Darwin’s theory of evolution by natural selection required time for its operation. Darwin (1859, 287) knew that “it is highly important for us to gain some notion, however imperfect, of the lapse of years.” He needed some idea of the total amount of time available and the rate at which evolution took place, but he lacked data on both. Perhaps he was minded of the situation he faced when cataloging the world’s coral reefs and developing a theory for their origin, when he had to resort to unquantified phrases such as “slowly sinking” and “prolonged subsidence” (Darwin 1842c). For evolution, he had some relative data on roughly in which order certain taxa had evolved through geological time, but he also lacked detail here, especially with regard to the most recent parts of the geological record, and so he kept a close eye on the rates of appearance of domesticated varieties in relation to the archaeological record (Darwin 1868b). He became entangled with involved discussions on matters for which we now have far more complete data, but where his instincts were broadly correct. On the other hand, he and his contemporaries lacked information on the complexity and rapidity of geological changes (e.g., during the Quaternary period) which might well have made a substantial difference to how he formulated and presented his theory of evolution. In this chapter, I briefly discuss these aspects of how knowledge, or lack of it, influenced Darwin’s ideas.

The Age of the Earth

The first edition of On the Origin of Species (Darwin 1859) predates any significant attempt at a figure for the Earth’s age. Darwin’s ideas matured in the early years of scientific discussion of topics for which contemporary answers had been provided by the Bible, and interpretations of it (including the suggestion of Buckland [1836] that “millions and millions of years” might have passed between the Creation and the Mosaic narrative). Scientific rationale for understanding the age of Earth was, however, in its infancy (Dalrymple 1991), and Darwin was concerned that objections would be raised against his theory of evolution by natural selection on the grounds that Earth was not sufficiently old, although many geologists were apparently thinking of increasingly long periods of time since the origin of Earth (A. Geikie 1893).