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Introduction
Evolution refers to the process by which forms of life have changed through time by what is
described as descent with modification. Evolution explains the wonderful diversity of living
things on earth and also represents the primary unifying concept in biology; all organisms can
trace their ancestry (and therefore, their unity) to the first cells (basic unit of life).
In a broad sense, evolution can be seen at the population level of biological organization as
populations change in response to dynamic environmental conditions. Adaptations, traits which
enhance survival, allow for organisms to be suited to their environment. The process of natural
selection is the mechanism which drives evolution and new species are created while others go
extinct. Extinction and evolution are closely related.
There are three major categories of scientific data used to support evolution.
1.) Fossils are the remains of once living organisms. Fossils may be preserved remnants of
actual body parts or impressions left behind by prehistoric life forms. The fossil record
relates these fossils in a standardized geologic time scale.
2.) Comparative anatomy studies similar patterns of development and anatomical features
among organisms. These comparative studies often examine embryological structures
as well as adult forms. Similar developmental patterns relate directly to ancestry in
many instances. Structures that are homologous represent shared ancestry.
Homologous structures are also supported by embryological similarity. Analogous
structures, while similar in form and function, are not supported by common ancestry
and are often the result of convergent evolution (similar environmental pressures
produce similar anatomical features without common ancestry).
3.) Biochemical evidence is becoming a more important source of evolutionary data. We
know from our studies of the cell that molecules of DNA for the basis for inheritance.
The genes which are encrypted on these DNA molecules are responsible for the structure
and function of the cells in a living thing.
Evolution and Taxonomy Laboratory
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