DAVID: The longest insect life cycle around. Why this evolved is any bodies guess. http://www.nature.com/news/long-lived-insects-raise-prime-riddle-1.13080-My guess is it's just one more invention by one of the countless intelligent genomes that have added their particular squiggle to the higgledy-piggledy bush. Cicada lovers, however, might argue that it is living proof of the cicacentric teleology of evolution.