What is a Theory? Everyday Language – Hunch; Guess Scientific Language – Created after years of experiments and observation – Based on testable evidence – Stood the test of time Based on gravitational theory, what do you think would happen if I dropped a pen? Based on gravitational theory, what do you think would happen if I dropped a pen?

Evolution Video Part I: Just a Theory

Acquired Inheritance: Early theory where changes acquired over a lifetime could be passed to offspring Ex: Evolution of the giraffe neck – Short neck ancestors stretched their necks to reach leaves – Stretched neck was passed to offspring Problem: Only traits linked to DNA can be passed to offspring

Silly Example of Acquired Inheritance Meet Jacob Jacob is in a car crash Jacob lost his left arm If Jacob has children in the future, how many arms will they have? If Jacob has children in the future, how many arms will they have?

Debate Over Geologic Change Early belief: – Earth ~6,000 years old – Life remained unchanged “New” Observations – Rock layers (strata) contained differing fossils – Deeper fossils (older) less complex – Environmental changes thought to affect life characteristics

Charles Darwin Observations: – Organisms have variations based on their environment – Variations provide advantages – Similarities between extinct fossils & modern life – Marine fossils atop mountains Natural Selection: Process where organisms with favorable traits survive and reproduce 1859: Published The Origin of Species Notch in shell Survive in areas with higher vegetation Notch in shell Survive in areas with higher vegetation No notch in shell Survive in areas with ground vegetation No notch in shell Survive in areas with ground vegetation So how did giraffes get a long neck? Those with short necks died. Those with longer necks survived and reproduced

Evolution Video Part II: Who was Charles Darwin

Adaptation vs. Variation Variation: Inherited traits that make an individual different from others – Ex: Galapagos finches vary in their beaks Adaptation: Variation that increases the chance of survival – Ex: Which finch would be better adapted to an island with large seeds for food? Variation 1 Variation 2

Natural Selection in Action: The Peppered Moth Analysis Before the industrial revolution, the trees in the forest around Manchester, England were a light grey/green due to the color of lichens (fungus) on their trunks.

Natural Selection in Action: The Peppered Moth Analysis Peppered moths, or Biston betularia, which lived in the area were found in two varieties: 1) Light with dark spots (most common) and 2) Dark with light spots (less common).

Natural Selection in Action: The Peppered Moth Analysis Because there were not enough resources to support the entire population, the two varieties of this species had to compete for survival. Their coloring, when against a similar background, served as camouflage against predators such as birds and lizards, thus increasing chances of survival.

Natural Selection in Action: The Peppered Moth Analysis As the Industrial Revolution progressed, the trees became covered with sulfur dioxide, which killed the light colored lichen and thus turning the tree trunks dark.

Year 1 Background Year 10 Background Light peppered moth Dark peppered moth

Year 1: Peppered Moths Light 556 Dark 64

Year 10: Peppered Moths Light 56 Dark 638

1)What is a theory? 2)What did acquired inheritance state and how was it thought to work? 3)What does natural selection state and how is it thought to work? 4)How can the general age of rocks (and fossils) be determined? 5)How does a variation and adaptation differ? Review