While genes vary from person to person, let alone between species and animal kingdoms, one sex-specific gene has been found in nearly all animals life, remaining unchanged for 600 million years.
A study published in PLoS Genetics by the Northwestern University Feinberg School of Medicine found that the gene, Boule, appears to be the only gene exclusively required for sperm production. The gene was found in all types of animals: mammals, fish, insect, and worms. The gene was even located in one of the most primitive creatures, a
