A Record of Life in the Rocks - Geology - page 247

Chapter 17
A Record of Life in the Rocks
In This Chapter
Understanding what evolution explains
Following the development of the theory of evolution
Using the fossil record to challenge predictions
Preserving body parts and behaviors
Considering bias in the fossil record
It may seem strange to find a chapter about biological change and evolution in the middle
of your geology topic. But it makes perfect sense if you consider that the record of life in
the rocks provides answers to questions about evolution and long-term biological
change. When scientists look at the geologic record, they find evidence and support for
biological theories of change, such as evolution and the relationships among different or-
ganisms.
In this chapter, I briefly explain the current theory of evolution, its development over the
last 150 years, how the geologic record provides a laboratory for testing this theory, and
how the preservation of past organisms in rocks allows scientists to reconstruct a de-
tailed history of evolution — of biological change through time.
Explaining Change, Not Origins: The The-
ory of Evolution
In Chapter 2, I explain exactly what scientists mean when they call something a theory. To
summarize, a scientific theory is not simply an assumption or a best guess. A scientific
theory has been tested repeatedly and accepted as an accurate explanation of a complic-
ated phenomenon, such as the theory of plate tectonics I explain in Part III. The theory of
evolution explains how biological organisms change through time.
A common misconception about the theory of evolution is that it explains how life on
earth began. This belief is false. Scientists have not yet figured out how life on earth