Now, a testtube rhino

last-ditch effort to save the world's most endangered mammal— the northern white rhino— from extinction, scientists have successfully used in vitro fertilisation (IVF) to create hybrid embryos. Only two females from the species survive after Sudan, the last known male, died in March. The scientists combined sperm from two dead male northern white rhinos with eggs from the more abundant southern white rhino—a closely related subspecies. The embryos will be implanted into surrogate female southern white rhinos to produce baby rhinos that are a mix of both subspecies. The hybrid babies can then ensure that at least some of the northern white rhino DNA is preserved, says a study published in Nature Communications. The team's goal is to have the first northern white rhino calf born in three years, says coauthor Thomas Hildebrandt, a professor at the Leibniz Institute for Zoo and Wildlife Research in Germany.