From Scientific American 公鳥生殖器不外露有原因？本周科學人解開你的疑惑！Why Did the Chicken Lose Its Penis?
這篇報導討論公鳥生殖器為何不外露。
科學人Scientific American的聽力補充，是為了強化大家的科普英文實力。
NPR則比較多社會科學或是藝術人文的素材。有機會多聽英文廣播絕對能讓聽力進步。記得要先耳聽眼到，多聽幾遍(精聽)，過程中看熟稿子，跟著唸之後，再來盲聽(泛聽)。兩者按照順序搭配練習，絕對有用。大家加油！
Why Did the Chicken Lose Its Penis?
Only 3 percent of bird species
have males with obvious organs of intromission, and now we know the genetics
behind that situation.
Most birds don’t have
penises. Good, I have your attention. Of
course female birds don’t have penises, but neither do most males. Now
researchers have unraveled the genetics遺傳學 behind the disappearance of this anatomical
apparatus生理上的構造. Their penetrating insights精闢的見解 are in the journal Current Biology.
Only 3 percent of avian species禽鳥類 have males with obvious organs of intromission插入器官. Ducks and other
water fowl 家禽are fairly
well endowed器官健全(碩大). But most birds have just rudimentary gear基礎配備, if
anything at all.就算有，也只有陽春的配備
To get to the root of this penile puzzle,
researchers compared the embryos胚胎 of chickens and
ducks. Both types of birds start to develop a member. But in chickens, this
so-called "genital tubercle生殖結節" shrinks before the little guys hatch孵化. And it’s because of a gene
called Bmp4.
Bmp4 basically tells cells to commit
suicide. This form of cell death keeps birds from sprouting teeth. And in developing male chickens, it causes the phallus to regress造成陽具內縮.
Why this happens is still a mystery. It may allow female birds to be more
selective about their mates. Because males with external equipment tend to impose it where
they will擁有外顯性生殖器官的雄性動物比較鴨霸. Whereas those without have to let the ladies rule the roost.擁有決定權/主宰
—Karen Hopkin
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