Over a dozen skeletons of an unknown, early Homo species found

As we very recently noted, the origin of our own genus is a mystery. Some of the features that help define Homo were found in a species, Australopithecus sediba , that belongs to an entirely different genus. Most of the earliest remains that appear to be Homo are fragmentary and tell us little about the individual they came from.

All of that makes a recent find from South Africa all the more exceptional. A cave in the Cradle of Humankind World Heritage Site has yielded a nearly complete skeleton and parts of 14 others. The remains define a new species, Homo naledi, that had a mix of features from Homo and Australopithecus, as well as a few of its own. The biggest mystery: when did the species live? Currently, we don't have even the slightest hint.

The World Heritage Site is in the same area that yielded the A. sediba fossils. People exploring a cave found what appeared to be remains in an area that's extremely difficult to reach. Lee Berger of the University of the Witwatersrand helped organize an expedition, backed by National Geographic (which has provided all the images here). A call went out for paleontologists with caving experience who could fit through an 18cm wide passage, resulting in a crew of six women who helped excavate part of the site.