Johannesburg is a new city by human standards, having been founded 125 years ago in 1886. But just a short drive from Joburg lie the remains of some of the oldest human descendants on earth. The Cradle of Humankind, 20 kilometers from town, is a 47,000-hectare World Heritage Site that produced the first adult australopithecine fossil, “Mrs. Ples,” discovered in 1947. Mrs. Ples is believed to be between 2.8 and 2.6 million years old. To date, more than 850 hominid fossils have been discovered in a series of dolomitic limestone caves scattered throughout the Cradle.