There are two main conflicting paradigms concerning the origins of life. This article gives important background information on both sides of this conflict so we can make informed decisions.
Defining the Terms
The concept that the present is the key to the past is called uniformitarianism. The term means that the processes in the world today existed in the past, and a study of present events can be used to create models of past events. Uniformitarianism has become basic to scientific thinking. It forms the cornerstone for current dating techniques.
Before 1780, uniformitarianism was not readily accepted. The dominant doctrine was catastrophism. According to this view, the earth's features and the fossil record were the consequence of a series of global catastrophes, each of which had wrought extensive changes, both in the physical features of the earth and in all living things.
The History of Uniformitarianism
James Hutton (1726-1797) first championed the idea of slow gradual change to account for changes in the earth's topography, but it was not until about 1830 that Charles Lyell (1797-1875), an Englishman sympathetic to the views of Hutton, documented uniformitarianism in his interpretation of the origin of the rocks and landforms of western Europe. Lyell argued that the earth must be very old for its many geological changes to have taken place by such gradual processes. What does the earth tell us about its age?
Charles Darwin was much influenced by the work of Lyell. During his voyage of the Beagle, he carried with him Lyell's Principles of Geology and noted all the geological features of the terrain he covered. The concepts of evolution were not entirely new to Charles Darwin, as his grandfather, Erasmus Darwin (1731-1802), had been an early popularizer of evolution. Charles Darwin's ideas on this issue only really crystallized during the voyage of the Beagle, and his experiences and observations on the lava-ridden Galapagos Islands off the coast of Ecuador probably had the most profound influence on his thinking.
On these islands, he found the most unusual collection of organisms—giant tortoises and iguanas, unusual plants, insects, reptiles, and many varieties of finches. The finches in particular interested him, as these normally seed-eating birds adapted the insect-eating habits of other bird species, such as warblers, that did not exist in the Galapagos islands. The subtle changes in form, structure, and habit of the finches stirred the evolutionary thought in Darwin, leading him to begin his first notebook on the Transmutation of Species in 1837.
It seemed reasonable to Darwin that the organisms on the islands had been transformed over time and that the new structures and habits had developed over time. However, the mechanism for the transformation of species was not nearly as easy to explain as the assumption that such transformation had indeed occurred. It must be noted that the world at that time had no knowledge of the science of genetics. Gregor Mendel (1822-1884), the father of genetics, was a contemporary of Darwin, but his work was unknown to the world at large and unavailable to Darwin.
Read about evolutionist Jean-Baptiste Lamarck in Lamarck Proposes Natural Selection, or Aristotle and Plato's thoughts on life's origins in The Rise of Evolutionary Thinking.