【轉貼】地球第一場性愛 5.7億年化石見證 When the earth first moved: Fossil was first animal to have sex 570million years ago

Funisia dorothea素描假想圖 (上圖) ; Sketch: How the rope-like creatures would look (top)

Funisia dorothea化石 (下圖) ; Fossil love: The funisia dorothea is thought to be the first creature to have sex 570m years ago (bottom)

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〔編譯陳成良／綜合報導〕

科學家最近在澳洲發現曾存活在距今至少5.7億年前的新物種化石標本，見證地球第一場動物性愛。這種管狀生物稱為「弗尼瑟．多蘿西」（Funisia dorothea，見上圖，下圖為素描假想圖，取自每日郵報網站），會成群地將自己固定在砂質淺灘的海床上，當初的棲息地現在已成為澳洲內陸。
生物性愛史前推3000萬年
研究人員認為，Funisia dorothea應該是地球第一種進行有性繁殖的動物，將地球的生物性愛史往前推了約3000萬年。
英國每日郵報報導， 距今5.7億年前，這種細長管狀生物已經在海洋中生存，據信牠們是以和珊瑚及海綿類似的方法繁殖。科學家認為，Funisia dorothea具有性繁殖的能力，因為化石標本是以群體的形式被發現，而且這群生物年齡相仿，而群聚生長的方式，讓牠們浮在水中的卵子和精子可以安全結合。
精卵結合 近似珊瑚繁殖
Funisia dorothea是負責這次化石挖掘的古生物學者瑪麗．卓瑟根據她母親的姓名來命名。
任教於美國加州大學河濱分校的卓瑟及同僚在「科學」期刊（Science）的報告中指出，由於沒有以Funisia dorothea為食的天敵，牠們的生活平和，有時進行有性生殖，有時則以出芽生殖等方式進行無性生殖。
Funisia dorothea可以長到約30公分，彈性的軀體能隨著海洋潮浪彎曲。由於牠們在幼體或受精卵階段附著於海床上，就無法尋覓交配伴侶，可能因此演化出與現代的珊瑚、海綿類似的繁殖方式。

When the earth first moved: Fossil was first animal to have sex 570million years ago

(News from Daily Mail) By CAROLINE GRANT Last updated at 16:20pm on 21st March 2008

It may be more than 570million years old and look like a knobbly rope, but scientist believe they have discovered the first animal on earth ever to have sex.
The fossilised remains of this new species of organism was unearthed in Australia where the tube-like creatures lived in abundant flocks.
The discovery of the animal, called Funisia dorothea, has put the history of sex back by about 30million years and set the scientific world into a frenzy.
It is thought that the sex lives of the long thin creature would be similar to corals and sponges.
Researchers came to the conclusion that the mysterious animals were sexually active because the fossil specimens were found in groups that all seemed to be of the same age.
Nothing appears to have evolved to eat them, so they lived peaceful lives, reproducing sexually at times and by asexual methods such as budding at other times, Mary Droser of the University of California Riverside and colleagues reported in the journal Science.
The remains of organisms were found in the Australian outback that would have once been a shallow, sandy seabed.
Scientists believe that sex for the creatures would have been functional rather than social.
Professor Droser said: "I think they would have been way too basic to have enjoyed sex.
"I don't think they would wind around each other. But I could be wrong - I would like to think they enjoyed it."
Professor Droser added: "They were complicated enough to have different modes of reproduction and a fairly complex ecosystem in general."
They lived in dense groups of similar size and aged animals, like mussels and oysters do.
"It is common modern ecological strategy, and these guys were doing it in the earliest animal ecosystems on this planet," she said.
"We think of these strategies as having been in response to competition and in response to predation."
Dense clusters, such as the ones these animals lived in, allow eggs and sperm floated in the water to meet up safely.
"They would have been hitting you mid-calf as you walked in these very dense clusters," said Professor Droser.
"Almost always, organisms that do this do it as a result of sexual reproduction."
Multicellular animal life is believed to have arisen around 600 million years ago.
The Funisia dorothea would have thrived in the Neoproterozoic era, which ended about 540million years ago and lasted for about 100million years.
They would have grown to about 30cm long and been flexible enough to bend with the currents and tides of the sea.
Once they had rooted themselves to the seabed as larva or a fertilised egg they would have been stuck in one place and unable to search for mates.
Professor Droser added: "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."
Funisia dorothea's name comes from the word for rope in Latin and dorothea after Dorothy, Droser's mother.