Termites and necrophagous insects associated with early Pleistocene (Gelasian) Australopithecus sediba at Malapa, South Africa

Abstract

This study focuses on two early Pleistocene Australopithecus sediba hominin specimens and associated fauna from Malapa, South Africa. These specimens have been interpreted as having fallen through a shaft opening into a cave, where they died and likely mummified, before being washed into a lower chamber. In order to better understand the taphonomy of the fossils and to identify the invertebrate agent(s) responsible for damage, we examined the fossils using high resolution imagery, and studied the site and associated breccia blocks in the laboratory for traces of invertebrate activity. We also conducted bone modification experiments with termites and hide beetles. Results show the presence of blowfly puparia within the cranium of the juvenile male (MH1), indicating that flies visited the facial orifices of the freshly decomposing corpse. Blowflies, which have a requirement to oviposit in daylight, imply that the body was exposed to sunlight for part of the day. A shaft opening that admitted sunlight is supported by the presence of a fossil fungus garden associated with MH2. Fungus gardens occur subsurface and sprout mushrooms in areas with dappled light. Analysis of the fossil surfaces revealed a pattern comprising 14 damage types that were made on relatively fresh bone. A bone modification experiment conducted with resident termites at the site showed that they created the same suite of microscopic surface features as those observed on the fossils. The features are mostly the result of harvesting symbiotic fungi from fresh bones and mineral-rich coatings from fossils. Damage resulting from the activity of hide beetles is similar to that of termites, apart from invasive edge gnawing produced by the beetles. This research highlights the importance of insect activity in the modification of fossils in the Cradle of Humankind World Heritage Site area and calls for consideration of this agent at other fossil sites in the region.