Evolution Intro to Evolution http://www.pbs.org/wgbh/evolution/library/04/3/l_043_01.html

Why evolutionary science? There are more then 1 million species identified yet all are fundamentally similar at the cellular and molecular level How have we got to the current range of diversity? How are fossils related to current life forms? Theo Dobzhansky: “Nothing in biology makes sense except in the light of evolution.” An explanation for HIV type 2

What is evolution? Broadly, it is the theory that explains the origin of all species and the history of the earth. Specifically it is the process in which significant changes occur in the genetic makeup of a species over time (billions of years). First supported in 1669 by Nicolas Steno and Robert Hooke. It is a theory because it has never been universally accepted. There are many cultural and religious theories as well, such as the creation story.

Today Most people/scientists agree that the world is dynamic. That is to say that changes due occur. However, it was believed 500 years ago that species and the world were always how we see them today: unchanging. This coincided with the theory that the world is flat.

Discovery of Fossils Fossils: preserved remains or traces of an organism and/or its activity; usually bone, shells, teeth and footprints. The fossil record provided valuable evidence about the diversity of species and those that have become extinct. This helped fuel the theory of evolution. Are there fossil samples?

Fossil Record Geographic location of fossils helped scientists determine patterns of evolution. For example, as early as the 15th century, da Vinci found sea shell fossils high in the Tuscan mountains, far away from any body of water. What could you hypothesize from this? This led him to believe that at some point in the earths history water (an ocean) must have been there. Also 40-50 million year old whale fossils have been found in the Egyptian deserts.

Fossilization Formed when bodies of organisms become trapped in sediments, which become compressed into layers over time, eventually hardening into sedimentary rock. In some cases, conditions are perfect to preserve whole specimens in tact == no decomposition Conditions are met in tar pits, volcanic ash, peat bogs, frozen ground, and amber. Marine species are more likely to become fossilized then land-dwellers. Why? Shells vs. soft bodies

Fossilization

Reading pgs 508-512 Fossil activity: jigsaw puzzle….