Introduction
While developing a theory to explain how species can change over time is key to
the study of evolution, such a theory must be supported by evidence from the
scientific study of the natural world. One of the difficulties faced by early
theories, such as those of Buffon and Lamarck, was a lack of such evidence.
Even Darwin's theory, which is the most widely accepted today, had to wait
several decades until scientific advances and fossil evidence convinced the
scientific community of its legitimacy.
Today, evidence for evolution comes from several different fields.
Paleontology shows us that gradual
change in organisms can be seen in the fossil record. The study of
biogeography gives us an idea of
how species spread to new habitats. Comparative
anatomy, a technique that has been
used since the very beginning of the study of evolution, allows us to judge
dissimilar organisms in an effort to see whether they share a common ancestor.
Most recently, the field of molecular
biology has shown us that even the
molecules of life change over time, and these can be used to tell just how far
back in history any two organisms last shared an ancestor.
