Biology

The Men of Biology

ARISTOTLE• Father of Biology• Natural philosopher,

identified some of the known living characteristics such as reproduction.

The Men of Biology

Galen

- Studied the functions of the kidneys and spinal cord using the Barbary ape.

The Men of Biology

Andres Vesalius- was the founder of

modern anatomy. - Broke traditions by

performing his own dissection using cadavers.

The Men of Biology

William Harvey

- Correctly described how the blood is pumped around the body by the heart

The Men of Biology

Marie Francois Bichat

French anatomist and physiologist whose systematic study of human tissues helped found the science of histology.

The Men of Biology

Henri Dutrochet- Was credited for the

formation of cell biology

- Discovered cells in plants and actual process of osmosis

Robert Hooke

• English physician, inventor

• Used early microscope to describe appearance of plants at microscopic level

• Credited with creating the term cell

Antony van Leeuwenhoek

• Dutch scientist, 1600s

• Used interest in developing magnifying lens to invent microscope

• First to describe appearance of bacteria, red blood cells, yeast, other microorganisms

The Men of Biology

Robert Hooke- Coined the term “Cell”- First to observe a

plant cell (cork cell)

Robert HookeRobert Hooke- 1665- found cork tissue contained little compartments he called “Cells”. They looked like little rooms in a monastery.

Hooke first to use the term cell

• Hooke had discovered plant cells -- more precisely, what Hooke saw were the cell walls in cork tissue.

• In fact, it was Hooke who coined the term "cells": the boxlike cells of cork reminded him of the cells of a monastery.

Robert Hooke: • Discovered the cell – cork tissue using a newly invented

microscope; called them cells because they reminded him of the cells of a monastery

• Published his book Micrographia in 1665• Created the compound microscope and illumination system

– Used it to observe such organisms as insects, sponges, bryozoans, foraminifera, bird feathers, etc.

• Observed fossils under the microscope and noted the similarities between petrified wood and real wood and created the theory that fossils are forms of animals

• Published two years after his death, Hooke’s Discourse of Earthquakes in which he explained that fossils found in inland regions are a result of times when that land was under water

Robert Hooke• Robert Hooke (1635-1703) was an experimental

scientist, mathematician, architect, and astronomer. Secretary of the Royal Society from 1677 to 1682, …

• Hooke was considered the “England’s Da Vinci” because of his wide range of interests.

• His work Micrographia of 1665 contained his microscopical investigations, which included the first identification of biological cells.

• In his drafts of Book II, Newton had referred to him as the most illustrious Hooke—”Cl[arissimus] Hookius.”

• Hooke became involved in a dispute with Isaac Newton over the priority of the discovery of the inverse square law of gravitation.

Micrographia

Cork Seen Through Microscope

Hooke:

Objects the Hooke

observed under the microscopeHooke’s compound

microscope

“1 The truth is, the science of Nature has been already too long made only a work of the brain and the fancy: It is now high time that it should return to the plainness and soundness of observations on material and obvious things. “ - Hooke

Microscope - 1662• In 1662 Robert Hooke was named Curator of Experimentsof the newly formed Royal Society of London. • Hooke devised the compound microscope and illumination system and used it in his demonstrations at the Royal Society's meetings. • He displayed plant cells! in a slice of cork (below).

The Men of Biology

Anton van Leeuwenhoek- Helped in the

improvement of the microscope

- First to describe muscles, blood flow in capillaries, spermatozoa, bacteria and protozoans

Microscope -1668• The father of microscopy, Anton van Leeuwenhoek of Holland, started as an apprentice in a dry goods store where magnifying glasses were used to count the threads in cloth. • He was the first to see and describe bacteria, yeast plants, the teeming life in a drop of water, and the circulation of blood corpuscles in capillaries.

" I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof' .

Anton Van Leeuwenhoek – 1600’s

• Dutch merchant used magnifying glass to view cloth

• Developed first usable microscope.

• First person to view small organisms in pond water.

Leeuwenhoek first to view bacteria

• Leeuwenhoek took samples of pond water and view them through his microscope.

• Spirochetes• Algae• Protists

Antony van Leeuwenhoek:(1632-1723)

• Inspired to take up microscopy by Hooke’s Micrographia

• Made over 500 microscopes, but only ten have survived to this day

• Leeuwenhoek was very skillful at grinding lenses and was able to use this skill to magnify objects over 200 times

• Hired an illustrator to create drawing of what he saw under his microscopes

• In 1673, Leeuwenhoek began to write letters to the Royal Society of London in which he described his findings under the microscopes – he would correspond with this organization for the next fifty years; his letters were collected and printed in the Philosophical Transactions of the Royal Society

• Observed lake water and discovered numerous types of algae and other small organisms

• Observed plaque from human teeth – the first known observation of living bacteria

• Leeuwenhoek observed animal and plant tissues, mineral crystals, and fossils

Leeuwenhoek:

• “. . . my work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof. “ - Leeuwenhoek

Daphnia, small organism that Leeuwenhoek found in lake water

Example of Leeuwenhoek’s microscopes

Maria Merian: 1647 – 1717AD

• Dutch• Studied plants and

animals• Wrote a book of

drawings of insects in various stages of development

• Went to Surinam in South America to study insects

• Fell ill with malaria and her health was never strong again

• Her book on Surinam insects was published in 1705AD

• First time European scientists were able to see South American insects

The Men of Biology

Carolus Linnaeus- Laid the foundations

for the modern scheme of Taxonomy

- Introduced the use of binomial nomenclature (genus + species)

Carl Linnaeus

• Linnaeus was born in 1707, the son of a Lutheran clergyman, at Rashult in Sweden.

• He began to study medicine at the University of Lund in 1727, transferring to the university of Uppsala the following year.

• Linnaeus headed an expedition to Lapland in 1732, travelling 4,600 miles and crossing the Scandinavian Peninsula by foot to the Arctic Ocean.

• On the journey he discovered a hundred botanical species.

• In 1734, he mounted another expedition to central Sweden.

• He finished his medical degree at the University of Hardewijk in Holland in 1735, then going to the University of Leiden for further studies.

• That year, he published Systema Naturae, his classification of plants based on their sexual parts

Carl Linnaeus

• His method of binomial nomenclature using genus and species names was further expounded when he published Fundmenta Botanica and Classes plantarum.

• This system used the flower and the number and arrangements of its sexual organs of stamens and pistils to group plants into twenty-four classes which in turn are divided into orders, genera and

species.

• In his publications, Linnaeus provided a concise, usable survey of all the world's plants and animals as then known, about 7,700 species of plants and 4,400 species of animals.

• These works helped to establish and standardize the consistent binomial nomenclature for species which he introduced on a world scale for plants in 1753, and for animals in 1758, and which is used today.

Carl Linnaeus• His Species Plantarum 10th edition,

volume 1(1758), have accordingly been accepted by international agreement as the official starting points for botanical and zoological nomenclature.

• Scientific names published before then have no validity unless adopted by Linnaeus or by later authors.

• This confers a high scientific importance on the specimens used by Linnaeus for their preparation, many of which are in his personal collections now treasured by the Linnean Society.

• Twenty-three of Linnaeus' students themselves became professors and this spread his methods widely, as did his extensive correspondence with leading naturalists all over Europe.

• In the mid-1700s, the Swedish biologist, Carolus Linnaeus, shortened the long descriptive terms for each organism to a binomial system, using only the genus (group) and species (individual kind) name.

• For example, the two oaks shown below belong to the genus Quercus (always italicized or underlined) for oaks, and phellos or rubra (always in lower case italics or underlined), for the willow or red oak

The Men of Biology

Charles Darwin- Pioneered the

evolutionary theory- Proponent of the

theory of natural selection

Darwin’s achievements

• Transformed biological science – Both style and content– Still the cornerstone of biology – Now the cutting edge of psychology

• Transformed attitudes of humanity to our place in the universe

His books (not just on evolution)

• Beagle voyage

• Coral reefs

• Volcanic islands

• Geology of South America

• Barnacles

• Species

• Man

• Emotions

• Climbing plants

• Domestication

• Cross and self fertilisation

• Orchids

• Worms

• Autobiography

Contribution to style of science

• Pre-Darwin, science was done in homage to God

• Was primarily descriptive

• Deduction and theorising was disparaged as “speculation”

• Darwin used detailed observation to explore much larger questions - helped change scientific methods

Charles Darwin: 1809 – 1882 AD

• British• Studied medicine and

to be a priest for the Anglican Church

• Spent most of his time collecting beetles and butterflies

• Went on a scientific expedition on the Beagle voyage

• From his observations, he developed the theory of evolution.

• Famous Evidence: the tortoises of the Galapagos Islands in the Pacific

Darwin’s Expedition - 1831 • Hired as Naturalist on H.M.S. Beagle

• Sailed on Five Year Scientific Expedition– Down East Coast of South America– Up Pacific Coast to Galapagos Islands– Made Stops on Mainland and Islands– Observed Variety of Life and Habitats

Joining the Beagle Voyage

• Not paid for 5 years on Beagle. • Actually, he had to pay! • Was lucky to get on

– replaced someone who was shot in a duel

– his father opposed him going

• Mainly asked because of his class, to keep Captain Fitzroy company

• It was the making of him

I have called this principle, by whicheach slight variation, if useful, is preserved,

by the term Natural Selection.

  —Charles Darwin from "The Origin of Species"Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

http://evolution.berkeley.edu/evolibrary/home.php

www.darwinday.org/englishL/life/beagle.htUsed by permission of Darwin Day Celebration (at DarwinDay.org), 2006

www.darwinday.org/englishL/life/beagle.html

http://evolution.berkeley.edu/evolibrary/home.php

Full-scale replica of the Beagle sailing off the coast of South America.

General plan of the Beagle based on a drawing by a shipmate during the voyage of the Beagle. Darwin wrote that, “I have just room to turn around and that is all.”

Voyage of HMS Beagle –1831-1836

A five year, circumnavigation of the globe, with the principal objective to map the coast line of South America.

Galapogos, 1835• Portrayed as a “Eureka” experience. • Actually, was hugely homesick• Did not recognise significance until back in

England, 1837.– Worked out theory much later.– First inkling of natural selection in 1838.

• Turtles & finches were key evidence– On boat home, ate turtles, dumped shells– Thought finches different species; didn’t even

label them properly

Darwin in Australia

• Only visited three places in Australia– Sydney, Jan 1836– Hobart, Feb 1836– Albany, Mar 1836

“On the whole I do not like New South Wales. It is no doubt an admirable place to accumulate pounds and shillings; but heaven forbid that I should live where every man is sure be somewhere between a petty rogue and a bloodthirsty villain.” (Darwin to Henslow)

“I have called this principle, by which each slight variation, if useful, is

preserved, by the term Natural Selection.”- CHARLES DARWIN

• Darwin was the British naturalist who became famous for his theories of evolution and natural selection.

• Like several scientists before him, Darwin believed all the life on earth evolved (developed gradually) over millions of years from a few common ancestors.

• From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world.

•

• In South America Darwin found fossils of extinct animals that were similar to modern species.

• On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America.

• The expedition visited places around the world, and Darwin studied plants and animals everywhere he went, collecting specimens for further study.

The Darwinian ThesisFact 1. Organisms have enormous reproductive potential (Malthus)

Time

Num

bers

Fact 2. Populations are at equilibrium (Observation)

Time

Num

bers

Exponential growth

Logistic Growth

Fact 3. Resources are limited (0bservation).

If organisms have enormous reproductive potential, yet do notrealize that potential owing to the fact that resources are limited, then there must be ….

Inference 1. … a struggle for existence.

Fact 4. Individuals are unique; there is individual variation. (Observation)

Variation in shell color and banding pattern within a single species of Caribbean snail.

Darwin was impressed with the fact that no two individuals are exactly alike.

In contrast to the Platonic idea that the eternal idealized type was what mattered, Darwin made individual variation an integral part of his theory of evolutionary change.

Fact 5. Some individual variation can be transmitted from one generation to the next (personal observation, experience with animal breeding).

Tra

it in O

ffsp

ring

Trait in Parents

Offspring resemble their parents, but not precisely. Thus, differences among individuals in the parental generation tend to be reflected in individuals of the descendent generation.

Inference 2. If there is a struggle for existence and there is individual variation, then some individuals, owing to their unique set of traits, will be better equipped to prevail in the struggle for existence. In other words,NATURE SELECTION will occur.

Inference 3. Natural selection, operating over the immensity of Geologic time, will produce evolutionary change, or DESCENT WITH MODIFICATION, to use Darwin’s expression.

IN SUMMARY: According to the Darwinian Thesis, evolution proceeds by means of agents of natural selection, operating on heritable variation within populations, to bring about ancestor-descendant change.

That substantial changes can be induced in plants and animals by artificial selection is obvious. Consider the many very different breeds of dogs, all descended from a single ancestral species (the wolf).

But can we find examples of natural selection operating in nature?

• Upon his return to London Darwin conducted thorough research of his notes and specimens.

• Out of this study grew several related theories:

• one, evolution did occur; • two, evolutionary change was

gradual, requiring thousands to millions of years;

• three, the primary mechanism for evolution was a process called natural selection;

• and four, the millions of species alive today arose from a single original life form through a branching process called “speciation.”

• Darwin's theory of evolutionary selection holds that variation within species occurs randomly and that the survival or extinction of each organism is determined by that organism's ability to adapt to its environment.

• He set these theories forth in his book called, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (1859) or “The Origin of Species” for short.

1836 – 1839

Back in London, Darwin became a well-known scientist/ naturalist, more of a geologist than a biologist. However, he began several notebooks on biology and evolution, having become convinced that species were not immutable but changed and evolved.

In 1838 he read Thomas Malthus’ essay on population and conceived the importance of natural selection in evolution.

In 1839 he married his first cousin. Emma Wedgwood, and they had 10 children born between 1841 and 1854.

Summary of Origin of Species

• Proposed Evolution Resulting from Natural Selection:– Organisms Produce Many Offspring– Competition for Food, Territory, Mates, etc.– Those With Best Traits Survive – Organisms Change Over Many Generations

• Time Frame: Millions of Years

Darwin’s Support for His Theory

• Characteristics of Organisms Coincide With Habitats

• Changes Produced by Breeding of Organisms

• Geologic Ages Suggested by Charles Lyell

• Similarities of Various Organisms

Limitations of Darwin’s Theory

• Apparent Limits to Variation

• No Mechanism For Sufficiently New Characteristics

• Transitional Forms Would Require Special Environments

• Oversimplified View of Living Cells

• The Origin of Life Unexplained

• Limitations of Fossil Record

• Sudden Appearance of Complex Life

• Lack of Clear Transitional Forms

• Gives More Evidence For Species Disappearance

Limitations of the Fossil Record

Chicago Daily News negatives collection, DN-0006585. Courtesy of the Chicago Historical Society. American Memory Collection

• Sudden Appearance of Complex Life

• Lack of Clear Transitional Forms

• Gives More Evidence For Species Disappearance

• Explanation of Strata Insufficient

Limitations of the Fossil Record

Scientists’ Initial Reactions to Darwin’s

Work • A Compilation of Assertions and

Hypotheses

• Unsupported by Scientific Testing

• Contains Assumptions that Cannot Be Supported

• Violates the Principles of Cause and Effect

• Illogical Conclusions

So Why Was It Eventually Accepted?

• It Passed Rigorous Scientific Testing?– No, His Hypotheses Are Not Testable 

• Were Transitional Fossils Found?– No Clearly Substantiated Links Found Yet

• A Mechanism to Produce New Traits Discovered?– Mutations Result in Lost Genetic Information

The Acceptance of Darwin’s Theory of

Evolution

• Natural Selection of Genetic Variations is Observable– Limited to Genes Already Present– New Traits Produced Only By Mutations– Overwhelming Odds Against Good

Mutations

Ultimately, Acceptance Depended On One Factor:

Willingness to Accept a Naturalistic Explanation

Ultimately, Acceptance Depended On One Factor:

Willingness to Accept a Naturalistic Explanation

• Darwin's work had a tremendous impact on religious thought.

• Many people strongly opposed the idea of evolution because it conflicted with their religious convictions.

• Darwin avoided talking about the theological and sociological aspects of his work, but other writers used his theories to support their own theories about society.

• Darwin was a reserved, thorough, hard working scholar who concerned himself with the feelings and emotions not only of his family, but friends and peers as well.

• It has been supposed that Darwin renounced evolution on his deathbed. Shortly after his death, temperance campaigner and evangelist Lady Elizabeth Hope claimed she visited Darwin at his deathbed, and witnessed the renunciation.

• Her story was printed in a Boston newspaper and subsequently spread. Lady Hope's story was refuted by Darwin's daughter Henrietta who stated, “I was present at his deathbed ... He never recanted any of his scientific views, either then or earlier.”

Charles Darwin

• Many people felt Darwin’s ideas clashed with the Bible’s story of Genesis

• Debate 1860 in Oxford: the Bishop of Oxford made a speech attacking Darwin

• Thomas Huxley defended Darwin’s ideas

• Unfortunately, people missed the important point of Darwin’s work that he said young animals inherit their features from their parents but he did not have the evidence for it

Religion did accommodate Darwin to some extent

Many religious leaders not literalist Science served religion, so its findings were taken as

revelations of God’s plan

Buried in Westminster Abbey The Times: “The Abbey needed Darwin more than Darwin

needed the Abbey.”

Religious conflict

• Samuel Wilberforce vs T.H.Huxley

“Was it from your mother’s side or your father’s side that you were descended from an ape?”

“If the question is whether I would rather have a miserable ape for a grandfather or a man of means and influence who uses these gifts to introduce ridicule into a grave scientific discussion, I unhesitatingly affirm my preference for the ape!”

“For once reality and his brain came into contact, and the result was fatal.”

Years later Wilberforce fell off his horse, landed on his head and was killed.

Darwin’s Theory of Evolution Challenged Christian Ideas

The value of human beings: made in God’s image just another animal

The purpose of human beings: part of God’s Plan accidental without purpose

The eternal future of human beings: eternal soul this life only

Varied Responses to Darwin• The Science vs Religion

Battle over-simplifies responses to Darwin

• Many Christians welcomed and supported Darwin’s ideas from the start

Varied Responses to Darwin1. Some Christians abandoned their faith

a. Industrialisation and Urbanisation had done much already to cut people’s links with the churches

b. Some became Humanists; some supported Social Darwinism

2. Some Christians rejected evolution – interpreted Genesis literally; USA Bible Belt; Monkey Trials

3. Many Christians welcomed and supported evolution from the start, reinterpreting their Christian message

Some Used Evolution as a Basis for Living: Social Darwinism

• Some used Darwin's theory of evolution and survival of the fittest to guide human society

• Competition weeds out the weak

• Charity, benefits or aid wrongly allow weak to survive

Criticism:• Misapplied DESCRIPTIVE biological theories • Became a PRESCRIPTIVE guide to how we should behave

The Men of Biology

Gregor Mendel- Father of Genetics- First to discover the

ability of organisms (pea plants) to pass traits from parents to offspring.

Major events in the history of Molecular Biology 1800 - 1870

• 1865 Gregor Mendel discover the basic rules of heredity of garden pea.

– An individual organism has two alternative heredity units for a given trait (dominant trait v.s. recessive trait)

• 1869 Johann Friedrich Miescher discovered DNA and named it nuclein.

Mendel: The Father of Genetics

Johann Miescher

Gregor Mendel• Gregor Mendel (1822 - 1884)

– Augustinian monk who taught natural science to high school students – Studied the theories of heredity based on his experiments with pea

plants during seven years-> basic laws of inheritance– His work was so brilliant and unprecedented at the time it appeared

that it took thirty-four years for the rest of the scientific community to catch up to it. He set the stage for the discovery of genes and DNA.

– Mendel was the first person to trace the characteristics of successive generations of a living thing

– From his studies, Mendel derived certain basic laws of heredity:• hereditary factors do not combine, but are passed intact• each member of the parental generation transmits only half of its

hereditary factors to each offspring (with certain factors "dominant" over others)

• different offspring of the same parents receive different sets of hereditary factors.

Gregor Mendel: 1822 – 1884 AD

• Austrian• Monk• Mendel realized that

the parent plants were passing on their features to their seedlings in the form of chemical messages in the pollen---genes

• Mendel’s pea plants for two genes for growing

• GS—grow short• GT---grow tall• But only one set of genes is

switched on• By counting the different

types of pea plant in each crop, Mendel found that plants carried the genes to Grow Short and Grow Tall always grew tall.

Mendel

• The only plants that grew short were those with the gene Grow Short and Grow Short.

• This was a dramatic discovery because it showed how genes work and some genes override each other.

• Mendel grew 28,000 pea plants.

• He studied their height, flower color, and five other characteristics.

• From his work, we get a new branch of biology called genetics.

How Molecular Biology came about?

• Microscopic biology began in 1665

• Robert Hooke (1635-1703) discovered organisms are made up of cells

• Matthias Schleiden (1804-1881) and Theodor Schwann (1810-1882) further expanded the study of cells in 1830s

• Robert Hooke

• Theodor Schwann

• Matthias Schleiden

The Men of Biology

James Watson and Francis Crick

- Discovered the double helix structure of the DNA