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Chapter 8. Multiple Sequence Alignments,... > The Morphological to the Molecular

8.1. The Morphological to the Molecular

In order to ground our discussion of the details of multiple sequence alignment, let's take another brief look at evolution. One of the goals of biology has been the creation of a taxonomy for living things, a method of organizing species in terms of their relationships to one another. Early biologists classified species solely according to their morphology—the physical appearance of the organism—and later, as dissection became a more common practice, their anatomy.

Naturalists also discovered fossils of creatures that didn't resemble anything alive at the time, but were thought to have once been living things. This evidence introduced the possibility that life on Earth had changed over time. It also suggested that the interrelationship between species isn't static, but rather is the result of an evolutionary process. As understanding of the geophysical processes of the planet improved, the amount of time required for such changes to occur became clearer. It is now widely accepted by scientists that life on Earth is approximately 3.5 billion years old. Fossil records of single-celled organisms resembling bacteria, with an estimated age of 3.5 billion years, have been found and catalogued.


  

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