Efforts to save one species can provide scientific knowledge that enables us to save other creatures in need.

Several parallel projects are running across the world to save the northern white rhinoceros (Ceratotherium simum simum), one of Africa's captivating and iconic wildlife species. With the death of the last male in 2018 and with only two females alive, the species is functionally extinct.

The most famous of these projects is an international research consortium called BioRescue. It was founded in 2019 by a team of scientists and conservationists under the leadership of the Leibniz Institute for Zoo & Wildlife Research in Berlin, Germany.

In one of its research lines, the BioRescue team collects mature eggs - scientifically called oocytes - from one of the only two northern white females. They reside in Kenya's Ol Pejeta Conservancy, a privately run wildlife sanctuary. These eggs will be fertilised with frozen sperm that were collected from several northern white male rhinos before their death.

The two remaining females, Najin and Fatu, are not capable of delivering offspring anymore. Najin's back legs are too weak to carry a pregnancy and Fatu has problems with her uterus. Therefore, the resulting embryos from the fertilised eggs will be transferred to surrogate mothers.

The most suitable surrogate mother would be...