Researchers have studied these fossils of early human ancestors and their long-lost relatives for decades.

Lucy, the most famous Australopithecus fossil in the world.

The study describing the findings was recently published in the journal Proceedings of the National Academy of Sciences.

The "Cradle of Humankind" is a (UNESCO) World Heritage Site in South Africa.

Made famous by the discovery of the first adult Australopithecus, an ancient hominin, in 1936.

Hominins include humans and their ancestral relatives.

However, other great apes are not hominins.

However, other great apes are not hominins.

Since 1936, hundreds of Australopithecus fossils have been found at the Sterkfontein Caves.