Welcome Homo naledi yet another new branch of the Human family tree – here are a few brief thoughts on what has come to light thus far.
So we finally got the big reveal from the Rising Star expedition, who on Thursday, Sept 10th, 2015, announced that fossil remains of over a dozen individuals had been found and collected from the depths of a cave in South Africa,
Surprising as this discovery was, the mosaic of archaic and modern features seemed to demonstrate once again that our ancestors remain as unpredictable as ever – Homo floresiensis for example was a completely unexpected find back in 2003, and caused a storm of controversy, with arguments that instead of being a new species of human, this was a modern specimen, deformed by illness.
There seems little doubt on the other hand that Homo naledi is the real deal, with its bewildering mix of modern and archaic traits. But despite all the cheering and flag waving across the internet and news media, two vital factors have yet to be resolved – the dating of te fossils, and DNA analysis, puzzling omissions which seemingly have yet to be addressed.
The bones were found lying around on a damp cave floor, rather than being in neatly organised sedimentary layers that could more easily date the remains – and here perhaps is the first clue that these hominins may have died out relatively recently, perhaps in the same time frame as the hobbits from Liang Bua cave on Flores – also found in wet and muddy conditions, dating back to the astonishingly recent date of 12,000 years ago. Somehow this relict population of archaic humans had survived in total isolation from the outside world on the tiny island of Flores, far later than would have been expected, and they were only finally wiped out when a volcano erupted around 12 kya
It has been suggested that the bones form Rising Star cave could date back hundreds of thousands of years, and that very early humans buried their dead, or had funerary rituals associated with death. This would be absolutely extraordinary, and has led some to make comparisons with the 28 individuals from Sima de los Huesos at Atapuerca, found at the bottom of a shaft, dating to perhaps 350 kya.
There has been speculation that these individuals, mainly juveniles and adolescents, had been deliberately placed in their collective tomb as part of a funerary rite, but there´s very little in the way of direct evidence that could confirm this.
By contrast, the individuals at Rising Star represent humans of all ages, from juveniles, through adults to those old enough to have been grandparents. Unlike Atatpuerca, where the bodies could simply have been dropped unceremoniously down a shaft, the route to the final resting place of the Rising Star individuals was much more difficult, as attested by the efforts that had to be made by the wiry female cavers who were hired specifically for the exploration. With passages narrowing to 18 inches, and in some parts 10 inches, whoever deposited the bones went to a lot of trouble to get the job done.
This would also indicate that it would have been too difficult to transport freshly dead bodies, rather that it was only the bones themselves that were buried, carried there by whoever took it upon themselves to carry out this task.
But rather than this being a burial that was undertaken hundreds of thousands of years ago, the preservation of the bones would suggest that this was a relatively recent occurrence – possibly in the same time frame of Flores, around 12,000 years ago. In turn this would mean, that like the hobbits of Flores, Homo naledi was also a relict population that had developed in situ, and survived in isolation until very recently, only dying out when either a calamitous event wiped them out, or their numbers declined to the extent that their extinction became inevitable.
The burying of bones is more a Neolithic phenomenon, or in the context of human evolution, an entirely modern behaviour. Indeed, it may have been modern humans who secreted the bones away – and maybe it was modern humans who discovered the Homo naledi people, and for reasons unknown, killed them off and decided to hide all trace of them deep in the cave system that was only recently rediscovered.
Many will be surprised that no DNA analysis has been offered, and given the state of preservation, it would appear that these bones are not so degraded to prevent this. The bones at Liang Bua were so waterlogged that DNA extraction has thus far proved impossible, but the Rising Star bones look fresh enough for DNA to be extracted. The results should be equally fascinating as the discovery itself, but until tests are done, we can only wait with bated breath.
Just a few reflections, rather than an exhaustive scientific review, and it´d be interesting to hear the thoughts of others regarding the points raised in this brief essay.
Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa Berger, Hawks et al 2015
The many mysteries of Homo naledi by Chris Stringer