SO ENDS this first of two weekends on the gene life cycle. This is at the heart of Darwinian evolution, although even the idea of genes was unknown to Darwin. New genetic material is the engine of diversity and fitness. Nature has found numerous inventive ways to freshen its genetic information content, in order to provide the organism with new phenotypes with which to conquer new niches. And very often, the timeframes involved in new gene generation and fixation are considerable.