科学美国人60秒 SSS 黑尾袋鼠一生都在怀孕 可同时怀两胎

This is Scientific American's 60-second Science, I'm Susanne Bard¹.

这里是科学美国人——60秒科学系列，我是苏珊娜·巴德。

Picture a small kangaroo. You're basically seeing something very much like the Australian marsupial² called the swamp wallaby. They're also known as black stinkers because of their distinctive³ odor.

想象一只小袋鼠。你想到的可能非常接近名为黑尾袋鼠的澳大利亚有袋类动物。这种动物也被称为“黑色臭家伙”，因为它们身上气味独特。

"I can't really describe it except to say it's quite a pungent⁴ smell. It's not terribly pleasant."

“我只能形容那是一种‘相当刺鼻的气味'。并不是很令人愉快的气味。”

University of Melbourne biologist Marilyn Renfree, who says that their unique scent⁵ isn't the only thing that sets swamp wallabies apart from their evolutionary⁶ relatives. She and her colleagues recently discovered that adult female swamp wallabies can carry two pregnancies⁷—in different stages of development—at the same time. That's possible because—like other kangaroos and wallabies—they have not just one uterus but two. But unlike their close relatives, pregnant swamp wallabies mate again a day or two before they give birth.

墨尔本大学的生物学家玛丽莲·伦弗里说到，她表示，黑尾袋鼠独特的气味并不是其与其它进化亲属的唯一区别。她和同事最近发现，成年雌性黑尾袋鼠可以在不同的发育阶段同时怀胎两次。这是可能的，因为像其它袋鼠和小袋鼠一样，它们不仅有一个子宫，而是有两个。但与其近亲不同的是，怀孕的黑尾袋鼠在临产前一两天会再次交配。

"We only know that strategy in one other mammal, and that's the European hare. And the European hare does this mating while they're pregnant—a phenomenon known as superfetation. So they '—the wallabies—' have effectively a fetus⁸ at an advanced stage of pregnancy⁹ and a very, very early conceptus at the same time."

“我们只知道另一种哺乳动物会采用这种策略，那就是欧洲野兔。欧洲野兔也在怀孕期间进行交配，这种现象被称为‘异期复孕’。因此，黑尾小袋鼠实际上肚子里同时有处于孕晚期的胎儿和处于非常非常早期的胚胎。”

Renfree and her team confirmed the simultaneous pregnancies using high-resolution ultrasound.

伦弗里及其研究团队用高分辨率超声波证实了这种同期妊娠现象。

"And so, for the first time we were able to actually prove that the swamp wallaby is pregnant its whole life. It's never not pregnant."

“因此，我们第一次能够证实黑尾袋鼠整个一生都在怀孕。没有不怀孕的时候。”

This revolving¹⁰ cycle of pregnancy means that after a female swamp wallaby gives birth to her first baby from one uterus, a second embryo¹¹ lies dormant¹² in her other uterus, while the first baby attaches to a teat within her pouch¹³. After nine months, the first baby leaves the pouch, triggering the second embryo to start developing. And right before the second baby is born, the mother mates again, and a third embryo is implanted back in the first uterus.

这种循环妊娠意味着，雌性黑尾袋鼠的一个子宫产下第一个幼崽后，第二个胚胎便休眠在另一个子宫里，而第一个幼崽则其其育儿袋内吃奶。九个月后，第一个幼崽离开育儿袋，触发第二个胚胎开始发育。就在第二个幼崽出生之前，母亲会再次交配，第三个胚胎被植入第一个子宫。

What's more, while the second baby lives inside the mother's pouch, the first baby hops¹⁵ around outside, continuing to suckle from a teat in her pouch. But she's able to supply each of them with milk tailored to their specific developmental needs.

另外，当第二个宝宝幼崽生活在母亲的育儿袋中时，在育儿袋外蹦蹦跳跳的第一个幼崽会继续在育儿袋吃奶。但母亲能为每个幼崽提供适合各自特定发育需要的奶水。

"The little baby is drinking a milk of a totally different composition."

“幼崽喝着的奶水成分完全不同。”

And once this second baby leaves the pouch, the third embryo starts to develop, and the cycle continues.

第二个幼崽一离开育儿袋，第三个胚胎就开始发育，就这样一直循环下去。

"So the swamp wallaby has it all. It has a continuous pregnancy and a continuous lactation for most of its life. Truly amazing animal."

“因此，黑尾袋鼠的一生都是这样。大部分时间都在不断怀孕和哺乳。真是神奇的动物。”

The study is in the Proceedings¹⁶ of the National Academy of Sciences.

这项研究发表在《美国国家科学院院刊》上。

Whatever evolutionary benefit exists to the swamp wallaby's unusual reproductive strategy remains¹⁷ to be seen. After all, being pregnant all the time isn't exactly a hop¹⁴ in the park.

黑尾袋鼠不寻常的繁殖策略在进化上有何好处，尚有待观察。毕竟，一直怀孕并不是一件容易的事。

Thanks for listening for Scientific American's 60-second Science. I'm Susanne Bard.

谢谢大家收听科学美国人——60秒科学。我是苏珊娜·巴德。

1 bard   

n.吟游诗人

参考例句：

• I'll use my bard song to help you concentrate!我会用我的吟游诗人歌曲帮你集中精神！
• I find him,the wandering grey bard.我发现了正在徘徊的衰老游唱诗人。

2 marsupial   

adj.有袋的，袋状的

参考例句：

• Koala is an arboreal Australian marsupial.考拉是一种澳大利亚树栖有袋动物。
• The marsupial has been in decline for decades due to urban sprawl from car accidentsdog attacks.这种有袋动物其数量在过去几十年间逐渐减少,主要原因是城市的扩张、车祸和狗的袭击。

3 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。

4 pungent   

adj.（气味、味道）刺激性的，辛辣的；尖锐的

参考例句：

• The article is written in a pungent style.文章写得泼辣。
• Its pungent smell can choke terrorists and force them out of their hideouts.它的刺激性气味会令恐怖分子窒息，迫使他们从藏身地点逃脱出来。

5 scent   

n.气味，香味，香水，线索，嗅觉；v.嗅，发觉

参考例句：

• The air was filled with the scent of lilac.空气中弥漫着丁香花的芬芳。
• The flowers give off a heady scent at night.这些花晚上散发出醉人的芳香。

6 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

7 pregnancies   

怀孕，妊娠( pregnancy的名词复数 )

参考例句：

• Since the wartime population needed replenishment, pregnancies were a good sign. 最后一桩倒不失为好现象，战时人口正该补充。
• She's had three pregnancies in four years. 她在四年中怀孕叁次。

8 fetus   

n.胎，胎儿

参考例句：

• In the fetus,blood cells are formed in different sites at different ages.胎儿的血细胞在不同时期生成在不同的部位。
• No one knows why a fetus is not automatically rejected by the mother's immune system. 没有人知道为什么母亲的免疫系统不会自动排斥胎儿。

9 pregnancy   

n.怀孕，怀孕期

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕早期常有恶心的现象。
• Smoking during pregnancy increases the risk of miscarriage.怀孕期吸烟会增加流产的危险。

10 revolving   

adj.旋转的，轮转式的；循环的v.（使）旋转( revolve的现在分词 )；细想

参考例句：

• The theatre has a revolving stage. 剧院有一个旋转舞台。
• The company became a revolving-door workplace. 这家公司成了工作的中转站。

11 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

12 dormant   

adj.暂停活动的；休眠的；潜伏的

参考例句：

• Many animals are in a dormant state during winter.在冬天许多动物都处于睡眠状态。
• This dormant volcano suddenly fired up.这座休眠火山突然爆发了。

13 pouch   

n.小袋，小包，囊状袋；vt.装...入袋中，用袋运输；vi.用袋送信件

参考例句：

• He was going to make a tobacco pouch out of them. 他要用它们缝制一个烟草袋。
• The old man is always carrying a tobacco pouch with him.这老汉总是随身带着烟袋。

14 hop   

n.单脚跳，跳跃；vi.单脚跳，跳跃；着手做某事；vt.跳跃，跃过

参考例句：

• The children had a competition to see who could hop the fastest.孩子们举行比赛，看谁单足跳跃最快。
• How long can you hop on your right foot?你用右脚能跳多远？

15 hops   

跳上[下]( hop的第三人称单数 )； 单足蹦跳； 齐足（或双足）跳行； 摘葎草花

参考例句：

• The sparrow crossed the lawn in a series of hops. 那麻雀一蹦一跳地穿过草坪。
• It is brewed from malt and hops. 它用麦精和蛇麻草酿成。

16 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

17 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。