Insights from a tribological analysis of the tribulum
Résumé
Since the 1980s, ‘‘strange'' microwear traces were found to occur on flint blades from sites in the Near East from the late Neolithic and
occurring in great abundance by the Early Bronze Age. Although these were considered by archaeologists to be sickles because they had visible
gloss on their edges, their use-traces could not be reproduced in harvesting experiments carried out in the field. Subsequently, several lines of
evidence were used to study the blades, including not only direct observation of microscopic wear traces, but also Near Eastern cuneiform texts
from the third and second millennium BC describing agricultural instruments and analogy with ethnographic and experimental reference
material. We found that these tools and their traces best matched traces on flint used to arm the underside of a tribulum (threshing sledge)
for threshing grain and cutting straw. We built a replica of the tribulum described in cuneiform texts from the Bronze Age, using copies of
the Bronze Age blades, and used this instrument in experiments.
The publication of S. A. Semenov's work concerning traceology of ancient implements [S.A. Semenov, Prehistoric Technology (M.W.
Thompson, Trans.), Cory, Adams and Mackay, London, 1964] awakened considerable interest in the possibilities of directly inferring tool function
from the microscopic traces left by use on ancient implements. However, the goal and purpose of microwear studies is to reconstruct, as
completely as possible, the economic activities of prehistoric groups, requiring a methodology that embraces all aspects relevant to the interpretation
of microwear traces [L. Keeley, The methodology of microwear analysis : a comment on Nance. American Antiquity 39 (1974) 126-128].
In this study, we apply the science of tribology, which studies the friction and the wear of solid bodies in contact, to the threshing sledge and
its blades.
Tribological analysis of the tribulum has thus far provided new explanations for the formation of traces of wear on flint inserts in threshing
sledges, while also revealing features on a far smaller scale, involving the role of a film deposit. We determine the mechanisms by which the
tribulum threshes grain, and, particularly, fine-cuts straw from the sheaves of cereal laid on the threshing floor. The superior functioning of
the tribulum compared to other methods of threshing and cutting straw is due to its great control of the rheologyethe deformation and
floweof the straw layer on the threshing floor. The study lead to insights as to the mastery, of what may be considered today to be complex
tribological principles, in the Bronze Age and probably beginning in the Late Neolithic [P.C. Anderson, Observations on the threshing sledge
and its products in ancient and present-day Mesopotamia, in: P.C. Anderson, L.S. Cummings, T.K. Schippers, B. Simonel, (Eds.), Le traitement
des récoltes: un regard sur la diversitédu Néolithique au présent, ADPCA, Antibes, 2003, pp. 417-438].
occurring in great abundance by the Early Bronze Age. Although these were considered by archaeologists to be sickles because they had visible
gloss on their edges, their use-traces could not be reproduced in harvesting experiments carried out in the field. Subsequently, several lines of
evidence were used to study the blades, including not only direct observation of microscopic wear traces, but also Near Eastern cuneiform texts
from the third and second millennium BC describing agricultural instruments and analogy with ethnographic and experimental reference
material. We found that these tools and their traces best matched traces on flint used to arm the underside of a tribulum (threshing sledge)
for threshing grain and cutting straw. We built a replica of the tribulum described in cuneiform texts from the Bronze Age, using copies of
the Bronze Age blades, and used this instrument in experiments.
The publication of S. A. Semenov's work concerning traceology of ancient implements [S.A. Semenov, Prehistoric Technology (M.W.
Thompson, Trans.), Cory, Adams and Mackay, London, 1964] awakened considerable interest in the possibilities of directly inferring tool function
from the microscopic traces left by use on ancient implements. However, the goal and purpose of microwear studies is to reconstruct, as
completely as possible, the economic activities of prehistoric groups, requiring a methodology that embraces all aspects relevant to the interpretation
of microwear traces [L. Keeley, The methodology of microwear analysis : a comment on Nance. American Antiquity 39 (1974) 126-128].
In this study, we apply the science of tribology, which studies the friction and the wear of solid bodies in contact, to the threshing sledge and
its blades.
Tribological analysis of the tribulum has thus far provided new explanations for the formation of traces of wear on flint inserts in threshing
sledges, while also revealing features on a far smaller scale, involving the role of a film deposit. We determine the mechanisms by which the
tribulum threshes grain, and, particularly, fine-cuts straw from the sheaves of cereal laid on the threshing floor. The superior functioning of
the tribulum compared to other methods of threshing and cutting straw is due to its great control of the rheologyethe deformation and
floweof the straw layer on the threshing floor. The study lead to insights as to the mastery, of what may be considered today to be complex
tribological principles, in the Bronze Age and probably beginning in the Late Neolithic [P.C. Anderson, Observations on the threshing sledge
and its products in ancient and present-day Mesopotamia, in: P.C. Anderson, L.S. Cummings, T.K. Schippers, B. Simonel, (Eds.), Le traitement
des récoltes: un regard sur la diversitédu Néolithique au présent, ADPCA, Antibes, 2003, pp. 417-438].