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In the savannahs of Kenya, two female [br]northern white rhinos, Nájin and Fatu,

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munch contentedly on the grass.

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At the time of this video’s publication,

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these are the last two known [br]northern white rhinos left on Earth.

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Their species is functionally extinct—

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without a male, [br]Nájin and Fatu can’t reproduce.

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And yet, there’s still hope to revive [br]the northern white rhino.

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How can that be?

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The story starts about 50 years ago,

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when poachers began illegally hunting [br]thousands of rhinos

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across Africa for their horns.

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This, combined with civil wars [br]in their territory,

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decimated northern white rhino [br]populations.

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Concerned conservationists began trying [br]to breed them in captivity in the 1970s,

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collecting and storing semen from males.

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Only four rhinos were ultimately born [br]through the ambitious breeding program.

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Nájin, and her daughter Fatu [br]were the last two.

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In 2014, conservationists discovered [br]that neither can have a calf.

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Though Nájin gave birth to Fatu, [br]she now has weak hindlegs,

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which could harm her health [br]if she became pregnant again.

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Fatu, meanwhile, [br]has a degenerated uterine lining.

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Then, the last northern white rhino male [br]of the species, Sudan, died in 2018.

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But there was one glimmer of hope: [br]artificial reproduction.

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With no living males and no females [br]able to carry a pregnancy,

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this is a complicated and risky process [br]to say the least.

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Though scientists had stored semen, [br]they would have to collect the eggs—

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a complex procedure that requires a female[br]to be sedated for up to two hours.

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Then, they’d create a viable embryo [br]in the lab—

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something that had never been done before,[br]and no one knew how to do.

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Even that was just the beginning—

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a surrogate mother [br]of another rhino species

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would have to carry the embryo to term.

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Females of a closely related species, [br]the southern white rhino,

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became both the key to developing [br]a rhino embryo in a lab

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and the leading candidates [br]for surrogate mothers.

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Northern and southern white rhinos [br]diverged about a million of years ago

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into separate— though still [br]closely-related— species.

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They inhabit different regions, and have [br]slightly different physical traits.

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In a fortunate coincidence, [br]several female southern white rhinos

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needed treatment [br]for their own reproductive problems,

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and researchers could collect eggs [br]as part of that treatment.

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In Dvůr Králové Zoo in October 2015,

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experts of IZW Berlin began collecting [br]eggs from southern white rhinos

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and sending them to Avantea, an animal [br]reproduction laboratory in Italy.

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There, scientists developed and perfected [br]a technique to create a viable embryo.

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Once they mastered the technique,

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researchers extracted Nájin and Fatu’s [br]eggs on August 22, 2019

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and flew them to Italy.

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Three days later, they fertilized [br]the eggs with sperm

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from a northern white rhino male.

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After another week, two of the eggs [br]made it to the stage of development

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when the embryo can be frozen [br]and preserved for future.

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Another collection in December 2019 [br]produced one more embryo.

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As of early 2020, the plan is to collect [br]Nájin and Fatu’s eggs three times a year

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if they’re healthy enough.

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In the meantime, [br]researchers are looking for

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promising southern white rhino [br]surrogate mothers—

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ideally who’ve carried a pregnancy [br]to term before.

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The surrogacy plan [br]is somewhat of a leap of faith—

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southern and northern white rhinos [br]have interbred

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both during the last glacial period [br]and more recently in 1977,

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so researchers are optimistic [br]a southern white rhino

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would be able to carry [br]a northern white rhino to term.

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Also, the two species’ pregnancies [br]are the same length.

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Still, transferring an embryo [br]to a rhino is tricky

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because of the shape of the cervix.

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The ultimate goal, [br]which will take decades,

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is to establish a breeding population [br]of northern white rhinos

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in their original range.

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Studies suggest that we have samples [br]from enough individuals

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to recreate a population with the genetic [br]diversity the species had a century ago.

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Though the specifics [br]of this effort are unique,

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as more species face critical endangerment[br]or functional extinction,

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it’s also an arena for big questions:

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do we have a responsibility to try [br]to bring species back from the brink,

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especially when human actions [br]brought them there in the first place?

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Are there limits to the effort [br]we should expend

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on saving animals threatened [br]with extinction?