The CENIEH researcher Ruth Blasco is the lead author of a paper published in Science Advances, which proposes the intentional conservation of certain food resources for delayed consumption during the Middle Pleistocene
The researcher Ruth Blasco, a specialist in Taphonomy at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), is the lead author of a paper published today by the journal Science Advances, in which the anthropogenic marks on faunal remains found at the Israeli archaeological site of Qesem Cave are analyzed, and it proposes the existence of a “pantry”, or an intentional storage of food resources for later consumption, during the Middle Pleistocene, about 400,000 years ago.
This paper, entitled “Bone marrow storage and delayed consumption at Middle Pleistocene Qesem Cave, Israel (420-200 ka)”, takes as starting point a number of questions which have always remained open about the consumption of bone marrow, a resource especially sought by human groups from very early times due to its high levels of fatty acids. One of these questions is whether the extraction of bone marrow is linked solely and exclusively to immediate consumption in Middle Pleistocene chronologies.
Another is to explore whether the deliberate storage of certain bones for the delayed consumption of marrow could have left some recognizable taphonomic signal in the archaeological record. And if so, to determine how long the marrow could have been conserved in optimal conditions if storage of that kind had taken place.
“To address all these questions, we carried out an experimental study of marrow extraction techniques, since they leave marks on the bones which can be identified archaeologically, as occurs with the notches produced by percussive impacts or bone flakes shed by this process, in addition to the damage caused during the extraction of skin and tendons at different stages of dryness”, explains Blasco.
Up to 9 weeks of conservation
In the experimental study for this paper, bones with a high marrow content, which in fact were metapodials (the distal zone of the paws), were processed. This was combined with chemical analyses which assessed the preservation of the nutrients contained in the marrow while it remains encapsulated within the bones after a period of exposure to the environmental conditions of up to nine weeks, taking into account factors such as the climate and seasonal variations.
In total, 79 metapodials distributed into three experimental series were used, corresponding to three different environmental scenarios. The first two series took into account seasonal variables (autumn, spring), and the third was conducted in an environmental simulation chamber at the Museo Nacional de Ciencias Naturales (MNCN) in Madrid, to reproduce the Mediterranean environmental conditions of Israel.
In the third series, the variant “without skin” was introduced for comparison by chemical means of any differences in the preservation of nutrients in the marrow, between the metapodials exposed with skin and those exposed after skinning. “At a microbiological level, earlier experimental studies have shown that the bone cover and the skin furnish protection against microbes and bacteria following prolonged exposure of the bones", Blasco adds.
The results of these experimental series have enabled specific marks linked to the extraction of dry skin to be isolated, and have also established a slow rate of degradation of marrow fat until about the sixth week of exposure, from which moment the loss of nutrients starts to speed up.
“After the experimentation, we applied the data to the faunal remains from Qesem Cave, which shows a skeletal profile biased toward bones with high marrow content. Comparison of the experimental marks with the archaeological ones has allowed us to raise the possibility of a secondary processing and, therefore, the possible later consumption of marrow in the case of cervid metapodials”, she states.
This scenario suggests the emergence of new behaviors which demand a certain capacity for planning and foresight among Middle Pleistocene populations in the Middle East. The deliberate accumulation of metapodials implies an advance concern for future needs, and a capacity for "time displacement" which goes beyond the "here and now" as a form of subsistence.
The other collaborators on this paper were researchers from Tel-Aviv University (Israel), the IPHES and the Universitat Rovira i Virgili (Tarragona), the Universidad de Lleida (Lleida), the University of Bern (Switzerland), and the IREC.