Download Evolution as a central theme in biology.

Jan. 15, 2013 – Historical Background
Seventeenth Century Knowledge of Fossils
1) They varied from objects having an obvious resemblance to organisms-shells
of mollusks and leaves of plants-through a complete gradation to others
resembling no known organism.
2) Their consistency was that of the stone in which they were situated and not
that of living or recently dead organisms.
3) The figured stones that resembled sea creatures occurred not only close to the
shore but also high in mountains far from the sea.
4) The organism-like structures might occur inside hard stones.
Nicolaus Steno (1666) - Tongue Stones of Malta
Robert Hooke (1665) - Micrographia
Leonardo da Vinci (1452-1519) - Codex Leicester
Baron Cuvier (1769–1832) – Extinction
Quarries of the Paris Basin
1) The first and uppermost layer, immediately below the soil, consisted of marls.
It contained many fossils of animals and plants characteristic of lakes and
freshwater marshes.
2) The second layer, at places more than 80 feet in thickness, consisted of marls
and sandstone. The fossils consisted mainly of shells of marine organisms.
3) The third layer consisted of gypsum, marls, and limestone, and the fossils
appeared to be of freshwater species.
4) The fourth layer consisted of a coarse-grained limestone with an abundance
of fossils belonging to about 400 different species, mainly marine but with a
few freshwater forms.
5) The fifth and lowest layer, resting on a chalk formation, consisted mostly of
clay and sand. The fossils were freshwater shells and driftwood.
Cuvier’s conclusions:
•Geological History
•The relative position of a layer is an indication of its relative age.
•Catastrophism
Cuvier’s contributions
•Catastrophism explained the patterns of fossils.
•Extinction has occurred.
•The earth is much older than 6,000 years.
Jean-Baptiste de Lamarck (1744-1829)
Proposed evolution as a mechanism to explain changes in fossils.
Lamarckian Evolution
•Simple organisms were constantly being “created” by spontaneous generation.
•Simple organisms then constantly increased in complexity, which was equated
with perfection.
•Organisms have an innate drive to strive for perfection.
Lamarck’s Mechanisms
•1) The principle of use and disuse
•2) Inheritance of acquired characteristics
•3) Inherent drive to complexity
Geology
Catastrophism - the present state of the earth is the result of violent catastrophes.
Uniformitarianism - the present state of the earth is the result of slow, uniform
action over eons of time.
Abraham Gottlob Werner (1750–1817)
“Neptunian” geology
James Hutton (1727-1817)
1) Sediments that are deposited, mainly in the ocean, become the strata.
2) Volcanic action uplifts the strata to form mountains.
3) Once the strata are elevated, they are subject to erosion.
4) These processes required vast amounts of time.
William Smith (1769-1839)
Developed the concept of the Geological Column.
The different strata found in Great Britain totaled over 100 kilometers thick.
Charles Lyell (1797-1875) - Principles of Geology (1830-1833)
Developed the principles of Uniformatarianism
Creationism
•God had created everything in its present form, which did not change.
•Adaptations were easy to explain - that is the way God did it.
John Ray (1627-1705) -The Wisdom of God Manifested in the Works of Creation (1691).
Developed the idea of Natural Theology.
People could learn about the Creator by studying his creation.
William Paley (1743-1805) - Natural Theology; or, Evidences of the Existence and
Attributes of the Deity, Collected from the Appearances of Nature (1802).
Bridgewater Treatises (1833-1836)
Eight volumes on biology, geology, mineralogy, meteorology, chemistry physics, and
astronomy.
Charles Darwin (1809-1882)
Voyage of the Beagle (1831-1836) What was known or believed in 1831?
•Catastrophism in Biology
•Uniformitarianism in Geology
•Natural Theology as paradigm
•Extinction accepted
•Evolution not accepted
•The earth is very old
Key observations
•South American plants and animals were distinct from those of Europe.
•Two very strange animals of the same sort, one living and one extinct, were found in the
same region of South America.
•Individuals of a species varied slightly from location to location - geographic variation.
The Galapagos were known to be of recent volcanic origin.
The animals and plants of the Galapagos resembled those of South America, but
they were different species.
How did these observations challenge Catastrophism?
Developing a mechanism for evolution.
Thomas Malthus (1766-1834) - An Essay on Population (1798)
On the Origin of Species by Means of Natural Selection, or the Preservation
of the Favoured Races in the Struggle for Life (1859)
1) As new adaptation arises, it is selected for - result is that a greater portion of the
population has the new adaptation.
2) Small changes accumulate in a population, making one population different
from another.
3) Over a long period of time, the population becomes a new species.
Why was Evolution accepted?
Evolution as a paradigm explained the patterns of organisms and fossils better than
Catastrophism.
Evidence for evolution was very well presented.
Why was Natural Selection not accepted?
Required inheritance of specific traits in a manner inconsistent with the idea of
Blending.