The dramatic account of how the earth’s great age was discovered is one of Leakey and Lewin’s most interesting stories. They explain how the Western world accepted for two millennia the Judeo-Christian story and how James Ussher (1581-1656), the archbishop of Armagh, calculated that the Creation had occurred in 4004 b.c. Dr. John Lightfoot of Cambridge University even narrowed down the event to nine o’clock on the morning of October 23. The evidence from geology, however, made this dating difficult to maintain, and true believers resorted to various explanations to ward off assaults from science. The diluvial theory, for example, explained fossils as the remains of animals drowned in the biblical Flood. When this hypothesis collapsed, French geologist Baron Georges Cuvier (1769-1832) proposed that the sequences of fossils found in sedimentary rock indicated a succession of catastrophes—hence, the term “catastrophe theory.”

In 1830, Charles Lyell (1797-1875) published the first volume of The Principles of Geology, thereby founding the modern science of geology. This great work was the beginning of the end for the faithful Creationists who followed Archbishop Ussher. Other scholars, such as Charles Darwin’s grandfather, Erasmus Darwin (1731-1802), had already done important research in embryology and comparative anatomy that suggested one single source for all life. Yet, even the most devoted of Erasmus Darwin’s followers could not explain exactly how life had evolved.

Jean Baptiste de Lamarck (1744-1829) theorized that evolution occurred through the inheritance of acquired...

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