Fossils in a South African Cave Reveal Homo naledi

In 2013, recreational cavers exploring the Rising Star Cave system in Gauteng province, South Africa, penetrated deep into the subterranean passages of the Cradle of Humankind. Squeezing through a narrow passage, they reached the remote Dinaledi Chamber, which lies about 30 meters underground. Scattered across the clay floor were numerous hominin bones. Photographs of the site prompted an intensive recovery mission led by paleoanthropologist Lee Berger. Because the route was so tight, the work was carried out by a small team of excavators able to fit through it, and during expeditions in November 2013 and March 2014 they recovered about 1,550 fossil specimens representing at least 15 individuals.

Formally introduced to science in 2015, the remains received the designation Homo naledi, drawing on the Sotho term for star. Because the fossils combined many primitive features with a braincase similar in size to those of australopiths, many researchers expected them to be far older than they proved to be. Dating studies published in 2017 dramatically shifted this timeline. By combining uranium-series and electron spin resonance dating of fossil teeth with uranium-thorium, luminescence and paleomagnetic analyses of the surrounding flowstones and sediments, researchers dated the Dinaledi fossils to between 335,000 and 236,000 years ago, during the Middle Pleistocene. The result showed that a morphologically primitive, small-brained hominin had survived in Africa into the later Pleistocene, at a time when other members of the genus Homo also lived there.