Research continues to reveal that non-human animals recognize death and express what we would call grief for the loss of a group member. There is no doubt that this narrows the perceived gap between humans and other animals and reinforces the continuity of life. As far as we know, however, we humans are the only species that is fully aware of our own mortality. With this realization comes the ability (or curse?) to anticipate and contemplate our death and the deaths of others. We express this "mortality salience" (to use the term of social psychologist Jeff Greenberg and his colleagues) in part through elaborate mortuary rituals. When did humans develop this mortality salience, and how might we tell?
While much of the symbolic meaning associated with these rituals does not fossilize, some behaviors, such as the creation and interment of grave goods, the intentional modification of human remains and, most pertinent to this post, the deliberate disposal of the dead, can potentially survive in the archaeological record. There is a growing consensus that by ~120,000 years ago Neandertals and other Middle Paleolithic humans intentionally buried their dead and, in some cases, perhaps even collected the bones of the dead for secondary burial (the evidence for grave offerings remains equivocal). The case for deliberate disposal before the Middle Paleolithic is more contentious, and the present debate revolves around the Sima de los Huesos in the Sierra de Atapuerca in Spain and the Dinaledi Chamber in the Rising Star Cave System of South Africa. Dated to between 300,000 and 600,000 years ago, these remarkable fossil assemblages are composed nearly exclusively of human bones. What is more, the skeletons are found in difficult-to-access chambers deep within the cave systems. These are extraordinary finds, and it is reasonable to ask: (1) if they represent the remains of corpses that were deliberately disposed of and, if so, (2) whether the process of corpse disposal was infused with some deeper cultural meaning, as it is among modern humans.
My colleagues and I recently put in our two cents worth on this topic in the Proceedings of the National Academy of Sciences (the study has garnered some modest publicity in Spain and the United States). Thankfully, both the Atapuerca and Rising Star research teams have published extensively so that their data are available to other paleoanthropologists. After my friend, colleague, and former PhD adviser Travis Pickering pored over the frequencies of skeletal elements from the Dinaledi Chamber, he told me the pattern was not what one would expect if complete bodies were being deposited in the cave. We therefore decided to put together a small database of skeletal element data from other sites with primate remains. I eventually found over 30 datasets that ranged from modern forensic cases and leopard-consumed baboons to 3.2-million-year-old autralopiths. Another good friend and colleague, Manuel Domínguez-Rodrigo, argued that a machine-learning approach would be appropriate here, since these sorts of algorithms might be able to distinguish among the different types of assemblages based on patterns of skeletal element preservation.
Essentially, we found that the pattern of bone preservation in the Sima de los Huesos and the Dinaledi Chamber is different from that seen in complete skeletons. Now, this in and of itself does not refute the hypothesis that the Sima and Dinaledi remains were deliberately disposed of--even intentionally buried bodies can be scavenged or moved around after their original deposition. (In fact, we think it is likely that carnivores consumed some of the softer bones at both sites.) What was most intriguing to us, though, was the fact that both the Sima and Dinaledi consistently clustered with an assemblage of baboon bones from an active cave system in South Africa called Misgrot. This cave, which was investigated by two other colleagues, Jason Heaton and Colin Menter, preserved over a thousand baboon bones, some of which were found as partial skeletons. Since the baboons aren't being intentionally dropped into the cave by conspecifics (the cave is used mainly as a sleeping site), it stands to reason that you don't need to invoke deliberate disposal to explain the skeletal part frequencies of either the Sima or Dinaledi. It is, in other words, possible to get a collection of partially complete, large-bodied primates into a cave through natural processes.
We are careful to note that these findings don't disprove the deliberate disposal hypothesis at these sites. Is it possible that some time before 300,000 years ago early humans were intentionally dumping bodies into caves? Sure. Is it even possible that this behavior had some sort of symbolic meaning behind it? Absolutely. But, as the aphorism made famous by Carl Sagan goes, "extraordinary claims require extraordinary evidence." So, to quote our paper, neither the Sima or Dinaledi "currently qualifies as unequivocal evidence for emergent mortality salience in the human lineage."
References:
Egeland, CP, Domínguez-Rodrigo, M, Pickering, TR, Menter, CG, Heaton, JL (2018). Hominin skeletal part abundances and claims of deliberate corpse disposal in the Middle Pleistocene. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.1718678115
While much of the symbolic meaning associated with these rituals does not fossilize, some behaviors, such as the creation and interment of grave goods, the intentional modification of human remains and, most pertinent to this post, the deliberate disposal of the dead, can potentially survive in the archaeological record. There is a growing consensus that by ~120,000 years ago Neandertals and other Middle Paleolithic humans intentionally buried their dead and, in some cases, perhaps even collected the bones of the dead for secondary burial (the evidence for grave offerings remains equivocal). The case for deliberate disposal before the Middle Paleolithic is more contentious, and the present debate revolves around the Sima de los Huesos in the Sierra de Atapuerca in Spain and the Dinaledi Chamber in the Rising Star Cave System of South Africa. Dated to between 300,000 and 600,000 years ago, these remarkable fossil assemblages are composed nearly exclusively of human bones. What is more, the skeletons are found in difficult-to-access chambers deep within the cave systems. These are extraordinary finds, and it is reasonable to ask: (1) if they represent the remains of corpses that were deliberately disposed of and, if so, (2) whether the process of corpse disposal was infused with some deeper cultural meaning, as it is among modern humans.
My colleagues and I recently put in our two cents worth on this topic in the Proceedings of the National Academy of Sciences (the study has garnered some modest publicity in Spain and the United States). Thankfully, both the Atapuerca and Rising Star research teams have published extensively so that their data are available to other paleoanthropologists. After my friend, colleague, and former PhD adviser Travis Pickering pored over the frequencies of skeletal elements from the Dinaledi Chamber, he told me the pattern was not what one would expect if complete bodies were being deposited in the cave. We therefore decided to put together a small database of skeletal element data from other sites with primate remains. I eventually found over 30 datasets that ranged from modern forensic cases and leopard-consumed baboons to 3.2-million-year-old autralopiths. Another good friend and colleague, Manuel Domínguez-Rodrigo, argued that a machine-learning approach would be appropriate here, since these sorts of algorithms might be able to distinguish among the different types of assemblages based on patterns of skeletal element preservation.
Essentially, we found that the pattern of bone preservation in the Sima de los Huesos and the Dinaledi Chamber is different from that seen in complete skeletons. Now, this in and of itself does not refute the hypothesis that the Sima and Dinaledi remains were deliberately disposed of--even intentionally buried bodies can be scavenged or moved around after their original deposition. (In fact, we think it is likely that carnivores consumed some of the softer bones at both sites.) What was most intriguing to us, though, was the fact that both the Sima and Dinaledi consistently clustered with an assemblage of baboon bones from an active cave system in South Africa called Misgrot. This cave, which was investigated by two other colleagues, Jason Heaton and Colin Menter, preserved over a thousand baboon bones, some of which were found as partial skeletons. Since the baboons aren't being intentionally dropped into the cave by conspecifics (the cave is used mainly as a sleeping site), it stands to reason that you don't need to invoke deliberate disposal to explain the skeletal part frequencies of either the Sima or Dinaledi. It is, in other words, possible to get a collection of partially complete, large-bodied primates into a cave through natural processes.
We are careful to note that these findings don't disprove the deliberate disposal hypothesis at these sites. Is it possible that some time before 300,000 years ago early humans were intentionally dumping bodies into caves? Sure. Is it even possible that this behavior had some sort of symbolic meaning behind it? Absolutely. But, as the aphorism made famous by Carl Sagan goes, "extraordinary claims require extraordinary evidence." So, to quote our paper, neither the Sima or Dinaledi "currently qualifies as unequivocal evidence for emergent mortality salience in the human lineage."
References:
Egeland, CP, Domínguez-Rodrigo, M, Pickering, TR, Menter, CG, Heaton, JL (2018). Hominin skeletal part abundances and claims of deliberate corpse disposal in the Middle Pleistocene. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.1718678115
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