An uninterrupted process of change from one condition, form or state to another. In biological evolution, all varieties of living things are seen as having developed by inheritable, incremental changes from unicellular structures to complex organisms such as humankind. Although the likelihood of some form of evolution had been postulated by scientists in the late 18th and early 19th centuries, the prime contribution to the development of biological evolutionary doctrine came from the British scientist, Charles Darwin, who argued in his book The Origin of Species by Means of Natural Selection (1859) that natural selection resulted in the survival of the ﬁttest organisms. The precise biological mechanism of evolution was not unravelled until the 20th century, with the discovery of CHROMOSOMES and GENES and the development of the science of genetics. Charles Darwin’s theory was based on his studies of the varied and unique animal life in the Galapagos Islands in the 19th century. He believed that the diversity of life on the planet could be ascribed to the combined eﬀects of random variation in living things, inherited by succeeding generations.
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