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  • In the savannahs of Kenya, two female northern white rhinos, Nájin and Fatu, munch contentedly on the grass.

    ケニヤのサバンナで、2 頭のキタシロサイのメス、ナジンとファトゥがムシャムシャと幸せそうに草を食べています。

  • At the time of this video's publication, these are the last two known northern white rhinos left on Earth.

    この動画の公開時点で、この 2 頭は、地球上に残された最後のキタシロサイとしてすでに知られているでしょう。

  • Their species is functionally extinctwithout a male, Nájin and Fatu can't reproduce.

    この 2 頭の種は、機能的絶滅状態にあります。オスがいないため、ナジンとファトゥは繁殖することができないのです。

  • And yet, there's still hope to revive the northern white rhino.


  • How can that be?


  • The story starts about 50 years ago, when poachers began illegally hunting thousands of rhinos across Africa for their horns.

    ことの始まりは 50 年前。密猟者がアフリカ大陸全土で違法な狩猟を始め、何千頭ものサイを狩ってしまったのです。目的は彼らの角でした。

  • This, combined with civil wars in their territory, decimated northern white rhino populations.


  • Concerned conservationists began trying to breed them in captivity in the 1970s, collecting and storing semen from males.

    懸念を抱いた自然保護論者たちは、檻の中での飼育を試みます。1970 年代のことでした。オスの精子を採取し保存したのです。

  • Only four rhinos were ultimately born through the ambitious breeding program.


  • jin, and her daughter Fatu were the last two.

    ナジンと彼女の娘のファトゥが最後の 2 頭です。

  • In 2014, conservationists discovered that neither can have a calf.

    2014 年、保護論者たちはどちらも仔牛を産むことができないことに気づきます。

  • Thoughjin gave birth to Fatu, she now has weak hind legs, which could harm her health if she became pregnant again.

    ナジンはファトゥを産んだものの、後ろ脚が弱くなってしまい、もう 1 度妊娠したとしても、健康を害する可能性があり、

  • Fatu, meanwhile, has a degenerated uterine lining.


  • Then, the last northern white rhino male of the species, Sudan, died in 2018.

    そして、最後のキタシロサイのオス、スーダンが 2018 年に亡くなってしまいました。

  • But there was one glimmer of hope: artificial reproduction.


  • With no living males and no females able to carry a pregnancy, this is a complicated and risky process to say the least.


  • Though scientists had stored semen, they would have to collect the eggs — a complex procedure that requires a female to be sedated for up to two hours.

    科学者たちが保存しておいた精子はあるものの、卵子を採取しなければなりません。それは、複雑な作業で、2 時間はメスを鎮痛剤で眠らせなくてはいけません。

  • Then, they'd create a viable embryo in the labsomething that had never been done before, and no one knew how to do.


  • Even that was just the beginning — a surrogate mother of another rhino species would have to carry the embryo to term.


  • Females of a closely related species, the southern white rhino, became both the key to developing a rhino embryo in a lab and the leading candidates for surrogate mothers.


  • Northern and southern white rhinos diverged about a million of years ago into separatethough still closely-relatedspecies.


  • They inhabit different regions, and have slightly different physical traits.


  • In a fortunate coincidence, several female southern white rhinos needed treatment for their own reproductive problems, and researchers could collect eggs as part of that treatment.


  • In Dvůr Králové Zoo in October 2015, experts of IZW Berlin began collecting eggs from southern white rhinos and sending them to Avantea, an animal reproduction laboratory in Italy.

    2015 年 10 月、ドヴール・クラーロヴェ動物園で、ベルリンにある IZW (ライプニッツ動物園野生生物研究所) の専門家がミナミシロサイの卵子の採取を始めました。そしてイタリアにあるアヴァンティアという動物繁殖研究所に送ります。

  • There, scientists developed and perfected a technique to create a viable embryo.


  • Once they mastered the technique, researchers extractedjin and Fatu's eggs on August 22, 2019 and flew them to Italy.

    その技術を習得すると、研究者たちはナジンとファトゥの卵子の抽出を行います。2019 年 8 月 22 日のことでした。そして、その卵子をイタリアまで送ったのです。

  • Three days later, they fertilized the eggs with sperm from a northern white rhino male.

    3 日後、彼女たちの卵子と、キタシロサイの精子の受精を行いました。

  • After another week, two of the eggs made it to the stage of development when the embryo can be frozen and preserved for the future.

    さらに 1 週間後、2 つの卵子が発育段階に到達。その胚を将来のために凍結保存することが可能になります。

  • Another collection in December 2019 produced one more embryo.

    2019 年 12 月、他で採取した卵子からも 1 つの胚が生成されます。

  • As of early 2020, the plan is to collectjin and Fatu's eggs three times a year if they're healthy enough.

    2020 年初頭の時点での計画は、ナジンとファトゥの卵子を 1 年間で 3 度採取することでした。彼女たちが健康であることが条件です。

  • In the meantime, researchers are looking for promising southern white rhino surrogate mothersideally who've carried a pregnancy to term before.


  • The surrogacy plan is somewhat of a leap of faithsouthern and northern white rhinos have interbred both during the last glacial period and more recently in 1977, so researchers are optimistic a southern white rhino would be able to carry a northern white rhino to term.

    代理出産計画は、やや思い切った取り組みではあります。ですが、ミナミシロサイとキタシロサイは、最終氷期と、最近では 1977 年に異種交配が成立していたため、研究者たちは前向きに考えています。ミナミシロサイがキタシロサイを妊娠し、出産できるだろうと考えているのです。

  • Also, the two species' pregnancies are the same length.


  • Still, transferring an embryo to a rhino is tricky because of the shape of the cervix.


  • The ultimate goal, which will take decades, is to establish a breeding population of northern white rhinos in their original range.


  • Studies suggest that we have samples from enough individuals to recreate a population with the genetic diversity the species had a century ago.


  • Though the specifics of this effort are unique, as more species face critical endangerment or functional extinction, it's also an arena for big questions.


  • Do we have a responsibility to try to bring species back from the brink, especially when human actions brought them there in the first place?


  • Are there limits to the effort we should expend on saving animals threatened with extinction?


  • How are conservationists and communities helping endangered species recover?


  • See how some regions are working to repopulate vulture communities by opening vulture restaurants with this video, or explore how we can sustainably farm the ocean to prevent overfishing with this video.


In the savannahs of Kenya, two female northern white rhinos, Nájin and Fatu, munch contentedly on the grass.

ケニヤのサバンナで、2 頭のキタシロサイのメス、ナジンとファトゥがムシャムシャと幸せそうに草を食べています。

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絶滅危惧種の最後の2頭 — キタシロサイの運命は?

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    Celine Chien に公開 2020 年 11 月 02 日