A landmark in the history of sex

Funisia dorothea was long, thin rope-like organism that lived on the sea floor about 570 million years ago has been identified as the first animal on Earth to have had sex (well reproduce sexually). Sadly for Funisia it is unlikely that the earth moved (unless there had been a seaquake at the time) and it is thought that is reproduced in a similar way to modern corals and sponges. However, the discovery has excited scientists who said that the fossils open a window on one of the most ancient ecosystems.

Researchers identified the creature’s capacity for sexual rather than asexual reproduction because fossil specimens were found in groups that all appeared to be the same age. Because they had found a foothold in a sandy seabed at the same time, it was considered they must have resulted from a simultaneous spawning instead of uncoordinated asexual births.

Mary Droser, the paleontologist who led the excavations, named the animal after her 80-year-old mother, Dorothy Droser, who took care of the paleontologist’s young children and cooked for the research team on several digs in the Australian outback. Mrs Droser said she was “thrilled to tears” at having a fossil named in her honour. She thought it appropriate that the ancient beast was the first to have sexual relations: “My family thinks it’s humorous. I have 11 grandchildren — obviously reproduction is a good thing.”

Funisia dorothea thrived on the sea floor in the Neoproterozoic era, a 100-million-year period ending about 540 million years ago, and formed part of the earliest known animal ecosystem. It was a soft-bodied creature that grew 30cm long and would have been safe from predators because it would be several more million years before they evolved. Even scavengers had yet to appear. Once the tubular animals had fixed themselves to the seabed, either as a larva or a fertilised egg, they were immobile and unable to go off in search of mates. Researchers, who reported their findings in the journal Science, were unable to identify a mouth or any other recognisable anatomy.

“In general, individuals of an organism grow close to each other, in part, to ensure reproductive success,” said Professor Droser, who co-authored the report with James Gehling of the South Australia Museum. “In Funisia, we are very likely seeing sexual reproduction in Earth’s early ecosystem – possibly the very first instance of sexual reproduction in animals on our planet. How Funisia appears in the fossils clearly shows that ecosystems were complex very early in the history of animals on Earth.”