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Lecture 5

Week 5 Notes

Course Code
William Seager

of 3
Philosophy Notes
Week 5 class 1 & 2
Evolution and Creationism
Theory of Evolution
Two Hypothesis
1. a single tree of life
2. modification by natural selection
-one tree of life means all living creatures are descended from oneoriginal organism
-modification by natural selection involves some extra hypothesis:
ooffsprings inherit the characteristics of their parents
othere is a slight variation in ____ some variations increase fitness of offspring
oe.g. artificial selection
A special case of: speciation
- evolution works by very general modifications
Population gets geography splintered so they evolve (natural selection) to surroundings
Three approaches to the problem of evolution
Theistic evolution
-god created world and stepped away
-let evolution take its course
Atheistic evolution
-there is no god
-only physical processes leading to evolution
-god created world
-god intervenes
-(young earth)
-(no speciation)
Weak Creationism Arguments
Evolution isonly a theory”
-this is true of all science
-the question is: what evidence for theory – hypothesis cant be proven
-although nothing in science can actually be proven, they just provide strong evidence to believe the
Thermodynamics makes evolution impossible
-impossible for order to arise from disorder by natural process
-but this is for “closed systems
-the earth is not closed so the second law is not correct – anything can happen
Problems with Creationism
-violent implausibility
- young earth creationism
- no speciation creations
- theory rejects science
Faith vs. Science
-is creationism science
-or religion
-which religion
Darwin’s Assumption
- life evolved from non life, and then descent with modification gave rise to the diversity we now observe
-Darwin noticed three things
oAll present day life is related
oOffspring resemble their parents
oOffspring are not identical to their parents
-Darwin hypothesized that:
- Some of the changes in offspring will effect their chances to mature and reproduce
-Compare artificial selection
Why believe in a common ancestry for life?
-obvious similarities of animals: 4 limits of, mammals, birds, reptiles and amphibians
-DNA shared by all creatures
-Subtle similarities cytochrome – C
-All creatures have very similar cytochrome- C
-The more evolutionary distant the more difference in their cytochromsome – C
-Human/chimp 0 difference
-Human/yeast 51 differences
-a correlation is when two types of things tend to occur together
-there are accidental, casual and common-casual correlations
oliving in Canada and liking hockey – casual
oliving in Iceland and breast cancer – accidental
obarometer readshigh” there is a storm the next day – common casual
evolution suggest that organisms will change to become better adapted to their environment
-this will be gradual process
-it will be constrained by the starting point of the organisms
-so we might expect to findimperfect or “incomplete” adaptation
Ex. Vestigial limbs and aquatic mammals
Imperfect Adaptation
-not perfectly adapted to the environment
e.g. human appendix, human pelvis, panda’s thumb
-imperfect adaptation suggest that evolution has generated the differences we see in life
-perfect adaptations are less interesting (connects to the surprise principle)
Natural Selection
-a novel mutation occurs, creating the variation upon which natural selection operates. Then natural
selection goes to work changing the composition of the population
-three characteristics needed”