The researchers who made the find have not been able to find out how long ago these creatures lived – but the scientist who led the team, Prof Lee Berger, told BBC News that he believed they could be among the first of our kind (genus Homo) and could have lived in Africa up to three million years ago.
Like all those working in the field, he is at pains to avoid the term “missing link”. Prof Berger says naledi could be thought of as a “bridge” between more primitive bipedal primates and humans.
“We’d gone in with the idea of recovering one fossil. That turned into multiple fossils. That turned into the discovery of multiple skeletons and multiple individuals.
“And so by the end of that remarkable 21-day experience, we had discovered the largest assemblage of fossil human relatives ever discovered in the history of the continent of Africa. That was an extraordinary experience.”
Prof Chris Stringer of the Natural History Museum said naledi was “a very important discovery”.
“What we are seeing is more and more species of creatures that suggests that nature was experimenting with how to evolve humans, thus giving rise to several different types of human-like creatures originating in parallel in different parts of Africa. Only one line eventually survived to give rise to us,” he told BBC News.
The haul of 15 partial skeletons includes both males and females of varying ages – from infants to elderly. The discovery is unprecedented in Africa and will shed more light on how the first humans evolved.
“We are going to know everything about this species,” Prof Berger told me as we walked over to the remains of H. naledi.
“We are going to know when its children were weaned, when they were born, how they developed, the speed at which they developed, the difference between males and females at every developmental stage from infancy, to childhood to teens to how they aged and how they died.”