Guards at the Ol Pejeta Conservancy,philosophy eroticism in Kenya, now only have to keep watch over two northern white rhinos -- and their much sought-after horns.

The last male northern white rhino, named Sudan, died at the wildlife conservancy this week after succumbing to old age and failing health.

There are just two females left from the subspecies, Fatu and Najin, who continue to graze at the protected wildlife park. Unless a still unproven reproductive technology in rhinos -- in vitro fertilization (IVF) -- is used to sustain the subspecies, the northern white rhinos will soon go extinct.

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There's a melancholy around the grounds, said Richard Vigne, head of the Ol Pejeta Conservancy, but even after Sudan is buried at the conservancy, Vigne insists the rhino won't be forgotten.

"Our aim is to build a legacy off the back of Sudan and use him as an ambassador for endangered species," he said in an interview.

But Vigne, like other rhino conservationists, isn't relying upon IVF technology -- which involves fertilizing an egg in a lab and then inserting the small embryo into a female rhino -- to be the savior of any rhino species, all five of which are endangered.

Headstones of rhino graves at the Ol Pejeta Conservancy. Credit: AFP/Getty Images

Protecting rhinos and finding secure land for them to roam requires a lot of cash, which is limited.

"The biggest challenge that faces rhino conservation is cost," said Vigne, who notes that the conservancy's revenue is dependent upon tourists visiting Kenya.

Generally, limited conservation cash leaves little for investment in expensive laboratory research solutions, like IVF. Achieving this technology is estimated to cost in the range of $9 million. Some might balk at that number, but it can also be viewed as a relatively small investment.

"Something like $35 billion is spent by the British [each year] to look after their dogs or cats," said Vigne. "So $9 million to save a species is not a lot of money."

Still, the technology doesn't yet exist. Rhinos, the second largest land mammals after elephants, can only realistically be saved the old fashioned way, by letting rhinos simply live as rhinos, according to the conservationists.

"We should be focusing conservation efforts on allowing white rhinos to do what they do best on the broad African landscape -- to roam the landscape and make lots of baby rhinos," said Michael Knight, Chairman of the International Union for Conservation of Nature (IUCN) African Rhino Specialist Group, in an interview.

The fate of Sudan and the northern whites can be counted as many things -- including failure and tragedy -- but Knight emphasizes that the other white rhino subspecies, the southern whites, is still here and doing significantly better. The southern whites number around 20,000 individuals, and as they're the same species, their genetic makeup is extremely similar, said Knight.

Armed guards at a black rhino reserve in Nanyuki, Kenya. Credit: LightRocket via Getty Images

Additionally, the remaining two northern whites aren't exactly representative of a healthy, vibrant population. Dwindling numbers meant that genetic variability -- necessary for sustaining large populations with diverse genes -- had largely diminished.

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"They're highly inbred so they’re a poor reflection of what they were like historically," said Knight.

All rhinos, however, face the same threat: Demand for their horns.

There's an old myth in some Asian countries that grinding rhino horns into powder and adding it to drinks can mend one's health. And today, drinking this powder has now become a symbol of wealth and status.

"It's rather like having a Porsche parked outside your front door," said Vigne.

"It puts a high price on a rhino's head."

Allowing the remaining African white and black rhinos to survive requires a "two-pronged" approach, said Vigne: Making it riskier to poach rhinos and decreasing demand for rhino horns.

Increasing hunting risk means adding "a good security arrangement" around rhinos, such as armed guards, and requiring strict punishments for horn poachers. Poachers have been sentenced up to 30 years in prison in Kenya.

To further discourage poachers, it's also become commonplace to repeatedly cut rhino horns off (they grow back), so they have less reason to shoot the animals.

Some have even proposed the more drastic measure of creating rhino farms, to produce horns to appease market demand, said Vigne. But this could open up a Pandora's Box of desire for rhino horn powder.

"It would be out of the box and impossible to put back in," said Vigne.

If the IVF reproductive technology is ever developed, however, it might also one day help other endangered rhinos, like the Sumatran, Javan, and African black rhino species, should their populations get poached down to such extreme levels.

"They're facing exactly the same challenges," said Leah Drury, a rhino keeper at the Longleat Safari Park in the UK. But, she notes the technology has never been proven in rhinos, so expectations should be tempered.

"I think we have a little way to go yet," said Drury.

Original image has been replaced. Credit: Mashable

Longleat has donated eggs from three of their rhino cows to the research cause, which in itself is an endeavor. Gathering the eggs requires reaching 1.5 meters into the animals. The eggs were frozen in 2017 and shipped to a lab in Italy, where they could be fertilized.

Proving IVF for rhinos might be a commendable achievement, but conservationists would need to insert the embryos into many southern white females (who would have to serve as surrogate mothers for the northern whites) to produce enough northern whites to sustain a genetically healthy population.

The challenges are many, so for now, rhino conservationists are concentrating on the more feasible challenge of finding protected land for rhinos to roam, graze, and "let natural selection work," said Knight.

"So if things start hitting the fan like increased poaching somewhere, at least you’ve got your eggs in many baskets," he said.

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