It was in the time period where neanderthals and homo sapiens began to roam the Earth that evidence of art and spirituality began to appear, suggesting that hominids had shifted from trying to stay alive through finding food and shelter, to now having the time and brain complexity to be thinking more abstract thought and performing spiritual and symbolic rituals, such as burials. There is evidence of these mass burial sites spanning back to the Palaeolithic period, when the neanderthals lived. However, it is difficult for archeologists to determine whether these burials were intentionally made, whether there was abstract or 'higher' thinking surrounding them, etc.
For example, in the Shanidar Cave in Iraq, the fossils of at least 10 neanderthals were discovered and are believed to date back 60,000-90,000 years. What made this discovery initially groundbreaking was the appearance of pollen alongside the fossilised skeletons, which made archeologists suggest flowers were placed beside them during burial. If true, this meant neanderthals were possibly capable of abstract and symbolic thinking, up to 90,000 years ago. Some scientists suggest that later hominids may have returned to the burial site to place the flowers later, or that it was actually mice who carried in traces of pollen from the outside environment into the burial site. So, scientists are still unsure whether these skeletons were buried intentionally with ritual or not.
In a cave in Atapuerca, Spain, nicknamed "the pit of bones", 600,500 bone fragments were discovered, of both animals and 28 hominins, believed to be of the Denisovan species. These fossils are believed to be at least 300,000 years old and may be as old as 600,000 years. Lack of evidence suggesting a flood or ground collapse that would have trapped the individuals in the cave have lead scientists to believe that these denisovan individuals were intentionally placed in the cave after their death. However, we don't know the reason why. The individuals may have been put in the cave after they died to remove the smell of rotting flesh, or to stop the corpses from being eaten by predators. Or, the individuals may have been diseased, and put in the cave to avoid transmission, but this would suggest these hominins had knowledge of disease transmission in the first place: due to the brain size of the denisovans, this is unlikely. But while they may have been placed there intentionally, the skeletons of these individuals were not arranged in the cave, which doesn't suggest a burial ritual happened.
However, in 2013, The Rising Star Cave in South Africa, the remains of fifteen Homo Naledis, dating to around 250,000 B.C were discovered. The remains were located in the 'Dinaledi Chamber', which could only be accessed through the 'Superman's crawl' and 'The Dragon's Back', stretches of cave which were only around 1ft tall. What is interesting about this site is that each of the remains were placed there gradually, over time. Scientists agree that while the Dinaledi chamber was used to dispose of the dead, they do not all agree that the cave is a definite burial site, where the skeletons were buried intentionally and with ritual. There is no evidence of symbolism that suggested higher thinking in these hominins, and the individuals could have again been placed there to remove the smell of rotting flesh, or to stop the corpses from being eaten by animals.
It was in the Qafzeh Cave in Mt. Precipice, Israel, that 15 skeletal remains dating back to 92,000 B.C were discovered. These fossils were of very early homo sapiens, buried alongside flint tools, seashells, and red ochre clay. What's interesting about the burial of these remains is that some of them were buried in an orderly fashion within the floor of the cave, rather than, for example, the "pit of bones" where remains seemed to be just dumped there in no particular arrangement. Two of the skeletons had deer antlers in their hands and some bones of the remains were coated in this red ochre clay: this is important because it suggests some aspect of symbolism, some higher thinking in the homo sapiens who buried them, as well as ritual and burial preparation. Since it was the bones coated in red ochre, and not flesh (which would not have been discovered in the fossil record), this indicates people went back to the burial site, perhaps to grieve these individuals. The tools they were buried with suggest homo sapiens could have had some form of belief in an afterlife, that these individuals would need the tools later. These discoveries at Qazef cave were really significant because it shows evidence of such profound cultural and spiritual evolution in homo sapiens by 92, 000 B.C. It indicates hominins were beginning to instead devote their time to more abstract and 'higher-up' thinking, signalling a shift from living to purely survive, to living for more abstract, perhaps religious, and more 'recreational' purposes. From there, homo sapiens continued to evolve culturally, moving onto cave paintings, the development of agriculture, permanent settlements, and eventually, more complex burial rituals, like those of Ancient Egyptian mummies. Today, every single culture on Earth have their own special burial rituals. I find it so interesting for us to be able to look back and see when and how our own archaic ancestors started it all.
