Download Aristotle Carolus Linnaeus Comte de Buffon

Aristotle
384 – 322 BC
• Greek philosopher
• Examined nature 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
• formed the basis for the western belief in a fixity of
species, each of which has a typical form
Comte
de Buffon
1707 – 1788 AD
Carolus
Linnaeus
1707 – 1778 AD
“The father of modern taxonomy”
• Classified organisms with a binomial
system
• Proposed a nested system of relationships
(as opposed to the Scala naturae)
• Recognized distinction between interbreeding vs. noninterbreeding organisms (same vs. different species)
• Believed in balance of nature
• Each species has its place in a divine plan
• Species do not change or go extinct
• Eventually acknowledged formation of new species by
hybridization
Erasmus
Darwin
1731 – 1802 AD
“Dégéneration”
• Believed life & species arise via 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, and new
environment changes them
• Change only happened within families: each family
conforms to an internal mold, but species can change
some over time.
Charles’ 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
• All of life consists of “one living filament” connecting all
living forms to a common ancestor
Jean-Baptiste
Lamarck
1744 – 1829 AD
Inheritance of acquired characters
• French professional naturalist
• Theory of transformism
• “Simple” organisms constantly arise by spontaneous
generation
• Organisms then progress through a hierarchy of evermore-advanced forms (Scala naturae in reverse?)
• 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
Thomas
Malthus
1766 – 1834 AD
Principle of overproduction
• English clergyman
• Major influence on Darwin & Wallace
• 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
Darwin
1809 – 1882 AD
Uniformitarianism
• English geologist
• Another major influence on Darwin &
Wallace
• Believed earth is constantly changing
• Processes that molded earth’s surface can be understood by
modern-day processes
• Uniformitarianism: earth is subject to gradual,
continuous change
• But there is no development or progress: earth remains at a
steady state – in particular, species composition doesn’t
change
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
The Voyage of the Beagle (1831–1836)
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
• 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?
For example: The rhea, a flightless
bird in South America
Charles
Darwin
1809 – 1882 AD
Biogeography on the Beagle
• Why do different groups of organisms live in
areas separated by barriers (like the ocean)?
On the Galapagos Islands,
Darwin noted that even islands
that were very close together
had giant tortoises that were
distinct from one another
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.
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.
Image credits
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.”
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
Tortoise: www.sandiegozoo.org
Wallace: www.d.umn.edu/cla/faculty/troufs/anth1602/pchistory.html