Struggle for Existence

Crucial to Darwin's theory of natural selection is the idea that far more plants and animals are produced than can survive. Plants and animals produce in very great numbers and would, within a short period, create very large populations. This applies both to those organisms that reproduce quickly, such as some species of insects, and to those organisms which reproduce slowly, such as elephants or humans. This is due to what Darwin calls the geometrical rate of reproduction. If a pair of elephants mates and produces four children, and each of those four children produce four more children, which each in turn produce four more children, after just three generations, two elephants will have produced sixty-four children. Over just fifteen generations, reproducing at this rate, the elephants produced from the single initial pair would number over one billion. These creatures must all compete with one another...