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Anatomy & Physiology I - Unit 4: Evolution and Natural Selection
Tree of Life ~2000
Tree pattern suggests evolution
- the hierarchy of life is a family tree in which populations change with time.
- in general, similarities between species are due to relatedness.
Fossils
Evidence for evolution
Evidence for Evolution:Structural Similarities
Gill pouch
Tail
Chick Human
Evidence for Evolution: Developmental Similarities
Homology: similarities caused by common descent
But how do species evolve?
Darwin figured out how.
It’s a process similar to how humans breed animals
Charles Darwin1809 - 1882
Animal breedingaka “Artificial
Selection”
Evolution in action:Giraffe neck length
Happy Giraffes
Hungry Giraffes
Surviving Giraffes
With Evolution You Get: Taller giraffes over time
Evolution:A change in a population over time
Natural selection
An environmental influence that gives some individuals in a population a reproductive or survival advantage over others.
Principal cause of evolution.
Requirements for Evolution
• Variability
• Heritability
• Differential survival or reproduction
Tall Giraffes
Mutation: random genetic changes
Speciation: separation by natural events that causes new species to develop
Discussion Question:Are humans still evolving?
Common Misperception:
“And now there go the Wilsons!... SeemsLike everyone’s evolving except us!”
Individualsevolve
Acquired characteristics are not inherited!
as in…..
Timmy & Gobbles
Evolution is slowGreat Calendar
Jan Feb Mar Apr May Jun Jul Aug Sep Oct DecNov
1 month 383 million years1 day 13 million years1 second 143 years
Earthforms
Firstlandplants
Firstalgae
Firstfossils
December
1 5 10 30252015
Landanimals
Dinosaursextinct
December 31
1 2 3 4 5 76 8 9 10 11 12 1 4 5 6 7 8 9 12111032
11:48 pmModern humans
leave Africa
11:58:23 pmNative
Americansreach
Americas
noon
Classroom Assignment:Building the Perfect Beast
- I want you to think about how the human body has evolved over time, and how it might have evolved better.
- Today you are in charge of the world, and you have to think about ways to make the human species better adapted to the environment.
Building the Perfect Beast
• Pick any ten attributes or parts of the human body
• Note the defect of that part, or how it might be made better
• Describe your changes, piece by piece, oh master of the universe…
• Draw me a picture of your perfect beast