It is estimated that 8,000 rhinoceros have been killed by humans in the last 10 years alone. There are 21,000 rhinoceros left in the world today. The evolutionary history of rhinoceros goes back 50 million years. The Northern White Rhinoceros is a subspecies of the White Rhinoceros that is said to be descended from Ceratotherium praecox that lived around seven million years ago.