Bone fat exploitation and the importance of fat as a resource
Dr Alan Outram
Dr Outram has an ongoing research interest in past human use of bone fats, i.e. bone marrow and bone grease. It is only relatively recently that fat, whether on people or in food, has become deeply unfashionable within Western society. This current perception tends to distract one from the extremely important role that the procurement of fat played in many past societies. The calorific value of fat is much higher than that of protein or carbohydrate, by a ratio of 9:4. As such, sources of are very unlikely to be ignored by people under any degree of subsistence stress. Fat can also be used as a fuel for lighting, for waterproofing animal skins and a host of other craft purposes. Bones are an excellent source of fat. Their marrow cavities are packed with fat and the rest of the bone can be broken up and boiled to extract grease. The processing of bones to extract fat will leave a very specific pattern of fracture and fragmentation within archaeological bone assemblages. In order to study these patterns, Alan has carried out many replicative experiments in fracturing bones.
He has applied his work to the study of Mesolithic assemblages from Britain and Alpine Italy, Palaeoeskimo and medieval Norse assemblages in Greenland and a Neolithic hunting site in Sweden. His work has shown interesting trends in levels of bone fat exploitation, which are almost certainly related to levels of subsistence stress at particular times of the year. This work was continued with a study of Icelandic medieval Norse sites, funded by the British Academy. The Greenlandic Norse were under exceptional subsistence stress and had to process their bones for every last drop of fat. In the end they had to abandon Greenland, having been forced to eat their dogs, but they never fished despite a plentiful supply! The Icelandic Norse did fish. Is this extra food resource reflected in the level of bone fat processing required?
Alan is currently studying the bone fat processing practices at a Plains Indian village at Mitchell, South Dakota. This is a site where, c. AD 1000, maize horticulturalists and bison hunters may well have been producing very large quantities of 'pemmican', a mixture of dried meat, berries and bone fat. At this site, he recently carried out an experiment into bone grease rendering and pemmican making.
Some of Dr Outram's work on this subject:
Dr Outram organised a session on the Animal Fats and Oils for the 2002 meeting of International Council for Zooarchaeology. He has edited the proceedings of this session for combined publication with another highly relevant session on dairying and dairy products:
Outram, A.K. (1999) A Comparison of Palaeoeskimo and Medieval Norse Bone fat Exploitation in Western Greenland. Arctic Anthropology 36:1, 103-117.
Outram, A.K. (2000) Hunting Meat and Scavenging Marrow: A seasonal explanation for Middle Stone Age subsistence strategies at Klasies River Mouth. In: P. Rowley-Conwy (ed.) Animal Bones and Human Societies. Oxford: Oxbow Books. 20-27.
Outram, A.K. (2001) A New Approach to Identifying Bone Marrow and Grease Exploitation: Why the "Indeterminate" Fragments should not be Ignored. Journal of Archaeological Science 28:4, 401 - 410.
Outram, A.K. (2002) Bone Fracture and Within-Bone Nutrients: An Experimentally Based Method for Investigating Levels of Marrow Extraction. In: P. Miracle and N. Milner (eds.) Consuming Passions and Patterns of Consumption. Cambridge: McDonald Institute for Archaeological Research. 51-64.
Outram, A.K. (2003) Comparing levels of subsistence stress amongst Norse settlers in Iceland and Greenland using levels of bone fat exploitation as an indicator. Environmental Archaeology 8:2, 119-128.
Outram, A.K. (2004) Identifying dietary stress in marginal environments: bone fats, optimal foraging theory and the seasonal round. In M. Mondini, S. Munoz and S. Wickler (eds) Colonisation, Migration, and Marginal Areas. A Zooarchaeological Approach. Oxford: Oxbow 74-85.
Outram, A.K. (2005) Distinguishing bone fat exploitation from other taphonomic processes: what caused the high level of bone fragmentation at the Middle Neolithic site of Ajvide, Gotland? In Mulville, J and Outram, A.K. (eds) The zooarchaeology of fats, oils, milk and dairying. Oxford: Oxbow, p32 - 43.
Mulville, J. and. Outram, A.K (eds) 2005: The Zooarchaeology of Fats, Oils, Milk and Dairying. Oxford: Oxbow Books.