Evolution Notes Evolution - process in which modern organisms have descended from ancient organisms; change in a species over time

Evolution of the Horse Note how the horse gradually lost toes and increased in size over time.

Supporting Evidence for Evolution A. Age of the Earth: 4.5 BILLION Years old

B. Fossil Evidence Fossil - preserved remains or traces of organisms (plants, animals, bacteria, etc.) Fossils can be found in sedimentary rocks The fossil record is the best evidence that evolution occurs

Youngest Complex Organism Oldest Simpler organisms

C. Comparative Anatomy Anatomy - relating to the structures of the body Comparative Anatomy is the study of differences and similarities in the anatomy of organisms Homologous Structures – similar structures with different functions (whale flipper, human arm, bat wing)

Vestigial Structures – structures that were once functional but no longer are

The human appendix, a vestigial structure.

D. Comparative Embryology – shows common ancestry among organisms when comparing embryos Embryo - an organism in early stages of growth and development prior to birth

very difficult to distinguish an early embryo of a fish, rabbit and a gorilla. All have tails and gill slits.

E. Comparative Cytology Cytology - the study of cell structures and their functions

F. Comparative Biochemistry Biochemistry - the study of chemical processes of living organisms Biochemical evidence – the closer the relationship between organisms, the greater the similarity of their chemicals (DNA, proteins) – Humans can use insulin from sheep and pigs!!