Primitive Homo naledi drew and buried

Scratched line patterns have been found in the difficult-to-access Rising Star cave in South Africa. Evidence of fire use and burials have also been found, which, like the engravings, are associated with the only known inhabitant of that cave: the unusual Homo naledi (ca. 300,000 to 200,000 years old). This H. naledi was a contemporary of modern humans Homo sapiens which originated about 300,000 years ago. The discovery of naledi caused quite a stir in 2015 due to its combination of relatively modern anatomical features with primitive features, such as its protruding face, the crooked fingers that seem more suitable for climbing trees, and especially the small brain size (600 cc, no larger than of a gorilla, versus 1,300 cc of H. sapiens). The researchers of the Rising Star cave, led by Lee Berger (University of Witwatersrand) on Monday describe their finds in three publications in Biorxiv (1, 2, 3).

Modern behavior

Lee Berger and his team, including archaeologist John Hawkes (University of Wisconsin), see their discoveries as proof that ‘modern behavior’ such as the use of fire and especially burials and deliberate engravings are not necessarily associated with a large brain capacity, such as those of Homo sapiens and Neanderthals. “Meaning creation is not limited to the niche of big-brained hominids,” they write. Petroglyphs and burials are regarded in archeology as strong indications of symbolic thinking.

A problem with the finds is that it is not yet certain whether all these actions were performed by H. naledi, even though he is the most obvious ‘perpetrator’. The engravings have not yet been dated and the use of fire has not been described extensively enough either, Dutch archaeologist Wil Roebroeks emphasizes when asked by e-mail. Furthermore, according to Roebroeks, the indications for naledi burials are also “possible” but “not yet convincing”. There may always be a lot, says Roebroeks.

And in recent decades there have been so many surprises in the field of human evolution, “that it would no longer be unexpected if hominid with a small brain like Homo naledi also made engravings or buried their dead,” writes Roebroeks. “However, there must be solid evidence for it. What I see now is only circumstantial evidence. There may also have been Homo sapiens in the cave later, although we have not found anything of that yet.”

The oldest known burials to date are some 100,000 years old, by Homo sapiens and Neanderthals. The more than 400,000-year-old ‘Pit of Bones’ (‘Sima de los Huesos’) in Spain is thought to contain the many bodies of early Neanderthals, but this idea is not generally accepted.

Immediately after the discovery of the H. naledi bones in the Rising Star Cave in 2015, it was also suggested that those bodies might have been buried there, mainly because it was considered unlikely that the skeletal remains could have ended up there by predators or running water.

Relatively small archaeologists

The cave can only be reached through a narrow tunnel that can only be traversed in ‘superman position’: with one arm stretched along the body and the other extended forward. Another bottleneck is less than 20 cm wide. A large part of the research on site has therefore been carried out by relatively small archaeologists, the underground astronauts of whom Hannah Morris, Marina Elliott, Becca Peixotto, Elen Feuerriegel and Alia Gurtov (all University of the Witwatersrand) are also involved in the current investigations. Lee Berger has himself been on a diet for months before he descended himself for the first time last year. Even for the tiny H. naledi – about 150 cm long – it must have been no easy traverse, especially lugging a dead body.

Comparable deliberate scratches as now found in the South African ‘naledi cave’ are also known from Homo sapiens, from the South African Blombos cave, ca. 100,000 years old. And there is also a mussel shell from Java, on which a Homo erectus already scratched a kind of zigzag line half a million years ago, a discovery by Wil Roebroeks himself and José Joordens from Leiden.

Earlier fire use

Fire use by humans is much older than the naledi cave, probably 400,000 years old, although there are also older estimates, up to two million years ago. The indications for the use of fire by naledi have not yet been described in detail. In their concluding piece, Lee Berger and his colleagues suffice with a reference to an internet news item about a lecture by Berger, which also states that the firewood found has not yet been properly investigated.

Berger and his team found at least two sites of disturbed soil in the cave containing a body of a Homo naledi, which appears to have decomposed undisturbed in place, with skeletal material in the correct anatomical position, covered by a few centimeters of sediment. In fact, they now suspect that their earlier finds of naledi skeletal material in the cave may have come from other burials. But according to Roebroeks, the analysis is not yet conclusive due to the lack of a detailed ‘micromorphological’ analysis of the sediment.

The geometric patterns and scratches believed to have been made by H. naledi were found on a pillar between two chambers in the cave. The lines are between five and fifteen centimeters long. It is striking that the surfaces appear to have been smeared with dye or sediment to make the characters stand out better. The nearly fifty scratches resemble an interplay of hashtags: ‘#’. Similar signs have also been found further in the cave, but they have not yet been properly investigated.

Also read about H. naledi: We are the last survivors of the great human family (2017)