Intently voyeuristic researchers came up with idea of “genetically altering fruit flies so that the heads of their sperm were fluorescent green or red” allowing them to get a better look at slutty wildlife and evolution:
Whenever a female mates with more than one male — and female promiscuity is more the rule
than the exception in nature — there are conflicts between the sexes over paternity, as well as
competition between rival ejaculates to fertilize eggs. Such postcopulatory sexual selection is a
powerful force for evolutionary change.