According to John Long, author of Swimming in Stone: The Amazing Gogo Fossils of the Kimberley the world's first male member may be as old as 400 million years.
John Long studies ancient vertebrates of the Gogo region in Western Australia. Since the discovery of a primitive mother fish with a fossilised embryo inside he has known that ancient fish had sex. Until now though, he didn't know how.
Talking on ABC radio's Science Show he said;
"It was another fantastic eureka moment when you make a big discovery that for 100 years has been completely overlooked."
Catch the full interview here: