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 News from Around the Americas | March 2008 
Fossil Sheds Light on the History of Sex
 Lewis Smith - Times Online
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| | Sex for the creature would have been "functional rather than a social affair" | | |
A long, thin rope-like creature standing erect on the sea floor up to 570 million years ago has been identified as the first animal on Earth to have had sex.
Fossilised remains of the mysterious tubular creature have been uncovered in Australia and put back the history of sex by up to 30 million years. While the experience was unlikely to have been memorable for the animals, the discovery has excited scientists who said that the fossils open a window on one of the most ancient ecosystems.
The knobbly animal, named Funisia dorothea, is thought most likely to have reproduced in a similar way to modern corals and sponges, but little else is understood of its biology.
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.”
Sex for the creature would have been functional rather than a social affair, Professor Droser, of the University of California, Riverside, said. “I think they would have been way too basic to have enjoyed the sex. I don’t think they would wind around each other. But I could be wrong — I would like to think they enjoyed it.”
The only time the Earth moved for the creatures, researchers suspect, was when a storm churned up the seabed and covered them with sand, killing them but allowing their bodies to be preserved. 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.” |
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