“Evolutionary history was probably different to what we had imagined”
is not a sentence you read every day, but that’s what John Hawks states. He’s part of the National Geographic (NG) funded research team that last week published findings of
“a new species of human ancestor”
after excavating a remote cave chamber near Johannesburg in South Africa. The team found at least 15 well-preserved partial skeletons of a creature they place in the same genus grouping as modern-day humans due to shared characteristics such as long legs and small teeth. They’ve named it Homo naledi. Professor Lee Berger, an NG explorer-in-residence who led the research team, suggests H.naledi link modern humans to primates.
Due to the difficulty of reaching the location, Prof. Berger believes the remains show
“deliberate disposal of the dead”
This hypothesis has huge implications, as symbolic actions were previously thought unique to modern humans. Much like trying to reach a TP bar on a Wednesday, the ritualistic journey involved worming through spaces as narrow as 7.5 inches.
Despite all the hype and celebration of news headlines, it wouldn’t be science without a healthy dose of scepticism. The American paleoanthropologist William Jungers described the fossils as
“more curioisities than game-changers for now”
as their age is completely unknown. Professor Tim White is a critic of Berger’s, and calls the research conclusions “speculation” siting the small excavation area – well under a cubed metre. He has boldly stated that “from what is presented here, they belong to a primitive Homo erectus, a species named in the 1800s”; Jungers has also made this suggestion. Chemical dating is on hold for now as the process is destructive and therefore deemed unethical by Berger until all observation is finished. He is also keen not to let age “contaminate” the morphology based discussions.
Professor Dr Christoph Zollikofer questions the bones’ distinctiveness. The characteristics used to define the creatures as a new species are also seen in more primitive hominins –
“they may represent individual variation, or variation at the population level.”
He and others have previously shown that there is as much variation between Homo erectus individuals as there is between modern-day humans, fuelling the argument of the Homo classification system being oversensitive.
Then there is the question of how the remains came to rest in a place so difficult to access. In addition, the route is pitch-black. The research team suggest that H.naledi used torches, a claim fervently disputed due to the lack of fire control evidence in any of our ancestors. “There has to be another entrance [to the chamber]” says another renowned paleoanthropologist Richard Leakey, who has seen the bones first-hand.
Zollikofer is again cynical, and says the intentional disposal claim isn’t “substantiated by the data presented in the publications”. Others have suggested the creatures got stuck after climbing in, that they drowned when the space filled with water, or were predated upon by carnivores but there are observations that rebut these. The remains are from hominins of all ages – the babies and the elderly probably wouldn’t have been able to make the difficult journey into the chamber. No sediment indicative of flowing water is found in the cave. The bones have no predator tooth marks.
Despite the contention the research team are unfazed and stick by their hypotheses.
“No matter what the age, it will have tremendous impact,” – Professor Lee Berger.
Praised for his inclusive research approach, he has again brought paleoanthropology into the public eye and sparked curiosity across the globe. To quote the NG video on the discovery,
“there’s a lot out there to be found.”