There are better ways to reproduce, it turns out, than by doing it. Microscopic animals split in two. Willow trees grow from cuttings. The Virginal greenfly gives birth to virgin young that are already pregnant with more pre-embryonic virgins. Some plants and animals have abandoned sex, some have it only occasionally.
Water fleas reproduce sexually only every few generations.
Sex is the queen of evolutionary problems, an accident, a luxury that should not exist. Stephen Jay Gould says sex may be an evolutionary relic of a time when it actually served a purpose. Like chins or little toes or appendixes, sex may no longer have a function in many species, it's just not easily got rid of. Biologists can't agree just why sex is necessary, only that it is. Birky Lab - Department of Ecology and Evolutionary Biology at University of Arizona .