Lesson 1 - Before

Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing why something happens

the process in which significant changes in the inheritable traits of a species (population) occurs over time.

Changes in DNA = MUTATIONS! can be neutral, harmful or helpful Helpful mutations = drive evolution

Simple organism fossils could be found at all depths of rock Complex organism fossils were only found at shallower depths. Recent fossils were more likely to resemble  living species. Each layer contained distinct species not found above or below.

local catastrophes (floods) = widespread extinctions - new species would be “created” to replace those lost • accounts for the separation of fossils in strata layers

• could not account for the changing species complexity • does not allow for calculation of fossil absolute age