventricles of the brain. He studies the mechanism of action of the
muscles and heart, and his dissections represent the first significant errors since
, Aristotle and Galen to exploit the advantages of comparative anatomy.
Although he realized the heart was actually a very powerful muscle, he generally
accepted Galen’s views on movement and distribution of the blood.
Da Vinci performed dissections in secret.
Paracelsus Paracelsus (1493-1541) was an alchemist. He believed nature was the divine book
of creation. Paracelsus ridiculed pharmacists and physicians and took away their
business by undercutting their prices and curing their disillusioned patients.
Paracelsus burned the works of Avicenna and Galen to show his contempt for
ancient dogma. Paracelsus claimed that through natural magic and alchemy
human beings would one day be able to make gold, cure disease and create life.
For the Paracelsians, natural magic was the key to understanding nature and her
laws.
Paracelsian alchemy provided new chemical analogies for physiological functions.
Paracelsus also argued that that specific remedies should be designed for specific
diseases in accordance with specific causes, while orthodox physicians and
pharmacists preferred expensive remedies that included exotic materials. He also
believed that violent diseases required violent remedies.
He was interested in poison and believed that only the dose of a substance makes
the poison. He was the founding father of toxicology.
Andreas Andres Vesalius (1514-1564) was the reformer of anatomy. He wrote the book “on
Vesalius the fabric of the human body”, that revolutionized ideas about the structure of the
human body. Human dissection was the foundation of Vesalian forms. When
Vesalius began to study anatomy, the authority of the ancient Galen had grown so
weighty that anatomist tended to explain discrepancies between his descriptions
and their own observation in term of individual abnormalities of changes in the
human body that had occurred since the time of Galen.
Vesalius was a medical student at the university of Paris, and assistant to Jacob
Sylvius, influence in Parisian anatomy and Galenist. Vesalius became critical of
professors who lectured about Galen’s words about things they never investigated
for themselves. Vesalius performed a lot of dissections but obtaining bodies for
dissection remained a chronic problem: Vesalius stole bones from a graveyard.
In 1540, as a mark of his independence from Galen, Vesalius assembled the bones
of an ape and a man to show that Galen had made loads of errors with respect to
human anatomy.
After publishing his book, critics attacked it on the grounds that students would
consider the illustrations a valid substitute for participation in dissections. Vesalius
decided to abandon research and became a court physician, like his father.
Given the academic climate of his time, it is remarkable that Vesalius confronted
and rejected the Galenic dogmas, that had been accepted without a question for
generations.
Vesalius conducted public dissections while not reading from Galen, and this way
showed the limitation of Galen’s anatomy.
