BIOLOGY 1B Chapter Notes - Chapter 22: Convergent Evolution, Gene Flow, Notochord
Document Summary
Aristotle viewed species as fixed (unchanging), he concluded that life-forms could be arranged on a large of increasing complexity ( scala naturae ) Linnaeus ascribed the resemblances among species to the pattern of the creation. The older the stratum, the more dissimilar its fossils were to current life-forms. James hutton proposed that earth"s geologic features could be explained by gradual mechanisms such as valleys being formed by rivers. Charles lyell incorporated hutton"s ideas into his proposal that the same geologic processes are operating today as in the past, and at the same rate. Use and disuse -- parts of the body that are used extensively become larger and stronger while those that are not used deteriorate. Inheritance of acquired characteristics -- organism could pass these modifications to its offspring. Homology is similarity resulting from common ancestry. Homologous structures show variations on a structural theme that was present in their common ancestor.
