long time periods from a single prototype cell. The other is the notion of natural selection, which assumes that beneficial changes (mutations) happen in creatures very suddenly and that these become permanent features in a species or kind, being passed on to the next generation. Darwin, however, did not invent the term ‘survival of the fittest’; this was coined five years after his On the Origin of Species was published and was used by Herbert Spencer in his 1864 book, Principles of Biology. Darwin