Download Aristotle Carolus Linnaeus Carolus Linnaeus

Aristotle
384 – 322 BC
Greek philosopher
Examined natural world for evidence of divine order
Scala naturae (“Chain of Being”)
• Hierarchical arrangement of forms
• Species arranged linearly along a scale:
God
Man
Mammals
Egg-laying animals
Insects
Plants
Non-living matter
Carolus
Linnaeus
1707 – 1778 AD
“The father of modern taxonomy”
• Classified organisms according to a
binomial system, giving each a specific and
a generic name, e.g. Homo sapiens
•
Genus species
• Proposed a nested system of relationships
(as opposed to the Scala naturae)
• Formed the basis for the western belief in a fixity
of species, each of which has a typical form
Carolus
Linnaeus
1707 – 1778 AD
“The father of modern taxonomy”
• The modernized Linnaean system
groups organisms into:
Kingdom
Phylum
Class
Humans
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
Carolus
Linnaeus
1707 – 1778 AD
“The father of modern taxonomy”
• Recognized fundamental difference between
• interbreeding organisms (within a species)
• non-interbreeding organisms (different species)
• Believed in balance of nature
• Each species has its place in a divine plan
• Species would not change or go extinct
Eventually acknowledged
limited formation of new
species by hybridization
Comte
de Buffon
1707 – 1788 AD
“Dégéneration”
• Believed that the origin of life & species
followed material processes
• Looked for evidence in the physical & biological world
• Believed Linnean hierarchy reflected common descent
(dégéneration), with divergence over time.
• Physical environment (somehow) changes organic particles
• New species form when animals migrate
• New environment then causes change to the species
Erasmus
Darwin
1731 – 1802 AD
Charles Darwin’ Grandfather
• British philosopher, naturalist & physician
• Wrote Zoonomia: Or The Laws of Organic Life
• Believed organisms constantly attempted to improve
themselves by adapting to their environment
• Transformism or transmutation
• Change only happen within families: each family
conforms to an internal mold. Species can change over
time but are limited to their original mold.
• All of life consists of “one living filament” connecting all
living forms to a common ancestor
Erasmus
Darwin
1731 – 1802 AD
Jean-Baptiste
Lamarck
1744 – 1829 AD
Organic life beneath the shoreless waves
Was born and nurs’d in ocean’s pearly caves;
First forms minute, unseen by spheric glass,
Move on the mud, or pierce the watery mass;
These, as successive generations bloom,
New powers acquire and larger limbs assume;
Whence countless groups of vegetation spring,
And breathing realms of fin and feet and wing.
The Temple of Nature (1802)
No real mechanism for this transformism
“Inheritance of acquired characters”
French professional naturalist
Theory of “transformism”
! Organisms progress through a hierarchy of ever-moreadvanced forms (Scala naturae in reverse?)
"Nature, in producing in succession every species of animal, and
beginning with the least perfect or simplest to end her work with
the most perfect, has gradually complicated their structure."
! At the base of this hierarchy, “simple” organisms constantly
arise by spontaneous generation
Jean-Baptiste
Lamarck
1744 – 1829 AD
“Inheritance of acquired characters”
Suggested a mechanism for this organic
progression in Philosophie zoologique (1809):
• First law: Use or disuse of a structure leads to its
development or diminishment
• Second law: These acquired characters can be
passed on to offspring
Charles
Lyell
1797 – 1875 AD
“Uniformitarianism”
• English geologist
• His Principles of Geology was a major
influence on Darwin & Wallace
• Believed earth is constantly changing
• Processes that molded earth’s surface can be understood by
modern-day events
• Uniformitarianism: earth is subject to gradual,
continuous change
• But without progress or development
• Earth remains at a steady state
Thomas
Malthus
1766 – 1834 AD
Principle of overproduction
• English clergyman
• Major influence on Darwin & Wallace
• An Essay on the Principle of Population (1797)
• Most organisms produce far more offspring than can possibly
survive
• Even when resources are
plentiful, populations tend to
grow geometrically until they
outstrip their food supply
• Poverty, disease, and famine are
inevitable, leading to a “struggle
for existence”.
Charles
Lyell
1797 – 1875 AD
“Uniformitarianism”
Lyell applied his views to the living world.
Initially he believed that some members of all classes of
organisms existed throughout the history of the earth.
What had changed was the abundance and location of
species as well as the exact form of each species.
“[S]pecies have a real existence in nature, and that each
was endowed, at the time of its creation, with the
attributes and organization by which it is now
distinguished.”
Charles
Darwin
1809 – 1882 AD
Charles
Darwin
1809 – 1882 AD
The Voyage of the Beagle (1831–1836)
The Man
• An English “gentleman of private means”
• Was able to focus on his life’s work: the development of
the theory of evolution by natural selection
Charles
Darwin
1809 – 1882 AD
Biogeography on the Beagle
• Noticed that two similar species often coexisted
in a “boundary zone” – neither one better
adapted than the other
• These species must compete with each other
Rheas - a flightless South American bird
Rhea americana (common rhea)
Pterocnemia pennata (Darwin’s rhea)
• Read Lyell’s Principles of Geology while on board (and correctly
applied the principle of uniformitarianism to the formation of
coral reefs)
• Developed an appreciation of biogeographical patterns
Charles
Darwin
1809 – 1882 AD
Biogeography on the Beagle
• Why do different groups of organisms live in
areas separated by barriers (like the ocean)?
Why are the rhea and
the ostrich so different,
even though they have
similar lifestyles under
similar circumstances?
Would a creator be
limited by boundaries
to migration?
Charles
Darwin
1809 – 1882 AD
Charles
Darwin
1809 – 1882 AD
Biogeography on the Beagle
Biogeography on the Beagle
• Why do different groups of organisms live in
areas separated by barriers (like the ocean)?
• Why do different groups of organisms live in
areas separated by barriers (like the ocean)?
On the Galapagos Islands,
Darwin was told that even
islands that were very close
together had giant tortoises that
were distinct from one another
Charles
Darwin
1809 – 1882 AD
"When I see these Islands in sight of each other, and
possessed of but a scanty stock on animals, tenanted by these
birds, but slightly differing in structure and filling the same
place in Nature, I must suspect they are only varieties....If
there is the slightest foundation for these remarks the zoology
of Archipelagoes - will be well worth examining; for such
facts would undermine the stability of Species." (1836)
Dr. Robert Rothman
Charles
Darwin
1809 – 1882 AD
Back in Britain:
The theory of natural selection
• Darwin recognized several critical facts:
• Variability exists within species
• Variant traits may be inherited (Darwin didn’t know how)
• Malthus’s Principle of Overproduction implies that many
individuals must die or fail to reproduce
• Individuals slightly better suited to their environment
must be more likely to survive
• Therefore, some variants will be preserved over time
more than others. The composition of populations
must change over time !Evolution by natural selection.
Alfred
R. Wallace
1823 – 1913 AD
Charles
Darwin
1809 – 1882 AD
The origin of species
• As natural selection acts on geographically
isolated populations, they become
increasingly different from each other
• This leads to the
formation of first
varieties within a
species, then separate
species, then genera,
etc., in an everbranching process.
Evolution made public
Natural selection co-discovered
• English professional naturalist
• In 1858, sent a letter to Darwin
describing his independent discovery of
natural selection
• Like Darwin, travelled around the world observing
biodiversity and biogeography
• Like Darwin, he’d read Lyell and Malthus, and
eventually realized that “[the] self-acting process [of natural
selection] would necessarily improve the race, because in every
generation the inferior would inevitably be killed off and the
superior would remain – that is, the fittest would survive.”
Charles Lyell and Joseph Hooker quickly arranged for
Darwin's and Wallace's views to be co-presented at the
meetings of the Linnean Society in London in 1858.
The next year, Darwin published The Origin of
Species by Means of Natural Selection. The depth
and breadth of Darwin's book, developed over twenty
years of thought and research, revolutionized science.
Gregor
Mendel
1822 – 1884 AD
Gregor
Mendel
1822 – 1884 AD
Mendelian genetics
Mendelian genetics
• The greatest weakness of the theory of
natural selection was lack of knowledge
of how inheritance worked
• Mendel’s work (re-discovered in 1900 by
Carl Correns & Hugo de Vries) clarified the
laws of inheritance (at least for discrete
• The greatest weakness of the theory of
natural selection was lack of knowledge
of how inheritance worked
traits like pea color)
R.1890
A.–Fisher
1962 AD
Uniting Mendelian and quantitative
genetics
• In 1918, Fisher showed that a large
number of Mendelian factors (genes)
influencing a trait would cause a nearly
continuous distribution of trait values
• Mendelian genetics can lead to an approximately
normal
distribution
• Mendel’s rules explain why
offspring tend to resemble their
parents.
• Show that variation is not lost over
time due to reproduction alone
• Still unclear whether these rules
apply to continuously varying traits
(height, weight, etc.)
Image credits
Aristotle: www.columbia.edu/cu/philosophy/ admissions/text/process.html
Linnaeus: www.nhm.ac.uk/library/linn/
Buffon: www.ucmp.berkeley.edu/history/buffon2.html
Erasmus Darwin: science.ntu.ac.uk/erasmus.html
Lamarck: www.biol.unipr.it/aai/galleria/lamarck.gif
Malthus: homepages.caverock.net.nz/~kh/bobperson.html
Lyell: athene.as.arizona.edu/~lclose/teaching/nats102/lyell.gif
Charles Darwin: www.nirgal.net/ori_life1.html
Beagle map: www.aboutdarwin.com
Rhea: www.sc.edu/library/spcoll/nathist/darwin/rhea.jpg
Ostrich: www.uct.ac.za/depts/fitzpatrick/docs/research.html
Finches: www.rit.edu/~rhrsbi/GalapagosPages/DarwinFinch.html
Tortoise: www.sandiegozoo.org
Wallace: www.d.umn.edu/cla/faculty/troufs/anth1602/pchistory.html
Mendel: www.biologie.uni-hamburg.de/b-online/e08_mend/mendel.htm
Correns: www.biologie.uni-hamburg.de/b-online/e08/correns.htm
de Vries: www.d.umn.edu/cla/faculty/troufs/anth1602/pchistory.html
Fisher: http://www.amphilsoc.org/library/guides/genetics/stern.htm
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Lines of Evidence for Evolution