2019-09-08 18:33:06 • ID: 2123
Artifact or Geofact- A continuing Dilemma
Figure 1-3: This is a delicate and thin Middle Paleolithic scraper with alternating retouches on a Levallois flake from Saint-Maixent-l'École, located in the Haut Val de Sèvre area of western France, about 64 km from La Rochelle.
The artifact shown here comes from a scatter with excellent products of Levallois origin, but other scatters nearby show an elaborated Quina System,too.
How do you know that this flint was made by Paleolithic men? - this is the most common question I heard during the last 40 years- from people without basic knowledge of lithic technology.
While Handaxes or Leaf-Points are normally recognized even by non-specialists immediately as artifacts made by humans, flake tools from the Lower and Middle Paleolithic are not so easily recognized as human work.
Even specialists in Paleolithic research sometimes have their trouble in their decision, whether a piece is an artifact or geofact. After more than 100 years of research the quantitative database is astonishing small, especially for non–retouched flakes and flakes, not made of flint, creating a a high degree of uncertainty.
This is one reason for a hypersceptic attitude of influential scientists when faced with probably very old artifacts from the Lower and early Middle Pleistocene in Central Europe.
Figure 4 is based on mainly qualitative data and proposes, that Human Percussive Fracture on Flint is usually characterized by:
- a Striking Platform
- a Point of Percussion
- a Bulb of Percussion
- Ripple Marks
- Specific modes of Distal Termination
For detailled description-see: https://peterborougharchaeology.org/archaeology-skills-techniques/identification-of-knapped-flints/ .
Please note that there is no strong consensus about the specificity of these diagnostic clues in the scientific Community.
It is important that each characteristic trait can either be stronger or weaker, depending for example on the raw material. Typical traits can be found on flint, homogeneous Obsidian and fine grained Quartzite. On the other hand they may be missing on limestone, Quartz or several volcanic stones (like Basalt).
Typical traits can be missed after secondary modifications - the bulb is sometimes removed, maybe for better hafting.
The presence and absence of characteristic clues depends on the knapping technique: For example hard hammer percussion tends to result in pronounced bulbs, whilst the use of soft hammers often results in either a small and discrete hemispherical bulb or one that is barely perceptible.
Last but not least, the presence of Diagnostic clues depends on the overarching technological system that was used (Discoidal, Levallois, Prismatic...).
On the other hand even laminar products can produced by natural forces in a high energy geological environment. This means, that we are talking not about certainties but about probabilities if a certain flake is a Geo– or an Artifact.
Lubinski and Terry used a comparative method for distinguishing flakes from geofacts by a Lithic debitage attribute scoring.
In their work, the probability of artifacts increased when there was a 1. Identifiable dorsal and ventral surface, 2. a Bulb of percussion, 3. a pronounced Bulb, 4. Eraillure scars, 5. Fissures, 6. Dorsal flake scar count of > n=3, 7. Dorsal flake scar orientation parallel to medial axis of the flake and the absence of any cortex, especially on the platform.
Regarding that we speak about the probability that a flake is an Artifact, it would be interesting to formalize the Attribute scoring approach further by ROC analysis and much more larger datasets for different raw materials.
The ROC (Receiver-Operator) curve analysis is a simple statistical tool, widely used for diagnostic tests in Medicine. To understand this approach it is useful to read the first external link. ROC curve analysis allows to create a complete sensitivity/specificity report.
In a ROC curve the true positive rate (Sensitivity; in this post true positives are possible artifacts) is plotted in function of the false positive rate (100-Specificity; in this post false positives are the rate of possible geofacts ) for different cut-off points of a parameter.
Each point on the ROC curve represents a sensitivity/specificity pair corresponding to a particular decision threshold. The area under the ROC curve (AUC) is a measure of how well a parameter can distinguish between two diagnostic groups (artifact/geofact).
The role of secondary Modifications: Artifacts are often characterized by secondary modifications. The most prominent feature on flake tools is the presence of a continuous retouche, which can be heardly found on Geofacts.
After 150 years of building a Paleolithic typology, the recognition of a specific tool class (a scraper, a denticulate...) also helps to differentiate between artifact and geofact.
Figure 5 for example is undoubtedly a typical Quina scraper, from the Type-site, underpinning the artificial nature of this piece of flint by the typical retouche, which is uncommon in Geofacts, although one important diagnostic clue for an artifact, a pronounced bulb on the dorsal side, is absent.
Style: Artifactual Modifications must exhibit a systematic shape, in other words they have to make "sense" for their user. A scraper needs a continuous retouche to fulfill its purpose and a denticulated tool needs a saw-like shape for a reasonable use.
Figure 6 and 7 shows a denticulated MSA-point from Erg Tit, with bilateral continuous denticulation, which makes "sense" within several contexts. In addition we see a clear bulb of percussion on the ventral side (Figure 7) and a facetted base (not shown here) suspicious for Levallois.
Bias: Older excavations and selective sampling of surface findings always carry the risk of Selection- and -Confirmation-Bias. These problems can be addressed by excavations, that capture the complete geological context of the finds, which have to be completely salvaged, without selection of artifact-like pieces during the field work . A Refitting approach in order to isolate artifacts from natural pieces is another successful strategy.
Depositional Environment: The depositional environment is mainly characterized by the energy implied from the sediments in which finds are embedded.
Specimens are often considered geofacts if found in dynamic, high- energy depositional environments that might have produced them naturally, such as talus cones at the base of cliffs in glacial till.
Flakes from local raw material are more suspicious for Geofacts, while the use of “exotic” raw material otherwise non-detectable in the site’s matrix is more suspicious for human agency.
Anyhow, the dilemma of separating Artifacts from Geofacts will remain as Pasda and Liebermann stated for a sample of unbiased material from Bilzingsleben:
Flint finds from the Middle Pleistocene travertine site at Bilzingsleben are revised. A discussion of the history of research in this context, and findings of recent excavations are presented.
These campaigns targeted the geological context and did not select artefacttype objects. This resulted in a twilight zone between certainly identified nonartefacts and artefact type exemplars, a zone which remains diffuse and resists qualitative, and thus also quantitative assessment.
Anyhow, in my opinion, this undeniable facts should not lead to a nihilist attitue, rather to an open mind of being ready for the new and unthinkable, for example the detection of ESA sites in Central Europe.
Lutz Fiedler recently published a paper about possible lithic industries dating back to 600 k- 1,2 Ma along the Rhine Rift Valley (last external link). I recommend reading this paper, because it provides the scientific rigor and strength that is necessary in the overheated discussion between the proponents of a "Long" or "Short" chronology.
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H. Floss et al: Steinartefakte: Vom Altpaläolithikum bis in die Neuzeit (Tübingen Publications in Prehistory); 2012
J. Hahn: Erkennen und Bestimmen von Stein- und Knochenartefakten. Einführung in die Artefaktmorphologie. ( = Archaeologica Venatoria, Bd. 10) (Archaeologica Venatoria); 1993
L Fiedler: Die Suche nach den kulturellen Anfängen. In: ders. (Hg.) Archäologie der ältesten Kultur in Deutschland. Materialien zur Vor- und Frühgeschichte von Hessen 18; 1997
I de la Torre : Omo revisited. Evaluating the technological skills of Pliocene hominids. Current Anthropology 45 439–465; 2004
N Goren-Inbar et al.: The Acheulian Site of Gesher Benot Ya‘aqov Volume IV: The Lithic Assemblages (Vertebrate Paleobiology and Paleoanthropology); 2018.
Figure 4: (Credit: José-Manuel Benito Álvarez / Wikimedia Commons)
Resources and images in full resolution:
- Image: 2019-09-08_maiq.jpg
- Image: 2019-09-08_maiy11.jpg
- Image: 2019-09-09_20190909_facett.jpg
- Image: 2019-09-09_Lithic_flake.png
- Image: 2019-09-11_quina_aggsbach_typsite.jpg
- Image: 2019-09-11_erg_tit.jpg
- Image: 2019-09-12_erg_tit2.jpg
- Extern Link: www.medcalc.org…roc-curves.php
- Extern Link: www.prehistoire.org…les-terrieres-fouille-paleolithique.html
- Extern Link: journals.openedition.org…3272?lang=en
- Extern Link: www.researchgate.net…266205355_Comparative_methods_for_distinguishing_flakes_from_geofacts_A_case_study_from_the_Wenas_Creek_Mammoth_site
- Extern Link: www.ag-evolutionsbiologie.net…vergessene-archaeologie.html
- Extern Link: www.mdpi.com…129