Homo naledi is an extinct species of archaic human discovered in 2013 in the Rising Star Cave system, Gauteng province, South Africa (See Cradle of Humankind), dating to the Middle Pleistocene 335,000–236,000 years ago.

They are estimated to have averaged 143.6 cm (4 ft 9 in) in height and 39.7 kg (88 lb) in weight, yielding a small relative brain size, encephalization quotient, of 4.5.

The persistence of small-brained humans for so long in the midst of bigger-brained contemporaries revises the previous conception that a larger brain would necessarily lead to an evolutionary advantage, and their mosaic anatomy greatly expands the known range of variation for the genus.

H. naledi anatomy indicates that, although they were capable of long-distance travel with a humanlike stride and gait, they were more arboreal than other Homo, better adapted to climbing and suspensory behaviour in trees than endurance running.

Some researchers suggest that H. naledi also may have carved crosshatched rock signs in a passage to what could be a burial chamber, but many paleontologists question this theory.

On 13 September 2013 while exploring the Rising Star Cave system in the Cradle of Humankind, South Africa, cavers Rick Hunter and Steven Tucker found hominin fossils at the bottom of the Dinaledi Chamber.

[2] On 24 September, they returned to the chamber and took photographs that they showed to South African palaeoanthropologists Pedro Boshoff and Lee Rogers Berger on 1 October.

[6] The fossils represent 737 anatomical elements – including portions of the skull, jaw, ribs, teeth, limbs, and inner ear bones – from old, adult, young, and infantile individuals.

Aside from the Sima de los Huesos collection and later Neanderthal and modern human samples, the excavation site has the most comprehensive representation of skeletal elements across the lifespan, and from multiple individuals, in the hominin fossil record by that time.

[6] The remains of at least three additional individuals (two adults and a child) were reported in the Lesedi Chamber of the cave by John Hawks and colleagues in 2017.

[10] The smaller-brained Homo floresiensis of Indonesia lived on an isolated island and, apparently, became extinct shortly after the arrival of modern humans.

[11] The ability of such a small-brained hominin to have survived for so long in the midst of bigger-brained Homo greatly revises previous conceptions of human evolution and the notion that a larger brain would necessarily lead to an evolutionary advantage.

If the latter, then several gracile hominin fossils from African sites that traditionally have been classified as late H. erectus might represent H. naledi specimens.

[17] It is unclear whether H. naledi inherited small brain size from the last common Homo ancestor, or whether it was evolved secondarily and more recently.

[6][18] The frontal lobe morphology is more or less the same in all Homo brains despite size, and differs from Australopithecus, a characteristic that has been implicated in the production of tools, the development of language, and sociality.

[18] Similarly to modern humans (but not to fossil hominins, including South African australopithecines, H. erectus, and Neanderthals) the permanent second molar of H. naledi erupted comparatively late in life, emerging alongside the premolars instead of before, a characteristic that indicates a slower maturation unusually comparable to modern humans.

[17] A juvenile specimen, DH7, is skeletally consistent with a growth rate similar to the faster ape-like trajectories of MH1 (A. sediba) and Turkana boy (H. ergaster).

[25] Concerning the spine, only the tenth and eleventh thoracic vertebrae (in the chest region) are preserved from presumably a single individual, which are proportionally similar to those of contemporary Homo, although being the smallest recorded of any hominin.

Conversely, the proximal phalanges are curved and are almost identical to those of A. afarensis and H. habilis, which is interpreted as an adaptation for climbing and suspensory behaviour.

The fingers are proportionally longer than those of any other fossil hominin, other than the arboreal Ardipithecus ramidus and a modern human specimen from Qafzeh cave, Israel, which is consistent with climbing behaviour.

[6] Like other Homo, they had strong insertion for the gluteus muscles, well-defined linea aspera (a ridge running down the back of the femur), thick patellae, long tibiae, and gracile fibulae.

Alternatively, because many more sites are known in the south than the north, carnivore spatial patterns may not be well-represented by the fossil record (preservation bias).

[34][35] H. naledi occupied a seemingly unique ecological niche from previous South African hominins, including Australopithecus and Paranthropus.

The teeth of all three species indicate that they needed to exert high shearing force to chew through perhaps plant or muscle fibres.

In this scenario, such industries and stone cutting techniques would have evolved independently several times among different Homo species and populations, or were transported over long distances by the inventors or apprentices and taught.

[10] Since the first publication of results from the Dinaledi Chamber, there has been scholarly debate on whether the fossils excavated from the cave provide evidence of H. naledi engaging in intentional burial activity.

The excavating team stated that it is possible that the bodies were dropped down a chute and fell slowly due to the narrowness and irregularity of the path down.

They proposed that placement in the chamber may have been done to remove decaying bodies from a settlement, prevent scavengers, or as a consequence of social bonding and grief.

[citation needed] In 2018, anthropologist Charles Egeland and colleagues echoed Val's arguments and stated that there is insufficient evidence to conclude that such an early hominid species had developed a concept of afterlife as often associated with burials.

[47] Foecke et al. reanalyzed the soil and were unable to replicate Berger's findings, thus undermining a key piece of evidence in the burial hypothesis.