Prehistoric human behaviour under the microscope

Dr Silvia Bello of the Natural History Museum explains how her experimental microscopic analysis of cut-marks on bone could provide an important new tool for reconstructing the subsistence strategies of early hominids and the funerary practices of prehistoric humans.

Cut-marks are scratches produced when a knife of flint or metal strikes the surface of a bone or tooth; they play a key role in interpreting past butchery practices, subsistence and tool use. When present on human remains, cut-marks can relate to funerary practices such as cannibalism or the de-fleshing and disarticulation of a body.

The interval between the death of an organism and the production of cut-marks, however, often remains uncertain, and our estimates rely on indirect evidence, such as the relation between carnivore tooth marks and human-made stone tool marks, the location and frequency of cuts and percussion damage, and the presence of human tooth marks.

This new Leverhulme Trust-funded project aims to determine whether cut-mark micro-morphology can be used to infer the decomposition stage of a carcass at the time when the cuts were made. Analysis of data produced from experimentation on non-human carcasses and two large human archaeological assemblages will be carried out using an environmental scanning electron microscope and the new Alicona 3D InfiniteFocus imaging microscope, which allows for three-dimensional reconstruction of surfaces at a microscopic level (figure 1).

The key objective is to provide diagnostic micro-morphometric characteristics of cut-marks, which can allow for better-informed estimates of the time elapsing between the death of an individual and the moment cut-marks were produced. This will directly influence two lines of archaeological enquiry.

Firstly, there has been considerable debate for over thirty years regarding early hominid carcass acquisition strategies (the hunting versus scavenging debate). This study aims to provide data to use as a reference for distinguishing between cuts made on fresh carcasses (i.e. those hunted by early humans) or decomposing bodies (i.e. those scavenged by opportunistic early humans).

Secondly, the research will enable reconstruction of funerary pathways that involve the cutting of a human body, by trying to distinguish between cut-marks associated with the cutting of a fleshy, human-looking corpse at the beginning of a funerary ritual and the cleaning of bones after a long period of decomposition has passed. Determining when cut-marks were made on human bodies during funerary practices will allow past funerary beliefs to be better understood and will enhance our knowledge of different attitudes towards death and dead bodies in the past.

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Figure 1: (A) Superior view of a human collar bone (Gough’s Cave collection, Gough’s Cave, Somerset, ~15,000 years BP; scale 10mm). (b1) Environmental Scanning Electron Microscope (ESEM) image of clusters of transverse short and deep slicing cut-marks, scale 1mm and (b2) ESEM detail of cut-marks showing internal microstriations and hertzian cones, scale 100µm. (B) Photo of a human rib (Gough’s Cave collection; scale 10mm) and (b1) Alicona 3D image of slicing cut-marks on the caudal end of the rib, scale 250µm.