All scientific theories must be able to make testable predictions. Such predictions are based on observations. Experiments can then be conducted to verify (or falsify) such predictions. Darwin theorized that evolution occurred through natural selection; however, this may not have occurred in a smooth process. Some evolutionary theorists suggest that evolution by natural selection occurred in step-wise fashion.

• Explain the concepts of phyletic gradualism and punctuated equilibrium.
• What predictions about the fossil record does punctuated equilibrium make?
• In this model, what are the processes that produce rapid evolution? Which evolutionary factors are responsible for the periods of relative stasis?
• Patterns of punctuated equilibrium have been observed in some cases, but the debate between punctuated equilibrium and phyletic gradualism continues and provides interesting areas of research. Based on your research into the scientific process, what evidence do we see today that supports a long history of life on the planet?
• What evidence do we see that supports evolution by gradual change?
• What evidence do we see that supports the concept of punctuated equilibrium?