5. Discovering that early Hominids buried their dead hundreds of thousands of years ago
The excitement about the newly discovered Homo naledi was not limited to the sheer number of bones, however. The condition and placement of those bones also upended preexisting assumptions about the behavior of primitive hominids. The bones lacked gnaw marks indicating that they had been dragged into the cave by carnivores. Between that and their placement deep in a shaft that they were unlikely to have ended up in by accident, it became clear that the bones had been deliberately placed in the cave by other Homo naledi individuals. I.e.; they were buried.
It was not the earliest known burial, as 28 skeletons dating to about 430,000 had been discovered years earlier in a Spanish cave. However, the Spanish skeletons came from a big brained Homo species that looked and behaved much like modern humans. Homo naledi on the other hand had a brain half the size of ours, and could not have been mistaken for a modern human. However, its burial practices demonstrated that its individuals understood mortality and the concept of something after death. That squashed the hitherto prevailing notion that such understanding and behavior required big brains, and forced a reexamination of early hominids’ culture and intelligence.