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Biology-Lecture 1-Historical Development of Evolutionary Theory Sep 11 2008


Course Code
Marcel Danesi

of 2
Reading Notes
Historical Development of Evolutionary Theory
y Sagan 24 Days Scale (24 days for every 1 billion years and 1 second for every 475 years)
y ³Big Bang´
y Sun formed, shortly after earth took shape
y Organic molecules- amino acids
y First fossil records
y Sept. 9= beginning of solar system, Sept. 25= origin of life on earth
y Dec. 31= 10:30-> human like primates appear
y Adaptation: traits that increase the chances of survival to leave offspring that will survive
y 65 million years ago= mammal like reptiles
y The Evolution of Evolution
y Views From Biology
y Charles Darwins Theory of Evolution
y Different species developed one from another over long periods of time
y Carolus Linnaeaus
y Similarities/differences among organisms
y Created system: naming ranking, classifying organisms (kingdom, class, genus, species)
y Each category contains groups of related organisms that share common traits
y Jean-Baptiste Lamarck
y Acquired characteristics could be inherited and evolved
y Individuals who in their lifetime developed characteristics helpful to survival would pass those
characteristics to future generations (changing physical make up -> Acquired Inheritance)
y This evolutionary process was guided by changing environments that altered the needs of organisms
y Ex: long neck giraffes- results of generation after generation of giraffes stretching necks to reach
high leaves
y Views From Geology
y Catstrophism: the world changed overtime by a series of divine catastrophic events
y Georges Cuvier
y Changes in the animal world could be attributed to catastrophes that had destroyed whole populations
of living things
y Quick series of catastrophes accounted for changes in the earth and the fossil record
y Opponents of Catstrophism: gradual process, rather than natural catastrophes, accounted for change
over time (erosion= ice, wind, water)
y George Buffon
y Uniformitarism: repeated uniform process, such as rivers cutting channels, wind, rain eroding
mountains, operated through out time. The earth is constantly being shaped and reshaped by natural
forces that have operated over vast periods of time
y Darwin & Wallace= observed individual variation in appearance within species
y Lamarcks theory of acquired inheritance did not support such variation within a species since it
predicted that eventually all organisms would adapt to the same form in the same environment
y Darwin and Wallace concluded that all species descend from other species
y The Origin of Species by Means of Natural Selection
y Species are not immutable; but that those belonging to the same genera are lineal decsendents of some
other generally extinct species
y His conclusions outraged biblical believers who thought that his theory had no direction
y Natural Selection: nature selects from existing variation those species best adopted to the environment
and will therefore have the greatest chance of surviving and reproducing successfully
y The Descent of Man and Selection in Relation to Sex
y Humanity is derived from an animal related to progenitors of the orangutan, chimpanzee, and gorilla
y During mid 19th century:
y Discovery of stone tools prompted investigations
y Cultural Relativism: all societies are equal and comparable, there are no superior or inferior societies,
and as a result, it is not possible to order cultures in an evolutionary scheme
y The Principles of Natural Selection
y Adaptive Traits: a trait that enhances survival and reproductive success in a particular environment
y Variation: differences in the genotype and phenotype of individual members of a species
y Heritability: the concept that traits are inherited from parent to offspring
y Differential Reproductive Success: Differences in the chances of an organism surviving to leaving
y Even though species may become more adapted to a particular environment overtime, we cannot say
that one species adapted to its environment ³better´ than another
y The Origin of Species
y Species: a population that consists of organisms able to interbreed and produce fertile and viable
y Speciation: The development of a new species - due to adapting to new environment etc.