5.3.3 Late Archaic Homo

Homo naledi: A Rising Star

The most recently described archaic Homo is known as Homo naledi. They were found in the Rising Star cave system in South Africa in 2013 and 2014 (Figures 5.14–5.15) and are dated to approximately 235,000–335,000 years old. Over 1,500 bones from as many as 15 individuals were recovered from the cave, which is possibly the largest assemblage of a single hominin species yet discovered. Despite their relatively recent date, they have exceptionally small cranial capacities, comparable to the robust and gracile australopithecines, which are around 560 cc. The encephalization quotient of H. naledi is estimated at 4.5, which is the same as H. floresiensis but notably smaller than all other Homo (contemporary Homo are all above 6). The presence of this small-brained hominin at the same time that Neanderthals and Homo heidelbergensis were around is further evidence that multiple hominin lineages were coexisting and evolving at the same time. The classification of H. naledi proved to be a challenge, as the specimens presented a mosaic of traits and characteristics associated with an array of other hominin species.

The site is shown to be located in an interior region of what is now the country of South Africa.
Figure 5.14 Maps showing the location of the Cradle of Humankind World Heritage Site in South Africa, where Homo naledi fossils were found in the Rising Star cave system. (credit: Hawks et al. (2017), eLife, CC BY 4.0)
Sketch of a cave, showing multiple geological features protruding from the ceiling and walls. The “excavation area” is on the floor of the cave, near a feature labelled “drain.”
Figure 5.15 The Rising Star cave system, showing geological features and the location of the excavation area where numerous Homo naledi specimens have been found. (credit: Paul H. G. M. Dirks et al. (2015), eLife/Wikimedia Commons, CC BY 4.0)
Front, side, and top views of skulls.
Figure 5.16 H. naledi skulls. It is apparent in these images that this species had rather pronounced prognathism (Credit: John Hawks, Marina Elliott, Peter Schmid et al. (2017), eLife/Wikimedia Commons, CC BY 4.0)
Side and top views of foot bones.
Figure 5.17 H. naledi feet were much like those of modern humans. (credit: W. E. H. Harcourt-Smith, Z. Throckmorton, K. A. Congdon, B. Zipfel, A. S. Deane, M. S. M. Drapeau, S. E. Churchill, L. R. Berger & J. M. DeSilva (2015)/Nature Communications/Wikimedia Commons, CC BY 4.0)
Left and right hand bones.
Figure 5.18 The hands of H. naledi display curved finger bones and large thumbs, indicating that it still had an adaptation for climbing trees. (credit: Lee R. Berger et al. (2015), eLife/Wikimedia Commons, CC BY 4.0)
Four different skulls, Homo habilis, Homo erectus, Homo floresiensis, and Homo naledi. Homo habilis is labelled with the following features: relatively high and thin skull; small brain volume; rounded occipital, no transverse torus; and large teeth, molars increase towards back. Homo erectus is labelled with the following features: relatively low and thick skull; small-medium brain volume; flexed occipital, transverse torus; large teeth, molar gradient varies. Homo floresiensis is labelled with the following features: relatively low and thick skull; small brain volume; flexed occipital, transverse torus; small teeth, molars decrease towards back. Homo naledi is labelled with the following features: relatively high and thin skull, small brain volume; flexed occipital, transverse torus; small teeth, molars increase towards back.
Figure 5.19 Comparison of some of the most commonly known Homo species (credit: Chris Stringer, Natural History Museum, United Kingdom (2015), eLife/Wikimedia Commons, CC BY 4.0)

Homo naledi: Did They Bury Their Dead?

Homo naledi has not yet been found in association with any stone tools. Despite a lack of established tool use, there is fairly convincing evidence that H. naledi may have used the cave system as a place to bury their dead. The hypothesis that H. naledi had a ritualistic mortuary practice is based on several observations, such as the bones appearing to lack evidence of gnawing marks from predators and the lack of evidence of layers of sediment that would suggest the bones were deposited by flooding (Dirks et al. 2015). In 2017 additional fossil remains were found in a second chamber in the Rising Star cave system (Hawks et al. 2017), but these remains don’t as yet appear to offer additional evidence to support the hypothesis of an intentional burial.

Some scientists believe that there is insufficient evidence to conclude that H. naledi were involved in funerary ritual practices. They have noted that the preservation of H. naledi specimens are similar to that of cave-dwelling baboons that have died natural deaths. At Sima de los Huesos, remains of about 28 Neanderthal and H. heidelbergensis fossils were found in a cave dated to about 430,000 years ago. Researchers who examined the scattering patterns of the remains at both the Rising Star cave system in Africa and the Sima de los Huesos site in Spain (Egeland et al. 2018) concluded that the sites showed evidence of having been scavenged but that this doesn’t disprove the possibility that they may also be deliberate burials. The verdict is still out on this. Lee Berger and other scientists are conducting further investigations of the H. naledi skeletal deposits to further explore the possibility they might be evidence of something more deliberate than the actions of predators.

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