A cluster of 78,000-year-old bones found at the mouth of a Kenyan cave represent the earliest known human burial in Africa, shedding light on how our ancient ancestors interacted with the dead.
The remains belong to a Middle Stone Age child believed to have been between 2.5 and 3 years old. The bones of the toddler, whom scientists nicknamed Mtoto ("child" in Swahili), come from the Panga ya Saidi cave complex in coastal southeast Kenya. The excavation site has yielded a rich trove of historical artifacts, including beads made from seashells and thousands of tools that reflect technological shifts from the Middle Stone Age to the Later Stone Age.
When archaeologists found Mototo's highly decomposed remains, they couldn't immediately identify them as human. In a study published Wednesday in the journal Nature, researchers from Germany's Max Planck Institute for the Science of Human History and the National Museums of Kenya detail how they came to conclude, through microscopic analysis of the bones and the surrounding soil, that the skeleton in a cave's shallow circular pit belonged to a child who'd intentionally been laid to rest.
"Deliberate burial of the dead is so far confined to just Homo sapiens and Neanderthals, setting us apart from all other ancient hominins, and any other animal," Nicole Boivin, an archaeological scientist and director of the Max Planck Institute for the Science of Human History, tells me. "Study of mortuary and burial practices gives us insight into the evolution of our own species, our thoughts, emotions and cosmological beliefs, and what it means to be human."
Earlier hominins also treated the dead in special ways. For example, the archaic human species Homo naledi appears to have placed bodies in the back of South Africa's Rising Star Cave about 300,000 years ago. That's a practice referred to as funerary caching.
Mtoto's case, in contrast, demonstrates a more complex process through evidence of a purposefully excavated pit followed by intentional covering of the corpse. The child appears to have been prepared for a tightly shrouded burial, placed on one side with knees drawn toward the chest. Even more notable is that the position of the child's head suggests it rested on some sort of support, like a pillow. That indicates the community may have performed a mourning rite.
The archaeologists first came upon parts of the bones in 2013, and four years later, discovered the burial pit about 10 feet (3 meters) under the cave floor.
"At this point, we weren't sure what we had found," says Emmanuel Ndiema of the National Museums of Kenya. "The bones were just too delicate to study in the field. So we had a find that we were pretty excited about, but it would be a while before we understood its importance."
Once they made plaster casts of the remains they brought those to the National Research Center on Human Evolution in Burgos, Spain, for further study.
It was there the team started uncovering parts of the skull and face, which still had some unerupted teeth in place. "The articulation of the spine and the ribs was also astonishingly preserved, even conserving the curvature of the thorax cage, suggesting that it was an undisturbed burial and that the decomposition of the body took place right in the pit where the bones were found," says professor María Martinón-Torres, director of the center.
The origin and evolution of human mortuary practices are subjects of intense interest and debate, as they can help reconstruct the past by illuminating details on cognition, migration, social strata, disease, religion and more. Evidence of burials of both Neanderthals and modern humans in Eurasia date back earlier in the Middle Stone Age, to as far as 120,000 years ago. But evidence of burials in Africa have been scarce, and hard to attach exact dates to.
"It is great to have such a well-dated example of a modern human from Africa being buried," says professor Andy Herries, head of archaeology at Australia's La Trobe University, who isn't affiliated with the Nature study. "I think, however, that the find, while being very important, perhaps raises more questions than it answers."
Questions, for example, about whether humans of the time buried one another according to specific rituals or whether our earliest ancestors thought about death and the afterlife the same way we do today.
Still, for anyone interested in human evolution, it's an exciting discovery -- both for what it could teach us about our forebears and the way it unfolded layer by sedimentary layer.
Herries calls Panga ya Saidi one of the most significant archaeological sites in the world. Archaeologists, geologists, earth scientists, paleoecologists and biological anthropologists plan to continue excavating the cave complex for more insights into the world of Mtoto, Mtoto's ancestors and the people who followed.