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| A big, black mane is hot, shaggy and attracts trophy hunters, but it makes a lion irresistibly sexy to the lionesses |
A big, black mane is hot, shaggy and attracts trophy hunters, but it makes a lion irresistibly sexy to the lionesses, researchers reported.
The bigger and darker the mane, the more mates a lion attracts, and the better his cubs survive, Peyton West and Craig Packer of the University of Minnesota wrote in Friday's issue of the journal Science.
A male with a long, dark mane intimidates other lions and for good reasons, they found. He has higher levels of testosterone and wins fights more often.
But he pays for this. He is hotter than lions with lighter manes, eats less in summer and produces more abnormal sperm, the researchers found.
"We suggest the mane's evolution is the result of sexual selection," said West, a doctoral candidate whose dissertation led to the paper.
Lions' manes vary from light blond to black and can be up to a foot long.
One big question about lions is why the males even have a mane, said West, who studied lions in Tanzania's Serengeti National Park.
Like a peacock's elegant but heavy tail, it signals biological fitness to females. Females choose mates with beautiful tails, or in the case of lions, with big, black manes, because it turns them on. Thus the trait is passed on.
West checked to see what good the mane does to a lion. Some people have suggested it protects the head and shoulders during fights or hunting, but West said their data didn't show the neck and head were a special target.
West set up pairs of model lions with short and long manes and watched to see which ones wild lions would approach. Males chose the short-maned dummy nine out of 10 times, she found, while females approached the darker-maned dummy, 13 out of 14 times.
West also found that the higher the testosterone level in the blood of male lions, the darker the mane. "Therefore, it isn't surprising that females would prefer darker manes and males would be intimidated," West said.
(Agencies)
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濃密烏黑的鬃毛雖然給雄獅帶來不少的麻煩，除了夏天格外悶熱之外，還會招來捕獵者的注意，不過研究人員發現，雄獅的鬃毛對母獅來說卻具有無法抵抗的性吸引力。
明尼蘇達州立大學的佩頓和克雷格·帕克在8月23日出版的《科學》周刊上寫到，鬃毛越長越黑，雄獅吸引的配偶就越多，而且也有助于其幼獅的生存。
他們發現，有著一頭又長又黑鬃毛的雄獅具備諸多良好的素質以脅迫其他獅子，這樣的雄獅能夠分泌更多雄性荷爾蒙，從而得以在爭斗中保持常勝。
不過"常勝"是要付出代價的。研究者發現，同那些鬃毛稀少的同類相比，鬃毛濃重的雄獅會感覺更熱，夏天的食量也少多了，而且排出異常精子的情況會更多。
著文指導該項研究的博士候選人瓦斯特說："我們認為鬃毛的進化是性別選擇的必然結果"。
獅子的鬃毛顏色從金黃色到黑色不等，而且長度可以達到一英尺。
曾在坦桑尼亞的塞倫蓋蒂國家公園研究獅子的瓦斯特說，有待我們研究的一個重要問題是，為什么只有雄獅才有鬃毛。
正如雄孔雀優美厚重的雀屏，那是一種向雌性表明自己體魄強健的生理標志。雌性孔雀通常會選擇有漂亮尾巴作為配偶，而母獅子則選擇有濃黑鬃毛的雄獅，因為這樣的鬃毛能刺激它們在交配過程中感到興奮。因而這種雄性特征就這樣遺傳給了下一代。
瓦斯特研究了鬃毛對雄獅的確切作用。有些人認為鬃毛可以在爭斗和獵捕時保護頭部和肩部，但是瓦斯特說他們收集到的數據并未表明獅子的頸部和頭部會受到特別的襲擊。
瓦斯特制作了幾對鬃毛長短不同的獅子模型，來觀察野生獅子到底會接近哪一對。結果她發現，在對雄獅10次測試里，它們有9次會選擇短鬃毛的獅子模型，而母獅則14次測試中有13次選擇了長鬃毛的模型。
瓦斯特在研究中還發現，雄獅的鬃毛越黑，它血液中睪酮的含量就越高。她說道："因此，鬃毛較黑的雄獅會得到母獅的青睞，而且讓其他雄獅相形見絀也就不足為奇了。"
(中國日報網站譯)
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Updated: 2002-08-28 01:00
