Men, remember this name. Boule. That is the name of the single gene that is responsible for sperm production. Apparently, it is the same gene that all animals carry, all the way back to the most simple of organisms such as sea anemones, snails, flies and fish. This means that going back about 600 million years, sperm production has been the necessary means of species continuation for all life, and remember, life only originated on this planet about 1 billion years ago. So the process of gamete-seeks-immobile-egg had stabilized as the primary means of sexual reproduction after about 400 million years of life.