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”

How do you get this?

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