What is it, to be human? Philosophers, prophets, priests, legislators, dictators and the sheep have been pondering the notion, since there are civilizations, and they wonder. Science, that is, facts, can increasingly contribute to the conversation. And it is taking surprising twists and turns, all the way into the bowels of the Earth.
Paleoanthropologist Lee Berger pleaded on social networks to find “tiny and small, specialised cavers and spelunkers with excellent archaeological, palaeontological and excavation skills”. Was the excavation of a mysterious hominin in the Rising Star Cave in South Africa more circus than science? “Underground astronauts” had to squeeze through a long, narrow chute less than 25 centimeters wide, to drop 30 meters into a fossil-filled cavern.
1550 fossils representing more than 15 individuals of a strange new kind of hominin, named Homo Naledi were found in a nearly impossible to reach cavity. The fossils are still undated: there is no stratigraphy in a cave 100 meters in, past two siphons. However, they confirm spectacularly what we already knew:
- There were, many profoundly different ways to be human. (We already knew this from the existence of Homo Florensis, who is very far from Homo Sapiens in physiology, but not achievements: he came with lots of sophisticated tiny weapons.)
- The Eurafricasian supercontinent enjoyed many areas covered with extremely diverse species of hominins. Homo Sapiens Sapiens is the fruit of a huge amount of group selection among vastly different possibilities on how to be human.
Although the fossils are still undated, making it hard to know where they sit in the human family tree, and, in particular, if they are ancestors to us, they already reveal a profoundly different way to be a member of our genus Homo. More than 60 researchers agree on the picture of “a relatively tall, skinny hominid with long legs, humanlike feet, with a core and shoulder that is primitive,” Berger says.
Paleoanthropologist T. Kivell of the University of Kent (UK) found that bones in the wrist were shaped like those in modern humans, suggesting that the palm at the base of the thumb was quite stiff, allowing forces to spread over a larger area of the hand than in more primitive hominins—a trait associated to tool use. However, H. Naledi had a weird long thumb and long, curving fingers, associated to climbing trees.
The foot is so modern, it may have been capable of not just walking, but running.
And what were those Naledis doing, so deep inside the cave? Datation is crucial. 300,000 years, or three millions? Were the Homo Naledi there for burial, caught there by a catastrophe, or carried there by other humans more recently? We don’t know. Only one owl and a few rodents accompanied the 1500 human fossils.
All we know is the big picture: that humans were all over, all over Eurafricasia, and all over all possibilities of what humanity could be.