Jul 12, 2023
Past human stone tool performance: experiments to test the influence of raw material variability and edge angle design on tool function
- Lisa Schunk1,2,
- Ivan Calandra2,3,
- Anja Cramer4,
- Walter Gneisinger2,
- Joao Marreiros2,5,6
- 1Institute of Archaeology, Faculty of Historical and Pedagogical Sciences, University of Wroclaw, Poland;
- 2TraCEr, Laboratory for Traceology and Controlled Experiments at MONREPOS Archaeological Research Centre and Museum for Human Behavioural Evolution, LEIZA, Neuwied, Germany;
- 3Imaging Lab, LEIZA;
- 4LEIZA, Leibniz-Zentrum für Archäologie. Mainz, Germany;
- 5Institute for Prehistoric and Protohistoric Archaeology, Johannes Gutenberg University, Mainz, Germany;
- 6ICArEHB, Interdisciplinary Center for Archaeology and Evolution of Human Behaviour, University of Algarve, Faro, Portugal
- TraCErMonreposLEIZA
Protocol Citation: Lisa Schunk, Ivan Calandra, Anja Cramer, Walter Gneisinger, Joao Marreiros 2023. Past human stone tool performance: experiments to test the influence of raw material variability and edge angle design on tool function. protocols.io https://dx.doi.org/10.17504/protocols.io.3byl4kr6ovo5/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
Created: April 23, 2021
Last Modified: July 12, 2023
Protocol Integer ID: 49365
Keywords: Controlled experiments, Keilmesser, tool durability, tool efficiency, edge angle, Middle Palaeolithic, Neanderthal technology, tool performance of late middle palaeolithic keilmesser, past human stone tool performance, edge angle design on tool function, late middle palaeolithic keilmesser, calculated edge angles from the analysed keilmesser, tool performance, edge angle values for the experimental standard sample, carving movement, unidirectional cutting, edge design, edge angle design, calculated edge angle, edge angle value, tool function, tool, edge angle, raw material variability, analysed keilmesser, stone, mechanical setup, experimental standard sample
Abstract
The goal of this sequential experiment was to test tool performance of Late Middle Palaeolithic Keilmesser by examining two relevant characteristics concerning their edge design: the raw material and the edge angle.
To do so, a controlled, mechanical setup was used. The samples and the contact material were standardised to limit the number of confounding factors. As tasks, unidirectional cutting and carving movements were performed. The edge angle values for the experimental standard samples were chosen to reflect the calculated edge angles from the analysed Keilmesser.
Protocol materials
Plurafac LF 901BTC Europe GmbH, Rheinpromenade 1, D-40789 MonheimCatalog #-
Modified bone-like polyurethaneSYNBONE®Catalog #PR0114
Isopropanol 70% Carl RothCatalog #CN09.4
Acetone ≥99.5 %Carl RothCatalog #5025.6
Technovit Provil Light regularKulzer GmbHCatalog #66009333
Documentation of the archaeological tools
The research question behind this here presented experiment is based on archaeological artefacts, so-called Keilmesser from the Late Middle Palaeoltihic. The artefacts are from the sites of Balver Höhle, the Upper site of Buhlen (both Germany) and Grotte de Ramioul (Belgium). For more information about the sites see the following (exemplary) references:
Citation
Citation
Citation
3D scanning
In total 175 N Keilmesser were analysed and scanned with an AICON smartScan-HE R8 from the manufacturer Hexagon (software version OptoCat 2018R1). The S-150 FOV (field of view) used has a point-to-point distance of 33 µm.
Equipment
smartScan-HE R8
NAME
3D structured light scanner
TYPE
AICON
BRAND
-
SKU
LINK
S-150 FOV, resolution of 33 µm
SPECIFICATIONS
Software
OptoCat
NAME
Hexagon Manufacturing Intelligence Software
DEVELOPER
The scanning settings are identical to the following protocol, and details can be found there:
The editing steps to create a closed 3D model are also the same as in the protocol mentioned above and were executed with GOM inspect, a free software for 3D measurement data.
Software
GOM Inspect
NAME
Hotfix 2, Rev. 111729, build 2018-08-22
OS
GOM
DEVELOPER
Edge angle calculation
The edge angle measurements on the 3D models of the Keilmesser were taken with 3D-EdgeAngle. For details about the method see (publication of the forthcoming paper):
For calculating the edge angles, the following parameters were applied:
- "2-lines" measuring procedure
- the length of the line was defined with 2 mm
- 10 mm as distance to the intersection
- only sections two to eight were used
Mean values were calculated in R, a free software and programming language for statistical computing and graphics.
Software
R Studio Desktop
NAME
The R Studio, Inc.
DEVELOPER
SOURCE LINK
See "analysis_EA_Keilmesser" within the following repository on GitHub:
Or in open access on Zenodo:
Sample preparation
Standardised tools
24 experimental standard samples were produced for the experiment:
6 x 35 ° Baltic flint sample
6 x 35 ° silicified schist sample
6 x 45 ° Baltic flint sample
6 x 45 ° silicified schist sample
Raw material
Baltic flint:
Southern Sweden (secondary deposit):
Silicified schist:
Balver Höhle
Buhlen
Note
In this experimental context, silicified schist is termed lydite. The experimental samples are labeled LYDITx-x (lydite in German = Lydit). Experimental flint samples are labeled FLTx-x. The first number identifies the nodule and the second number identifies the blade cut from the nodule.
Blanks
Raw material nodules/ blocks (step #2.1) were first cut into rectangular cuboids (blanks) of the following dimensions:
10 mm thickness
25 mm width
60 mm minimum length
Equipment
Goliath 450
NAME
Lapidary rock saw
TYPE
Steinschleifmaschinen & Lapidary tools Ltd.
BRAND
-
SKU
LINK
-
SPECIFICATIONS
a) cut 10 mm slices
Cutting slice (here: flint).
Cutting slice, with safety cover lifted for photo (here: flint).
Cut to provide level surface, photo with safety cover lifted (here: flint).
Slice, side view (here: flint).
Slice, top view (here: flint).
b) cut slices into blanks
Blank, top view (here: flint).
Blank, lateral view (here: flint).
Hardness measurement
The hardness of the blanks (step #2.2) was measured with a Leeb rebound hardness tester.
Equipment
Equotip 550
NAME
Portable hardness tester
TYPE
Proceq
BRAND
-
SKU
LINK
Leeb C probe
SPECIFICATIONS
The blanks were placed on a stable base of sufficient mass (here a polished granite slab of about 20 kg ). Since the samples did not fulfill the requirements for minimum sample size and weight, coupling paste was used between the sample and the base. Each blank was measured ten times to insure and test intra-blank variability.
Setup for measuring Leeb rebound hardness with the devices/components labeled.
Measuring Leeb rebound hardness.
Edge angle
One end of the blanks (step #2.2) was cut to produce samples with a 35 ° / 45 ° edge angle , with the following dimensions:
10 mm thickness
25 mm width
30 mm minimum length
Equipment
310 CP
NAME
Diamond band saw
TYPE
Exact
BRAND
-
SKU
LINK
Cutting the edge angle.
Positioning blank, close-up (here: flint).
Cutting the edge angle, close-up (here: flint).
Experimental standard sample without chamfered edge, view of side A (corresponding to the "dorsal" side of bifacial lithic artefact; here: flint).
Experimental standard sample without chamfered edge, view of side D (corresponding to the "lateral" side of bifacial lithic artefact; here: flint).
Chamfered edge
To avoid catastrophic breakage of the edge during experiments, the leading edge of the experimental standard samples (step #2.4) was chamfered to a 45 ° angle (see #2.6 for photos).
Equipment
310 CP
NAME
Diamond band saw
TYPE
Exact
BRAND
-
SKU
LINK
Cutting chamfered edge (here: flint).
The cut with the band saw left a small burr between the two adjacent surfaces at the edge of the chamfered surface and the lateral side D. This burr was manually removed with a diamond drill bit in a mini drill.
Coordinate system
Three ceramic beads were adhered onto each side of the cutting edge to provide a coordinate system on each side.
Final experimental standard sample with beads, view of side A (corresponding to the "dorsal" side of bifacial lithic artefact; here: flint).
Final experimental standard sample with beads, view of side C (corresponding to the "ventral" side of bifacial lithic artefact; here: flint).
For details, see:
Citation
LINK
Summary of the standard sample production
Standard sample production. The rock nodules (left; here Baltic flint) are cut into blanks (middle; step #2.2) with a Lapidary rock saw. A diamond band saw was used to cut the blank to create a typical standard sample with a defined edge angle (step #2.4) and a 45° chamfered edge (right, step #2.5). Highlighted are the three beads used as coordinate system (step #2.6).
Cleaning
100 mL Cleaning solution
1 Mass / % volume
Plurafac LF 901BTC Europe GmbH, Rheinpromenade 1, D-40789 MonheimCatalog #-
Equipment
Sonorex Digitec DT255H
NAME
Heated ultrasonic bath
TYPE
Bandelin
BRAND
-
SKU
LINK
4.5 L
SPECIFICATIONS
40 °C
00:05:00
5m
Contact material
Standardised contact material
Three synthetic bone platesModified bone-like polyurethaneSYNBONE®Catalog #PR0114 with the following dimensions were used as contact material:
250 mm length
250 mm width
6 mm thickness
75 % Shore hardness D (+/- 5)
Artificial bone plate.
Mechanical device
General settings
Linear unidirectional movements (cutting & carving): 2000 strokes split in 4 cycles .
The cycles are defined by the following number of strokes:
1 strokes to 50 strokes
51 strokes to 250 strokes
251 strokes to 1000 strokes
1001 strokes to 2000 strokes
Experimental setup
Equipment
SMARTTESTER
NAME
Modular material tester
TYPE
Inotec AP
BRAND
-
SKU
LINK
recorded values with the time stamps: - for each drive: position, speed, acceleration (+ deceleration) - penetration depth with distance sensor - apllied force with force sensor 1 (strain gauge sensor) - friction with force sensor 2 (strain gauge sensor)
SPECIFICATIONS
Linear movement from start point to end point:
5 kg dead weights (= ~ 50 N)
170 mm movement length
600 mm/s movement speed
4000 mm/s2 movement acceleration
10 Hz reading frequency (for each channel)
Experimental design.
Setup sample holder
The length of the spring of the sample holder was adjusted to compensate for the weight of the sample holder (without dead weights and sample).
Adjust the position of the upper end of the spring on the rail, so that:
- the sample holder almost touches the frame, and
- at the same time, there should be no pull from the spring onto the sample holder.
Zeroing sample holder.
Setup sample
The experimental standard sample (step #2) was clamped in the sample holder (SMARTTESTER) and manually oriented in all directions.
a) cutting movement
the active edge was parallel to the contact material and the blade is mounted perpendicular to it
(90 ° angle )
Sample FLT8-2 set up above bone plate, ready for the cutting experiment.
b) carving movement
the active edge was orientated in a flat angle towards the contact material (20 ° angle )
Sample LYDIT5-13 set up above bone plate, ready for the carving experiment.
Setup contact material
The bone plates (step #3) were clamped in a custom-made sample holder and fixed with a screw in the middle of the bone plate (see photos in step #5.2).
The plate was aligned with the X-axis.
Program cutting and carving movement
The program is identical for cutting and carving. For each sample, a new template was created (named with the sample ID and the stroke number).
a) Move down in Z-direction to start position
The z-value of the starting point was defined as follows: the sample holder on the z-drive was moved down slowly until the edge of the sample was in contact with the bone plate. 5 mm were added to the position of the z-drive in order to give the sample the possibility to penetrate into the bone plate without cutting through the 6mm-thick bone plate.
b) Move forward in X-direction 170 mm (linear movement)
c) Move up in Z-direction approx. 20 mm (above bone plate; no contact between contact material and sample)
d) Move backwards in X-direction to starting point
e) Loop 50 times over steps #5.4a-5.4d and export data to CSV
f) Loop 200 times over steps #5.4a-5.4d and export data to CSV
g) Loop 750 times over steps #5.4a-5.4d and export data to CSV
h) Loop 1000 times over steps #5.4a-5.4d and export data to CSV
The experiment was planned as a sequential experiment. The 2000 strokes were therefore split into four sequences (steps #5.4e-h). The experimental standard samples were documented after each sequence (step #6).
For each sequence, five CSV files were exported, one for each recorded channel:
- Penetration depth as measured by the distance sensor in the sample holder.
- Force applied (Z-direction) as measured by the force sensor in the sample holder.
- Friction as measured by the force sensor on the stage for the contact material.
- Position of the X-drive (travel range).
- Velocity of the X-drive.
Program as seen in the GUI. Blue = sensors, red = actuators (drives) and green = control flow elements.
Program for sample FLT8-1 as example:
FLT8-1_cutting_template.Smart Run program
Each sample was used for a duration of ~ 07:00:00 (= running time SMARTTESTER)
The following samples were used for the experiment:
Cutting 35° edge angle:
FLT8-4
FLT8-5
FLT8-6
LYDIT5-5
LYDIT5-6
LYDIT5-7
Cutting 45° edge angle:
FLT8-1
FLT8-2
FLT8-3
LYDIT5-2
LYDIT5-3
LYDIT5-4
Carving 35° edge angle:
FLT8-7
FLT8-8
FLT8-9
LYDIT5-11
LYDIT5-12
LYDIT5-13
Carving 45° edge angle:
FLT8-10
FLT8-11
FLT8-12
LYDIT5-8
LYDIT5-9
LYDIT5-10
7h
Documentation
Sample documentation
Before the experiment as well as after each cycle all 24 samples were documented in an identical way following these steps:
- cleaning with tap water and commercial washing up liquid
- weight measurement (threefold repetition)
Equipment
Kern PCB 3500.2
NAME
weighing scale
TYPE
Kern
BRAND
-
SKU
LINK
accuracy of 0.1g
SPECIFICATIONS
- 3D scanning of all samples (identical settings for all scans; step #1.1)
- based on the 3D models, the volume of each sample could be calculated
Equipment
smartScan-HE R8
NAME
3D structured light scanner
TYPE
AICON
BRAND
-
SKU
LINK
S-150 FOV, resolution of 33 µm
SPECIFICATIONS
- 3D scanning of the contact material (only before and after 2000 strokes)
Equipment
smartScan-HE R8
NAME
3D structured light scanner
TYPE
AICON
BRAND
-
SKU
LINK
M-450 FOV, resolution of 108 µm
SPECIFICATIONS
- optical documentation of three of the four surfaces per sample (one lateral and the two main surfaces)
Equipment
Smartzoom 5
NAME
digital microscope
TYPE
Zeiss
BRAND
-
SKU
LINK
PlanApo D 1.6x/0.10 objective; EDF-stitched images
SPECIFICATIONS
- cleaning the area of interest with a cotton bud with Isopropanol 70% Carl RothCatalog #CN09.4
- cleaning the area of interest with a cotton bud withAcetone ≥99.5 %Carl RothCatalog #5025.6
- moulding of the two main sample surfaces with
Technovit Provil Light regularKulzer GmbHCatalog #66009333
Moulding of one of the two surfaces (here: flint).
Data acquisition
After conducting the experiment and the final documentation of all experimental standard samples, further data was acquired:
- the edge angles of the samples
- the depth and width of the cuts and scratches on the artificial bone plate
Edge angle of the experimental standard samples
The 3D models (samples + contact material) were imported as STL files into GOM Inspect and existing mesh holes were closed. 3D models were edited as described in the previously mentioned protocol:
Software
GOM Inspect
NAME
Hotfix 2, Rev. 111729, build 2018-08-22
OS
GOM
DEVELOPER
Based on the closed models, the volume could be calculated.
Additionally, the edge angles of the samples after each cycle were calculated by means of GOM Inspect. To calculate the edge angle, 3D-EdgeAngle was applied again as for the archaeological artefacts (see step #1.2). Note that the parameters changed slightly ('3-points" instead of "2-lines" measuring procedure), since the "3-points" measuring procedure seems to be more suitable for simple morphologies as represented by the standard samples.
The following parameters were applied:
- "3-points" measuring procedure
- length of the line was defined with 2 mm
- as distance to the intersection the mean for distance three to six was calculated
- only sections two to eight were used
Penetration depth / dimensions of the grooves on the contact material
In addition, the contact material was documented with a Sensofar S-wide (Sensofar Metrology, Spain), a 3D optical metrology system. This way, the cuts and the scratches on the bone plate could be quantified.
Equipment
S wide
NAME
3D optical metrology system
TYPE
Sensofar
BRAND
-
SKU
LINK
- each bone plate was documented in four quadrants due to the limited travel range of the stage
Acquisition settings used with the Sensfar S-wide.
The data was processed in ConfoMap (a derivative of MountainsMap Imaging Topography developed by Digital Surf, Besançon, France; version ST 8.1.9286).
Software
ConfoMap (MountainsMap Imaging Tophography)
NAME
Digital Surf, Besançon, France
DEVELOPER
SOURCE LINK
In total, two templates were used:
a) "Patch surfaces of the bone plates acquired with the Sensofar S-wide"
An initial template was needed to patch the single quadrants together, so that the grooves are complete again. This involves levelling and aligning. Afterwards, each groove can be exported individually.
BP-I-TFE_S-wide_cutting_2000strokes_20210803_A-B.pdf b) "Processing on single grooves"
This template extracts the topography layer of the grooves and calculates a mean profile of a series of 30 profiles. After levelling the mean profiles, the height and the width of each groove can be calculated.
BP-I-TFE_S-wide_cutting_2000strokes_20210803_FLT8-1_45deg.pdf The ConfoMap templates for each surface in MNT and PDF formats are available in open access on Zenodo (https://doi.org/10.5281/zenodo.7565158). This also includes all original and processed surfaces.
Data analysis
Data analysis
The data acquired within the experiment was analysed in R.
Software
R Studio Desktop
NAME
The R Studio, Inc.
DEVELOPER
SOURCE LINK
The different datasets were split in separate analyses:
a) "analysis_HLC"
This R script imports and plots the Leeb rebound hardness data acquired on the experimental standard samples (see step #2.3).
b) "analysis_EA"
This R script deals with the calculated edge angles from the experimental standard samples (see step #7.1).
c) "analysis_ST.all_sensors"
These R scripts contain the analysis of the data acquired with the five sensors connected to the SMARTTESTER (see step #5.4). However, plots concern only the data from the penetration depth.
d) "analysis_S.wide"
These R scripts deal with the penetration depth of the experimental standard samples into the contact material. The penetration depth is already part of "analysis_ST.all_sensors", but was additionally calculated with a Sensofar S-wide (see step #7.2).
e) "analysis_VW"
This R script contains the volume and the weight measurements for all experimental standard samples from before and after the experiment (see step #6).
The entire repository with all R analyses can be found on GitHub:
and on Zenodo:
Citations
Step 1
K. Günther. Die altsteinzeitlichen Funde der Balver Höhle, Münster
Step 1
O. Jöris. Der spätmittelpaläolithische Fundplatz Buhlen (Grabungen 1966-69): Stratigraphie, Steinartefakte und Fauna des oberen Fundplatzes
Step 1
M. Ulrix-Closset. Le paleolithique moyen dans le bassin mosan en Belgique, Liege
Step 2.6
Calandra I, Schunk L, Rodriguez A, Gneisinger W, Pedergnana A, Paixao E, Pereira T, Iovita R & Marreiros J. Back to the edge: relative coordinate system for use-wear analysis
https://doi.org/10.1007/s12520-019-00801-y