Nairobi, April 11 -- In the heart of Laikipia County, the clock is ticking for Najin and her daughter Fatu.

Every minute, these two northern white rhinos - the only ones left in the world - teeter on the brink of extinction.

Five years ago, Sudan, the last male, died of old age. A chance to reproduce naturally, for the two females left behind went with him. The cruel hand of nature would also strike, preventing Fatu, the youngest and most capable, from conceiving.

Now, scientists are racing against time while hoping that science will save the critically endangered species whose physical safety is guaranteed 24 hours a day by armed guards.

Oblivious to this fact, Najin and Fatu bask in the safety and comfort of their enclosure, grazing...